AAT2500B

PRODUCT DATASHEET AAT2500B SystemPowerTM General Description The AAT2500B is a three-channel regulator consisting of a step-down converter with an input voltage range of 2.7V to 5.5V plus two low dropout (LDO) linear regulators. The step-down converter delivers up to 800mA of output current, while consuming 30μA of typical no load quiescent current. The switching frequency is 2MHz, minimizing the size of external components. The two LDOs (LDOA/LDOB) have independent inputs and are capable of delivering up to 500mA and 150mA respectively. A Power-OK (POK) function provides an open drain output signal when LDOA is within regulation. Both LDOs feature low quiescent current and a low dropout voltage. The output voltages for both LDOs are adjustable to as low as 0.6V. The linear regulators have independent Enable pins. The AAT2500B is available in a Pb-free 3x4mm QFN34-20 package and is rated over the -40°C to +85°C temperature range. Adjustable 3-Channel Regulator Features • VIN Range: 2.7V to 5.5V • 800mA Buck Converter • Linear Regulators ▪ LDOA: 500mA ▪ LDOB: 150mA • Adjustable Output Voltage • Low Dropout Voltage • High Output Accuracy: ±1.5% • High Efficiency Step-Down Converter • 85μA (Typical) of Total IQ • Independent Enable Pins • Integrated Power MOSFETs • 2MHz Switching Frequency • Over-Temperature and Current Limit Protection • QFN34-20 Package • -40°C to +85°C Temperature Range Applications • • • • • Cellular Phones Digital Cameras Handheld Instruments Microprocessor/DSP Core/IO Power PDAs and Handheld Computers Typical Application L LX AAT2500B FB VIN VIN VLDOA VLDOB VP SYNC ENA ENB EN PGND AGND OUTA 100kΩ POK FBA OUTB OUTB POK VOUT (Buck) R1 R1A OUTA C OUT R1B FBB R2A 2.2μF 2.2μF R2 R2B 2500B.2008.03.1.0 www.analogictech.com 1 PRODUCT DATASHEET AAT2500B AAT2500B SystemPowerTM Pin Descriptions Pin # 1 2 3 4 5 6 7 8, 9 10 11, 12 13 14 15 16 17 18 19 20 EP Adjustable 3-Channel Regulator Symbol FBB ENA ENB SYNC FB AGND PGND LX VP N/C VIN EN POK FBA OUTA VLDOA VLDOB OUTB Function Feedback input pin for LDOB. This pin is connected to OUTB. It is used to see the output of LDOB to regulate to the desired value via an external resistor divider. For fixed versions, short FBB to OUTB. Enable pin for LDOA. When connected low, LDOA is disabled and consumes less than 1μA of current. When connected high, normal operation. Enable pin for LDOB. When connected low, LDOB is disabled and consumes less than 1μA of current. When connected high, normal operation. Oscillator synchronization pin for the step-down converter. The internal oscillator is disabled and the stepdown converter can be synchronized to an external clock applied to this pin. Feedback input pin for the step-down converter. This pin is connected to the converter output. It is used to see the output of the converter to regulate to the desired value via an external resistor divider. Ground connection pin. Main power ground return pin for the step-down converter. Connect to the output and input capacitor return. Connect inductor to this pin. Switching node internally connected to the drain of both high- and low-side MOSFETs. Bias supply. Supply power for the internal circuitry. Connect to input power via low pass filter with decoupling to AGND. Not connected. Input supply voltage for the converter. Must be closely decoupled. Enable for the step-down converter. A logic low disables the converter and it consumes less than 1μA of current. A logic high enables normal operation. Power-OK pin with open drain output. It is pulled low when the OUTA pin is outside the regulation window of ±10%. Place a pull-up resistor between POK and OUTA. Feedback input pin for LDOA. This pin is connected to OUTA. It is used to see the output of LDOA to regulate to the desired value via an external resistor divider. For fixed versions, short FBA to OUTA. LDOA output pin; should be closely decoupled with a low-ESR ceramic capacitor. Input voltage pin for linear regulator A; should be closely decoupled. Input voltage pin for linear regulator B; should be closely decoupled. LDOB output pin; should be closely decoupled with a low-ESR ceramic capacitor. Exposed paddle; connect to ground directly beneath the package. Pin Configuration QFN34-20 (Top View) OUTA VLDOA VLDOB OUTB 20 19 18 17 FBB ENA ENB SYNC FB AGND 1 2 3 4 5 6 10 9 7 8 16 15 14 13 12 11 FBA POK EN VIN N/C N/C 2 www.analogictech.com VP LX LX PGND 2500B.2008.03.1.0 PRODUCT DATASHEET AAT2500B AAT2500B SystemPowerTM Absolute Maximum Ratings1 Symbol VP, VIN, VLDO VLX VFB VEN TJ TLEAD Adjustable 3-Channel Regulator Description Input Voltage and Bias Power to GND LX to GND FB to GND EN and EN_LDO to GND Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Value 6.0 -0.3 to VP + 0.3 -0.3 to VP + 0.3 -0.3 to 6.0 -40 to 150 300 Units V V V V °C °C Thermal Information Symbol PD θJA Description Maximum Power Dissipation (TA = 25°C) Thermal Resistance2 Value 2.0 50 Units W °C/W 1. 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. 2. Mounted on an FR4 board. 2500B.2008.03.1.0 www.analogictech.com 3 PRODUCT DATASHEET AAT2500B AAT2500B SystemPowerTM Electrical Characteristics1 VIN = 3.6V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Description Conditions ENA = ENB = EN = VIN; ILOAD = 0 ENA = ENB = EN = GND VIN Rising Hysteresis VIN Falling Adjustable 3-Channel Regulator Min Typ 80 Max 145 1.0 2.6 Units μA μA V mV V V % V mV mV %/V V V μA °C °C % of VOUT % of VOUT V μA Bias Power Supply IQ Quiescent Current ISHDN Shutdown Current UVLO Under-Voltage Lockout Voltage 250 2.0 1.8 -1.5 -2.5 0.593 5.5 1.5 2.5 0.607 500 150 0.09 0.6 1.5 LDOA, LDOB Input Voltage VLDO VOUT VFB VDOA VDOB ΔVOUT/ VOUT*ΔVIN VEN(L) VEN(H) ISHT TSD THYS LDOA VPOK VPOKHYS VPOK(LO) IPOK Output Voltage Tolerance Feedback Voltage Dropout Voltage2, 3 Dropout Voltage2, 3 Line Regulation4 Enable Threshold Low Enable Threshold High Shutdown Current Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Power-OK Trip Threshold Power-OK Hysteresis Power-OK Output Voltage Low Power-OK Output Leakage Current ISINK = 1mA VPOK