AAT3110 MicroPower™ Regulated Charge Pump General Description Features The AAT3110 ChargePump™ 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 ChargePump™ is a member of AnalogicTech's Total Power Management IC product family. • • • • • • Step-up type voltage converter Input Range • AAT3110-5: 2.7V to 5V • AAT3110-3.3: 2.3V to 3.3V MicroPower consumption: 13µA 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 1µA Short-circuit/over-temperature protection 2kV ESD Rating SC70JW-8 or SOT23-6 package Preliminary Information The AAT3110 is available in a surface mount 6-pin SOT23 or 8-pin SC70JW package and is rated from -40 to 85°C. • • • ChargePump™ 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 VOUT C+ GND VIN SHDN C- 1uF COUT 10uF ON/OFF VIN CIN 10uF 3110.2001.9.0.92 1 AAT3110 MicroPower™ Regulated Charge Pump Pin Descriptions Pin # SOT-23-6 SC70JW-8 Symbol Function 1 1 VOUT Regulated output pin. Bypass this pin to ground with at least 6.8µF low ESR capacitor 2 2, 3, 4 GND Ground connection 3 5 SHDN 4 6 C- Flying capacitor negative terminal 5 7 VIN Input supply pin. Bypass this pin to ground with at least 6.8µF low ESR capacitor 6 8 C+ Flying capacitor positive terminal Shutdown input. Active low signal disables the converter. Pin Configuration SOT23-6 SHDN 3 C+ 5 VIN 4 C- VOUT GND GND GND 1 2 8 7 2 2 6 1 GND 2 2 1 1 VOUT SC70JW-8 3 6 4 5 C+ VIN CSHDN 3110.2001.9.0.92 AAT3110 MicroPower™ Regulated Charge Pump Absolute Maximum Ratings Symbol (TA=25°C unless otherwise noted) Description VIN VOUT VSHDN tSC TJ TLEAD VESD 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 Value Units -0.3 to 6 -0.3 to 6 -0.3 to 6 Indefinite -40 to 150 300 2000 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 1.5kΩ resistor into each pin. Thermal Information Symbol Description ΘJA PD Rating Units 150 667 °C/W mW Maximum Thermal Resistance (SOT23-6 or SC70JW-8) Maximum Power Dissipation (SOT23-6 or SC70JW-8) Note 2: Mounted on an FR4 board. Electrical Characteristics (TA = -40 to 85°C unless otherwise noted. Typical values are at TA=25°C, CFLY=1µF, CIN=10µF, COUT=10µF) AAT3110-5 Symbol VIN IQ Description Conditions Min Input Voltage No Load Supply Current 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 2.7 VOUT Output Voltage ISHDN Shutdown Supply Current VRIPPLE η fOSC VIH VIL IIH IIL tON ISC 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 4.8 4.8 Typ Max Units 13 5 5 0.01 VOUT 30 5.2 5.2 1 2.5 V µA V V 25 30 83 750 mVP-P 1.4 SHDN = VIN SHDN = GND VIN = 3V, IOUT = 0mA VIN = 3V, VOUT = GND, SHDN = 3V 0.3 1 1 -1 -1 0.2 300 µA % kHz V V µA µA ms mA Note 3: Under short-circuit conditions, the device may enter overtemperature protection mode. 3110.2001.9.0.92 3 AAT3110 MicroPower™ Regulated Charge Pump Electrical Characteristics (TA = -40 to 85°C unless otherwise noted. Typical values are at TA=25°C, CFLY=1µF, CIN=10µF, COUT=10µF) AAT3110-3.3 Symbol VIN IQ VOUT ISHDN VRIPPLE η fOSC VIH VIL IIH IIL tON ISC 4 Description Conditions Min Input Voltage No Load Supply Current 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 2.3 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 3.17 3.17 Typ 10 3.30 3.30 0.01 20 71 750 Max Units VOUT 30 3.43 3.43 1 V µA V V µA mVP-P % kHz V V µA µA ms mA 1.4 SHDN = VIN SHDN = GND VIN = 3V, IOUT = 0mA VIN = 3V, VOUT = GND, SHDN = 3V 0.3 1 1 -1 -1 0.2 300 3110.2001.9.0.92 AAT3110 MicroPower™ Regulated Charge Pump Typical Characteristics—AAT3110-5 (Unless otherwise noted, VIN = 3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC) Supply Current vs. Supply Voltage AAT3110-5 Output Voltage vs. Output Current AAT3110-5 24 5.1 Supply Current (µA) Output Voltage (V) 5.15 VIN=3.6 5.05 5 VIN=3.0 4.95 VIN=2.7 VIN=3.3 4.9 4.85 IOUT=0 A CFLY=1µF VSHDN=VIN 22 20 18 16 14 12 10 4.8 0 50 100 2.5 150 3 Supply Current vs VSHDN AAT3110-5 95% 5 5.5 VIN=5.5V 20 VIN=3.3V 15 VIN=2.8V 25 mA 90% IOUT=0µA Efficiency (%) Supply Current (µA) 4.5 Efficiency vs. Supply Voltage AAT3110-5 30 10 4 Supply Voltage (V) Output Current (mA) 25 3.5 85% 80% 75% 70% 65% 50 mA 100 mA 60% 55% 50% 5 45% 2.70 0 0 1 2 3 4 3.00 3.50 4.00 4.50 5.00 Supply Voltage (V) 5 VSHDN Control Voltage (V) Oscillator Frequency vs. Supply Voltage AAT3110-5 100% VIN = 2.7V 90% Efficiency (%) 80% 70% 60% VIN = 3.0V VIN = 3.6V 50% 40% VIN = 3.3V 30% 20% 10% 0% 0.01 0.1 1 10 Load Current (mA) 3110.2001.9.0.92 100 1000 Oscillator Frequency (kHz) Efficiency vs. Load Current AAT3110-5 1200 1100 1000 - 40º C 900 800 700 25º C 600 500 400 2.7 85º C 3.0 3.5 4.0 4.5 5.0 Supply Voltage (V) 5 AAT3110 MicroPower™ Regulated Charge Pump Typical Characteristics—AAT3110-5 (Unless otherwise noted, VIN = 3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC) Startup Time with 100 mA Load AAT3110-5 Startup Time with 50 mA Load AAT3110-5 SHDN 2V/DIV SHDN 2V/DIV VOUT 1V/DIV VOUT 1V/DIV 50µS/DIV 50µS/DIV Load Transient Response for 50mA AAT3110-5 IOUT 0mA to 50mA 20mA/DIV Load Transient Response for 100mA AAT3110-5 IOUT 0mA to 100 mA 50mA/DIV VIN=3.0V VOUT AC COUPLED 20mV/DIV VIN=3.0V VOUT AC COUPLED 20mV/DIV 50µS/DIV 50µS/DIV Output Ripple with IOUT=50 mA AAT3110-5 VOUT AC Coupled 10 mV/DIV VOUT AC Coupled 10 mV/DIV VIN=3.0V VIN=3.0V 2µS/DIV 6 Output Ripple with IOUT=100 mA AAT3110-5 2µS/DIV 3110.2001.9.0.92 AAT3110 MicroPower™ Regulated Charge Pump Typical Characteristics—AAT3110-5 (Unless otherwise noted, VIN = 3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC) VIN vs. VIL VIN vs. VIH 1.00 1.00 0.95 -40°C 0.95 0.90 0.90 25°C 0.80 0.80 VIL (V) VIH (V) -40°C 0.85 0.85 0.75 0.70 0.65 25°C 0.75 0.70 85°C 0.65 0.60 85°C 0.60 0.55 0.55 0.50 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0.50 5.5 2.0 2.5 3.0 VIN (V) Normalized Output Voltage (%) VSHDN Threshold (V) 0.95 0.90 VIH 0.80 0.75 0.70 VIL 0.60 0.55 0.50 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Normalized Output Voltage vs Temperature 1.00 0.65 4.0 VIN (V) VSHDN Threshold vs. Supply Voltage AAT3110-5 0.85 3.5 4.5 5.0 5.5 1.20% IOUT=25mA 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 Temperature (C) VIN (V) 3110.2001.9.0.92 7 AAT3110 MicroPower™ Regulated Charge Pump Typical Characteristics—AAT3110-3.3 (Unless otherwise noted, VIN = 2.3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC) Output Voltage vs. Output Current AAT3110-3.3 Supply Current vs. Supply Voltage AAT3110-3.3 24 3.35 Supply Current (µA) Output Voltage (V) 3.4 VIN=3V 3.3 VIN=2.7V 3.25 3.2 VIN=2.3V 3.15 IOUT=0 A CFLY=1µF VSHDN=VIN 22 20 18 16 14 12 10 3.1 0 50 100 150 2.3 200 2.5 2.7 2.9 3.1 3.3 Supply Voltage (V) Output Current (mA) Efficiency vs. Supply Voltage AAT3110-3.3 Supply Current vs VSHDN AAT3110-3.3 30 80 70 Efficiency (%) Supply Current (µA) IOUT=0µA 25 20 VIN=3.3V 15 VIN=2.8V 10 5 60 50 40 30 IOUT=100mA 20 10 0 0 0 1 2 3 2 3.3 2.5 VSHDN Control Voltage (V) Efficiency vs. Output Current AAT3110-3.3 Oscillator Frequency (kHz) 90.0% 80.0% VIN=2.25V 50.0% 40.0% 30.0% 20.0% 10.0% 0.0% 0.01 0.1 1 I-Load (mA) 8 3.5 Oscillator Frequency vs. Supply Voltage AAT3110-3.3 100.0% 70.0% 60.0% 3 Supply Voltage (V) 10 100 1200 1100 1000 - 40°C 900 800 25°C 700 600 85°C 500 400 2.3 2.5 2.7 2.9 3.1 3.3 Supply Voltage (V) 3110.2001.9.0.92 AAT3110 MicroPower™ Regulated Charge Pump Typical Characteristics—AAT3110-3.3 (Unless otherwise noted, VIN = 2.3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC) Startup Time with 100 mA Load AAT3110-3.3 Startup Time with 50 mA Load AAT3110-3.3 SHDN 2V/DIV SHDN 2V/DIV VOUT 1V/DIV VOUT 1V/DIV 100µS/DIV 100µS/DIV Load Transient Response for 50mA AAT3110-3.3 IOUT 0mA to 50mA 20mA/DIV Load Transient Response for 100mA AAT3110-3.3 IOUT 0mA to 100mA 50mA/DIV VIN=2.3V COUT=10µF VOUT AC COUPLED 20mV/DIV VIN=2.3V COUT=10µF VOUT AC COUPLED 20mV/DIV 20µS/DIV 50µS/DIV Output Ripple for 50mA Load AAT3110-3.3 VOUT AC Coupled 10mV/DIV VOUT AC Coupled 10mV/DIV VIN=2.3V VIN=2.3V 2µs/DIV 3110.2001.9.0.92 Output Ripple for 100mA Load AAT3110-3.3 2µs/Div. 9 AAT3110 MicroPower™ Regulated Charge Pump Typical Characteristics—AAT3110-3.3 (Unless otherwise noted, VIN = 2.3V, CIN=COUT=10µF, CFLY=1µF, TA = 25ºC) VIN vs. VIH AAT3110-3.3 VIN vs. VIL AAT3110-3.3 1.00 1.00 0.95 0.95 -40°C 0.90 0.90 0.85 25°C 0.80 VIL (V) VIH (V) 0.85 0.75 0.70 -40°C 0.80 0.75 25°C 0.70 0.65 0.65 85°C 0.60 0.60 85°C 0.55 0.55 0.50 0.50 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.3 2.0 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 VSHDN Threshold (V) 1.00 0.95 0.90 0.85 0.80 VIH 0.75 0.70 0.65 VIL 0.60 0.55 0.50 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.3 VIN (V) 10 3110.2001.9.0.92 AAT3110 MicroPower™ Regulated Charge Pump Functional Block Diagram VIN S2 S1 SHDN CONTROL C+ CVREF 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 2×VIN 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 13µA 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 ≈ CFLY×(2×VIN-VOUT) The relative average current that the charge pump can supply to the output may be approximated by the following expression: IOUT(AVG) α CFLY×(2×VIN-VOUT)×FSW 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 145°C. The charge pump will remain disabled until the fault condition is relieved. 11 AAT3110 MicroPower™ Regulated Charge Pump Applications Information is high, or if the value of CIN is too low. This situation can be remedied by increasing the value of CIN. External Capacitor Selection Capacitor Characteristics 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 (<100mΩ) ceramic capacitors are used for CIN and COUT and CFLY. In general, low ESR may be defined as less then 200mΩ . 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. 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. Typically as a starting point, a capacitor value of 10µF should be used for CIN and COUT with 1µF 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 1µF and a CFLY value of 0.1µF. CIN and COUT may range from 1µF for light loads to 10µF or more for heavy output load conditions. CFLY may range from 0.01µF to 2.2µF 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 = 10µF and CFLY = 1µF, 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 12 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 0.1µF 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 2.2µF 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 10µF Y5V capacitor could be reduced to less than 5µF 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. 3110.2001.9.0.92 AAT3110 MicroPower™ Regulated Charge Pump Applications Information Charge Pump Efficiency The AAT3110 is a regulated output voltage doubling charge pump. The efficiency (η) can simply be defined as a linear voltage regulator with an effective output voltage that is equal to two times the input voltage. Efficiency (η) for an ideal voltage doubler can typically be expressed as the output power divided by the input power. η = 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 (η) can be rewritten as: η=POUT/PIN=(VOUT×IOUT)/(VIN×2IOUT)=VOUT/2VIN η(%) = 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. 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 145°C, the thermal shutdown will disable the charge pump switching cycle operation. The thermal limit system has 10°C 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 135°C, the charge pump will then become active again. The 3110.2001.9.0.92 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 = 10µF and CFLY = 1µF. 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 10µF COUT capacitor can be increased to 22µF or more. Larger values for the COUT capacitor (22µF and greater) will by nature have lower ESR and can improve both high and low frequency components of the charge 13 AAT3110 MicroPower™ 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 1µF 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. VOUT (5V) COUT2 1µF COUT1 22µF + VOUT 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). C+ AAT3110 GND ON/OFF Layout Considerations SHDN CFLY 1µF VIN + CIN 10µF VIN (2.7V to 5V) C- Figure 1: Application using tantalum capacitor VOUT (5V) RFILTER 1.5 ohms VOUT CFILTER 33µF COUT 10µF C+ AAT3110 GND CFLY 1µF VIN CIN 10µF ON/OFF SHDN VIN (2.7V to 5V) C- Figure 2: Application with output ripple reduction filter 14 3110.2001.9.0.92 AAT3110 MicroPower™ 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) VOUT COUT 10µF C+ CFLY 1µF AAT3110-5 GND VIN CIN 10µF ON/OFF SHDN VIN (2.7V to 5V) C- Figure 6: Typical charge pump boost converter circuit CFLY 1µF CVIN VIN (USB Port Vout) C+ VOUT VOUT 5V 100mA SHDN CIN 10µF AAT3110-5 COUT 10µF GND GND (USB Port Return) GND Figure 7: 5 Volt, 100mA supply powered from a USB port 3110.2001.9.0.92 15 AAT3110 MicroPower™ Regulated Charge Pump VIN LI-Ion Battery 2.7V to 4.2V 10µF C+ 10µF AAT3110-5 SHDN ON/OFF VOUT 120 120 120 120 1µF C- Figure 8: 5 Volt LED or Display Driver from a Li-Ion Battery Source VIN = 3.0V to 5V SHDN CIN 10µF VOUT = 5V IOUT = 200mA VOUT VIN C+ AAT3110-5 (A) SHDN C- CFLY 1µF GND VOUT VIN C+ AAT3110-5 (B) SHDN C- CFLY 1µF COUT 10µF GND Figure 9: 5 Volt, 200mA Step-Up Supply from a 3.0V to 5V Source. 16 3110.2001.9.0.92 AAT3110 MicroPower™ Regulated Charge Pump Ordering Information Output Voltage Package 3.3V Part Number Marking Bulk Tape and Reel SOT-23-6 N/A AAT3110IGU-3.3-T1 5.0V SOT-23-6 N/A AAT3110IGU-5-T1 3.3V SC70JW-8 N/A AAT3110IJS-3.3-T1 5.0V SC70JW-8 N/A AAT3110IJS-5-T1 Package Information SOT-23-6 t e1 Dim e L2 E L f C GAUGE PLANE D A2 A A1 A2 b c D E E1 e e1 f L L1 L2 t 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 0º 10º 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 0º 10º A b A1 3110.2001.9.0.92 17 AAT3110 MicroPower™ Regulated Charge Pump SC70JW-8 e e e Dim E b D 0.048REF c A2 A E E1 L A A1 A2 D e b c Θ Θ1 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 8º 4º 10º 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 8º 4º 10º A1 Θ1 L E1 Θ 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