Serial to Parallel Parallel to Serial Converters and Load Switch Controllers with SMBus Interface

SMBus Interfaced Controller Simplifies Power Plane Switching

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The MAX1661/MAX1662/MAX1663 serial-to-parallel/parallel-to-serial converters are intended to control external power MOSFETs in power-plane switching applications. These small, low-cost devices can be used on a system motherboard to control point-of-load switching from a 2-wire SMBus™ serial interface. Each device has three high-voltage open-drain outputs that double as TTL-level logic inputs, giving them bidirectional capabilities. The I/O pins can withstand +28V, so they can control battery voltage-distribution switches in notebook computers.

The MAX1661 is intended for driving N-channel MOSFETs and its outputs are low upon power-up. The MAX1662/MAX1663 are intended for P-channel MOSFETs, and their outputs are high-impedance upon power-up. This ensures that the MOSFETs are off at power-up, so the system can enforce power-plane sequencing.

The active-low SMBSUS control input selects control data between two separate data registers. This feature allows the system to select between two different power-plane configurations asynchronously, eliminating latencies introduced by the serial bus. Other features include thermal-overload and overcurrent protection, ultra-low supply current, and both hardware and software interrupt capabilities. These devices are available in the space-saving 10-pin µMAX® package.
MAX1661, MAX1662, MAX1663: Typical Operating Circuits MAX1661, MAX1662, MAX1663: Typical Operating Circuits Enlarge+

Key Features

  • Performs Serial-to-Parallel and Parallel-to-Serial Conversions
  • Three General-Purpose Digital Input/Output Pins (withstand +28V)
  • SMBus 2-Wire Serial Interface
  • Supports SMBSUS-bar Asynchronous Suspend Mode
  • 3µA Supply Current
  • +2.7V to +5.5V Supply Range
  • Space-Saving, Low-Cost 10-Pin µMAX Package


  • Computers: Desktop, Workstation, Server
  • Notebook and Subnotebook Computers
  • Point-of-Load Power-Bus Switching
  • Power-Plane Switching
  • Smart Battery Packs/Chargers

Technical Documents

App Note 3336

Quality and Environmental Data

Request Reliability Report for: MAX1663 
Lead-Free Package Tin (Sn) Whisker Reports
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

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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Type ID PDF Title
App Note 3336

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05/29/2020 - 05/31/2020, Detroit, MI
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