AAT2503

PRODUCT DATASHEET AAT2503178 SystemPowerTM General Description The AAT2503 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 optimizes power efficiency throughout the load range. Pulling the MODE/SYNC pin high enables “PWM Only” mode, maintaining constant frequency and low output ripple across the operating range. Alternatively, the converter may be synchronized to an external clock input to the MODE/SYNC pin. 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 150mA each. Ultra low input voltage on the VLDOA and VLDOB pins (down to 1.62V) allows for efficient post-buck regulation. 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 AAT2503 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 • 800mA Step-Down Converter ▪ VIN Range: 2.7V to 5.5V ▪ VOUT Range: 0.9V to VIN ▪ High Efficiency ▪ 2MHz Switching Frequency • Two 150mA Low Dropout Regulators ▪ LDO Input Voltage Range: 1.62V to 5.5V ▪ VOUT Range: 0.6V to VIN ▪ High Output Accuracy: ±1.5% • 85μA of Total IQ • Independent Enable Pins • Integrated Power MOSFETs • Over-Temperature 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 L1 LX AAT2503 VIN VIN VLDOA VLDOB VP MODE/SYNC ENA ENB EN VOUT (Buck) FB OUTA R3 100kΩ POK FBA OUTB OUTB POK R1 R4 OUTA C2 10μF R5 FBB R8 PGND AGND C6 2.2μF R7 C5 2.2μF R2 2503.2008.02.1.4 www.analogictech.com 1 PRODUCT DATASHEET AAT2503178 AAT2503178 SystemPowerTM Pin Descriptions Pin # 1 2 3 4 Adjustable 3-Channel Regulator Symbol FBB ENA ENB MODE/SYNC Function Feedback input pin for LDOB. This pin is connected to OUTB via an external resistor. 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. Connect to ground for PWM/PFM mode and optimized efficiency throughout the load range. Connect high for low noise PWM operation under all operating conditions. Connect to an external clock for synchronization (PWM only). Feedback input pin for the step-down converter. This pin is connected to the converter output via an external resistor. 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. Input supply voltage for the converter. Must be closely decoupled. Not connected. Bias supply. Supply power for the internal circuitry. Connect to input power via low pass filter with decoupling to AGND. 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. Place a pull-up resistor between POK and OUTA. Feedback input pin for LDOA. This pin is connected to OUTA via an external resistor. 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. 5 6 7 8, 9 10 11, 12 13 14 15 16 17 18 19 20 EP FB AGND PGND LX VP N/C VIN EN POK FBA OUTA VLDOA VLDOB OUTB 2 www.analogictech.com 2503.2008.02.1.4 PRODUCT DATASHEET AAT2503178 AAT2503178 SystemPowerTM Pin Configuration QFN34-20 (Top View) Adjustable 3-Channel Regulator OUTA VLDOA VLDOB OUTB 20 19 18 17 FBB ENA ENB MODE/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 VP LX LX PGND Absolute Maximum Ratings1 Symbol VP, VIN, VLDO VLX VFB VN TJ TLEAD Description Input Voltage and Bias Power to GND LX to GND FB to GND EN, MODE/SYNC 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. 2503.2008.02.1.4 www.analogictech.com 3 PRODUCT DATASHEET AAT2503178 AAT2503178 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 1.62 -1.5 -2.5 0.593 Adjustable 3-Channel Regulator Min Typ 85 Max 145 1.0 5.5 1.5 2.5 0.607 150 0.09 0.6 Units μA μA V % V mV %/V V V mA μA °C °C % of VOUT % of VOUT V μA Bias Power Supply IQ Quiescent Current ISHDN Shutdown Current LDOA, LDOB; IOUT = 150mA VLDO Input Voltage VOUT VFB VDO ΔVOUT/ VOUT*ΔVIN VEN(L) VEN(H) IOUT ISHT TSD THYS LDOA; IOUT VPOK VPOKHYS VPOK(LO) IPOK Output Voltage Tolerance Feedback Voltage Dropout Voltage2 Line Regulation3 Enable Threshold Low Enable Threshold High Output Current Shutdown Current Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis = 150mA Power-OK Trip Threshold Power-OK Hysteresis Power-OK Output Voltage Low Power-OK Output Leakage Current IOUT = 1mA to 150mA TA = 25°C TA = -40°C to +85°C 0.6 IOUT = 150mA VIN = VOUT + 1 to 5.0V 1.4 150 VIN = 5V 140 15 VOUT Rising, TA = 25°C ISINK = 1mA VPOK