MAX1798

19-1655; Rev 1; 2/01 NUAL KIT MA ATION U L A E V E BL AVAILA CDMA Cellular/PCS System Power Supplies Features o One 300mA Low-Noise LDO o Four 150mA Low-Noise LDOs o 45µVRMS Noise from 10Hz to 100kHz o >60dB Crosstalk Isolation Below 10kHz o >60dB PSRR Below 10kHz o 125mV (max) Dropout (OUT1 at 200mA) o 100mV (max) Dropout (OUT2–5 at 100mA) o Programmable Output Voltages 1.8V to 3.3V in 32 Steps o 140ms (min) Reset Timer o SPI- or I2C-Compatible Serial Interface o Push-On/Push-Off Control Logic o Two 150mA General Purpose Open-Drain Outputs o Overcurrent and Thermal Protection (all LDOs) o 1µA Shutdown Current o 20-Pin Thermally-Enhanced TSSOP or QFN Packages General Description The MAX1798/MAX1798A/MAX1799/MAX1799A system power supplies are designed specifically for CDMA cellular/PCS handsets. Each device contains five lowdropout linear regulators (LDOs), a 140ms (min) reset timer, a serial interface, push-on/push-off control logic, and two general-purpose open-drain outputs. Only the serial interface is different between the MAX1798/ MAX1798A/MAX1799/MAX1799A: the MAX1798/ MAX1798A feature an SPI™-compatible serial interface, and the MAX1799/MAX1799A feature an I2C™-compatible interface. The “A” parts have a -13% reset threshold, the non-A parts have a 9.5% threshold. The “A” parts have a 175 delay on a reset-triggered shutdown, the non-A shutdown instantly. Each linear regulator features extremely low dropout voltage, specified at two-thirds of the maximum output curren...