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AAT3110
MicroPowerTM Regulated Charge Pump
General Description
The AAT3110 ChargePumpTM is a MicroPower switched-capacitor voltage converter that delivers a regulated output. No external inductor is required for operation. Using three small capacitors, the AAT3110 can deliver up to 150mA to the voltage regulated output. The AAT3110 features very low quiescent current and high efficiency over a large portion of its load range making this device ideal for battery-powered applications. Furthermore, the combination of few external components and small package size keeps the total converter board area to a minimum in space restricted applications. The AAT3110 operates in an output-regulated voltage doubling mode. The regulator uses a pulse-skipping technique to provide a regulated output from a varying input supply. The AAT3110 contains a thermal management circuit to protect the device under continuous output short circuit conditions. The AAT3110 is available in a surface mount 6-pin SOT23 or 8-pin SC70JW package and is rated from -40 to 85C. The AAT3110 ChargePumpTM is a member of AnalogicTech's Total Power Management IC product family.
Features
* *
ChargePumpTM
* * *
*
* * * * *
Step-up type voltage converter Input Range * AAT3110-5: 2.7V to 5V * AAT3110-3.3: 2.3V to 3.3V MicroPower consumption: 13A 5V, 3.3V Regulated 4% output 5V Output Current * 100mA with VIN 3.0V * 50mA with VIN 2.7V 3.3V Output Current * 150mA with VIN 2.7V * 100mA with VIN 2.3V High Frequency 750 kHz operation Shutdown mode draws less than 1A Short-circuit/over-temperature protection 2kV ESD Rating SC70JW-8 or SOT23-6 package
Preliminary Information
Applications
* * * * * * * Cellular Phones Portable Communication Devices Handheld Electronics Digital Cameras PDAs Battery Back Up Supplies LED/Display Back Light Driver
Typical Operating Circuits
AAT3110
VOUT
COUT VOUT C+
1uF
10uF
GND
VIN CCIN
VIN
ON/OFF
SHDN
10uF
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AAT3110
MicroPowerTM Regulated Charge Pump
Pin Descriptions
Pin #
SOT-23-6 SC70JW-8
Symbol
VOUT GND SHDN CVIN C+
Function
Regulated output pin. Bypass this pin to ground with at least 6.8F low ESR capacitor Ground connection Shutdown input. Active low signal disables the converter. Flying capacitor negative terminal Input supply pin. Bypass this pin to ground with at least 6.8F low ESR capacitor Flying capacitor positive terminal
1 2 3 4 5 6
1 2, 3, 4 5 6 7 8
Pin Configuration
SOT23-6 SC70JW-8
6
VOUT GND SHDN
1
C+ VIN C-
2
5
3
4
VOUT GND GND GND
1 2
8 7
3 4
6 5
C+ VIN CSHDN
1
1 2
2
2
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AAT3110
MicroPowerTM Regulated Charge Pump
Absolute Maximum Ratings
Symbol
VIN VOUT VSHDN tSC TJ TLEAD VESD
(TA=25C unless otherwise noted) Value
-0.3 to 6 -0.3 to 6 -0.3 to 6 Indefinite -40 to 150 300 2000
Description
VIN to GND VOUT to GND SHDN to GND Output to GND Short-Circuit Duration Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec) ESD Rating1 -- HBM
Units
V V V s C C V
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. Note 1: Human body model is a 100pF capacitor discharged through a 1.5k resistor into each pin.
Thermal Information
Symbol
JA PD
Description
Maximum Thermal Resistance (SOT23-6 or SC70JW-8) Maximum Power Dissipation (SOT23-6 or SC70JW-8)
Rating
150 667
Units
C/W mW
Note 2: Mounted on an FR4 board.
Electrical Characteristics (TA = -40 to 85C unless otherwise noted.
CFLY=1F, CIN=10F, COUT=10F) AAT3110-5 Symbol
VIN IQ VOUT ISHDN VRIPPLE fOSC VIH VIL IIH IIL tON ISC
Typical values are at TA=25C,
Description
Input Voltage No Load Supply Current Output Voltage Shutdown Supply Current Ripple Voltage Efficiency Frequency SHDN Input Threshold High SHDN Input Threshold Low SHDN Input Current High SHDN Input Current Low VOUT Turn-on time Short-circuit current3
Conditions
VOUT=5.0V 2.7V < VIN < 5V, IOUT=0mA, SHDN=VIN 2.7V < VIN < 5V, IOUT 50mA 3.0V < VIN < 5V, IOUT 100mA 2.7V < VIN < 3.6V, IOUT =0mA, VSHDN=0 3.6V < VIN < 5V, IOUT =0mA, VSHDN=0 VIN = 3V, IOUT = 50mA VIN = 3V, IOUT = 100mA VIN = 3V, IOUT = 50mA Oscillator Free Running
Min
2.7 4.8 4.8
Typ
13 5 5 0.01 25 30 83 750
Max
VOUT 30 5.2 5.2 1 2.5
Units
V A V V A mVP-P % kHz V V A A ms mA
1.4 SHDN = VIN SHDN = GND VIN = 3V, IOUT = 0mA VIN = 3V, VOUT = GND, SHDN = 3V -1 -1 0.2 300 0.3 1 1
Note 3: Under short-circuit conditions, the device may enter overtemperature protection mode.
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AAT3110
MicroPowerTM Regulated Charge Pump
Electrical Characteristics (TA = -40 to 85C unless otherwise noted.
CFLY=1F, CIN=10F, COUT=10F) AAT3110-3.3 Symbol
VIN IQ VOUT ISHDN VRIPPLE fOSC VIH VIL IIH IIL tON ISC
Typical values are at TA=25C,
Description
Input Voltage No Load Supply Current Output Voltage Shutdown Supply Current Ripple Voltage Efficiency Frequency SHDN Input Threshold High SHDN Input Threshold Low SHDN Input Current High SHDN Input Current Low VOUT Turn-on time Short-circuit current
Conditions
VOUT=3.3V 2.3V < VIN < 3.3V, IOUT=0mA 2.3V < VIN < 3.3V, IOUT=50mA 2.5V < VIN < 3.3V, IOUT=100mA 2.3V < VIN < 3.3V, IOUT =0mA, VSHDN=0 VIN = 2.3V, IOUT = 50mA VIN = 2.3V, IOUT = 25mA Oscillator Free Running
Min
2.3 3.17 3.17
Typ
10 3.30 3.30 0.01 20 71 750
Max
VOUT 30 3.43 3.43 1
Units
V A V V A mVP-P % kHz V V A A ms mA
1.4 SHDN = VIN SHDN = GND VIN = 3V, IOUT = 0mA VIN = 3V, VOUT = GND, SHDN = 3V -1 -1 0.2 300 0.3 1 1
4
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AAT3110
MicroPowerTM Regulated Charge Pump
Typical Characteristics--AAT3110-5
(Unless otherwise noted, VIN = 3V, CIN=COUT=10F, CFLY=1F, TA = 25C) Output Voltage vs. Output Current AAT3110-5
5.15 24 5.1 5.05 5 4.95 4.9 4.85 4.8 0 50 100 150
Supply Current vs. Supply Voltage AAT3110-5
Supply Current (A) IOUT=0 A CFLY=1F VSHDN=VIN
Output Voltage (V)
VIN=3.6
22 20 18 16 14 12 10 2.5
VIN=3.0 VIN=2.7 VIN=3.3
3
3.5
4
4.5
5
5.5
Output Current (mA)
Supply Voltage (V)
Supply Current vs VSHDN AAT3110-5
30 25 20 95%
Efficiency vs. Supply Voltage AAT3110-5
IOUT=0A Efficiency (%)
90% 85% 80% 75% 70% 65% 60% 55% 50% 45% 2.70 3.00 3.50 4.00 4.50 5.00
25 mA
VIN=5.5V
Supply Current (A)
VIN=3.3V
15 10 5 0 0 1 2 3 4 5
50 mA 100 mA
VIN=2.8V
Supply Voltage (V)
VSHDN Control Voltage (V)
Efficiency vs. Load Current AAT3110-5
Oscillator Frequency (kHz)
100% 90% 80%
Oscillator Frequency vs. Supply Voltage AAT3110-5
1200 1100 1000 900 800 700 600 500 400 2.7
VIN = 2.7V
Efficiency (%)
- 40 C
70% 60% 50% 40% 30% 20% 10% 0% 0.01 0.1 1 10 100 1000
VIN = 3.6V VIN = 3.3V
VIN = 3.0V
25 C 85 C
3.0 3.5 4.0 4.5 5.0
Load Current (mA)
Supply Voltage (V)
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AAT3110
MicroPowerTM Regulated Charge Pump
Typical Characteristics--AAT3110-5
(Unless otherwise noted, VIN = 3V, CIN=COUT=10F, CFLY=1F, TA = 25C) Startup Time with 50 mA Load AAT3110-5
SHDN 2V/DIV SHDN 2V/DIV
Startup Time with 100 mA Load AAT3110-5
VOUT 1V/DIV
VOUT 1V/DIV
50S/DIV
50S/DIV
Load Transient Response for 50mA AAT3110-5
IOUT 0mA to 50mA 20mA/DIV VIN=3.0V VOUT AC COUPLED 20mV/DIV 50S/DIV VOUT AC COUPLED 20mV/DIV IOUT 0mA to 100 mA 50mA/DIV
Load Transient Response for 100mA AAT3110-5
VIN=3.0V
50S/DIV
Output Ripple with IOUT=50 mA AAT3110-5
Output Ripple with IOUT=100 mA AAT3110-5
VOUT AC Coupled 10 mV/DIV
VOUT AC Coupled 10 mV/DIV VIN=3.0V 2S/DIV VIN=3.0V
2S/DIV
6
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AAT3110
MicroPowerTM Regulated Charge Pump
Typical Characteristics--AAT3110-5
(Unless otherwise noted, VIN = 3V, CIN=COUT=10F, CFLY=1F, TA = 25C) VIN vs. VIH
1.00 0.95 0.90 0.85 1.00
VIN vs. VIL
0.95 0.90 0.85
-40C
-40C 25C
VIH (V)
VIL (V) 85C
0.80 0.75 0.70 0.65 0.60 0.55 0.50 2.0
25C
0.80 0.75 0.70 0.65 0.60 0.55
85C
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0.50 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VIN (V)
VIN (V)
Normalized Output Voltage (%)
VSHDN Threshold vs. Supply Voltage AAT3110-5
1.00 0.95
Normalized Output Voltage vs Temperature
1.20% 1.00% 0.80% 0.60% 0.40% 0.20% 0.00% -0.20% -0.40% -0.60% -50 -25 0 25 50 75 100 125
IOUT=25mA
VSHDN Threshold (V)
0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
VIH
VIL
Temperature (C)
VIN (V)
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AAT3110
MicroPowerTM Regulated Charge Pump
Typical Characteristics--AAT3110-3.3
(Unless otherwise noted, VIN = 2.3V, CIN=COUT=10F, CFLY=1F, TA = 25C) Output Voltage vs. Output Current AAT3110-3.3
3.4 24 3.35 3.3 3.25 3.2
Supply Current vs. Supply Voltage AAT3110-3.3
Supply Current (A) IOUT=0 A CFLY=1F VSHDN=VIN
Output Voltage (V)
VIN=3V VIN=2.7V
22 20 18 16 14 12 10
VIN=2.3V
3.15 3.1 0 50 100 150 200
2.3
2.5
2.7
2.9
3.1
3.3
Output Current (mA)
Supply Voltage (V)
Supply Current vs VSHDN AAT3110-3.3
30
Efficiency vs. Supply Voltage AAT3110-3.3
IOUT=0A
80 70
Supply Current (A)
25
Efficiency (%)
20
60 50 40 30 20 10 0 2 2.5 3 3.5
VIN=3.3V
15 10 5 0 0 1 2 3 3.3
VIN=2.8V
IOUT=100mA
VSHDN Control Voltage (V)
Supply Voltage (V)
Efficiency vs. Output Current AAT3110-3.3
Oscillator Frequency (kHz)
100.0% 90.0% 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% 0.01
Oscillator Frequency vs. Supply Voltage AAT3110-3.3
1200 1100 1000 900 800 700 600 500 400 2.3 2.5 2.7 2.9 3.1 3.3
- 40C 25C 85C
VIN=2.25V
0.1
1
10
100
I-Load (mA)
Supply Voltage (V)
8
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AAT3110
MicroPowerTM Regulated Charge Pump
Typical Characteristics--AAT3110-3.3
(Unless otherwise noted, VIN = 2.3V, CIN=COUT=10F, CFLY=1F, TA = 25C) Startup Time with 50 mA Load AAT3110-3.3
SHDN 2V/DIV SHDN 2V/DIV
Startup Time with 100 mA Load AAT3110-3.3
VOUT 1V/DIV 100S/DIV
VOUT 1V/DIV 100S/DIV
Load Transient Response for 50mA AAT3110-3.3
IOUT 0mA to 50mA 20mA/DIV VOUT AC COUPLED 20mV/DIV 20S/DIV VIN=2.3V COUT=10F IOUT 0mA to 100mA 50mA/DIV VOUT AC COUPLED 20mV/DIV
Load Transient Response for 100mA AAT3110-3.3
VIN=2.3V COUT=10F
50S/DIV
Output Ripple for 50mA Load AAT3110-3.3
Output Ripple for 100mA Load AAT3110-3.3
VOUT AC Coupled 10mV/DIV
VOUT AC Coupled 10mV/DIV
VIN=2.3V
VIN=2.3V
2s/DIV
2s/Div.
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AAT3110
MicroPowerTM Regulated Charge Pump
Typical Characteristics--AAT3110-3.3
(Unless otherwise noted, VIN = 2.3V, CIN=COUT=10F, CFLY=1F, TA = 25C) VIN vs. VIH AAT3110-3.3
1.00 0.95 0.90 0.85 1.00 0.95
VIN vs. VIL AAT3110-3.3
-40C 25C
0.90 0.85
VIH (V)
VIL (V)
0.80 0.75 0.70 0.65 0.60 0.55 0.50 2.0
0.80 0.75 0.70 0.65
-40C 25C
85C
0.60 0.55 0.50 2.0 2.2 2.4 2.6
85C
2.8 3.0 3.2 3.3
2.2
2.4
2.6
2.8
3.0
3.2 3.3
VIN (V)
VIN (V)
VSHDN Threshold vs. Supply Voltage AAT3110-3.3
1.00
VSHDN Threshold (V)
0.95 0.90 0.85 0.80 0.75 0.70 0.65 0.60 0.55 0.50 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.3
VIH
VIL
VIN (V)
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AAT3110
MicroPowerTM Regulated Charge Pump
Functional Block Diagram
VIN
S2
SHDN
CONTROL
S1
C+ C-
VREF
S4
S3
VOUT
+
GND
Functional Description
Operation (Refer to block diagram)
The AAT3110 uses a switched capacitor charge pump to boost an input voltage to a regulated output voltage. Regulation is achieved by sensing the charge pump output voltage through an internal resistor divider network. A switched doubling circuit is enabled when the divided output drops below a preset trip point controlled by an internal comparator. The charge pump switch cycling enables four internal switches at two non-overlapping phases. During the first phase, switches S1 and S4 are switched on (short) and switches S2 and S3 are off (open). The flying capacitor CFLY is charged to a level approximately equal to input voltage VIN. On the second phase, switches S1 and S4 are turned off (open), S2 and S3 are turned on (short). The low side of the flying capacitor CFLY is connected to GND during the first phase. During the second phase, the flying capacitor CFLY is switched so that the low side is connected to VIN. The voltage at the high side of the flying capacitor CFLY is bootstrapped to 2xVIN and connected to output through a switch. For each cycle phase, charge from input node VIN is transported from a lower voltage to a higher voltage. This cycle repeats itself until the output node voltage is high enough to exceed the preset input threshold of the control comparator. When the output voltage exceeds the internal trip point level, the switching cycle stops and the charge pump circuit is tem3110.2001.9.0.92
porarily placed in an idle state. When idle, the AAT3110 has a quiescent current of 13A or less. The closed loop feed back system containing the voltage sense circuit and control comparator allows the AAT3110 to provide a regulated output voltage to the limits of the input voltage and output load current. The switching signal, which drives the charge pump is created by an integrated oscillator within the control circuit block. The free running charge pump switching frequency is approximately 750kHz. The switching frequency under an active load is a function of VIN, VOUT, COUT and IOUT. For each phase of the switching cycle, the charge transported from VIN to VOUT can be approximated by the following formula: VPHASE CFLYx(2xVIN-VOUT) The relative average current that the charge pump can supply to the output may be approximated by the following expression: IOUT(AVG) CFLYx(2xVIN-VOUT)xFSW The AAT3110 has complete output short circuit and thermal protection to safeguard the device under extreme operating conditions. An internal thermal protection circuit senses die temperature and will shut down the device if the internal junction temperature exceeds approximately 145C. The charge pump will remain disabled until the fault condition is relieved. 11
AAT3110
MicroPowerTM Regulated Charge Pump
Applications Information
External Capacitor Selection
Careful selection of the three external capacitors CIN, COUT and CFLY is very important because they will affect turn on time, output ripple and transient performance. Optimum performance will be obtained when low ESR (<100m) ceramic capacitors are used for CIN and COUT and CFLY. In general, low ESR may be defined as less then 200m . If desired for a particular application, low ESR Tantalum capacitors may be substituted; however optimum output ripple performance may not be realized. Aluminum Electrolytic capacitors are not recommended for use with the AAT3110 due the their inherent high ESR characteristic. Typically as a starting point, a capacitor value of 10F should be used for CIN and COUT with 1F CFLY when the AAT3110 is used under maximum output load conditions. Lower values for CIN, COUT and CFLY may be utilized for light load current applications. Applications drawing a load current of 10mA or less may use a CIN and COUT capacitor value as low as 1F and a CFLY value of 0.1F. CIN and COUT may range from 1F for light loads to 10F or more for heavy output load conditions. CFLY may range from 0.01F to 2.2F or more. If CFLY is increased, COUT should also be increased by the same ratio to minimize output ripple. As a basic rule, the ratio between CIN, COUT and CFLY should not exceed a ratio of 10 to 1. The compromise for lowering the value of CIN, COUT and the flying capacitor CFLY is the output ripple voltage may be increased. In any case, if the external capacitor values deviate greatly from the recommendation of CIN = COUT = 10F and CFLY = 1F, the AAT3110 output performance should be evaluated to assure the device meets the application requirements. In applications where the input voltage source has very low impedance, it is possible to omit the CIN capacitor. However, if CIN is not used, circuit performance should be evaluated to assure desired operation is achieved. Under high peak current operating conditions that are typically experienced during circuit start up or when load demands create a large inrush current, poor output voltage regulation can result if the input supply source impedance
is high, or if the value of CIN is too low. This situation can be remedied by increasing the value of CIN.
Capacitor Characteristics
Ceramic composition capacitors are highly recommended over all other types of capacitors for use with the AAT3110. Ceramic capacitors offer many advantages over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has very low ESR, is lower cost, has a smaller PCB footprint and is non-polarized. Low ESR ceramic capacitors help maximize charge pump transient response. Since ceramic capacitors are non-polarized, they are not prone to incorrect connection damage. Equivalent Series Resistance (ESR): ESR is a very important characteristic to consider when selecting a capacitor. ESR is a resistance internal to a capacitor, which is caused by the leads, internal connections, size or area, material composition and ambient temperature. Typically capacitor ESR is measured in milliohms for ceramic capacitors and can range to more then several ohms for tantalum or aluminum electrolytic capacitors. Ceramic Capacitor Materials: Ceramic capacitors less then 0.1F are typically made from NPO or COG materials. NPO and COG materials typically have tight tolerance and are very stable over temperature. Large capacitor values are typically composed of X7R, X5R, Z5U or Y5V dielectric materials. Large ceramic capacitors, typically greater than 2.2F are often available in low cost Y5V and Z5U dielectrics. If these types of capacitors are selected for use with the charge pump, the nominal value should be doubled to compensate for the capacitor tolerance which can vary more than 50% over the operating temperature range of the device. A 10F Y5V capacitor could be reduced to less than 5F over temperature, this could cause problems for circuit operation. X7R and X5R dielectrics are much more desirable. The temperature tolerance of X7R dielectric is better than 15%. Capacitor area is another contributor to ESR. Capacitors that are physically large will have a lower ESR when compared to an equivalent material smaller capacitor. These larger devices can improve circuit transient response when compared to an equal value capacitor in a smaller package size.
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AAT3110
MicroPowerTM Regulated Charge Pump
Applications Information
Charge Pump Efficiency
The AAT3110 is a regulated output voltage doubling charge pump. The efficiency () can simply be defined as a linear voltage regulator with an effective output voltage that is equal to two times the input voltage. Efficiency () for an ideal voltage doubler can typically be expressed as the output power divided by the input power. = POUT / PIN In addition, with an ideal voltage doubling charge pump the output current may be expressed as half the input current. The expression to define the ideal efficiency () can be rewritten as: =POUT/PIN=(VOUTxIOUT)/(VINx2IOUT)=VOUT/2VIN (%) = 100(VOUT / 2VIN) For a charge pump with an output of 5 volts and a nominal input of 3.0 volts, the theoretical efficiency is 83.3%. Due to internal switching losses and IC quiescent current consumption, the actual efficiency can be measured at 82.7%. These figures are in close agreement for output load conditions from 1mA to 100mA. Efficiency will decrease as load current drops below 0.05mA or when level of VIN approaches VOUT. Refer to the Typical Characteristics section for measured plots of efficiency versus input voltage and output load current for the given charge pump output voltage options.
thermal protection system will cycle on and off if an output short circuit condition persists. This will allow the AAT3110 to operate indefinitely a short circuit condition without damage to the device.
Output Ripple and Ripple Reduction
There are several factors that determine the amplitude and frequency of the charge pump output ripple, the values of COUT and CFLY, the load current IOUT and the level of VIN. Ripple observed at VOUT is typically a sawtooth waveform in shape. The ripple frequency will vary depending on the load current IOUT and the level of VIN. As VIN increases the ability of the charge pump to transfer charge from the input to the output becomes greater, as it does, the peak-to-peak output ripple voltage will also increase. The size and type of capacitors used for VIN. COUT and CFLY have an effect on output ripple. Since output ripple is associated with the R/C charge time constant of these two capacitors, the capacitor value and ESR will contribute to the resulting charge pump output ripple. This is why low ESR capacitors are recommended for use in charge pump applications. Typically, output ripple is not greater than 50mVP-P when VIN = 3.0V, VOUT = 5.0V, COUT = 10F and CFLY = 1F. When the AAT3110 is used in light output load applications where IOUT < 10mA, the flying capacitor CFLY value can be reduced. The reason for this effect is when the charge pump is either under very light load conditions the transfer of charge across CFLY is greater during each phase of the switching cycle. The result is higher ripple seen at the charge pump output. This effect will be reduced by decreasing the value of CFLY. Caution should be observed when decreasing the flying capacitor. If the output load current rises above the nominal level for the reduced CFLY value, charge pump efficiency can be compromised. There are several methods that can be employed to reduce output ripple depending upon the requirements of a given application. The most simple and straightforward technique is to increase the value of the COUT capacitor. The nominal 10F COUT capacitor can be increased to 22F or more. Larger values for the COUT capacitor (22F and greater) will by nature have lower ESR and can improve both high and low frequency components of the charge
Short Circuit and Thermal Protection
In the event of a short circuit condition, the charge pump can draw a much as 100mA to 400mA of current from VIN. This excessive current consumption due to an output short circuit condition will cause a rise in the internal IC junction temperature. The AAT3110 has a thermal protection and shutdown circuit that continuously monitors the IC junction temperature. If the thermal protection circuit senses the die temperature exceeding approximately 145C, the thermal shutdown will disable the charge pump switching cycle operation. The thermal limit system has 10C of system hysteresis before the charge pump can reset. Once the over current event is removed from the output and the junction temperature drops below 135C, the charge pump will then become active again. The
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AAT3110
MicroPowerTM Regulated Charge Pump
Applications Information
and low frequency components of the charge pump output ripple response. If a higher value tantalum capacitor is used for COUT to reduce low frequency ripple elements, a small 1F low ESR ceramic capacitor should be added in parallel to the tantalum capacitor (see Figure 1). The reason for this is tantalum capacitors typically have higher ESR than equivalent value ceramic capacitors and are less able to reduce high frequency components of the output ripple. The only disadvantage to using large values for the COUT capacitor is the AAT3110 device turn-on time and in-rush current may be increased. If additional ripple reduction is desired, an R/C filter can be added to the charge pump output in addition to the COUT capacitor (see Figure 2). An R/C filter will reduce output ripple by primarily attenuating high frequency components of the output ripple waveform. The low frequency break point for the R/C filter will significantly depend on the capacitor value selected.
Layout Considerations
High charge pump switching frequencies and large peak transient currents mandate careful printed circuit board layout. As a general rule for charge pump boost converters, all external capacitors should be located as close as possible to the device package with minimum length trace connections. Maximize the ground plane around the AAT3110 charge pump and make sure all external capacitors are connected to the immediate ground plane. A local component side ground plane is recommended. If this is not possible due the layout design limitations, assure good ground connections by the use of large or multiple pcb via's. Refer to the following AAT3110 evaluation board for an example of good charge pump layout design (Figures 3 through 5).
VOUT (5V)
COUT2 1F
COUT1 22F
+
VOUT GND
C+ CFLY 1F
+
AAT3110
VIN
CIN 10F
VIN (2.7V to 5V)
ON/OFF
SHDN
C-
Figure 1: Application using tantalum capacitor
VOUT (5V)
RFILTER 1.5 ohms
VOUT
CFILTER 33F
C+ CFLY 1F CIN 10F
COUT 10F
AAT3110
GND VIN
VIN (2.7V to 5V)
ON/OFF
SHDN
C-
Figure 2: Application with output ripple reduction filter
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AAT3110
MicroPowerTM Regulated Charge Pump
Figure 3: Evaluation board top side silk screen layout / assembly drawing
Figure 4: Evaluation board component side layout
Figure 5: Evaluation board component side layout
Typical Application Circuits
VOUT (5V)
COUT 10F
VOUT GND
C+ CFLY 1F CIN 10F
AAT3110-5
VIN
VIN (2.7V to 5V)
ON/OFF
SHDN
C-
Figure 6: Typical charge pump boost converter circuit
CFLY 1F
VIN (USB Port Vout)
CVIN
C+ VOUT
SHDN CIN 10F
VOUT 5V 100mA
COUT 10F
AAT3110-5
GND
GND (USB Port Return)
Figure 7: 5 Volt, 100mA supply powered from a USB port
GND
3110.2001.9.0.92
15
AAT3110
MicroPowerTM Regulated Charge Pump
VIN
LI-Ion Battery 2.7V to 4.2V 10F
VOUT C+
10F 1F 120 120 120 120
AAT3110-5
SHDN C-
ON/OFF
Figure 8: 5 Volt LED or Display Driver from a Li-Ion Battery Source
VIN = 3.0V to 5V
VIN CIN 10F
VOUT C+
VOUT = 5V IOUT = 200mA
AAT3110-5 (A)
SHDN GND C-
SHDN
CFLY 1F
VIN
VOUT C+ COUT 10F
AAT3110-5 (B)
SHDN GND C-
CFLY 1F
Figure 9: 5 Volt, 200mA Step-Up Supply from a 3.0V to 5V Source.
16
3110.2001.9.0.92
AAT3110
MicroPowerTM Regulated Charge Pump
Ordering Information
Output Voltage 3.3V 5.0V 3.3V 5.0V Package SOT-23-6 SOT-23-6 SC70JW-8 SC70JW-8 Marking Part Number Bulk N/A N/A N/A N/A Tape and Reel AAT3110IGU-3.3-T1 AAT3110IGU-5-T1 AAT3110IJS-3.3-T1 AAT3110IJS-5-T1
Package Information
SOT-23-6
e1 e t
Dim A A1 A2 b c D E E1 e e1 f L L1 L2 t
L2
E
L
f D
GAUGE PLANE
C
Millimeters Min Max 0.95 1.45 0.05 0.15 0.90 1.30 0.35 0.50 0.08 0.20 2.84 3.00 1.50 1.70 2.60 3.00 0.95 BSC 1.90 BSC 0.50 BSC 0.23 0.40 0.10 BSC 0.60 BSC 0 10
Inches Min Max 0.037 0.057 0.002 0.006 0.035 0.051 0.0137 0.019 0.0031 0.0078 0.1118 0.118 0.059 0.0669 0.102 0.118 0.0374 BSC 0.0748 BSC 0.0197 BSC 0.009 0.016 0.039 BSC 0.0236 BSC 0 10
A2
A
b A1
3110.2001.9.0.92
17
AAT3110
MicroPowerTM Regulated Charge Pump
SC70JW-8
e e e
Dim E E1 L A A1 A2 D e b c 1
E
b D 0.048REF c A2 A
Millimeters Min Max 2.10 BSC 1.75 2.00 0.23 0.40 1.10 0 0.10 0.70 1.00 2.00 BSC 0.50 BSC 0.15 0.30 0.10 0.20 0 8 4 10
Inches Min Max 0.083 BSC 0.069 0.079 0.009 0.016 0.043 0.004 0.028 0.039 0.079 BSC 0.020 BSC 0.006 0.012 0.004 0.008 0 8 4 10
A1 1 L E1
Advanced Analogic Technologies, Inc.
1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086 Phone (408) 524-9684 Fax (408) 524-9689 18
3110.2001.9.0.92

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