AAT3111 ANALOGICTECH | Alldatasheet

Document overview

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Technical content

Features

  • Step-up type voltage converter
  • Input Range
  • AAT3111-3.6: 1.8V to 3.6V
  • AAT3111-3.3: 1.8V to 3.3V
  • MicroPower consumption: 20µA
  • 3.6V, 3.3V Regulated ±4% output
  • 3.6V Output Current
  • 100mAwith V IN ≥ 3.0V
  • 20mAwith V IN ≥ 2.0V
  • 3.3V Output Current
  • 100mAwith V IN ≥ 2.5V
  • 20mAwith V IN ≥ 1.8V
  • 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

Applications

  • Handheld Electronics
  • Digital Cameras
  • PDAs
  • Battery Back Up Supplies
  • MP3 Players Typical Application VIN VOUT GND SHDN VIN AAT3111 VOUT 1uF 10uF 10uF ON/OFF COUT CIN

Pin # SOT-23-6 SC70JW-8 Symbol Function 11 V OUT 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 Shutdown input. Active low signal disables the converter. 4 6 C- Flying capacitor negative terminal 57 V IN Input supply pin. Bypass this pin to ground with at least 6.8µF low ESR capacitor 6 8 C+ Flying capacitor positive terminal AAT3111 MicroPower™ Regulated Charge Pump 2 3111.2002.3.0.91

MicroPower™ Regulated Charge Pump 3111.2002.3.0.91 3 Absolute Maximum Ratings (TA=25°C unless otherwise noted) Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at cond i- tions 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 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) Note 3: IQ = IVIN + IVOUT. VOUT is pulled up to 3.8V to prevent switching. AAT3111-3.3 Symbol Description Conditions Min Typ Max Units VIN Input Voltage V OUT=3.3V 1.8 V OUT V IQ No Load Supply Current 3 1.8V < VIN < 3.3V, IOUT=0mA, SHDN = VIN 20 30 µA ISHDN Shutdown Supply Current 1.8V < V IN < 3.3V, IOUT =0mA, VSHDN=0 0.01 1 µA VRIPPLE Ripple Voltage V IN = 2.0V, IOUT = 50mA 20 mV P-P η Efficiency V IN = 1.8V, IOUT = 25mA 91 % fOSC Frequency Oscillator Free Running 750 kHz VIH SHDN Input Threshold High 1.4 V VIL SHDN Input Threshold Low 0.3 V IIH SHDN Input Current High SHDN = V IN -1 1 µA IIL SHDN Input Current Low SHDN = GND -1 1 µA tON VOUT Turn-on time V IN = 1.8V, IOUT = 0mA 0.2 ms ISC Short-circuit current 4 VIN = 1.8V, VOUT = GND, SHDN = 3V 300 mA Symbol Description Rating Units Θ JA Maximum Thermal Resistance (SOT23-6 or SC70JW-8) 150 °C/W PD Maximum Power Dissipation (SOT23-6 or SC70JW-8) 667 mW Symbol Description Value Units VIN VIN to GND -0.3 to 6 V VOUT VOUT to GND -0.3 to 6 V VSHDN SHDN to GND -0.3 to 6 V tSC Output to GND Short-Circuit Duration Indefinite s TJ Operating Junction Temperature Range -40 to 150 °C TLEAD Maximum Soldering Temperature (at leads, 10 sec) 300 °C VESD ESD Rating1 — HBM 2000 V

Electrical Characteristics (TA = -40 to 85°C unless otherwise noted. Typical values are at TA=25°C, CFLY=1µF, CIN=10µF, COUT=10µF) Note 4: Under short-circuit conditions, the device may enter overtemperature protection mode. Note 5: IQ = IVIN + IVOUT. VOUT is pulled up to 4.1V to prevent switching. AAT3111-3.6 Symbol Description Conditions Min Typ Max Units VIN Input Voltage V OUT=3.6V 1.8 V OUT V IQ No Load Supply Current 5 1.8V < VIN < 3.6V, IOUT=0mA, SHDN=VIN 20 30 µA ISHDN Shutdown Supply Current 1.8V < V IN < 3.6V, IOUT =0mA, VSHDN=0 0.01 1 µA VRIPPLE Ripple Voltage VIN = 2.5V, IOUT = 50mA 25 mVP-PVIN = 3V, IOUT = 100mA 30 η Efficiency V IN = 2.0V, IOUT = 20mA 90 % fOSC Frequency Oscillator Free Running 750 kHz VIH SHDN Input Threshold High 1.4 V VIL SHDN Input Threshold Low 0.3 V IIH SHDN Input Current High SHDN = V IN -1 1 µA IIL SHDN Input Current Low SHDN = GND -1 1 µA tON VOUT Turn-on time V IN = 1.8V, IOUT = 0mA 0.2 ms ISC Short-circuit current 4 VIN = 1.8V, VOUT = GND, SHDN = 3V 300 mA AAT3111 MicroPower™ Regulated Charge Pump 4 3111.2002.3.0.91

MicroPower™ Regulated Charge Pump 3111.2002.3.0.91 5 Typical Characteristics — AAT3111-3.3 (Unless otherwise noted, VIN = 3V, CIN = COUT =10µF, CFLY = 1µF, TA = 25°C) VSHDN Threshold vs. Supply Voltage 0.4 0.5 0.6 0.7 0.8 0.9 Supply Voltage (V) VSHDN Threshold (V) VIH VIL Startup Time (100µs/div.) SHDN (2V/div) VOUT (1V/div)ILOAD=100mA VIN=2.3V ILOAD=25mA VIN=2.0V ILOAD=50mA VIN=2.0V Efficiency vs. Load Current 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.01 0.1 1 10 100 Load Current (mA) Efficiency (%) VIN=1.8V VIN=2.0V VIN=2.6V Efficiency vs. Supply Voltage 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% Supply Voltage (V) Efficiency (%) 100mA 5mA 50mA Supply Current vs. Supply Voltage Supply Voltage (V) Supply Current (µA) No Load, Switching No Load, Not Switching Output Voltage vs. Output Current 3.20 3.25 3.30 3.35 3.40 0.01 0.1 1 10 100 1000 Output Current (mA) Output Voltage (V) VIN=1.7V VIN=2.3V VIN=2.6V VIN=2.0V

Typical Characteristics — AAT3111-3.3 (Unless otherwise noted, VIN = 3V, CIN = COUT =10µF, CFLY = 1µF, TA = 25°C) Output Ripple IOUT=100mA VIN=2.5V Time (1µs/div.) VOUT AC Coupled (10mV/div.) Output Ripple IOUT=50mA VIN=2.0V Time (2µs/div.) VOUT AC Coupled (10mV/div.) Load Transient Response VIN=2.6V Time (50µs/div.) IOUT 50mA/div VOUT AC Coupled 20mV/div Load Transient Response VIN=2.0V Time (50µs/div.) IOUT 20mA/div VOUT AC Coupled 20mV/div AAT3111 MicroPower™ Regulated Charge Pump 6 3111.2002.3.0.91

Typical Characteristics — AAT3111-3.6 (Unless otherwise noted, VIN = 3V, CIN = COUT =10µF, CFLY = 1µF, TA = 25°C) VSHDN Threshold vs. Supply Voltage 0.4 0.5 0.6 0.7 0.8 0.9 Supply Voltage (V) VSHDN Threshold (V) VIH VIL Startup Time (100µs/div.) SHDN (2V/div) VOUT (1V/div)ILOAD=100mA VIN=2.1V ILOAD=50mA VIN=2.1V Efficiency vs. Load Current 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0.01 0.1 1 10 100 Load Current (mA) Efficiency (%) VIN=2.0V VIN=2.3V VIN=2.6V Efficiency vs. Supply Voltage 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100% Supply Voltage (V) Efficiency (%) 10mA 100mA 50mA Supply Current vs. Input Voltage Input Voltage (V) Supply Current (µA) No Load, Switching No Load, Not Switching Output Voltage vs. Output Current 3.45 3.50 3.55 3.60 3.65 3.70 3.75 0.01 0.1 1 10 100 1000 Output Current (mA) Ooutput Voltage (V) VIN=2.0V VIN=2.9V VIN=2.3V AAT3111 MicroPower™ Regulated Charge Pump 3111.2002.3.0.91 7

Typical Characteristics — AAT3111-3.6 (Unless otherwise noted, VIN = 3V, CIN = COUT =10µF, CFLY = 1µF, TA = 25°C) Output Ripple IOUT=100mA VIN=3.0V Time (1µs/div.) VOUT AC Coupled (10mV/div.) Output Ripple IOUT=50mA VIN=2.5V Time (2µs/div.) VOUT AC Coupled (10mV/div.) Load Transient Response VIN=2.4V Time (50µs/div.) IOUT 50mA/div VOUT AC Coupled 20mV/div Load Transient Response VIN=2.1V Time (50µs/div.) IOUT 20mA/div VOUT AC Coupled 20mV/div AAT3111 MicroPower™ Regulated Charge Pump 8 3111.2002.3.0.91

MicroPower™ Regulated Charge Pump 3111.2002.3.0.91 9 Functional Description Operation (Refer to block diagram) The AAT3111 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 inter- nal 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 C FLY is charged to a level approxi- mately equal to input voltage V IN. On the second phase, switches S1 and S4 are turned off (open), S2 and S3 are turned on (short). The low side of the fly- ing capacitor C FLY is connected to GND during the first phase. During the second phase, the flying capacitor C FLY 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 is connected to the output through switch S3. For each cycle phase, charge from input node V IN 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 tem- porarily placed in an idle state. When idle, the AAT3111 has a quiescent current of 20µA or less. The closed loop feed back system containing the voltage sense circuit and control comparator allows the AAT3111 to provide a regulated output voltage to the limits of the input voltage and output load cur- rent. 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 a load is a function of V IN, 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: I OUT(AVG) α CFLY × (2 × VIN - VOUT) × FSW The AAT3111 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 temper- ature exceeds approximately 145°C. The charge pump will remain disabled until the fault condition is relieved. Functional Block Diagram VREF CONTROL SHDN VIN VOUT GND

MicroPower™ Regulated Charge Pump 10 3111.2002.3.0.91 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 (<100mΩ) ceramic capaci- tors are used for C IN and COUT and CFLY. In gener- al, low ESR may be defined as less than 100mΩ. If desired for a particular application, low ESR Tantalum capacitors may be substituted; however optimum output ripple performance may not be real- ized. Aluminum Electrolytic capacitors are not rec- ommended for use with the AAT3111 due to their inherent high ESR characteristic. Typically as a starting point, a capacitor value of 10µF should be used for C IN and COUT with 1µF for CFLY when the AAT3111 is used under maximum output load conditions. Lower values for CIN, COUT and CFLYmay be utilized for light load current appli- cations. Applications drawing a load current of 10mA or less may use a C IN and COUT capacitor value as low as 1µF and a CFLYvalue of 0.1µF. CIN and COUT may range from 1µF for light loads to 10µF or more for heavy output load conditions. C FLY 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 C IN, COUT and CFLY should be approximately 10 to 1. The compromise for lowering the value of C IN, 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 C IN = COUT = 10µF and C FLY = 1µF, the AAT3111 output performance should be evaluated to assure the device meets application requirements. In applications where the input voltage source has very low impedance, it is possible to omit the C IN capacitor. However, if CIN is not used, circuit per- formance 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 regula- tion can result if the input supply source impedance is high, or if the value of C IN is too low. This situa- tion can be remedied by increasing the value of CIN. Capacitor Characteristics Ceramic composition capacitors are highly recom- mended over all other types of capacitors for use with the AAT3111. Ceramic capacitors offer many advantages over their tantalum and aluminum elec- trolytic 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-polar- ized, 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, inter- nal connections, size or area, material composition and ambient temperature. Typically capacitor ESR is measured in milliohms for ceramic capacitors and can range to more than several ohms for tan- talum or aluminum electrolytic capacitors. Ceramic Capacitor Materials:Ceramic capacitors less than 0.1µF are typically made from NPO or COG materials. NPO and COG materials typically have tight tolerance and are very stable over tem- perature. Large capacitor values are typically com- posed of X7R, X5R, Z5U or Y5V dielectric materi- als. 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. A10µF 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.

MicroPower™ Regulated Charge Pump 3111.2002.3.0.91 11 Applications Information Charge Pump Efficiency The AAT3111 is a regulated output voltage dou- bling 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 = P OUT / 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 (h) can be rewritten as: η = P OUT / PIN = (VOUT × IOUT) / (V IN × 2IOUT) = VOUT / 2VIN η(%) = 100(VOUT / 2VIN) For a charge pump with an output of 3.3 volts and a nominal input of 1.8 volts, the theoretical efficien- cy is 91.6%. Due to internal switching losses and IC quiescent current consumption, the actual effi- ciency can be measured at 91%. These figures are in close agreement for output load conditions from 1mA to 100mA. Effici ency will decrease as load current drops below 0.05mA or when the level of V IN approaches VOUT. Refer to the Typical Char- acteristics 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 100mAto 400mAof cur- rent from V IN. This excessive current consumption due to an output short circuit condition will cause a rise in the internal IC junction temperature. The AAT3111 has a thermal protection and shutdown circuit that continuously monitors the IC junction temperature. If the thermal protection circuit sens- es the die temperature exceeding approximately 145°C, the thermal shutdown will disable the charge pump switching cycle operation. The ther- mal 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 thermal protection system will cycle on and off if an output short circuit condition persists. This will allow the AAT3111 to operate indefinitely in a short circuit condition without damage to the device. Output Ripple and Ripple Reduction There are several factors that determine the ampli- tude and frequency of the charge pump output rip- ple, the values of C OUT 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 I OUT and the level of VIN. As VIN increases the abili- ty 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 C IN, 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 35mV P-P when VIN = 2.0V, V OUT = 3.3V, COUT = 10µF and CFLY = 1µF. When the AAT3111 is used in light output load applications where IOUT < 10mA, the flying capaci- tor CFLY value can be reduced. The reason for this effect is when the charge pump is under very light load conditions, the transfer of charge across C FLY 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 C FLY. Caution should be observed when decreasing the flying capacitor. If the output load current rises above the nominal level for the reduced C FLYvalue, charge pump efficiency can be compromised. There are several methods that can be employed to reduce output ripple depending upon the require- ments of a given application. The most simple and straightforward technique is to increase the value of the C OUT capacitor. The nominal 10µF COUT capac- itor can be increased to 22µF or more. Larger val- ues for the C OUT capacitor (22µF and greater) will by nature have lower ESR and can improve both high

MicroPower™ Regulated Charge Pump 14 3111.2002.3.0.91

Ordering Information

Package Information

b A2 A E D f t L C GAUGE PLANE e Output Voltage Package Marking Part Number Bulk Tape and Reel 3.3V SOT23-6 N/A AAT3111IGU-3.3-T1 3.6V SOT23-6 N/A AAT3111IGU-3.6-T1 3.3V SC70JW-8 N/A AAT3111IJS-3.3-T1 3.6V SC70JW-8 N/A AAT3111IJS-3.6-T1 Dim Millimeters Inches Min Max Min Max A 0.95 1.45 0.037 0.057 A1 0.05 0.15 0.002 0.006 A2 0.90 1.30 0.035 0.051 b 0.35 0.50 0.0137 0.019 c 0.08 0.20 0.0031 0.0078 D 2.84 3.00 0.1118 0.118 E 1.50 1.70 0.059 0.0669 E1 2.60 3.00 0.102 0.118 e 0.95 BSC 0.0374 BSC e1 1.90 BSC 0.0748 BSC f 0.50 BSC 0.0197 BSC L 0.23 0.40 0.009 0.016 L1 0.10 BSC 0.039 BSC L2 0.60 BSC 0.0236 BSC t 0º 10º 0º 10º

MicroPower™ Regulated Charge Pump 3111.2002.3.0.91 15 SC70JW-8 Θ 1 D AA2 b E e e e L Θ c 0.048REF Dim Millimeters Inches Min Max Min Max E 2.10 BSC 0.083 BSC E1 1.75 2.00 0.069 0.079 L 0.23 0.40 0.009 0.016 A 1.10 0.043 A1 0 0.10 0.004 A2 0.70 1.00 0.028 0.039 D 2.00 BSC 0.079 BSC e 0.50 BSC 0.020 BSC b 0.15 0.30 0.006 0.012 c 0.10 0.20 0.004 0.008 Θ 08 º08 º Θ1 4º 10º 4º 10º

MicroPower™ Regulated Charge Pump 16 3111.2002.3.0.91 Advanced Analogic Technologies, Inc.

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