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FEATURES
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LTC3562 I2C Quad Synchronous Step-Down DC/DC Regulator 2 x 600mA, 2 x 400mA DESCRIPTION
The LTC(R)3562 is a quad high efficiency monolithic synchronous step-down regulator with an I2C interface. Two regulators are externally adjustable and can have their feedback voltages programmed between 425mV and 800mV in 25mV steps (Type A). The other two regulators are fixed output regulators whose output voltages can be programmed between 600mV and 3.775V in 25mV steps (Type B). All four regulators operate independently and can be put into pulse skip, LDO, Burst Mode operation, or forced Burst Mode operation through I2C control. The Type-A regulators have separate RUN pins that can be enabled if I2C control is unavailable. The 2.85V to 5.5V input voltage range makes the LTC3562 ideally suited for single Li-Ion battery-powered applications. At low output load conditions, the regulators can be switched into LDO, Burst Mode operation, or forced Burst Mode operation, extending battery life in portable systems. The quiescent current drops to under 100A with all regulators in LDO mode, and under 0.1A when all regulators are shut down. Switching frequency is internally set to 2.25MHz, allowing the use of small surface mount inductors and capacitors. All regulators are internally compensated. The LTC3562 is available in a low profile 3mm x 3mm QFN package.
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Four Independent I2C Controllable Step-Down Regulators (2 x 600mA, 2 x 400mA) Two I2C Programmable Feedback Voltage Regulators (R600A, R400A): VFB 425mV to 800mV Two I2C Programmable Output Voltage Regulators (R600B, R400B): VOUT 600mV to 3.775V (R) Programmable Modes: Pulse Skip, LDO, Burst Mode, Forced Burst Mode Operation Quiescent Current < 100A (All Regulators Enabled in LDO Mode) Fixed 2.25MHz Switching Frequency (Pulse Skip Mode) Slew Limiting Reduces Switching Noise Power-On Reset Output for Regulator R600A Small, Thermally Enhanced, 20-Lead 3mm x 3mm QFN Package
APPLICATIONS
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Miscellaneous Handheld Applications with Multiple Supply Rails Personal Information Appliances Wireless and DSL Modems Digital Still Cameras MP3 Players Portable Instruments
TYPICAL APPLICATION
High Efficiency Quad Step-Down Converter with I2C
MICROPROCESSOR Li-Ion/Polymer 3.4V TO 4.2V
R600x Burst Mode Efficiency and Power Loss vs Load Current
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 VOUT = 1.2V, 1.8V, 2.5V VOUT = 3.3V 1 VIN = 3.8V 0.1 1 10 100 LOAD CURRENT (mA) 10
+
10F VIN SCL SDA DVCC POR600A SW600A FB600A RUN600A 499k 4.7H 10F SW400B SW600B OUT400B PGND AGND OUT600B
3562 TA01
100k 3.3H
VOUT 400A 1.5V 400mA
4.7H 10F 10pF 475k
RUN400A SW400A LTC3562
VOUT 600A 1.8V 600mA 634k
SDA SCL DVCC POR
VOUT = 3.3V VOUT = 2.5V VOUT = 1.8V VOUT = 1.2V
10000
1000 POWER LOSS (mW)
100
10pF
10F
FB400A 536k VOUT 400B 1.2V 400mA
3.3H
VOUT 600B 3.3V 10F 600mA
10 0 0.01
0.1 1000
3562 TA01b
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LTC3562 ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
PIN CONFIGURATION
TOP VIEW RUN600A VIN RUN400A 15 POR600A 14 FB600A 21 13 OUT600B 12 SW600B 11 PGND 6 SW400A 7 VIN 8 VIN 9 10 SW600A DVCC
VIN ............................................................... -0.3V to 6V RUN600A ...................................... -0.3V to (VIN + 0.3V) RUN400A ...................................... -0.3V to (VIN + 0.3V) FBx ............................................................... -0.3V to 6V SWx ............................................................. -0.3V to 6V OUTx ............................................................ -0.3V to 6V DVCC , POR600A, SDA, SCL ......................... -0.3V to 6V ISW400x (DC) ........................................................600mA ISW600x (DC) ........................................................850mA Operating Temperature (Note 2)...............-40C to 85C Storage Temperature Range...................-65C to 125C Junction Temperature (Note 3) ............................. 125C
SDA AGND 1 FB400A 2 OUT400B 3 SW400B 4 PGND 5
20 19 18 17 16
UD PACKAGE 20-LEAD (3mm x 3mm) PLASTIC QFN TJMAX = 125C, JA = 68C/W EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH LTC3562EUD#PBF TAPE AND REEL LTC3562EUD#TRPBF PART MARKING LCPV PACKAGE DESCRIPTION 20-Lead (3mm x 3mm) Plastic QFN TEMPERATURE RANGE -40C to 85C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C, VIN = 3.8V, unless otherwise noted.
PARAMETER VIN Input Voltage Range VIN Input Current (Per Regulator Enabled) Pulse Skip Mode, IOUT = 0 Burst Mode Operation, IOUT = 0 Forced Burst Mode Operation, IOUT = 0 LDO Mode, IOUT = 0 Shutdown Mode, IOUT = 0, DVCC = 1.8V All Regulators in Shutdown, DVCC = 0V
l l
ELECTRICAL CHARACTERISTICS
CONDITIONS
l
SCL
MIN 2.7
TYP 220 35 25 24 0.7 0.1
MAX 5.5 60 40 40 3 1 0.3
UNITS V A A A A A A V V A A % ms
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VIN Shutdown Current RUN600A, RUN400A Input High Threshold RUN600A, RUN400A Input Low Threshold RUN600A, RUN400A Input High Current RUN600A, RUN400A Input Low Current POR600A Threshold POR600A On-Resistance POR600A Delay
1.0 -1 -1 -8 16 231 40 1 1
RUNx = VIN RUNx = 0V Percentage of R600A's Final Output Voltage
2
LTC3562 ELECTRICAL CHARACTERISTICS
PARAMETER I2C Port DVCC Operating Voltage DVCC Operating Current DVCC UVLO Threshold Voltage VIL SDA, SCL (Low Level Input Voltage) VIH SDA, SCL (High Level Input Voltage) VOL SDA (Digital Output Low) Serial Port Timing (Note 4) tSCL tBUF tHD,STA tSU,STA tSU,STO tHD,DAT(OUT) tHD,DAT(IN) tSU,DAT tLOW tHIGH tf tr tSP Clock Operating Frequency Bus Free Time Between Stop and Start Conditions Hold Time After (Repeated) Start Condition Repeated Start Condition Setup Time Stop Condition Setup Time Data Hold Time Input Data Hold Time Data Setup Time Clock Low Period Clock High Period Clock Data Fall Time Clock Data Rise Time Spike Suppression Time 1.3 0.6 0.6 0.6 225 0 100 1.3 0.6 20 20 50 300 300 900 400 kHz s s s s ns ns ns s s ns ns ns IPULLUP = 3mA 0.7 * DVCC 0.08 DVCC = 1.8V, Serial Port Idle 1 0.3 * DVCC
l
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C, VIN = 3.8V, unless otherwise noted.
CONDITIONS MIN 1.5 TYP MAX 5.5 1 UNITS V A V V V V
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C, VIN = 3.8V, VOUTx = 1.5V, unless otherwise noted.
PARAMETER Regulators R600A, R400A, R600B, R400B fOSC Maximum Duty Cycle LDO Mode Closed Loop ROUT Regulators R600A, R600B PMOS Switch Current Limit PMOS RDS(ON) NMOS RDS(ON) LDO Mode Open Loop ROUT Available Output Current SW Pull-Down in Shutdown LDO Mode Forced Burst Mode LDO, VOUT = 1.2V Shutdown 75 50 Pulse Skip Mode 850 1200 0.38 0.38 2.2 140 2.5 1500 mA mA mA k Pulse Skip Mode LDO Mode 1.91 100 0.25 2.25 2.59 MHz % CONDITIONS MIN TYP MAX UNITS
BUCK DC/DC ELECTRICAL CHARACTERISTICS
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LTC3562 ELECTRICAL CHARACTERISTICS
PARAMETER Regulators R400A, R400B PMOS Switch Current Limit PMOS RDS(ON) NMOS RDS(ON) LDO Mode Open Loop ROUT SW Pull-Down in Shutdown Available Output Current Regulators R600A, R400A VFB(MAX) VFB(MIN) VFB(STEP) (0 to 15) IFB Regulators R600B, R400B VOUT(MIN) VOUT(MAX) VOUT(STEP) (0 to 127) VIN = 4V, DAC = 0000000, Pulse Skip Mode VIN = 4V, DAC = 1111111, Pulse Skip Mode VIN = 4V
l l
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C, VIN = 3.8V, VOUTx = 1.5V, unless otherwise noted.
CONDITIONS Pulse Skip Mode MIN 600 TYP 800 0.5 0.5 LDO Mode Shutdown Forced Burst Mode LDO Mode, VOUT = 1.2V DAC = XXX1111, Pulse Skip Mode DAC = XXX0000, Pulse Skip Mode FB Input Current DAC = XXX1111
l l
MAX 1000
UNITS mA k mA mA
3 2.5 50 50 0.776 0.412 100
0.800 0.425 25
0.824 0.438
V V mV
-50 0.582 3.661
0 0.600 3.775 25
50 0.618 3.889
nA V V mV
Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTC3562E is guaranteed to meet performance specifications from 0C to 85C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with statistical process control.
Note 3: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Overtemperature protection is active when junction temperature exceeds the maximum operating junction temperature. Continuous operation above the specified maximum operating junction temperature may result in device degradation or failure. Note 4: The serial port is tested at rated operating frequency. Timing parameters are tested and/or guaranteed by design.
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LTC3562 TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs Load Current
100 90 FORCED Burst Mode OPERATION 100 90 80 EFFICIENCY (%) EFFICIENCY (%) 600mA BUCKS 70 60 50 40 30 20 VIN = 3.8V VOUT = 1.2V 0.1 1 10 IOUT (mA) 100 1000
3562 G01
Efficiency vs Load Current
FORCED Burst Mode OPERATION 600mA BUCKS PULSE SKIP Burst Mode OPERATION 100 90 80 70 60 50 40 30 20 VIN = 3.8V VOUT = 1.8V 0.1 1 10 IOUT (mA) 100 1000
3562 G02
Efficiency vs Load Current
FORCED Burst Mode OPERATION 600mA BUCKS PULSE SKIP Burst Mode OPERATION
EFFICIENCY (%)
80 Burst Mode 70 OPERATION 60 50 40 30 20 10 0 0.01 PULSE SKIP
10 0 0.01
10 0 0.01 0.1 1 10 IOUT (mA)
VIN = 3.8V VOUT = 2.5V 100 1000
3562 G03
Efficiency vs Load Current
100 FORCED Burst Mode 90 OPERATION 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 0.01 0.1 1 10 IOUT (mA) VIN = 3.8V VOUT = 3.3V 100 1000
3562 G04
Efficiency vs Input Voltage Burst Mode Operation
100 90 600mA BUCKS EFFICIENCY (%) 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 2.5 IOUT = 0.1mA IOUT = 1mA IOUT = 10mA IOUT = 100mA IOUT = 400mA 3 4 4.5 3.5 INPUT VOLTAGE (V) 5 5.5 VOUT = 1.2V 100 90 80 70 60 50 40 30 20 10 0
Efficiency vs Input Voltage Burst Mode Operation
VOUT = 1.8V
PULSE SKIP Burst Mode OPERATION
IOUT = 0.1mA IOUT = 1mA IOUT = 10mA IOUT = 100mA IOUT = 400mA 2.5 3 4 4.5 3.5 INPUT VOLTAGE (V) 5 5.5
3562 G05
3562 G06
Output Transient Burst Mode Operation
VOUT400B 50mV/DIV AC COUPLED VOUT400A 50mV/DIV AC COUPLED 300mA IOUT400B 5mA 50s/DIV VOUT400B = 1.2V VOUT400A = 1.2V IOUT400A = 20mA
3562 G07
Output Transient Pulse Skip Mode
VOUT400B 50mV/DIV AC COUPLED VOUT600B 50mV/DIV AC COUPLED 300mA IOUT400B 5mA 50s/DIV VOUT400B = 1.8V VOUT600B = 1.2V IOUT600B = 15mA
3562 G08
Start-Up Transient Pulse Skip Mode
VOUT600A 500mV/DIV INDUCTOR CURRENT IL = 100mA/ DIV RUN600A OFF 2V/DIV ON 50s/DIV VOUT600A = 1.2V RLOAD = 6
3562 G09
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LTC3562 TYPICAL PERFORMANCE CHARACTERISTICS
R600A Feedback Voltage vs Temperature
0.810 0.808 0.806 0.804 VOLTAGE (mV) 0.802 0.800 0.798 0.796 0.794 0.792 0.790 -50 -25 25 50 0 TEMPERATURE (C) 75 100 fOSC (MHz) IOUT = 1mA 2.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5 -50 1.190 -25 25 50 0 TEMPERATURE (C) 75 100 0 100 300 400 200 LOAD CURRENT (mA) 500 600 VIN = 5.5V VIN = 3V VOLTAGE (V) VIN = 2.7V 1.210 PULSE SKIP 1.205 1.200 1.195 VIN = 3.8V
Oscillator Frequency vs Temperature
1.220 1.215
Output Voltage vs Load Current (B Version)
VIN = 3.8V VOUT = 1.2V (TYPE-B)
3562 G10
3562 G11
3562 G12
Dynamic Supply Current vs Input Voltage
45 IOUT = 0mA VOUT = 1.2V Burst Mode OPERATION IIN (A) 35 6 5 CURRENT (mA) 4 3 2 1 LDO MODE 20 2.7 3.1 3.5 0 3.9 4.3 4.7 VIN VOLTAGE (V) 5.1 5.5
Dynamic Supply Current vs Input Voltage
IOUT = 0mA CONTINUOUS OPERATION
Burst Mode Operation
VOUT600A 50mV/DIV AC COUPLED SW 2V/DIV INDUCTOR CURRENT IL = 100mA/ DIV 2s/DIV PVIN = 3.8V LOAD = 50mA
3562 G15
40
30 FORCED Burst Mode OPERATION
25
PULSE SKIP OPERATION 2 4.5 3.5 4 VOLTAGE (V) 400mA - VOUT = 1.2V 600mA - VOUT = 1.2V 400mA - VOUT = 1.8V 600mA - VOUT = 1.8V 2.5 3 5 5.5 6
3562 G14
3562 G13
400mA - VOUT = 2.5V 600mA - VOUT = 2.5V 400mA - VOUT = 3.3V 600mA - VOUT = 3.3V
Forced Burst Mode Operation
VOUT600A 50mV/DIV AC COUPLED SW 2V/DIV 1.22 1.21 1.20 1.19 VOLTAGE (V) 1.18 1.17 1.16 1.15 2s/DIV PVIN = 3.8V LOAD = 50mA
3562 G16
Output Voltage vs Load Current
700 FORCED Burst Mode OPERATION SWITCH RDS(ON) ()
Switch RDS(ON) vs Input Voltage
600 400mA PMOS 500 400 300 200 100 0 600mA NMOS
400mA NMOS 600mA PMOS
INDUCTOR CURRENT IL = 150mA/ DIV
LDO MODE
1.14 1.13 1.12 0 VIN = 3.8V VOUT = 1.2V (TYPE-B) 20 60 80 100 40 LOAD CURRENT (mA) 120 140
3562 G17
2.7
3.1
3.5
3.9 4.3 4.7 VIN VOLTAGE (V)
5.1
5.5
3562 G18
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LTC3562 PIN FUNCTIONS
AGND (Pin 1): Analog Ground Pin. All small-signal components should connect to this ground, which in turn connects to PGND at one point. FB400A (Pin 2): Feedback Pin for R400A. When the control loop is complete, this pin servos to 1 of 16 possible set-points based on the programmed value from the I2C serial port (see Table 4). OUT400B (Pin 3): Output Voltage Feedback Pin for R400B. An I2C programmable internal resistor divider divides the output voltage down for comparison to the internal reference voltage. This pin converges to 1 of 128 possible set-points based on the programmed value from the I2C serial port (see Tables 5 and 6). This node must be bypassed to GND with a 10F or greater ceramic capacitor. SW400B (Pin 4): Switch Node Connection to the Inductor for R400B. This pin connects to the drains of the internal power MOSFET switches of R400B. PGND (Pins 5, 11): Power Ground Pin. Connect this pin closely to the (-) terminal of CIN. SW400A (Pin 6): Switch Node Connection to the Inductor for R400A. This pin connects to the drains of the internal power MOSFET switches of R400A. VIN (Pins 7, 8, 9): Input Supply Pin. This pin must be closely decoupled to GND with a 10F or greater ceramic capacitor. SW600A (Pin 10): Switch Node Connection to the Inductor for R600A. This pin connects to the drains of the internal power MOSFET switches of R600A. SW600B (Pin 12): Switch Node Connection to the Inductor for R600B. This pin connects to the drains of the internal power MOSFET switches of R600B. OUT600B (Pin 13): Output Voltage Feedback Pin for R600B. An I2C programmable internal resistor divider divides the output voltage down for comparison to the internal reference voltage. This pin converges to 1 of 128 possible set-points based on the programmed value from the I2C serial port (see Tables 5 and 6). This node must be bypassed to GND with a 10F or greater ceramic capacitor. FB600A (Pin 14): Feedback Pin for R600A. When the control loop is complete, this pin servos to 1 of 16 possible set-points based on the programmed value from the I2C serial port (see Table 4). POR600A (Pin 15): Power-On Reset for R600A. This opendrain output goes high impedance after a 230ms delay after the output of R600A reaches 92% of its regulation voltage. This output gets pulled to GND whenever R600A falls below 92% of its regulation voltage. RUN400A (Pin 16): Enable Pin for R400A, Active High. Apply a voltage greater than 1V to enable this regulator. RUN600A (Pin 17): Enable Pin for R600A, Active Low. Apply a voltage less than 0.3V to enable this regulator. DVCC (Pin 18): Supply Voltage for I2C Lines. This pin sets the logic reference level of the LTC3562. A UVLO circuit on the DVCC pin forces all registers to a default setting whenever DVCC is < 1V. Bypass to GND with a 0.1F capacitor. SCL (Pin 19): I2C Clock Input. Serial data is shifted one bit per clock to control the LTC3562. The logic level for SCL is referenced to DVCC. SDA (Pin 20): I2C Data Input. The logic level for SDA is referenced to DVCC. Exposed Pad (Pin 21): Ground. Must be soldered to PCB ground for electrical contact and optimum thermal performance.
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LTC3562 BLOCK DIAGRAM
17 18 20 19 16
DVCC SDA SCL
DVCC SDA I
2C
RUN600A EN
4 1 1
RUN400A
VIN 7, 8, 9
SCL MODE DATA
2 7 4
R600A REF600A EN 0.425V-0.8V REF MODE FB FB600A
14
D/A
SW600A
10
R400A
4
D/A
REF400A EN 0.425V-0.8V REF MODE FB FB400A
2
SW400A
6
1
AGND
1
R600B
EN 0.6V REF
SW600B OUT600B
12 13
MODE
7
FB
R400B
1
EN 0.6V REF
SW400B OUT400B
4 3
MODE
15
FB
POR600A 230ms Delay POWER GOOD R600A
7
PGND 5,11
3562 BD
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LTC3562 OPERATION
Introduction The LTC3562 is a highly integrated power management IC that contains four I2C controllable, monolithic, high efficiency step-down regulators. Two regulators provide up to 600mA of output current and the other two regulators produce up to 400mA. All four regulators are 2.25MHz, constant-frequency, current mode switching regulators that can be independently controlled through I2C. All regulators are internally compensated eliminating the need for external compensation components. The LTC3562 offers two different types of adjustable step-down regulators. The two Type-A regulators (R600A, R400A) can have the feedback voltages adjusted through I2C from 425mV to 800mV in 25mV increments. The two Type-B regulators (R600B, R400B) can have the output voltages adjusted through I2C control from 600mV to 3.775V in 25mV increments. All four converters support 100% duty cycle operation (low dropout mode) when their input voltage drops very close to their output voltage. To suit a variety of applications, four selectable mode functions are available on the LTC3562's step-down regulators to trade-off noise for efficiency. At moderate to heavy loads, the constant-frequency pulse skip mode provides the lowest output switching noise solution. At lighter loads, either Burst Mode operation, forced Burst Mode operation or LDO mode may be selected to optimize efficiency. The switching regulators also include soft-start to limit inrush current when powering on, shortcircuit current protection, and switch node slew limiting circuitry to reduce radiated EMI. No external compensation components are required. VFB Adjustable (Type-A) Regulators The two Type-A step-down regulators (R600A and R400A) have individual programmable feedback servo voltages via I2C control. Given a particular feedback servo voltage, the output voltage is programmed using a resistor divider from the switching regulator output connected to the feedback pins (Figure 1). The output voltage is related to the feedback servo voltage by the following equation: R1 VOUTxA = VFBxA +1 R2 Through I2C control, VFBxA can be programmed from 800mV (full scale) down to 425mV in 25mV increments. When the RUN pins (RUN600A and RUN400A) are used to activate these regulators, the default feedback servo voltage is set to 800mV.
LTC3562 SWxA CFB FBxA 425mV to 800mV GND
3562 F01
L R1 CO
R2
Figure 1. Type-A Regulator Application Circuit
Typical values for R2 are in the range of 40k to 1M. The capacitor CFB cancels the pole created by the feedback resistors and the input capacitance of the FB pin and also helps to improve transient response for output voltages much greater than 0.8V. A variety of capacitor sizes can be used for CFB but a value of 10pF is recommended for most applications. Experimentation with capacitor sizes between 2pF and 22pF may yield improved transient response. Regulators R600A and R400A have individual RUN pins that can enable the regulators without accessing the I2C port. The RUN600A and RUN400A pins are OR'ed with the enable signals coming from the I2C port (refer to the Block Diagram) such that regulators R600A and R400A can be enabled if the I2C port is unavailable. The RUN600A pin is active low and the RUN400A pin is active high. When the RUN pins are activated, the Type-A regulators are enabled in a default setting. The default mode for the regulators is pulse skip mode and the default feedback servo voltage setting is 800mV. Once enabled with these default settings, the settings can always be changed on the fly through I2C once the I2C terminal is available. The maximum operating output current of regulators R600A and R400A are 600mA and 400mA, respectively.
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LTC3562 OPERATION
VOUT Adjustable (Type-B) Regulators Unlike the Type-A regulators, the two Type-B regulators do not require an external resistor divider network to program its output voltage. Regulators R600B and R400B have feedback resistor networks internal to the chip whose values can be adjusted through I2C control. These internal feedback resistors can be configured such that the output voltages can be programmed directly. The output voltages can be programmed from 600mV to 3.775V in 25mV increments. Pins OUT600B and OUT400B are feedback sense pins that connect to the top of the internal resistor divider networks. These output pins should sense the output voltages of the regulators right at the output capacitor CO (after the inductor), as illustrated in Figure 2. The maximum operating current for regulators R600B and R400B are 600mA and 400mA, respectively. The Type-B regulators do not have individual run pins as do the Type-A regulators. Thus regulators R600B and R400B can only be enabled through control of the I2C port. When the part initially powers up, the Type-B regulators default to shutdown mode and remain disabled until programmed through I2C. Regulator Operating Modes All of the LTC3562's switching regulators include four possible operating modes to meet the noise/power needs of a variety of applications. In pulse skip mode, an internal latch is set at the start of every cycle which turns on the main P-channel MOSFET switch. During each cycle, a current comparator compares
LTC3562 L SWxB CO OUTxB 600mV to 3.775V
the peak inductor current to the output of an error amplifier. The output of the current comparator resets the internal latch which causes the main P-channel MOSFET switch to turn off and the N-channel MOSFET synchronous rectifier to turn on. The N-channel MOSFET synchronous rectifier turns off at the end of the 2.25MHz cycle or if the current through the N-channel MOSFET synchronous rectifier drops to zero. Using this method of operation, the error amplifier adjusts the peak inductor current to deliver the required output power. All necessary compensation is internal to the switching regulator requiring only a single ceramic output capacitor for stability. At light loads in pulse skip mode, the inductor current may reach zero on each pulse which will turn off the N-channel MOSFET synchronous rectifier. In this case, the switch node (SW) goes high impedance and the switch node voltage will "ring." This is discontinuous mode operation, and is normal behavior for a switching regulator. At very light loads in pulse skip mode, the switching regulators will automatically skip pulses as needed to maintain output regulation. At high duty cycle (VOUT > VIN/2) it is possible for the inductor current to reverse at light loads, causing the step-down switching regulator to operate continuously. When operating continuously, regulation and low noise output voltage are maintained, but input operating current will increase to a couple mA. In forced Burst Mode operation, the switching regulators use a constant-current algorithm to control the inductor current. By controlling the inductor current directly and using a hysteretic control loop, both noise and switching losses are minimized. In this mode output power is limited. While operating in forced Burst Mode operation,
GND
3562 F02
Figure 2. Type-B Regular Application Circuit
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LTC3562 OPERATION
the output capacitor is charged to a voltage slightly higher than the regulation point. The step-down converter then goes into sleep mode, during which the output capacitor provides the load current. In sleep mode, most of the regulator's circuitry is powered down, helping conserve battery power and increase efficiency. When the output voltage drops below a predetermined value, the switching regulator circuitry is powered on and another burst cycle begins. The duration for which the regulator operates in sleep mode depends on the load current. The sleep time decreases as the load current increases. Forced Burst Mode operation has a maximum deliverable output current of about 140mA for the 600mA regulators and 100mA for the 400mA regulators. Beyond the maximum deliverable output current, the step-down switching regulator will not enter sleep mode and the output will drop out of regulation. Forced Burst Mode operation provides a significant improvement in efficiency at light loads at the expense of higher output ripple when compared to pulse skip mode. For many noise-sensitive systems, forced Burst Mode operation might be undesirable at certain times (i.e., during a transmit or receive cycle of a wireless device), but highly desirable at others (i.e., when the device is in low power standby mode). The I2C port can be used to enable or disable forced Burst Mode operation at any time, offering both low noise and low power operation when they are needed. In Burst Mode operation, the switching regulator automatically switches between fixed frequency pulse skip operation and hysteretic control as a function of the load current. At light loads the regulators operate in hysteretic mode and at heavy loads they operate in constant-frequency mode. The constant-frequency mode provides the same output ripple and efficiency as pulse skip mode while hysteretic mode provides slightly lower output ripple than forced Burst Mode operation at the expense of slightly lower efficiency. Finally, the switching regulators have an LDO mode that gives a DC option for regulating their output voltages. In LDO mode, the switching regulators are converted to linear regulators and deliver continuous power from their SWx pins through their respective inductors. This mode gives the lowest possible output noise as well as low quiescent current at light loads. Dropout Operation It is possible for VIN to approach a switching regulator's programmed output voltage (e.g., a battery voltage of 3.4V with a programmed output voltage of 3.3V). When this happens, the PMOS switch duty cycle increases until it is turned on continuously at 100%. In this dropout condition, the respective output voltage equals the regulator's input voltage minus the voltage drops across the internal P-channel MOSFET and the inductor. Soft-Start Operation Soft-start is accomplished by gradually increasing the peak inductor current for each switching regulator over a 500s period. This allows each output to rise slowly, helping minimize the battery in-rush current. A softstart cycle occurs whenever a given switching regulator is enabled, or after a fault condition has occurred (thermal shutdown). A soft-start cycle is not triggered by changing operating modes. This allows seamless output operation when transitioning between Burst Mode operation, forced Burst Mode operation, pulse skip mode or LDO mode. Switching Slew Rate Control The step-down switching regulators contain new patent pending circuitry to limit the slew rate of the switch node (SWx). This new circuitry is designed to transition the switch node over a period of a couple nanoseconds, significantly reducing radiated EMI and conducted supply noise, while keeping efficiency high. Step-Down Switching Regulator in Shutdown The step-down switching regulators are in shutdown when not enabled for operation. In shutdown, all circuitry in the step-down switching regulator is disconnected from the switching regulator input supply, leaving only a few nano-amps of leakage current. The step-down switching regulator outputs are individually pulled to ground through a 2k resistor on the switch pin (SWx) when in shutdown.
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LTC3562 OPERATION
I2C Interface The LTC3562 may communicate with a host (master) using the standard I2C 2-wire interface. The Timing Diagram in Figure 4 shows the timing relationship of the signals on the bus. The two bus lines, SDA and SCL, must be high when the bus is not in use. External pull-up resistors or current sources, such as the LTC1694 SMBus Accelerator, are required on these lines. The LTC3562 is a receive-only (slave) device. The I2C control signals, SDA and SCL are scaled internally to the DVCC supply. DVCC should be connected to the same power supply as the microcontroller generating the I2C signals. The I2C port has an undervoltage lockout on the DVCC pin. When DVCC is below approximately 1V, the I2C serial port is cleared and the two switching Type-A regulators are set to full scale. Bus Speed The I2C port is designed to be operated at speeds of up to 400kHz. It has built-in timing delays to ensure correct operation when addressed from an I2C compliant master device. It also contains input filters designed to suppress glitches should the bus become corrupted. START and STOP Conditions A bus master signals the beginning of a communication to a slave device by transmitting a start condition. A start condition is generated by transitioning SDA from high to low while SCL is high. When the master has finished communicating with the slave, it issues a stop condition by transitioning SDA from low to high while SCL is high. The bus is then free for communication with another I2C device. Byte Format Each byte sent to the LTC3562 must be 8 bits long followed by an extra clock cycle for the Acknowledge bit to be returned by the LTC3562. The data should be sent to the LTC3562 most significant bit (MSB) first. Acknowledge The Acknowledge signal is used for handshaking between the master and the slave. An Acknowledge (active LOW) generated by the slave (LTC3562) lets the master know that the latest byte of information was received. The Acknowledge-related clock pulse is generated by the master. The master releases the SDA line (HIGH) during the Acknowledge clock cycle. The slave-receiver must pull down the SDA line during the Acknowledge clock pulse so that it remains a stable low during the high period of this clock pulse. Slave Address Byte The LTC3562 responds to only one 7-bit address which has been factory programmed to 11001010. The eighth bit of the address byte (R/W) must be 0 for the LTC3562 to recognize the address since it is a write-only device. This effectively forces the address to be 8 bits long where the least significant bit of the address is 0. If the correct 7-bit address is given but the R/W bit is 1, the LTC3562 will not respond. Sub-Address Byte The sub-address byte uses bits A7 through A4 to specify the regulator(s) being programmed by that particular three-byte sequence (refer to Table 2). A specific regulator gets programmed if its corresponding sub-address bit is high, whereas the regulator ignores the 3-byte sequence if its sub-address bit is low. Note that multiple regulators can be programmed by the same 3-byte sequence if more than one of the sub-address bits are high. Bits A1 and A0 of the sub-address byte are used to program the operating mode (Table 3). Bits A3 and A2 of the sub-address byte are not used. Data Byte The data byte only affects the regulators that are specified to be programmed by the sub-address byte. The MSB of the data byte (B7) is used to enable or disable the regulator(s) being programmed. A high B7 indicates an enable command, whereas a low B7 indicates a shutdown command.
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LTC3562 OPERATION
SUB-ADDRESS ADDRESS 1 START SDA 1 1 0 0 1 0 1 0 ACK A7 A6 A5 A4 A3 A2 A1 A0 ACK 7 1 6 2 5 3 4 4 3 5 2 6 1 7 0 8 ACK 1 0 0 1 0 1 WR 0 A7 A6 A5 A4 A3 A2 A1 A0 B7 B6 B5 B4 B3 B2 B1 B0 STOP DATA BYTE
SCL
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
9
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Figure 3. Bit Assignments
SDA tSU, DAT tLOW SCL tHD, STA START CONDITION tr tHIGH tf REPEATED START CONDITION tSP STOP CONDITION START CONDITION tHD, DAT tSU, STA tHD, STA tBUF tSU, STO
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Figure 4. Timing Parameters
Table 1. Write Word Protocol Used by the LTC3562
1 S 7 Slave Address 1 WR 1 A 8 *Sub-Address 1 A 8 Data Byte 1 A 1 P**
S = Start Condition, WR = Write Bit = 0, A = Acknowledge, P = Stop Condition * The sub-address uses only the first four most significant bits, A7, A6, A5, and A4, for sub-addressing. The two least significant bits, A1 and A0, are used to program the regulator operating mode. **Stop can be delayed until all of the data registers have been written.
Table 2. Sub-Address and Data Byte Mapping
SUB-ADDRESS BYTE A7 PROGRAM R600A A6 PROGRAM R400A A5 PROGRAM R600B A4 PROGRAM R400B A3 A2 A1 A0 B7 B6 B5 NOT USED ENABLE REGULATOR OPERATING REGULATOR MODE (SEE TABLE 3) DATA BYTE B4 B3 B2 B1 B0 DAC CODE (See Tables 4, 5 and 6)
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LTC3562 OPERATION
If a Type-A regulator is being programmed, then bits B3 through B0 program the DAC that controls the regulator's feedback servo voltage. This 4-bit sequence programs the feedback voltage from 425mV to 800mV in 25mV increments (Table 4). Bits B6 through B4 are not used when programming a Type-A regulator. If a Type-B regulator is being programmed, then bits B6 through B0 program the DAC that controls the regulator's output voltage. This 7-bit sequence programs the output voltage from 600mV to 3.775V in 25mV increments (Tables 5 and 6). Bus Write Operation The master initiates communication with the LTC3562 with a start condition and a 7-bit address followed by the write bit R/W = 0. If the address matches that of the LTC3562, the LTC3562 returns an Acknowledge. The master should then deliver the sub-address byte for the regulator(s) being programmed. Again the LTC3562 acknowledges and then the data byte is delivered starting with the most significant bit. The data byte and the two mode bits in the sub-address byte are transferred to an internal holding latch for each programmed regulator upon the return of an Acknowledge. After the sub-address byte and data byte have been transferred to the LTC3562, the master may terminate the communication with a stop condition. Alternatively, a repeat-start condition can be initiated by the master and the entire sequence can be repeated, this time accessing a different sub-address code to program another regulator. Likewise, the master can also initiate a Repeat-Start so that another chip on the I2C bus can be addressed. This cycle can continue indefinitely and the LTC3562's regulators will remember the last input of valid data that it received. Once all chips on the bus have been addressed and sent valid data, a global stop condition can be sent and the LTC3562 will update its regulators with the data that it had received. In certain circumstances the data on the I2C bus may become corrupted. In these cases the LTC3562 responds appropriately by preserving only the last set of complete data that it has received. For example, assume the LTC3562 has been successfully addressed and is receiving data when a stop condition mistakenly occurs. The LTC3562 will ignore this stop condition and will not respond until a new start condition, correct address, new set of data and stop condition are transmitted. Likewise, with only one exception, if the LTC3562 was previously addressed and sent valid data but not updated with a Stop, it will respond to any Stop that appears on the bus, independent of the number of Repeat-Starts that have occurred. If a Repeat-Start is given and the LTC3562 successfully acknowledges its address, it will not respond to a Stop until all three bytes of the new data have been received and acknowledged. I2C Examples To program R600A in forced Burst Mode operation with its feedback servo voltage set to 600mV: Sub-Address Byte - 1000XX10 Data Byte - 1XXX0111 To program R600B and R400B in LDO mode with their output voltages set to 1.250V: Sub-Address Byte - 0011XX01 Data Byte - 10011010 To put the entire chip in shutdown and disable all regulators: Sub-Address Byte - 1111XXXX Data Byte - 0XXXXXXX Disabling the I2C Port The I2C serial port can be disabled by grounding the DVCC pin. In this mode, regulators R600A and R400A can only be activated through the individual logic input pins RUN600A and RUN400A. Disabling the I2C port also resets the feedback servo voltages to the default setting of 0.8V. Note that if the I2C port gets disabled while a Type-A regulator is enabled and its RUN pin is activated, the regulator will remain enabled and its feedback voltage will immediately be reset to the default setting of 0.8V. If the I2C port gets disabled and the RUN pins are not activated, then the regulators will immediately go into shutdown mode. Since regulators R600B and R400B do not have RUN pins, they immediately go into shutdown once the I2C port gets disabled.
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LTC3562 OPERATION
Table 3. Regulator Operating Modes
A1 0 0 1 1 A0 0 1 0 1 REGULATOR MODE Pulse Skip Mode LDO Mode Forced Burst Mode Operation Burst Mode Operation B6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 B5 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 B4 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 B3 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 B2 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1
Table 5. Type-B Regulator Base Output Voltage Programming
TYPE-B REGULATOR BASE OUTPUT VOLTAGE 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400 1.500 1.600 1.700 1.800 1.900 2.000 2.100 2.200 2.300 2.400 2.500 2.600 2.700 2.800 2.900 3.000 3.100 3.200 3.300 3.400 3.500 3.600 3.700
Table 4. Type-A Regulator Servo Voltage Programming
B3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 B2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 B1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 B0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 TYPE-A REGULATOR SERVO (FEEDBACK) VOLTAGE 0.425 0.450 0.475 0.500 0.525 0.550 0.575 0.600 0.625 0.650 0.675 0.700 0.725 0.750 0.775 0.800
POR600A Pin The POR600A pin is an open-drain output used to indicate that regulator R600A has been enabled and has reached its final voltage. POR600A remains low impedance until regulator R600A reaches 92% of its regulation value. A 230ms delay is included to allow a system microcontroller ample time to reset itself. POR600A may be used as a power on reset to the microprocessor powered by regulator R600A or may be used to enable regulator R400A for supply sequencing. POR600A is an open drain output and requires a pull-up resistor to the output voltage of regulator R600A or another appropriate power source.
Table 6. Type-B Regulator Incremental Output Voltage Programming
B1 0 0 1 1 B0 0 1 0 1 TYPE-B REGULATOR INCREMENTAL OUTPUT VOLTAGE +0.000 +0.025 +0.050 +0.075
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LTC3562 APPLICATIONS INFORMATION
Inductor Selection Many different sizes and shapes of inductors are available from numerous manufacturers. Choosing the right inductor from such a large selection of devices can be overwhelming, but following a few basic guidelines will make the selection process much simpler. The step-down converters are designed to work with inductors in the range of 2.2H to 10H. For most applications a 4.7H inductor is suggested for the lower power switching regulators R400A and R400B and 3.3H is recommended for the more powerful switching regulators R600A and R600B. Larger value inductors reduce ripple current which improves output ripple voltage. Lower value inductors result in higher ripple current and improved transient response time, but will reduce the available output current. To maximize efficiency, choose an inductor with a low DC resistance. For a 1.2V output, efficiency is reduced about 2% for 100m series resist-ance at 400mA load current, and about 2% for 300m series resistance at 100mA load current. Choose an inductor with a DC current rating at least 1.5 times larger than the maximum load current to ensure that the inductor does not saturate during normal operation. If output short circuit is a possible condition, the inductor should be rated to handle the maximum peak current specified for the step-down converters. Different core materials and shapes will change the size/current and price/current relationship of an inductor. Toroid or shielded pot cores in ferrite or PermalloyTM materials are small and do not radiate much energy, but generally cost more than powdered iron core inductors with similar electrical characteristics. Inductors that are very thin or have a very small volume typically have much higher core and DCR losses, and will not give the best efficiency. The choice of which style inductor to use often depends more on the price versus size, performance, and any radiated EMI requirements than on what the LTC3562 requires to operate. The inductor value also has an effect on Burst Mode and forced Burst Mode operations. Lower inductor values will cause the Burst Mode and forced Burst Mode switching frequencies to increase. Table 7 shows several inductors that work well with the LTC3562's general purpose regulators. These inductors offer a good compromise in current rating, DCR and physical size. Consult each manufacturer for detailed information on their entire selection of inductors.
Table 7. Recommended Inductors
INDUCTOR L TYPE (H) DB318C D312C DE2812C DE2818C 4.7 3.3 4.7 3.3 4.7 3.3 4.7 3.3 MAX IDC (A) 1.07 1.20 0.79 0.90 1.15 1.37 1.25 1.45 0.9 1.1 0.5 0.6 0.75 1.3 1.59 0.8 0.97 1.29 1.42 1.08 1.31 1.1 1.3 MAX DCR () 0.1 0.07 0.24 0.20 0.13* 0.105* 0.072* 0.052* 0.11 0.085 0.17 0.123 0.19 0.162 0.113 0.246 0.165 0.117* 0.104* 0.153* 0.108* 0.2 0.13 SIZE (mm) (L x W x H) 3.8 x 3.8 x 1.8 3.8 x 3.8 x 1.8 3.6 x 3.6 x 1.2 3.6 x 3.6 x 1.2 3.0 x 2.8 x 1.2 3.0 x 2.8 x 1.2 3.0 x 2.8 x 1.8 3.0 x 2.8 x 1.8 4 x 4 x 1.8 4 x 4 x 1.8 3.2 x 3.2 x 1.2 3.2 x 3.2 x 1.2 4.9 x 4.9 x 1
MANUFACTURER Toko www.toko.com
CDRH3D16 4.7 3.3 CDRH2D11 4.7 3.3 CLS4D09 4.7 SD3118 SD3112 SD12 SD10 LPS3015 4.7 3.3 4.7 3.3 4.7 3.3 4.7 3.3 4.7 3.3
Sumida www.sumida.com
3.1 x 3.1 x 1.8 Cooper 3.1 x 3.1 x 1.8 www.cooperet.com 3.1 x 3.1 x 1.2 3.1 x 3.1 x 1.2 5.2 x 5.2 x 1.2 5.2 x 5.2 x 1.2 5.2 x 5.2 x 1.0 5.2 x 5.2 x 1.0 3.0 x 3.0 x 1.5 Coil Craft 3.0 x 3.0 x 1.5 www.coilcraft.com
* Typical DCR
Input/Output Capacitor Selection Low ESR (equivalent series resistance) ceramic capacitors should be used at the switching regulator outputs as well as the input supply. Only X5R or X7R ceramic capacitors should be used because they retain their capacitance over wider voltage and temperature ranges than other ceramic types. A 10F output capacitor is sufficient for most applications. For good transient response and stability the output capacitor should retain at least 4F of capacitance over operating temperature and bias voltage. The input supply should be bypassed with a 10F capacitor, or greater. Consult with capacitor manufacturers for detailed information on their selection and specifications of ceramic capacitors. Many manufacturers now offer
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LTC3562 APPLICATIONS INFORMATION
very thin (<1mm tall) ceramic capacitors ideal for use in height-restricted designs. Table 8 shows a list of several ceramic capacitor manufacturers.
Table 8. Recommended Ceramic Capacitor Manufacturers
AVX Murata Taiyo Yuden Vishay Siliconix TDK www.avxcorp.com www.murata.com www.t-yuden.com www.vishay.com www.tdk.com
result in higher thermal resistances. Furthermore, due to its high frequency switching circuitry, it is imperative that the input capacitors, inductors, and output capacitors be as close to the LTC3562 as possible and that there be an unbroken ground plane under the LTC3562 and all of its external high frequency components. High frequency currents on the LTC3562 tend to find their way along the ground plane in a myriad of paths ranging from directly back to a mirror path beneath the incident path on the top of the board. If there are slits or cuts in the ground plane due to other traces on that layer, the current will be forced to go around the slits. If high frequency currents are not allowed to flow back through their natural least-area path, excessive voltage will build up and radiated emissions will occur. There should be a group of vias directly under the grounded backside of the package leading directly down to an internal ground plane. To minimize parasitic inductance, the ground plane should be on the second layer of the PC board.
Printed Circuit Board Layout Considerations To deliver maximum current under all conditions, it is critical that the exposed metal pad on the backside of the LTC3562 package be soldered to the PC board ground. Correctly soldered to a 2500mm2 double-sided 1oz. copper board, the LTC3562 has a thermal resistance of less than 68C/W. Failure to make thermal contact between the exposed pad on the backside of the package and the copper board will
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Figure 5. High Frequency Ground Currents Follow Their Incident Path. Slices in the Ground Cause High Voltage and Increased Emissions.
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LTC3562 TYPICAL APPLICATION
Quad Step-Down Converter with Push Button Control and Power Sequencing
100k
Li-Ion BATTERY 3.4V TO 4.2V
C5 10F VIN SDA SCL DVCC R5 100k VOUT 600A 1.8V 600mA C6 10pF C1 10F POR SCL SDA
VOUT 600B 3.3V 600mA
L3 3.3H SW600B C3 10F L4 4.7H C4 10F SW400B OUT400B OUT600B
LTC3562 POR600A SW600A FB600A RUN600A L1 3.3H
VCC CORE VCC I/O MICROPROCESSOR
R1 634k R2 499k
VOUT 400B 1.2V 400mA
RUN400A SW400A FB400A PGND AGND
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L2 4.7H R3 1070k R4 499k C7 10pF C2 10F
VOUT 400A 2.5V 400mA
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LTC3562 PACKAGE DESCRIPTION
UD Package 20-Lead Plastic QFN (3mm x 3mm) (Reference LTC DWG # 05-08-1720 Rev O)
0.70 0.05
3.50 0.05 (4 SIDES)
1.65 0.05
2.10 0.05
PACKAGE OUTLINE 0.20 0.05 0.40 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED BOTTOM VIEW--EXPOSED PAD PIN 1 NOTCH R = 0.20 TYP OR 0.25 x 45 CHAMFER 19 20 0.40 0.10 1 2 1.65 0.10 (4-SIDES)
3.00 0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6)
0.75 0.05 R = 0.05 TYP
R = 0.115 TYP
(UD20) QFN 0306 REV A
0.200 REF 0.00 - 0.05 NOTE: 1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE
0.20 0.05 0.40 BSC
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
19
LTC3562 RELATED PARTS
PART NUMBER LTC3406/ LTC3406B LTC3407/ LTC3407-2 LTC3410/ LTC3410B DESCRIPTION 600mA IOUT, 1.5MHz, Synchronous Step-Down DC/DC Converter Dual 600mA/800mA IOUT, 1.5MHz/2.25MHz, Synchronous Step-Down DC/DC Converter 300mA IOUT, 2.25MHz, Synchronous Step-Down DC/DC Converter COMMENTS 96% Efficiency, VIN(MIN) = 2.5V, VIN(MAX) = 5.5V, VOUT(MIN) = 0.6V, IQ = 20A, ISD < 1A, ThinSOTTM Package 95% Efficiency, VIN(MIN) = 2.5V, VIN(MAX) = 5.5V, VOUT(MIN) = 0.6V, IQ = 40A, ISD < 1A, MS10E and DFN Packages 95% Efficiency, VIN(MIN) = 2.5V, VIN(MAX) = 5.5V, VOUT(MIN) = 0.8V, IQ = 26A, ISD < 1A, SC70 Package 95% Efficiency, VIN(MIN) = 1.8V, VIN(MAX) = 5.5V, VOUT(MIN): 2V to 5V, IQ = 16A, ISD < 1A, ThinSOT and DFN Packages 95% Efficiency, VIN(MIN) = 2.4V, VIN(MAX) = 5.5V, VOUT(MIN): 2.4V to 5.25V, IQ = 35A, ISD < 1A, MS10 and DFN Packages 95% Efficiency, VIN(MIN) = 2.5V, VIN(MAX) = 5.5V, VOUT(MIN) = 0.6V, IQ = 26A, ISD < 1A, 2mm x 2mm DFN Package
LTC3531/LTC3531-3/ 200mA IOUT, 1.5MHz, Synchronous Buck-Boost DC/DC Converter LTC3531-3.3 LTC3532 LTC3542 LTC3544/LTC3544B LTC3547/ LTC3547B 500mA IOUT, 2MHz, Synchronous Buck-Boost DC/DC Converter 500mA IOUT, 2.25MHz, Synchronous Step-Down DC/DC Converter
Quad 300mA and 2 x 200mA and 100mA, 2.25MHz, 95% Efficiency, VIN(MIN) = 2.5V, VIN(MAX) = 5.5V, VOUT(MIN) = 0.8V, IQ = 70A, ISD < 1A, 3mm x 3mm QFN Package Synchronous Step-Down DC/DC Converter Dual 300mA, 2.25MHz, Synchronous Step-Down DC/DC Converter 96% Efficiency, VIN(MIN) = 2.5V, VIN(MAX) = 5.5V, VOUT(MIN) = 0.6V, IQ = 40A, ISD < 1A, 2mm x 3mm DFN Package 95% Efficiency, VIN(MIN) = 2.5V, VIN(MAX) = 5.5V, VOUT(MIN) = 0.6V, IQ = 40A, ISD < 1A, MS10E and DFN Packages 95% Efficiency, VIN(MIN) = 2.5V, VIN(MAX) = 5.5V, VOUT(MIN) = 0.6V, IQ = 16A, ISD < 1A, ThinSOT Package
LTC3548/LTC3548-1/ Dual 400mA and 800mA IOUT, 2.25MHz, Synchronous Step-Down DC/DC Converter LTC3548-2 LTC3560 800mA IOUT, 2.25MHz, Synchronous Step-Down DC/DC Converter
ThinSOT is a trademark of Linear Technology Corporation
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20 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 1207 REV A * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2007

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