AAT2504_08

PRODUCT DATASHEET AAT2504178 SystemPowerTM General Description The AAT2504 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 two LDOs have an input voltage range of 1.8V to 5.5V, making them well-suited for post regulating from the step-down converter. The step-down converter optimizes power efficiency throughout the load range. Pulling the MODE/SYNC pin high enables “PWM Only” operation, maintaining constant frequency and low output ripple across the operating range. Alternatively, the converter may be synchronized to an external clock to the MODE/ SYNC pin. The step-down converter delivers up to 800mA of output 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 300mA 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. Typical no load quiescent current is a low 80μA when the step-down converter and LDOs are enabled. The AAT2504 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 Buck Converter ▪ VIN Range: 2.7V to 5.5V ▪ VOUT Range: 0.9V to VIN, Adjustable ▪ High Efficiency: 95% ▪ 2MHz Switching Frequency ▪ Synchronizable to External Clock ▪ Internal Soft Start • Two 300mA Linear Regulators ▪ LDO Input Voltage Range: 1.62V to 5.5V ▪ Low Dropout Voltage ▪ High Output Accuracy: ±1.5% • Low Total Quiescent Current IQ (80μA) • Independent Enable Pins • 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 L LX AAT2504 VIN VIN VLDOA VLDOB VP MODE/SYNC ENA ENB EN VOUT (Step-down) FB OUTA 100kΩ POK FBA OUTB OUTB POK R1 R1A OUTA C OUT R1B FBB R2A 2.2μF 2.2μF R2 R2B PGND AGND 2504.2008.02.1.2 www.analogictech.com 1 PRODUCT DATASHEET AAT2504178 AAT2504178 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 used to regulate the output of LDOB to the desired value via an external resistor divider. Enable pin for LDOA. Active high. Enable pin for LDOB. Active high. PWM operation and oscillator synchronization pin. Connect to ground for PWM/Light Load operation and optimized efficiency throughout the load range. Connect high for low noise PWM operation under all operating conditions. When connected to an external clock, the internal oscillator is disabled and the step-down converter is synchronized to an external clock applied to this pin (PWM only). Feedback input pin for the step-down converter. This pin 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. Active high. 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 used to regulate the output of LDOA to the desired value via an external resistor divider. 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 Pin Configuration QFN34-20 (Top View) 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 2 www.analogictech.com VP LX LX PGND 2504.2008.02.1.2 PRODUCT DATASHEET AAT2504178 AAT2504178 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. 2504.2008.02.1.2 www.analogictech.com 3 PRODUCT DATASHEET AAT2504178 AAT2504178 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 2.2 Units μA μA V mV V V % V mV %/V V V mA μA °C °C % of VOUT % of VOUT V μA V % V V μA μA μA A mΩ mΩ % %/V MHz °C °C V V μA Bias Power Supply IQ Quiescent Current ISHDN Shutdown Current UVLO Under-Voltage Lockout Voltage 250 1.7 1.62 -1.5 -2.5 0.593 5.5 1.5 2.5 0.607 300 0.09 0.6 LDOA, LDOB VLDO Input Voltage VOUT VFB VDO Output Voltage Tolerance Feedback Voltage Dropout Voltage2, 3 Line Regulation4 Enable Threshold Low Enable Threshold High Output Current Shutdown Current Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis IOUT = 1mA to 300mA TA = 25°C TA = -40°C to +85°C 0.6 ΔVLINEREG/VIN VEN(L) VEN(H) IOUT ISHT TSD THYS LDOA Power-OK Trip Threshold VPOK VPOKHYS Power-OK Hysteresis VPOK(LO) Power-OK Output Voltage Low IPOK Power-OK Output Leakage Current Step-Down Converter VIN Input Voltage VOUT Output Voltage Tolerance VOUT Programmable Range VOUT VFB Feedback Threshold Voltage ISHDN Shutdown Current ILX_LEAK LX Leakage Current IFB Feedback Leakage ILIM Current Limit RDS(ON)H High Side Switch On Resistance RDS(ON)L Low Side Switch On Resistance ΔVLOADREG/VOUT Load Regulation ΔVLINEREG/VIN Line Regulation Oscillator Frequency FOSC TSD Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis THYS VEN(L) Enable Threshold Low Enable Threshold High VEN(H) IEN EN Input Leakage IOUT = 300mA VIN = VOUT + 1 to 5.0V 1.4 300 VLDO (MIN) = 2.5 VIN = 5V 1.0 140 15 VOUT Rising, TA = 25°C ISINK = 1mA VPOK