The PT1502 is a integrated power management unit for small handheld portable applications.

PT1502_ DS Rev EN_1. 7 PT 1502 GENERAL DESCRIPTION
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The PT1502 is a integrated power management unit for small handheld portable applications. It contains a single - cell Lithium Ion battery charger , a synchronous step - down DC - DC converter and 2 Low Dropout Regulators. It allows charging from both wall adapter and USB port. W hen charging from wall adapter, the PT1502 increases the charging current automatically. The battery charger is a highly integrated charging management device targeted at space limited portable applications. It offers an integrated MOSFET and current sensor, reverse blocking protection, high accuracy current and voltage regulation, and charge termination . It charges a battery in three phases: trickle charging, constant current, and constant voltage. No external sense r esistor is needed, and no blocking diode is required due to the internal MOSFET architecture. The thermal feedback regulates the charging current to limit the chip temperature during high power operation or high ambient temperature to maximize the charge r ate without risk of overheating . The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor. The PT 15 02 automatically terminates the charge cycle when the charge current drops to 1/10 the programmed valu e after the final float voltage is reached. The PT 15 02 automatically re - starts the charge if the battery voltage falls below an internal threshold. The step - down converter is a high efficiency monolithic current mode synchronous buck regulator with a const ant operation frequency. A main switch and a synchronous switch are integrated in PT1 5 02, the device has high efficiency and no external Schottky diode needed. 100% duty cycle provides low dropout operation, extending battery life in portable systems. Auto matic burst mode operation at light loads provides high efficiency . Internal 1. 5 MHz switching frequency allowing the use of small surface mount inductors and capacitors. T he output voltage can be adjusted by external resistors. The two low - dropout voltage regulators are designed for portable and wireless applications . It can provides better than 60dB PSRR at 1kHz. The output current can be up to 3 0 0mA. One regulator ’ s output voltage is fixed at 3.0V, and the other one is adjusted to 2.5V,2.8V,3.0V,3.3V b y two control pins. F EATURES  Integrated switch for USB/AC Adapter supply  120uA quiescent supply current(includes step - down DC - DC converters and two low dropout regulators)  Integrated single - cell lithium ion battery charger  Auto thermal regulated  Chargi ng current up to 1.2 A  Charging current adjusted by external resistor  Integrated step - down DC - DC converter  Output voltage adjusted by external resistor  Output current up to 8 00mA  1.5M Hz fixed switching frequency  Over - current and over - temperature protectio n  Integrated two low dropout regulators  LDO1: output voltage 3.0V ， up to 3 00mA output current  LDO2: output voltage optional for 2.5V/2.8V/3.0V/3.3V ， up to 3 00mA output current  PSRR: 60dB@1k Hz  Over - current and over - temperature protection  QFN20 （ 4X4 ） package  RoHS compliant A PPLICATIONS  MP3/4  PDAs  GSM/CDMA mobile phone  P ort able media players    
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