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.

Applications

# 2- or 3-Cell NiMH, NiCd, or Alkaline Systems
# CDMA Cellular/PCS Handsets
# Handy Terminals
# Palmtop Computers
# PDAs
# Single-Cell Li+ Systems

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.

Source