CALMIRCO CM3702-50DF

PRELIMINARY
CM3702
CALIFORNIA MICRO DEVICES
Micropower Low-Noise Charge-Pump and Linear Regulator
Features
•
•
•
•
•
•
•
•
•
Block Diagram
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
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
Lead-free Finish
Pins
Package
Ordering Part
Number
Part Marking
Ordering Part
Number
Part Marking
10
MSOP-10
CM3702-50MR
3702 50S
CM3702-50MS
3702 50
10
TDFN-10
CM3702-50DF
CM370 250DF
CM3702-50DE
CM370 250DE
© 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
CM3702
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.
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 500Ω 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
© 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
CM3702
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
Unit
V
V
V
°C
Unit
V
°C
°C/W
mA
µF
µF
Symbol
VCS
Electrical Operating Characteristics
(VIN = 5.0V; IOUT =100mA; COUT=10uF; CP = 1µF; CS = 10µF; unless specified otherwise)
Parameter
Conditions
MIN
TYP
MAX
5.5
5.8
7
Charge pump output voltage
VOUT = 5V, 1mA ≤ IOUT ≤ 100mA;
VOUT
Regulator Output Voltage
VIN = 4.0V; 1mA ≤ IOUT ≤ 100mA;
VR LOAD
Load Regulation
IOUT = 1mA to 100mA
0.2
%
VR LINE
Line Regulation
0.02
%
RDISCHG
VOUT Discharge Resistance
Vary VIN from 3.0V to 5.0V
LDO regulator disabled
EN2 (pin 6) grounded; VIN = 5V
Shutdown (EN2 grounded)
500
Ω
IGND
LDO Regulator Ground Current via
GND pin
Regulator Enabled, IOUT = 0mA
180
µA
Regulator Enabled, IOUT = 100mA
180
µA
EN1 (pin 7) grounded, VIN = 5.0V
1
IDGND
Charge Pump Shutdown Current
via DGND pin
PSRR
Power Supply Rejection
eNO
Output Voltage Noise
eNO
Output Voltage Noise
VIH
VIL
ILIM
ISC
TJSD
THYS
EN1, EN2 Input High threshold
EN1, EN2 Input Low threshold
Overload Current Limit
Output Short Circuit Current
Thermal Shutdown Junction Temp
Thermal Shutdown Hysteresis
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)
4.85
5.15
1
10
10
V
µA
µA
42
42
dB
dB
35
µVrms
38
µVrms
300
200
170
25
V
V
mA
mA
°C
°C
2.0
0.5
200
100
UNIT
V
© 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
CM3702
CALIFORNIA MICRO DEVICES
Typical Performance Characteristics (T=25°C)
CM3702 noise spectrum (Cp=0.47uF, Cs=1.5uF, Co=Cbyp=0.1uF, Iout=100mA)
1.00E-03
Voltage [V]
1.00E-04
noise floor
Cs=1.5uF
1.00E-05
1.00E-06
1.00E-07
1.00E-08
10
100
1000
10000
100000
Frequency [Hz ]
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
PSRR [dB]
50.0
40.0
30.0
20.0
10.0
0.0
10
100
1000
10000
100000
Frequency [Hz]
Measured by forcing VIN voltage to 3.3V & 5.0V dc, then sweeping 100mV ac on VIN.
COUT = 10uF, CBYP = 0.1uF
© 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
CM3702
CALIFORNIA MICRO DEVICES
Typical Performance Characteristics (T=25°C, Cp=1uF, Cs=10uF, Cbyp=0.1uF, C_OUT=10uF unless stated)
V_OUT v s. I_OUT (V_IN = 5V)
V_EN Threshold vs. V_IN
5.1
5.08
2
5.06
1.9
1.8
1.7
5.02
V_EN [V]
V_OUT [V]
5.04
5
4.98
4.96
1.6
1.5
1.4
1.3
4.94
1.2
4.92
1.1
4.9
0
20
40
60
80
1
100
3
3.5
4
I_OUT [mA]
5
5.5
5
5.5
I_IN vs. V_IN
V_OUT vs. V_IN
300
5.1
I_OUT=0mA
5.08
250
I_OUT=100mA
I_IN [uA]
5.06
5.04
V_OUT [V]
4.5
V_IN [V]
5.02
5
4.98
4.96
4.94
200
150
100
50
4.92
4.9
3
3.5
4
4.5
5
0
5.5
3
V_IN [V]
3.5
4
4.5
V_IN [V]
CS pin vs. V_IN
I_IN vs. I_OUT
7
250
6.75
200
6
I_IN [mA]
CS pin [V]
6.5
6.25
5.75
5.5
150
100
5.25
V_IN=3.1V
50
5
3
3.5
4
4.5
5
V_IN=5V
5.5
0
V_IN [V]
0
20
40
60
80
100
I_OUT [mA]
Overcurrent characteristic (LDO only)
400
6
300
5
200
V_O UT [V]
V DO [mV]
DROPOUT VOLTAGE (LDO ONLY)
at T=150'C, T=85'C and T=25'C
100
0
0
10
20
30
40
50
60
70
80
90
100
I_OUT [mA]
4
3
2
1
0
0
0.1
0.2
0.3
0.4
0.5
I_OUT [A]
© 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
5
PRELIMINARY
CM3702
CALIFORNIA MICRO DEVICES
Typical Performance Characteristics (T=25°C, 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
© 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
CM3702
CALIFORNIA MICRO DEVICES
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
Voltage [V]
5.05
I_OUT=0
I_OUT=30mA
I_OUT=75mA
I_OUT=100mA
I_OUT=150mA
5.00
4.95
4.90
-50
-25
0
25
50
75
100
125
150
T emperature ['C]
I_IN Leakage current (Pins 6, 7 = 0V)
V_OUT with V_IN = 3.0V, I_OUT= 100mA
5
5.1
4.5
4
3.5
5
Current [uA]
V_OUT Voltage [V]
5.05
4.95
4.9
3
2.5
2
1.5
4.85
1
4.8
0.5
-50
-25
0
25
50
75
100
125
0
Temperature ['C]
-50
-25
0
25
50
75
100
125
150
Temperature ['C]
Bypass pin voltage
Unde rv oltage lockout
1.65
3
1.645
1.64
2.5
V_IN Voltage [V]
Voltage [V]
1.635
1.63
1.625
1.62
1.615
1.61
2
1.5
1
0.5
1.605
0
1.6
-50
-25
0
25
50
75
100
125
150
Temperature ['C]
-50
-25
0
25
50
75
100
125
150
Temperature ['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
CM3702
Applications Information
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(µF) = I_OUT(mA) / 85
If V_IN= 5.0V +/- 10%, then minimum value of Cp(µF) = 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=10µF, 25°C)
Cp=0.47µF
Cp=1µF
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. 0.1µF - 100µF
recommended.
(5) Cbyp, the bypass capacitor helps reduce noise in the LDO. 0.1µF 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
© 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
CM3702
CALIFORNIA MICRO DEVICES
The MSOP-10 package heats at a rate of about 200°C/W (θJA). (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 θJA of 200, the part’s internal temperature will be about 100°C higher
than the ambient temperature. If the ambient temperature is 70°C then the internal temperature will be approximately
170°C which will typically trigger the overtemperature circuit and depower the part.
Internal temperature = Ambient temperature + ( θJA * Power dissipation )
(Must be less than 170°C)
Note that the evaluation pcb has a θJA of less than 150°C/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 85°C.
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 θJA 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.
© 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
© 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
© 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