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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming General Description
The AAT1210 is a high power DC/DC boost (step-up) converter with an input voltage range from 2.7 to 5.5V. The output voltage can be set from VIN + 0.5V to 18V. The total solution is less than 1mm in height. High operating efficiency makes the AAT1210 the ideal solution for battery powered and consumer applications. The step-up converter operates at frequencies up to 2MHz, enabling ultra-small external filtering components. Hysteretic current mode control provides excellent transient response with no external compensation, achieving stability across a wide operating range with minimal design effort. The AAT1210 true load disconnect feature extends battery life by isolating the load from the power source when the EN/SET pin is pulled low, ensuring zero volts output during the disable state. This feature eliminates the external boost converter leakage path and achieves standby quiescient current <1A without an external switching device. A fixed output voltage is set using two external resistors. Alternatively, the output may be adjusted dynamically across a 2.0x range. The output can toggle between two preset voltages using the SEL logic pin. Optionally, the output can be dynamically set to any one of 16 programmed levels using AnalogicTech's patented Simple Serial ControlTM (S2CwireTM) interface. The AAT1210 is available in a Pb-free, thermallyenhanced 16-pin 3x4mm TDFN low-profile package and is rated over the -40C to +85C temperature range.
AAT1210
Features
* *
SwitchRegTM
* * *
* * * * * * * * *
VIN Range: 2.7V to 5.5V Maximum Continuous Output -- 900mA at 5V -- 300mA at 12V -- 150mA at 18V Up to 2MHz Switching Frequency Ultra-Small Inductor and Capacitors -- 1mm Height Inductor -- Small Ceramic Capacitors Hysteretic Current Mode Control -- No External Compensation -- Excellent Transient Response -- High Efficiency at Light Load Up to 90% Efficiency Integrated Low RDS(ON) MOSFET Switches Low Inrush with Integrated Soft Start Cycle-by-Cycle Current Limit Short-Circuit and Over-Temperature Protection True Load Disconnect Optional Dynamic Voltage Programming TDFN34-16 Package -40C to +85C Temperature Range
Applications
* * * * * * GPS Systems DVD Blu-Ray Handheld PCs PDA Phones Portable Media Players USB OTG
Typical Application
VIN 3.6V AAT1210 TDFN34-16 VIN EN/SET SEL GND C1 4.7F 0603 LIN SW FB1 FB2 R3 4.99k R2 40.2k C2 10F 0603 L1 0.47H D1 VOUT 5V @ 900mA
AAT1210 Boost Converter Output Capability
(TDFN34-16; TAMB = 25C; TC(RISE) = +50C) VIN = 4.5V VIN = 3.6V VIN = 2.7V
14 00 7
Output Current (mA)
12 00 10 00 80 0 60 0 40 0 20 0 0 5 6
7
8
9
10
11
12
13
14
15
16
17
18
Output Voltage (V)
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Pin Descriptions
Pin #
1, 2 3
AAT1210
Symbol
LIN FB1
Function
Switched power input. Connect to the power inductor. Feedback pin for high output voltage set point. Pin set to 1.2V when SEL is high and disabled when SEL is low. Disabled with S2Cwire control. Tie directly to FB2 pin for static (fixed) output voltage. Feedback pin for low output voltage set point. Pin set to 0.6V when SEL is low and disabled when SEL is high. Voltage is set from 0.6V to 1.2V with S2Cwire control. Tie directly to FB1 pin for static (fixed) output voltage. Ground pin. Power ground for the boost converter; connected to the source of the N-channel MOSFET. Connect to the input and output capacitor return. Boost converter switching node. Connect the power inductor between this pin and the LIN pin. No connection. Input voltage for the converter. Connect this pin directly to the VP pin. Logic high selects FB1 high output reference. Logic low selects FB2 low output reference. Pull low for S2Cwire control. Active high enable pin. Alternately, input pin for S2Cwire control using the FB2 reference. Input power pin; connected internally to the source of the P-channel MOSFET. Connect externally to the input capacitor(s). Exposed paddle (bottom). Connected internally to the SW pins. Can be tied to bottom side PCB heat sink to optimize thermal performance.
4
FB2
5 6, 7, 8 9, 10 11 12 13 14 15, 16 EP
GND PGND SW N/C VIN SEL EN/SET VP
Pin Configuration
TDFN34-16 (Top View)
LIN LIN FB1 FB2 GND PGND PGND PGND
1 2 3 4 5 6 7 8
16 15 14 13 12 11 10 9
VP VP EN/SET SEL VIN N/C SW SW
2
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Absolute Maximum Ratings1
Symbol
VIN, VP SW LIN, EN/SET, SEL, FB1, FB2 TJ TS TLEAD
AAT1210
Description
Input Voltage Switching Node Maximum Rating Operating Temperature Range Storage Temperature Range Maximum Soldering Temperature (at leads, 10 sec)
Value
-0.3 to 6.0 20 VIN + 0.3 -40 to 150 -65 to 150 300
Units
V V V C C C
Recommended Operating Conditions
Symbol
JA PD
Description
Thermal Resistance Maximum Power Dissipation (TA = 25C)
Value
44 2270
Units
C/W mW
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 1210.2007.02.1.2
3
High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Electrical Characteristics1
VIN = 3.6V, TA = -40C to +85C, unless otherwise noted. Typical values are TA = 25C. Symbol
Power Supply VIN VOUT IOUT(MAX)
AAT1210
Description
Input Voltage Range Output Voltage Range Output Current
Conditions
Min
2.7 VIN + 0.5V
Typ
Max
5.5 18
Units
V V mA
2
VUVLO
UVLO Threshold
IQ ISHDN FB1 FB2 VLOADREG VLINEREG/VIN RDS(ON)L RDS(ON)IN TSS TSD THYS ILIM
Quiescent Current VIN Pin Shutdown Current FB1 Reference Voltage FB2 Reference Voltage Load Regulation Line Regulation Low Side Switch On Resistance Input Disconnect Switch On Resistance Soft-Start Time Over-Temperature Shutdown Threshold Shutdown Hysteresis N-Channel Current Limit
VIN = 2.7V, VOUT = 5V VIN = 2.7V, VOUT > 5V VIN = 3.6V, VOUT > 5V VIN Rising Hysteresis VIN Falling SEL = GND, VOUT = 5V, No Load, Switching3 SEL = GND, FB2 = 1.5V, Not Switching EN/SET = GND IOUT = 0 to IOUT(MAX) mA, VIN = 2.7V to 5.0V, SEL = High IOUT = 0 to IOUT(MAX) mA, VIN = 2.7V to 5.0V, SEL = Low IOUT = 0 to IOUT(MAX) mA VIN = 3.0V to 5.5V
600 See note 2 900 2.7 150 1.8 250 40 70 1.0 1.164 0.582 1.2 0.6 0.01 0.6 0.06 0.18 1.236 0.618
V mV V A A A V V %/mA %/V ms C C A
From Enable to Output Regulation; VOUT = 15V , COUT = 10F
2.5 140 15
VIN = 3.6V , L =2.2H
3.0
1. Specifications over the -40C to +85C operating temperature range are assured by design, characterization and correlation with statistical process controls. 2. Maximum output power and current is dependent upon operating efficiency and thermal/mechanical design. Output current and output power derating may apply. See Figure 1. 3. Total input current with prescribed FB resistor network can be reduced with larger resistor values.
4
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Electrical Characteristics1
VIN = 3.6V, TA = -40C to +85C, unless otherwise noted. Typical values are TA = 25C. Symbol
SEL, EN/SET VSEL(L) VSEL(H) VEN/SET(L) VEN/SET(H) TEN/SET LO TEN/SET HI MIN TEN/SET HI MAX TOFF TLAT IEN/SET
AAT1210
Description
SEL Threshold Low SEL Threshold High Enable Threshold Low Enable Threshold High EN/SET Low Time Minimum EN/SET High Time Maximum EN/SET High Time EN/SET Off Timeout EN/SET Latch Timeout EN/SET Input Leakage
Conditions
VIN VIN VIN VIN = = = = 2.7V 5.5V 2.7V 5.5V
Min
Typ
Max
0.4
Units
V V V V s ns s s s A
1.4 0.4 1.4 0.3 50 75 500 500 1 75
-1
1. Specifications over the -40C to +85C operating temperature range are assured by design, characterization and correlation with statistical process controls. 1210.2007.02.1.2
5
High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Typical Characteristics
Efficiency vs. Load
(VOUT = 5V)
95 85 2
AAT1210
DC Regulation
(VOUT = 5V) VIN = 4.5V
75 65 55 45 35 25 0.1 1 10
Output Error (%)
Efficiency (%)
VIN = 3.6V VIN = 4.2V VIN = 4.5V
1 0 -1 -2 -3 -4 -5
VIN = 4.2V VIN = 3.6V VIN = 3.0V VIN = 2.7V
0.1 1 10 100 1000
100
1000
Output Current (mA)
Output Current (mA)
Efficiency vs. Load
(VOUT = 9V)
95 85
DC Regulation
(VOUT = 9V)
2 1
VIN = 5.5V
Output Error (%)
VIN = 5.5V
VIN = 4.5V
Efficiency (%)
75 65 55 45 35 25 0.1 1 10 100 1000
0 -1 -2 -3 -4 -5 0.1 1 10
VIN = 3.6V
VIN = 4.2V VIN = 4.5V
VIN = 4.2V VIN = 3.6V VIN = 3.0V VIN = 2.7V
100 1000
Output Current (mA)
Output Current (mA)
Efficiency vs. Load
(VOUT = 12V)
95 85
DC Regulation
(VOUT = 12V)
2 1
VIN = 5.5V
VIN = 4.5V
Output Error (%)
VIN = 5.5V VIN = 4.2V VIN = 3.6V VIN = 3.0V VIN = 2.7V
1 10 100
VIN = 4.5V
Efficiency (%)
75 65 55 45 35 25 0.1 1 10 100 1000
0 -1 -2 -3 -4 -5 0.1
VIN = 3.6V VIN = 4.2V
1000
Output Current (mA)
Output Current (mA)
6
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Typical Characteristics
Efficiency vs. Load
(VOUT = 15V)
95 85 2
AAT1210
DC Regulation
(VOUT = 15V) VIN = 5.5V VIN = 4.2V VIN = 3.6V VIN = 3.0V VIN = 2.7V
1 10 100 1000
VIN = 5.5V
VIN = 4.5V
Output Error (%)
1 0 -1 -2 -3 -4
VIN = 4.5V
Efficiency (%)
75 65 55 45 35 25 0.1 1 10 100 1000
VIN = 3.6V VIN = 4.2V
-5 0.1
Output Current (mA)
Output Current (mA)
Line Regulation
(VOUT = 12V)
2 1.5 1 0.5 0 -0.5 -1 -1.5 -2 2.5 3 3.5 4 4.5 5 5.5 6
Output Voltage Error vs. Temperature
(VIN = 3.6V; VOUT = 12V; IOUT = 100mA)
0.5 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 -40 -15 10 35 60 85
VIN = 5.5V
VIN = 2.7V VIN = 3.6V VIN = 3.0V
Output Error (%)
VIN = 4.2V
Accuracy (%)
Input Voltage (V)
Temperature (C)
No Load Input Current vs. Input Voltage
(EN = High)
3 0.34 0.33 0.32 0.31 0.3 0.29 0.28 0.27 0.26
No Load Input Current vs. Temperature
(VIN = 3.6V; VOUT = 5V)
Supply Current (mA)
2.5 2 1.5 1 0.5 0 2.5 3
VOUT = 18V
VOUT = 9V
VOUT = 12V
VOUT = 5V
Supply Current (mA)
3.5
4
4.5
5
5.5
6
0.25 -40
-15
10
35
60
85
Input Voltage (V)
Temperature (C)
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Typical Characteristics
AC Output Ripple vs. Output Current
(VOUT = 9V)
70 15.1
AAT1210
Output Ripple
(VIN = 3.6V; VOUT = 15V; IOUT = 150mA; L = 1.2H)
12 10
Output Voltage (mV)
60 50 40 30 20 10 0 0 50
VIN = 2.7V VIN = 5.5V VIN = 3.6V
VIN = 3.0V
Output Voltage (top) (V)
15.05 15 14.95 14.9 14.85 14.8 14.75 14.7
Inductor Current (bottom) (A)
8 6 4 2 0 -2 -4
VIN = 4.2V
100
150
200
250
300
Output Current (mA)
Time (500ns/div)
Output Ripple
(VIN = 3.6V; VOUT = 15V; No Load; L = 1.2H)
15.1 15.05 3.5 3 5.2 5
Load Transient Response
(VIN = 3.6V; VOUT = 5V; IOUT = 0mA to 600mA)
Output Current (A) (middle) Inductor Current (A) (bottom)
7 6 5 600mA 0mA 4 3 2 1 0 -1
Inductor Current (bottom) (A)
Output Voltage (top) (V)
14.95 14.9 14.85 14.8 14.75 14.7
2 1.5 1 0.5 0 -0.5
Output Voltage (top) (V)
15
2.5
4.8 4.6 4.4 4.2 4 3.8 3.6
Time (200ns/div)
Time (20s/div)
Load Transient Response
(VIN = 3.6V; VOUT = 5V; IOUT = 120mA to 360mA)
Output Current (A) (middle) Inductor Current (A) (bottom)
5.05 5
7 6 5 360mA 120mA 4 3 2 1 0 -1 12.4 12.2
Load Transient Response
(VIN = 3.6V; VOUT = 12V; IOUT = 0mA to 200mA)
Output Current (A) (middle) Inductor Current (A) (bottom)
7 6 5 4 200mA 0mA 3 2 1 0 -1
Output Voltage (top) (V)
4.9 4.85 4.8 4.75 4.7 4.65
Output Voltage (top) (V)
4.95
12 11.8 11.6 11.4 11.2 11 10.8
Time (20s/div)
Time (20s/div)
8
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Typical Characteristics
Load Transient Response
(VIN = 3.6V; VOUT = 12V; IOUT = 40 to 120mA)
Output Current (middle) (A) Inductor Current (bottom) (A)
12.4 12.2 7 6 5 4 120mA 40mA 3 2 1 0 -1
AAT1210
Line Response
(VOUT = 15V @ 100mA)
15.5 15.25 7.2 6.6 6 5.4 4.8 4.2 3.6 3 2.4
Output Voltage (top) (V)
Output Voltage (top) (V)
12 11.8 11.6 11.4 11.2 11 10.8
15 14.75 14.5 14.25 14 13.75 13.5
Input Voltage (bottom) (V)
Time (20s/div)
Time (100s/div)
Line Response
(VOUT = 5V @ 100mA)
5.4 5.2 7.2 6.6 6 5.4 4.8 4.2 3.6 3 2.4
P-Channel RDS(ON) vs. Input Voltage
300 280 260 120C 100C
Output Voltage (top) (V)
5 4.8 4.6 4.4 4.2 4 3.8
Input Voltage (bottom) (V)
RDS(ON) (m)
240 220 200 180 160 140 120 100 2.5 3 3.5 4 4.5 5 5.5 6 25C 85C
Time (100s/div)
Input Voltage (V)
N-Channel RDS(ON) vs. Input Voltage
Enable Voltage (middle) (V) Output Voltage (top) (V)
110 100 120C
20 15 10 5 0 -5 -10 -15 -20 1.04V
Soft Start
(VIN = 3.6V; CIN = 2.2F; IOUT = 100mA; VOUT = 15V)
3.5 3 2.5 2 1.5 1 0.5 0 -0.5
RDS(ON) (m)
90 80 70 60 50 40 2.5 3
100C
Input Current (bottom) (A)
85C 25C
3.5
4
4.5
5
5.5
6
Input Voltage (V)
Time (500s/div)
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Typical Characteristics
Soft Start
(VIN = 3.6V; CIN = 2.2F; IOUT = 100mA; VOUT = 5V)
Output Voltage (top) (V) Enable Voltage (middle) (V)
8 6 4 2 0 -2 -4 -6 -8 1.04V 1.75 1.5 1.25 1 0.75 0.5 0.25 0 -0.25
AAT1210
Input Current (bottom) (A)
Time (500s/div)
10
1210.2007.02.1.2
High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Functional Block Diagram
VIN
AAT1210
VP
LIN
Soft-Start Timer EN/SET Control FB1 VREF1 Output Select VREF2 FB2 SEL GND PGND SW
Functional Description
The AAT1210 consists of a DC/DC boost (step-up) controller, an integrated slew rate controlled input disconnect MOSFET switch, and a MOSFET power switch. A high voltage rectifier, power inductor, capacitors and resistor divider network are required to implement a DC/DC boost converter. The minimum output voltage must be 0.5V above the input voltage and the maximum output voltage is 18V. The operating input voltage range is 2.7V to 5.5V.
voltage. This allows the voltage loop to directly program the required inductor current in response to changes in the output load. The switching cycle initiates when the N-channel MOSFET is turned ON and current ramps up in the inductor. The ON interval is terminated when the inductor current reaches the programmed peak current level. During the OFF interval, the input current decays until the lower threshold, or zero inductor current, is reached. The lower current is equal to the peak current minus a preset hysteresis threshold, which determines the inductor ripple current. The peak current is adjusted by the controller until the output current requirement is met. The magnitude of the feedback error signal determines the average input current. The AAT1210 controller implements a programmed current source connected to the output capacitor and load resistor. There is no right-half plane zero, and loop stability is achieved with no additional compensation components. 11
Control Loop
The AAT1210 provides the benefits of current mode control with a simple hysteretic feedback loop. The device maintains exceptional DC regulation, transient response, and cycle-by-cycle current limit without additional compensation components. The AAT1210 modulates the power MOSFET switching current in response to changes in output
1210.2007.02.1.2
High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming
Increased load current results in a drop in the output feedback voltage (FB1 or FB2) sensed through the feedback resistors (R1, R2, R3 in Figure 2). The controller responds by increasing the peak inductor current, resulting in higher average current in the inductor. Alternatively, decreased output load results in an increase in the output feedback voltage. The controller responds by decreasing the peak inductor current, resulting in lower average current in the inductor. At light load, the inductor OFF interval current goes below zero, which terminates the off period, and the boost converter enters discontinuous mode operation. Further reduction in the load results in a corresponding reduction in the switching frequency. The AAT1210 provides optimized light load operation which reduces switching losses and maintains the highest possible efficiency at light load. The AAT1210 switching frequency varies with changes in the input voltage, output voltage, and inductor size. Once the boost converter has reached continuous mode, further increases in the output load will not significantly change the operating frequency and constant ripple current in the boost inductor is maintained. Alternatively, the output voltage may be dynamically programmed to any of 16 voltage levels using the S2Cwire serial digital input. The single-wire S2Cwire interface provides high-speed output voltage programmability across a 2.0X output voltage range. S2Cwire functionality is enabled by pulling the SEL pin low and providing S2Cwire digital clock input to the EN/SET pin which sets the FB2 voltage level from 0.6V to 1.2V. Table 6 details the FB2 reference voltage versus S2Cwire rising clock edges.
AAT1210
Soft Start / Enable
The input disconnect switch is activated when a valid input voltage is present and the EN/SET pin is pulled high. The slew rate control on the P-channel MOSFET ensures minimal inrush current as the output voltage is charged to the input voltage, prior to switching of the N-channel power MOSFET. Monotonic turn-on is guaranteed by the integrated soft-start circuitry. Soft-start time of approximately 2.5ms is internally programmed to minimize inrush current and eliminate output voltage overshoot across the full input voltage range under all loading conditions.
Output Voltage Programming
The FB reference voltage is determined by the logic state of the SEL pin. The output voltage is programmed through a resistor divider network (R1, R2, R3) from the positive output terminal to FB1/FB2 pins to ground. Pulling the SEL pin high activates the FB1 pin which maintains a 1.2V reference voltage, while the FB2 reference is disabled. Pulling the SEL pin low activates the FB2 pin which maintains a 0.6V reference, while the FB1 reference is disabled. The FB1 and FB2 pins may be tied together when a static DC output voltage is desired. Toggling the SEL pin programs the output voltage between two distinct output voltages across a 2.0X range (maximum). With FB1, FB2 tied together, the output voltage toggles between two voltages with a 2.0X scaling factor. An additional resistor between FB1 and FB2 pins allows toggling between two voltages with a <2.0X scaling factor.
Current Limit and Over-Temperature Protection
The switching of the N-channel MOSFET terminates if the current limit of 3.0A (minimum) is exceeded. This minimizes power dissipation and component stresses under overload and short-circuit conditions. Switching resumes when the current decays below the current limit. Thermal protection disables the AAT1210 if internal power dissipation becomes excessive. Thermal protection disables both the N-channel and P-channel MOSFETs. The junction over-temperature threshold is 140C with 15C of hysteresis. The output voltage automatically recovers when the over-temperature or over-current fault condition is removed.
Under-Voltage Lockout
Internal bias of all circuits is controlled via the VIN input. Under-voltage lockout (UVLO) guarantees sufficient VIN bias and proper operation of all internal circuitry prior to activation.
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Applications Information
Output Current and Power Capability
The AAT1210 boost converter provides a high voltage, high current, regulated DC output voltage from a low voltage DC input. The operating input voltage range is 2.7 to 5.5V. Figure 1 details the output current and power capability of the AAT1210 for output voltages from 5V to 18V with DC input of 2.7V, 3.6V and 4.5V. The maximum output current/power curves are based on +50C case temperature rise over ambient using the TDFN34-16 package. Ambient temperature at 25C, natural convection is assumed. Up to 1.3A of output current is possible with 4.5V input voltage. As shown in Figure 1, the output capability is somewhat reduced at higher output voltage and reduced input voltage. The AAT1210 schematic and PCB layout are provided in Figures 2, 6, and 7. The PCB layout includes a small 1 ounce copper power plane on top and bottom layers which is tied to the paddle of the TDFN34-16 package. The top plane is soldered directly to the paddle, and tied to the bottom layer with plated through vias. Details of the PCB layout are provided in Figures 6, 7, and 8. Actual case temperature may vary and depends on the boost converter efficiency and the system thermal design; including, but not limited to airflow, local heat sources, etc. Additional derating may apply.
AAT1210
Selecting the Output Diode
To ensure minimum forward voltage drop and no recovery, a high voltage Schottky diode is considered the best choice for use with the AAT1210 boost converter. The AAT1210 output diode is sized to maintain acceptable efficiency and reasonable operating junction temperature under full load operating conditions. Forward voltage (VF) and package thermal resistance (JA) are the dominant factors to consider in selecting a diode. The diode's published current rating may not reflect actual operating conditions and should be used only as a comparative measure between similarly rated devices. 20V rated Schottky diodes are recommended for outputs less than 15V, while 30V rated Schottky diodes are recommended for outputs greater than 15V.
AAT1210 Boost Converter Maximum Output Capability
1400 7
Maximum Output Current (mA)
1200
6
Maximum Output Power (W)
1000
VIN = 4.5V VIN = 3.6V
Output Current Output Power
5
800
4
600
3
400
2
200
VIN = 2.7V
1
0 5 6 7 8 9 10 11 12 13 14 15 16 17 18
0
Output Voltage (V)
Figure 1: Maximum Output Power Vs. Output Voltage for TC(RISE) = +50C (assumes TDFN34-16 paddle heatsinking; see Figures 6, 7, and 8).
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming
D1 Schottky
AAT1210
L1 0.47H 9V at 300mA 5V at 600mA
1 2 3 4 5 6 7 8
U1 R1 36.5k LIN VP 15 LIN VP 14 FB1 EN/SET 13 FB2 SEL 12 GND VIN 11 PGND N/C 10 PGND SW 9 PGND SW AAT1210_TDFN34-16
16
VIN: 2.7V to 5.5V R4 10K JP1
1 2 3
C2 4.7F R2 10V 549
R3 4.99k
C1 4.7uF
Enable JP2
1 2 3
Select
U1 AAT1210 TDFN34-16 C1 6.3V 0603 4.7F C2 10V 0805 10F D1 30V 0.5A MBR0530T1 SOD-123 L1 0.47H SD10-R47-R R1 36.5k 0603 R2 549 0603 R3 4.99k 0603 R4 10k 0603
Figure 2: AAT1210 Demo Board Schematic.
The switching period is divided between ON and OFF time intervals.
1 = TON + TOFF FS
During the ON time, the N-channel power MOSFET is conducting and storing energy in the boost inductor. During the OFF time, the N-channel power MOSFET is not conducting. Stored energy is transferred from the input supply and boost inductor to the output load through the output diode. Duty cycle is defined as the ON time divided by the total switching interval.
The maximum duty cycle can be estimated from the relationship for a continuous mode boost converter. Maximum duty cycle (DMAX) is the duty cycle at minimum input voltage (VIN(MIN)).
DMAX =
VOUT - VIN(MIN) VOUT
The average diode current during the OFF time can be estimated.
IAVG(OFF) =
IOUT 1 - DMAX
TON D= TON + TOFF = TON FS
The following curves show the VF characteristics for different Schottky diodes (100C case). The VF of the Schottky diode can be estimated from the average current during the off time.
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1210.2007.02.1.2
High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming
10000
AAT1210
Forward Current (mA)
B340LA 1000 MBR0530 ZHCS350 100
ode. PCB heatsinking the anode may degrade EMI performance. The reverse leakage current of the rectifier must be considered to maintain low quiescent (input) current and high efficiency under light load. The rectifier reverse current increases dramatically at high temperatures.
0.70
BAT42W
10 0.00 0.10 0.20 0.30 0.40 0.50 0.60
Forward Voltage (V)
Figure 3: Forward Voltage vs. Forward Current for Various Schottky Diodes. The average diode current is equal to the output current.
IAVG(TOT) = IOUT
Additional considerations may apply to satisfy short circuit conditions. A short circuit across the output terminals results in high currents through the inductor and output diode. The output diode must be sized to prevent damage and possible failure of the diode under short circuit conditions. The inductor may saturate without incurring damage. When current limit of (3A minimum) is reached, switching of the low side N-channel MOSFET is disabled. Although switching is disabled, DC current continues to build to a level determined by the DC resistance in the path of current flow. For portable applications, the source resistance (RSOURCE) of the Li-ion battery pack is between 100-300m and should also be considered.
(VIN(MAX) - VF) (RSOURCE + RDC + RDS(ON)IN)
The average output current multiplied by the forward diode voltage determines the loss of the output diode.
PLOSS_DIODE = IAVG * VF = IOUT * VF
ISHT-CKT(MAX) =
Diode junction temperature can be estimated.
TJ = TAMB + JA * PLOSS_DIODE
The junction temperature should be maintained below 110C, but may vary depending on application and/or system guidelines. The diode JA can be minimized with additional PCB area on the cath-
The AAT1210 controller will generate an over-temperature (OT) event under extended short circuit conditions. OT disables the high side P-channel MOSFET, which terminates current flow in the output diode. Current flow continues when OT hysteresis (cool-down) is met. This continues until the short circuit condition is removed. In portable applications, the battery pack over-current protection may be enabled prior to an OT event.
Manufacturer
Diodes, Inc. ON Semi Zetex Central Semi
Part Number
BAT42W MBR0530T ZHCS350 CMDSH2-3
Rated Forward Current (A)
0.2 0.5 0.35 0.2
Non-Repetitive Peak Surge Current (A)
4.0 5.5 4.2 1.0
Rated Voltage (V)
30 30 40 30
Thermal Resistance (JA, C/W)
500 206 330 500
Case
SOD-123 SOD-123 SOD-523 SOD-323
Table 1: Typical Surface Mount Schottky Rectifiers for Various Output Levels.
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming
The diode non-repetitive peak surge current (IFSM) rating should be greater than ISHT_CKT(MAX) to ensure diode reliability under short circuit conditions. Typically, IFSM current is specified for conduction periods from 8-10ms. If short circuit survivability is required, it is recommended to verify ISHT_CKT(MAX) under actual operating conditions across the expected operating temperature range.
AAT1210 Peak Inductor Current vs. Output Power
Peak Inductor Current (mA)
3500 3000 2500 2000 1500 1000 500 0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
AAT1210
VIN = 2.7V
VIN = 3.6V
VIN = 4.5V
Selecting the Boost Inductor
The AAT1210 controller utilizes hysteretic control and the switching frequency varies with output load and input voltage. The value of the inductor determines the maximum switching frequency of the boost converter. Increased output inductance decreases the switching frequency, resulting in higher peak currents and increased output voltage ripple. The required inductance increases with increasing output voltage. The inductor is sized from 0.47H to 2.2H for output voltages from 5V to 18V. This selection maintains high frequency switching (up to 2MHz), low output ripple and minimum solution size. A summary of recommended inductors and capacitors for 5V to 18V fixed outputs is provided in Table 2. The physical size of the inductor may be reduced when operating at greater than 2.7V input voltage and/or less than maximum rated output power is desired (see Figure 1 for maximum output power estimate). Figure 4 provides the peak inductor current (IPEAK) versus output power for different input voltage levels. The curves are valid for all output voltages and assume the corresponding inductance value provided in Figure 4. The inductor is selected to maintain IPEAK current less than the specified saturation current (ISAT).
Output Power (W)
Figure 4: Peak Inductor Current (IPEAK) vs. Output Power. The RMS current flowing through the boost inductor is equal to the DC plus AC ripple components. Under worst-case RMS conditions, the current waveform is critically continuous. The resulting RMS calculation yields worst-case inductor loss. The RMS value should be compared against the manufacturer's temperature rise, or thermal derating, guidelines.
IRMS =
IPEAK
3
In most cases, the inductor's specified IRMS current will be greater than the IRMS current required by the boost inductor. For a given inductor type, smaller inductor size leads to an increase in DCR winding resistance and, in most cases, increased thermal impedance. Winding resistance degrades boost converter efficiency and increases the inductor operating temperature.
PLOSS_INDUCTOR = IRMS2 * DCR
VOUT
5.0 9.0 12.0 15.0 18.0
C1 (Input Capacitor)
4.7F 4.7F 4.7F 4.7F 4.7F
C2 (Output Capacitor)
10F/6.3V, 10V 10F/10V 10F/16V 10F/16V 4.7F/25V
L1 (Boost Inductor)
0.47H 0.47H 1.0/1.2H 1.0/1.2H 2.2H
Table 2: Output Inductor and Capacitor Values Vs. Output Voltage
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming
To ensure high reliability, the inductor temperature should not exceed 100C. Manufacturer's recommendations should be consulted. In some cases, PCB heatsinking applied to the AAT1210 LIN node (nonswitching) can improve the inductor's thermal capability. PCB heatsinking may degrade EMI performance when applied to the SW node (switching) of the AAT1210. Shielded inductors provide decreased EMI and may be required in noise sensitive applications. Unshielded chip inductors provide significant space savings at a reduced cost compared to shielded (wound and gapped) inductors. Chip-type inductors have increased winding resistance when compared to shielded, wound varieties.
AAT1210
Selecting DC/DC Boost Capacitors
Recommended input and output capacitors for output voltages from 5V to 18V are provided in Table 4. The high output ripple inherent in the boost converter necessitates low impedance output filtering. Multilayer ceramic (MLC) capacitors provide small size and high capacitance, low parasitic equivalent series resistance (ESR) and equivalent series inductance (ESL), and are well suited for use with the AAT1210 boost regulator. MLC capacitors of type X7R or X5R are recommended to ensure good capacitance stability over the full operating temperature range.
Manufacturer
Sumida www.sumida.com
Part Number
CDRH5D16-1R4 CDRH5D16-1R4 CDRH3D11/HP-1R5 CDRH3D11/HP-2R7 LQH55DNR47M03 LQH55DN1R0M03 LQH55DN1R5M03 LQH55DN2R2M03 SD3814-R47 SD3814-1R2 SD3814-2R2 SD10-R47-R SD10-1R0-R SD10-2R2-R SD18-2R2-R
Max Max IRMS DC ISAT Inductance Current Current DCR (H) (A) (A) (m)
1.4 2.2 1.5 2.7 0.47 1.0 1.5 2.2 0.47 1.2 2.2 0.47 1 2.2 2.2 4.7 3.0 2.0 1.55 4.8 4.0 3.7 3.2 4.44 2.67 1.9 3.54 2.25 1.65 2.16 4.7 2.85 1.45 1.3 2.81 1.85 1.43 2.59 1.93 1.35 2.55 14.6 35.9 80 100 13 19 22 29 20 46 77 24.9 44.8 91.2 39.8
Size LxWxH (mm)
5.8x5.8x1.8 5.8x5.8x1.8 4.0x4.0x1.2 4.0x4.0x1.2 5.7x5.0x4.7 5.7x5.0x4.7 5.7x5.0x4.7 5.7x5.0x4.7 4.0x4.0x1.4 4.0x4.0x1.4 4.0x4.0x1.4 5.2x5.2x1.0 5.2x5.2x1.0 5.2x5.2x1.0 5.2x5.2x1.8
Type
Shielded Shielded Shielded Shielded Non-Shielded Non-Shielded Non-Shielded Non-Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded
Murata www.murata.com
Cooper www.cooperet.com
Table 3: Recommended Inductors. Value (F)
4.7 4.7 4.7 10 10 10 10
Manufacturer
Part Number
GRM188R60J475KEAD GRM21BR61A475KA73L GRM21BR61E475KA12L GRM188R60J106ME47D GRM21BR61A106KE19L GRM219R61A106KE44D GRM21BR61C106KE15L
Voltage Rating (V)
6.3 10 25 6.3 10 10 16
Temp. Co.
X5R X5R X5R X5R X5R X5R X5R
Case Size
0603 0805 0805 0603 0805 0805 (H = 0.85mm) 0805
Murata www.murata.com
Table 4: Recommended MLC Capacitors.
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming
The output capacitor is sized to maintain the output load without significant voltage droop (VOUT) during the power switch ON interval, when the output diode is not conducting. A ceramic output capacitor from 4.7F to 10F is recommended. Output capacitors should be rated from 10V to 25V, depending on the maximum desired output voltage. Ceramic capacitors sized as small as 0603 are available which meet these requirements. Minimum 6.3V rated ceramic capacitors are required at the input. Ceramic capacitors sized as small as 0603 are available which meet these requirements. Output capacitors should be rated from 6.3V to 25V, depending on the maximum desired output voltage. MLC capacitors exhibit significant capacitance reduction with applied voltage. Output ripple measurements should confirm that output voltage droop and converter stability is acceptable. Voltage derating can minimize this factor, but results may vary with package size and among specific manufacturers. Output capacitor size can be estimated at a switching frequency (FSW) of 500kHz (worst-case).
AAT1210
Setting the Output Voltage
The minimum output voltage must be greater than the specified maximum input voltage plus 0.5V margin to maintain proper operation of the AAT1210 boost converter. The output voltage may be programmed through a resistor divider network located from the output to FB1 and FB2 pins to ground. Pulling the SEL pin high activates the FB1 pin which maintains a 1.2V reference voltage, while the FB2 reference is disabled. Pulling the SEL pin low activates the FB2 pin which maintains a 0.6V reference, while the FB1 reference is disabled. The AAT1210 output voltage can be programmed by one of three methods. First, the output voltage can be static by pulling the SEL logic pin either high or low. Second, the output voltage can be dynamically adjusted between two pre-set levels within a 2X operating range by toggling the SEL logic pin. Third, the output can be dynamically adjusted to any of 16 preset levels within a 2X operating range using the integrated S2Cwire single wire interface via the EN/SET pin. See Table 5 for static and dynamic output voltage settings. Table 5 provides details of resistor values for common output voltages from 5V to 18V for SEL = High and SEL = Low options. SEL = High corresponds to VOUT(1) and SEL = Low corresponds to VOUT(2). Option 1: Static Output Voltage Most DC/DC boost converter applications require a static (fixed) output voltage. If a static voltage is desired, the FB1 pin should be connected directly to FB2 and a resistor between FB1 and FB2 pins is not required. A static output voltage can be configured by pulling the SEL either high or low. SEL pin high activates the FB1 reference pin to 1.2V (nominal). Alternatively, the SEL pin is pulled low to activate the FB2 reference at 0.6V (nominal). Table 5 provides details of resistor values for common output voltages from 5V to 18V for SEL = High and SEL = Low options.
I * DMAX COUT = OUT FS * VOUT
The boost converter input current flows during both ON and OFF switching intervals. The input ripple current is less than the output ripple and, as a result, less input capacitance is required. A ceramic output capacitor from 4.7F to 10F is recommended. The voltage rating of the capacitor must be greater than, or equal to, the maximum operating output voltage. X5R ceramic capacitors are available in 6.3V, 10V, 16V and 25V rating. Ceramic capacitors sized as small as 0603 are available which meet these requirements. Minimum 6.3V rated ceramic capacitors are required at the input. Ceramic capacitors sized as small as 0603 are available which meet these requirements.
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming
Option 2: Dynamic Voltage Control Using SEL Pin The output may be dynamically adjusted between two output voltages by toggling the SEL logic pin. Output voltages VOUT(1) and VOUT(2) correspond to the two output references, FB1 and FB2. Pulling the SEL logic pin high activates VOUT(1), while pulling the SEL logic pin low activates VOUT(2). In addition, the ratio of output voltages VOUT(2)/VOUT(1) is always less than 2.0, corresponding to a 2X (maximum) programmable range. Option 3: Dynamic Voltage Control Using S2Cwire Interface The output can be dynamically adjusted by the host controller to any of 16 pre-set output voltage levels using the integrated S2Cwire interface. The EN/SET pin serves as the S2Cwire interface input. The SEL pin must be pulled low when using the S2Cwire interface. VOUT(1) VOUT(2) R3 = 4.99k (SEL = High) (SEL = Low) R1 (k) R2 (k)
5.0V 6.0V 7.0V 8.0V 9.0V 10.0V 12.0V 15.0V 16.0V 18.0V 9.0V 10.0V 12.0V 15.0V 15.0V 16.0V 18.0V 15.0V 16.0V 18.0V 18.0V 5.0V 6.0V 7.0V 8.0V 9.0V 10.0V 12.0V 15.0V 16.0V 18.0V 5.0V 9.0V 10.0V 10.0V 12.0V 10.0V 10.0V 12.0V 12.0V 12.0V 15.0V 15.8 20.0 24.3 28.0 32.4 36.5 44.2 57.6 61.9 69.8 36.5 45.3 53.6 61.9 69.8 78.7 95.3 121 127 143 36.5 66.5 75 76.8 90.9 76.8 78.7 90.9 93.1 93.1 115 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.549 4.02 3.32 1.65 3.01 1.24 0.562 3.01 2.49 1.65 3.32
AAT1210
S2Cwire Serial Interface
AnalogicTech's S2Cwire serial interface is a proprietary high-speed single-wire interface. The S2Cwire interface records rising edges of the EN/SET input and decodes into 16 different states. Each state corresponds to a voltage setting on the FB2 pin, as shown in Table 6.
S2Cwire Output Voltage Programming
The AAT1210 is programmed through the S2Cwire interface according to Table 6. The rising clock edges received through the EN/SET pin determine the feedback reference and output voltage setpoint. Upon power-up with the SEL pin low and prior to S2Cwire programming, the default feedback reference voltage is set to 0.6V.
Table 5: SEL Pin Voltage Control Resistor Values (1% resistor tolerance).
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming
EN/SET Rising Edges
1 2 3 4 5 6 7 8
AAT1210
FB2 Reference Voltage (V)
0.60 (Default) 0.64 0.68 0.72 0.76 0.80 0.84 0.88
EN/SET Rising Edges
9 10 11 12 13 14 15 16
FB2 Reference Voltage (V)
0.92 0.96 1.00 1.04 1.08 1.12 1.16 1.20
attempt should be made to optimize the layout in order to minimize parasitic PCB effects (stray resistance, capacitance, inductance) and EMI coupling from the high frequency SW node. A suggested PCB layout for the AAT1210 boost converter is shown in Figures 6, 7, and 8. The following PCB layout guidelines should be considered: 1. Minimize the distance from Capacitor C1 and C2 negative terminal to the PGND pins. This is especially true with output capacitor C2, which conducts high ripple current from the output diode back to the PGND pins. 2. Place the feedback resistors close to the output terminals. Route the output pin directly to resistor R1 to maintain good output regulation. R3 should be routed close to the output GND pin, but should not share a significant return path with output capacitor C2. 3. Minimize the distance between L1 to D1 and switching pin SW; minimize the size of the PCB area connected to the SW pin. 4. Maintain a ground plane and connect to the IC PGND pin(s) as well as the GND terminals of C1 and C2. 5. Consider additional PCB area on D1 cathode to maximize heatsinking capability. This may be necessary when using a diode with a high VF and/or thermal resistance. 6. To maximize thermal capacity, connect the exposed paddle to the top and bottom power planes using plated through vias. Top and bottom planes should not extend far beyond the TDFN34-16 package boundary to minimize stray EMI.
Table 6: S2Cwire Voltage Control Settings (SEL = Low).
S2Cwire Serial Interface Timing
The S2Cwire serial interface has flexible timing. Data can be clocked-in at speeds up to 1MHz. After data has been submitted, EN/SET is held high to latch the data for a period TLAT. The output is subsequently changed to the predetermined voltage. When EN/SET is set low for a time greater than TOFF, the AAT1210 is disabled. When disabled, the register is reset to the default value, which sets the FB2 pin to 0.6V if EN is subsequently pulled high.
PCB Layout
Boost converter performance can be adversely affected by poor layout. Possible impact includes high input and output voltage ripple, poor EMI performance, and reduced operating efficiency. Every
THI TLO T LAT TOFF
EN/SET
1 2 n-1 n 16
Data Reg
0
n-1
0
Figure 5: S2Cwire Timing Diagram.
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming
AAT1210
Figure 6: AAT1210 Evaluation Board Top Side Layout.
Figure 7: AAT1210 Evaluation Board Bottom Side Layout.
Figure 8: Exploded View of AAT1210 Evaluation Board Top Side Layout Detailing Plated Through Vias.
1210.2007.02.1.2
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming Ordering Information
Package
TDFN34-16
AAT1210
Marking1
VDXYY
Part Number (Tape and Reel)2
AAT1210IRN-0.6-T1
All AnalogicTech products are offered in Pb-free packaging. The term "Pb-free" means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/pbfree.
Package Information3
TDFN34-16
3.000 0.050 1.600 0.050 Detail "A"
Index Area
4.000 0.050
3.300 0.050
0.350 0.100
Top View
Bottom View
C0.3
(4x)
0.850 MAX
0.050 0.050
0.229 0.051
Side View Detail "A"
All dimensions in millimeters.
1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection.
22
0.450 0.050
Pin 1 Indicator (optional)
0.230 0.050
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High Power DC/DC Boost Converter with Optional Dynamic Voltage Programming
AAT1210
(c) Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech's standard warranty. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737- 4600 Fax (408) 737- 4611
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