CDMA Cellular/PCS System Power Supplies

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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.
MAX1798, MAX1799: Typical Operating Circuit MAX1798, MAX1799: Typical Operating Circuit Enlarge+

Key Features

  • One 300mA Low-Noise LDO
  • Four 150mA Low-Noise LDOs
  • 45µVRMS Noise from 10Hz to 100kHz
  • > 60dB Crosstalk Isolation Below 10kHz
  • > 60dB PSRR Below 10kHz
  • 125mV (max) Dropout (OUT1 at 200mA)
  • 100mV (max) Dropout (OUT2–5 at 100mA)
  • Programmable Output Voltages
    • 1.8V to 3.3V in 32 Steps
  • 140ms (min) Reset Timer
  • SPI- or I²C-Compatible Serial Interface
  • Push-On/Push-Off Control Logic
  • Two 150mA General-Purpose Open-Drain Outputs
  • Overcurrent and Thermal Protection (all LDOs)
  • 1µA Shutdown Current
  • 20-Pin Thermally-Enhanced TSSOP or TQFN Packages


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

See parametric specs for Linear Regulators (134)

Part NumberVIN

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.
Request Reliability Report for: MAX1799 
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Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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