The MAX1798/MAX1798A/MAX1799/MAX1799A system power supplies are designed specifically for CDMA cellular/PCS handsets. Each device contains five low-dropout 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 current. LDO1 is rated for 300mA, while LDOs 2–5 are each rated for 150mA. All LDOs are optimized for low noise and isolation. Each LDO can be individually enabled and disabled through the serial port, as well as individually programmed to any of 32 voltages from 1.8V to 3.3V.The MAX1798/MAX1798A/MAX1799/MAX1799As' wide 2.5V to 5.5V input voltage range makes them compatible with a wide range of input supplies, including a single Li+ cell battery. Both devices are available in thermally enhanced 20-pin TSSOP and TQFN exposed pad (EP) packages. Evaluation kits (MAX1798EVKIT and MAX1799EVKIT) are available to facilitate designs.Applications2- or 3-Cell NiMH, NiCd, or Alkaline SystemsCDMA Cellular/PCS HandsetsHandy TerminalsPalmtop ComputersPDAsSingle-Cell Li+ Systems