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PRELIMINARY
CALIFORNIA MICRO DEVICES
CM3702
Micropower Low-Noise Charge-Pump and Linear Regulator
Features
* * * * * * * * * * * Low noise regulator with integrated charge pump voltage-booster 5V output with input voltage as low as 2.8V Charge pump can also power external LDO Low noise in 20Hz to 20kHz audio band Up to 200mA continuous output current Low operating and shutdown currents Stable with low-ESR ceramic or tantalum capacitors 10-Lead MSOP and TDFN packages Lead-free finishing
Block Diagram
Applications
5V analog supply for audio codec in notebook computers, PDAs, MP3 players, etc. 3.3V to 5V conversion in PCMCIA cards, PCI Express Cards, other applications needing 5V
Product Description
The CM3702 low-noise charge pump LDO regulator is designed to provide accurate and "clean" power to a subsystem, e.g an audio codec, LED driver, or flash memory. The 5V output provides up to 100mA continuous current for input voltages from 2.8V to 5.5V, and up to 200mA for a narrower range. This is accomplished with an integrated charge pump that boosts the input voltage before feeding it to an internal LDO linear regulator. The charge pump is designed to maintain a nominal 0.8V differential between the input and output of the LDO regulator. This allows the LDO regulator to operate with good power supply ripple rejection across the audio band while maintaining good power efficiency. The charge pump works with two external capacitors and operates at 250kHz, well outside the audible frequency band. In addition, separate analog and digital ground pins are provided for the charge pump and the rest of the circuitry to eliminate ground noise feed-through from the charge pump to the regulated output. The CM3702 is fully protected, offering both overload current limiting and high temperature thermal shutdown. Two enable inputs provide flexibility in powering down the device. For maximum power saving in shutdown, both the charge pump and LDO regulator should be disabled. For applications that require the 5V output to be reestablished with minimum delay after shutdown, the charge pump can be left enabled while the regulator is disabled. This avoids the delay that may otherwise be required for the charge pump to reach full operating voltage after being disabled. The CMOS LDO regulator features low quiescent current even at full load, making it very suitable for power sensitive applications. A bandgap reference bypass pin is provided to further minimize noise by connecting an external capacitor between this pin and ground. Another, external, regulator can be connected to the charge pump output pin Cs, if required. The CM3702 is available in 10-pin MSOP and TDFN packages, both with optional lead-free finishing, and are ideal for space critical applications.
STANDARD PART ORDERING INFORMATION
Standard Finish Pins 10 10 Package MSOP-10 TDFN-10 Ordering Part Number CM3702-50MR CM3702-50DF Part Marking 3702 50S CM370 250DF Lead-free Finish Ordering Part Number CM3702-50MS CM3702-50DE Part Marking 3702 50 CM370 250DE
(c) 2004 California Micro Devices Corp. All rights reserved.
9/22/04
430 N. McCarthy Blvd, #100, Milpitas , CA 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
1
PRELIMINARY
CALIFORNIA MICRO DEVICES
Pin Descriptions
VIN (pin 2) is the input power source for the device. Since the charge pump draws current in pulses at the 250kHz internal clock frequency, a low-ESR input decoupling capacitor is usually required close to this pin to ensure low noise operation. CP+ and CP- (pins 9, 10) are used to connect the external "flying" capacitor CP to the charge pump. The charge stored in CP is transferred to the reservoir capacitor CS at the 250kHz internal clock rate. CS (pin 3) is the output of the charge pump and is connected to the external reservoir capacitor Cs. This should be a low-ESR capacitor. When the voltage on this pin reaches about 5.8V then the charge pump pauses until the voltage on this pin drops to about 5.7V. This gives rise to at least 100mV of `ripple' (the frequency and amplitude of this ripple depends upon values of Cp and Cs and also the ESR of Cs). Note that current may be drawn from this pin for other applications (for example an additional, independent, 5V LDO) as long as the total current is less than 100mA (otherwise the part may overheat). DGND (pin 1) is the ground for the charge pump circuit. This should be connected to the system (noisy) ground. GND (pin 4) is the ground reference for all internal circuits except the charge pump. This pin should be connected to a "clean" low-noise analog ground.
CM3702
EN_LDO, EN_Chip (pins 6, 7) are active-high TTL-level logic inputs to enable the linear regulator and charge pump according to the following truth table: EN_Chip EN_LDO CHARGE REGULATOR Pin 7 Pin 6 PUMP 1 1 Enabled Enabled 1 0 Enabled Disabled 0 1 Disabled Disabled 0 0 Disabled Disabled When the LDO Regulator is disabled, an internal pulldown with a nominal resistance of 500 is activated to discharge the 5V output rail to ground. When the charge pump is disabled or paused, the internal 250kHz oscillator is disabled. The "flying capacitor" CP will then stay connected between V_IN and DGND, and CS will stay connected to the input of the LDO regulator. In this mode, CS will discharge at a rate determined by the input current of the LDO regulator. BYP (pin 5) is connected to the internal voltage reference of the LDO regulator. An external bypass capacitor CBYP of 0.1uF is recommended to minimize internal voltage reference noise and maximize power supply ripple rejection. VOUT (pin 8) is the regulated output. An output capacitor may be added to improve noise and load-transient response. When the LDO regulator is disabled, an internal pull-down is activated to discharge the VOUT rail to GND.
Pinout Diagrams
Typical Application Circuit
(c) 2004 California Micro Devices Corp. All rights reserved
09/22/04
430 N. McCarthy Blvd, #100, Milpitas, California 95035
Tel: (408) 263-3214 Fax: (408) 263-7846
www.calmicro.com
2
PRELIMINARY
CALIFORNIA MICRO DEVICES
Absolute Maximum Ratings Parameter Rating ESD Protection (HBM) 2000 VIN , VOUT Voltages + 5.5, Gnd - 0.5 VEN Logic Input Voltage VIN + 0.5, Gnd - 0.5 Temperature: Storage -40 to +150 Operating Ambient 0 to +70 Operating Junction 0 to +170 Standard Operating Conditions Parameter Range VIN - Input Voltage Range 3.0 to 5.5 Ambient Operating Temperature 0 to +70 200 (approx) JA of MSOP package on pcb IOUT - Output Load Current 0 to 200 CBYP 0.1 COUT 0 to 100
CM3702
Unit V V V C
Unit V C C/W mA F F
Symbol VCS VOUT VR LOAD VR LINE RDISCHG
Electrical Operating Characteristics (VIN = 5.0V; IOUT =100mA; COUT=10uF; CP = 1F; CS = 10F; unless specified otherwise) Parameter Conditions MIN TYP MAX 5.5 5.8 7 Charge pump output voltage VOUT = 5V, 1mA IOUT 100mA; Regulator Output Voltage Load Regulation Line Regulation VOUT Discharge Resistance LDO Regulator Ground Current via GND pin Charge Pump Shutdown Current via DGND pin Power Supply Rejection Output Voltage Noise Output Voltage Noise EN1, EN2 Input High threshold EN1, EN2 Input Low threshold Overload Current Limit Output Short Circuit Current Thermal Shutdown Junction Temp Thermal Shutdown Hysteresis VIN = 4.0V; 1mA IOUT 100mA; IOUT = 1mA to 100mA Vary VIN from 3.0V to 5.0V LDO regulator disabled EN2 (pin 6) grounded; VIN = 5V Shutdown (EN2 grounded) Regulator Enabled, IOUT = 0mA Regulator Enabled, IOUT = 100mA 4.85 0.2 0.02 500 1 180 180 1 42 42 35 38 2.0 0.5 200 100 300 200 170 25 10 10 5.15
UNIT V V % % A A A A dB dB Vrms Vrms V V mA mA C C
IGND
IDGND PSRR eNO eNO VIH VIL ILIM ISC TJSD THYS
EN1 (pin 7) grounded, VIN = 5.0V IOUT = 100mA; CBYP=0.1uF f = 100Hz f = 10kHz BW=22Hz-22kHz; COUT=10uF; CBYP=0.1uF; IOUT = 100mA BW=22Hz-22kHz; Cp=1uF, CS=3uF COUT=CBYP=0.1uF; IOUT = 100mA VIN = 5.0V VIN = 5.0V (LDO only) (LDO only)
(c) 2004 California Micro Devices Corp. All rights reserved
09/22/04
430 N. McCarthy Blvd, #100, Milpitas, California 95035
Tel: (408) 263-3214 Fax: (408) 263-7846
www.calmicro.com
3
PRELIMINARY
CALIFORNIA MICRO DEVICES
Typical Performance Characteristics (T=25C)
CM3702 noise spectrum (Cp=0.47uF, Cs=1.5uF, Co=Cbyp=0.1uF, Iout=100mA)
1.00E-03
CM3702
1.00E-04
Voltage [V]
1.00E-05
noise floor Cs=1.5uF
1.00E-06
1.00E-07
1.00E-08 10 100 1000 Frequency [Hz ] 10000 100000
Note: Noise peaks may appear for different values of Cp, Cs & IOUT, and are due to the ripple frequency of the charge pump (see later).
PSRR with VIN=3.3V (upper curve) and VIN=5V (lower curve), IOUT =100mA 70.0 60.0 50.0 PSRR [dB] 40.0 30.0 20.0 10.0 0.0 10 100 1000 Frequency [Hz] 10000 100000
Measured by forcing VIN voltage to 3.3V & 5.0V dc, then sweeping 100mV ac on VIN.
COUT = 10uF, CBYP = 0.1uF
(c) 2004 California Micro Devices Corp. All rights reserved
09/22/04
430 N. McCarthy Blvd, #100, Milpitas, California 95035
Tel: (408) 263-3214 Fax: (408) 263-7846
www.calmicro.com
4
PRELIMINARY
CALIFORNIA MICRO DEVICES
CM3702
Typical Performance Characteristics (T=25C, Cp=1uF, Cs=10uF, Cbyp=0.1uF, C_OUT=10uF unless stated)
V_OUT v s. I_OUT (V_IN = 5V)
5.1 5.08 5.06 5.04
V_EN Threshold vs. V_IN
2 1.9 1.8 1.7
V_OUT [V]
V_EN [V]
0 20 40 60 80 100
5.02 5 4.98 4.96 4.94 4.92 4.9
1.6 1.5 1.4 1.3 1.2 1.1 1 3 3.5 4 4.5 5 5.5
I_OUT [mA]
V_IN [V]
V_OUT vs. V_IN
5.1 5.08 5.06 5.04 5.02 5 4.98 4.96 4.94 4.92 4.9 3 3.5 4 4.5 5 5.5
I_IN vs. V_IN
300
I_OUT=0mA I_OUT=100mA
250 200 150 100 50 0 3 3.5 4 4.5 5 5.5
V_OUT [V]
V_IN [V]
I_IN [uA]
V_IN [V]
CS pin vs. V_IN
7 6.75 6.5
250
I_IN vs. I_OUT
200
CS pin [V]
6.25
I_IN [mA]
6 5.75 5.5 5.25 5 3 3.5 4 4.5 5 5.5
150
100 V_IN=3.1V V_IN=5V
50
V_IN [V]
0 0 20 40 60 80 100
I_OUT [mA]
DROPOUT VOLTAGE (LDO ONLY) at T=150'C, T=85'C and T=25'C
400 300
Overcurrent characteristic (LDO only)
6 5 4 3 2 1 0 0 0.1 0.2 0.3 0.4 0.5 I_OUT [A]
VDO [mV]
100 0 0 10 20 30 40 50 60 70 80 90 100
I_OUT [mA]
(c) 2004 California Micro Devices Corp. All rights reserved
09/22/04
430 N. McCarthy Blvd, #100, Milpitas, California 95035
Tel: (408) 263-3214 Fax: (408) 263-7846
V_O UT [V]
200
www.calmicro.com
5
PRELIMINARY
CALIFORNIA MICRO DEVICES
CM3702
Typical Performance Characteristics (T=25C, Cp=1uF, Cs=10uF, Cbyp=0.1uF, C_OUT=10uF unless stated)
LOAD REGULATION (0 to 100mA) COLD START / POWER-UP
LOAD REGULATION (2mA to 100mA) LDO POWER-UP
LINE REGULATION LDO POWER-DOWN
(c) 2004 California Micro Devices Corp. All rights reserved
09/22/04
430 N. McCarthy Blvd, #100, Milpitas, California 95035
Tel: (408) 263-3214 Fax: (408) 263-7846
www.calmicro.com
6
PRELIMINARY
CALIFORNIA MICRO DEVICES
CM3702
Typical Performance Characteristics (V_IN=5V, Cp=1uF, Cs=10uF, Cbyp=0.1uF, C_OUT=10uF unless stated)
Note: temperature quoted is ambient temperature, not die temperature
V _OUT w ith V _IN = 5V
5.10
5.05
5.00
I_OUT=0 I_OUT=30mA I_OUT=75mA I_OUT=100mA I_OUT=150mA
Voltage [V]
4.95
4.90 -50 -25 0 25 50 75 100 125 150 T emperature ['C]
V_OUT with V_IN = 3.0V, I_OUT= 100mA
5.1 5.05
5 4.5 4 3.5 Current [uA] 3 2.5 2 1.5 1
I_IN Leakage current (Pins 6, 7 = 0V)
V_OUT Voltage [V]
5 4.95 4.9 4.85 4.8 -50 -25 0 25 50 75 100 125
0.5 0 -50 -25 0 25 50 75 100 125 150
Temperature ['C]
Temperature ['C]
Bypass pin voltage
Unde rv oltage lockout
1.65 1.645 1.64 1.635
3 2.5 V_IN Voltage [V] 2 1.5 1 0.5 0
-50 -25 0 25 50 75 100 125 150
Voltage [V]
1.63 1.625 1.62 1.615 1.61 1.605 1.6
-50
-25
0
25
50
75
100
125
150
Temperature ['C]
Temperature ['C]
(c) 2004 California Micro Devices Corp. All rights reserved
09/22/04
430 N. McCarthy Blvd, #100, Milpitas, California 95035
Tel: (408) 263-3214 Fax: (408) 263-7846
www.calmicro.com
7
PRELIMINARY
CALIFORNIA MICRO DEVICES
Applications Information
CM3702
Ripple Frequency The charge pump internal oscillation frequency is about 250kHz. However, this is the continuous, free-running frequency, which is usually only seen while the charge pump is powering up. After the charge pump output voltage (CS) reaches approximately 5.8V, the charge pump pauses until the CS voltage drops to approximately 5.7V. Then the charge pump restarts and runs until the CS voltage is greater than approximately 5.8V, when it pauses again, and this process repeats. This gives rise to a sawtooth `ripple' waveform on CS which can have a much lower frequency than 250kHz. This mode of operation is necessary to conserve power - if it were not done this way then a much larger package with heatsink would be required. The frequency of this `ripple' is affected by V_IN, I_OUT, Cs capacitor value and Cp capacitor value. Guidelines for choosing values for external capacitors. (1) To find Cp: specify value of V_IN, and highest value of I_OUT: If V_IN= 3.3V +/- 5%, then minimum value of Cp(F) = I_OUT(mA) / 85 If V_IN= 5.0V +/- 10%, then minimum value of Cp(F) = I_OUT(mA) / 700 (2) Ci, the V_IN decoupling capacitor, should typically be much greater than Cp to prevent voltage droop during Cp charging. Excessive glitches on V_IN will affect the output voltage V_OUT. Typically Ci is 10X greater than Cp. But usually there are already some capacitors on this supply, so adding extra capacitors is not necessary - simply move an already-present low-ESR capacitor close to the CM3702. This is especially important for V_IN = 5V. (3) Choose value of Cs. Cs should be small to ensure that the ripple frequency is high, but Cs should be at least 2x greater than Cp otherwise the ripple amplitude will be very high. Reducing the value of Cs will increase the ripple frequency. Examples of Cs ripple frequencies: (Cs=10F, 25C) Cp=0.47F Cp=1F V_IN=3.14, I_OUT=15mA CS Frequency=46kHz V_IN=3.14, I_OUT=100mA CS Frequency=250kHz V_IN=3.60, I_OUT=15mA CS Frequency=35kHz V_IN=3.60, I_OUT=100mA CS Frequency=110kHz V_IN=4.50, I_OUT=70mA CS Frequency=76kHz V_IN=4.50, I_OUT=100mA CS Frequency=67kHz V_IN=5.50, I_OUT=70mA CS Frequency=56kHz V_IN=5.50, I_OUT=100mA CS Frequency=49kHz (4) Co, the V_OUT decoupling capacitor helps minimize noise and improve load regulation. 0.1F - 100F recommended. (5) Cbyp, the bypass capacitor helps reduce noise in the LDO. 0.1F recommended. After choosing external component values, check in-system performance (at min/max V_IN, max temperature, and min/max I_OUT). See troubleshooting guide on next page for tips if there are problems. Charge Pump Noise The charge pump is `digital' in operation and can produce digital noise at both the free-running frequency and at the ripple frequency. To minimize noise PCB grounding is important! This part requires short, low-impedance ground connections for DGND (pin 1), GND (pin 4), the V_IN decoupling capacitor (pin 2), the CS capacitor (pin 3), the Bypass decoupling capacitor (pin 5) and the V_OUT decoupling capacitor (pin 8). All decoupling capacitors and the Cs capacitor should be low-ESR ceramics. The Cp capacitor does NOT need to be low-ESR. Efficiency The power efficiency in % of the combined charge pump and LDO is approximately: 100 * (VOUT) / (VIN*2) Power Dissipation The dissipation of the part is approximately: ((VIN*2) - VOUT) * IOUT
(c) 2004 California Micro Devices Corp. All rights reserved
09/22/04
430 N. McCarthy Blvd, #100, Milpitas, California 95035
Tel: (408) 263-3214 Fax: (408) 263-7846
www.calmicro.com
8
PRELIMINARY
CALIFORNIA MICRO DEVICES
CM3702
The MSOP-10 package heats at a rate of about 200C/W (JA). (Note that this value is approximate because it depends upon the copper tracks and ground planes on the pcb.) If V_IN = 5V and I_OUT = 100mA then the power dissipation will be approximately 500mW. Multiplying this by the JA of 200, the part's internal temperature will be about 100C higher than the ambient temperature. If the ambient temperature is 70C then the internal temperature will be approximately 170C which will typically trigger the overtemperature circuit and depower the part. Internal temperature = Ambient temperature + ( JA * Power dissipation )
(Must be less than 170C)
Note that the evaluation pcb has a JA of less than 150C/W, based upon measured performance. How to reduce the power dissipation of the part, and how to get more than 100mA If V_IN = 5V typ., then the charge pump / LDO combination is capable of providing more than 100mA. The only problem is power dissipation. If the input voltage is lowered using an external diode then the output current can be increased without causing the part to overheat:
Using this circuit I_OUT can be 200mA if V_IN = 4.75V, and yet the part will not overheat even if V_IN = 5.25V, I_OUT=200mA and the ambient temperature is 85C. Warnings The charge pump output CS (pin 3) must not be shorted to GND or held below its internally-set voltage while the part is powered. This usually results in the destruction of the part. With V_IN = 5V, the maximum current that can be continuously drawn from CS is approximately 100mA dc. Never short Cp+ (pin 9) to Cp- (pin 10). This will cause large currents to flow from V_IN to DGND through the part, usually causing its destruction. This will happen even if EN_Chip and EN_LDO are off. Troubleshooting Guide 1. Is the output voltage is drooping under heavy loads? Perhaps the charge pump cannot provide the necessary current. Try increasing the value of Cp. If that does not work then is V_IN too low? Is V_IN dropping during the Cp charging cycle? If V_IN is not suitably decoupled and drops below 3.1V then the available current will be very low. 2. Is the output voltage oscillating between 5V and 0V? The part may be reaching its overtemperature limit. Reduce current consumption, reduce JA or add an external diode on the input to reduce V_IN. 3. Is the part too noisy? Try increasing value (or reducing ESR) of Cs, Ci, Co, Cb. At minimum current the charge pump ripple frequency will be low. If VOUT noise is at the charge pump ripple frequency then change values of Cp and Cs. Reducing the input voltage VIN will reduce the charge pump ripple frequency noise on VOUT. 4. Will the part power up? Pin 6 must be HIGH to power up. Even if pin 7 is HIGH, pin 6 must also be high to power up. 5. Can the cold start power-up time be reduced? Yes, by reducing the value of the BYP capacitor.
(c) 2004 California Micro Devices Corp. All rights reserved
09/22/04
430 N. McCarthy Blvd, #100, Milpitas, California 95035
Tel: (408) 263-3214 Fax: (408) 263-7846
www.calmicro.com
9
PRELIMINARY
CALIFORNIA MICRO DEVICES
CM3702
(c) 2004 California Micro Devices Corp. All rights reserved
09/22/04
430 N. McCarthy Blvd, #100, Milpitas, California 95035
Tel: (408) 263-3214 Fax: (408) 263-7846
www.calmicro.com
10
PRELIMINARY
CALIFORNIA MICRO DEVICES
CM3702
(c) 2004 California Micro Devices Corp. All rights reserved
09/22/04
430 N. McCarthy Blvd, #100, Milpitas, California 95035
Tel: (408) 263-3214 Fax: (408) 263-7846
www.calmicro.com
11

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