ZSPM4121 Under-Voltage Load Switch for Smart Battery Management

The ZSPM4121 battery management load switch can be used to protect a battery from excessive discharge. It actively switches the battery power source off if it drops to a set threshold (Off Mode). When the input battery voltage is above the threshold, the load switch is on (On Mode). The ZSPM4121 threshold voltage (VTHRESH) is programmed at manufacturing to a setpoint in the range of 1.2V to 4.2V with 100mV steps between options.

When the input battery voltage has been switched off by the ZSPM4121, the quiescent current draw on the battery is in the order of 100pA (typical). The quiescent current in the on state is as low as 70nA.

The ZSPM4121 consists of an internally generated threshold voltage, a comparator with hysteresis, slew rate control for the load switch, a P-channel load switch, and an open-drain indicator pin. The 500mV hysteresis between the Off Mode and the On Mode prevents intermittent operation. The ZSPM4121 also provides some over-current protection.



  • Best in class ultra low quiescent current in Off Mode: 100pA typical
  • Ultra-low quiescent current in On Mode: 70nA typical
  • Accurate on/off voltage threshold
  • Low Rds(on): 175mΩ (typical) @5V


  • Power source is activity switched off when VCC drops below a set threshold (programmed at manufacturing)
  • Wide input voltage range: 1.2V to 5.5V
  • Threshold voltage options of 1.2V to 4.2V in 100mV steps (factory programmed)
  • Supervisory over-current limit shutdown
  • Low drop out disconnect from VCC to loads
  • Controlled turn-on slew rate
  • 500mV Off Mode to On Mode
  • Over currrent shutdown
  • 8-pin DFN package (2mm x 2mm)




Contact Information

Servoflo Corporation
75 Allen Street
Lexington, MA 02421

Phone: (781) 862-9572
Fax: (781) 862-9244

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