MIC4043 Series 1.245V SMT Low Voltage Secondary Side Shunt Regulator - SOT-143-4

Mfr Part#: MIC4043YM4-TR
Mounting Method:  Surface Mount
Package Style:  SOT-143 (TO-253-4)
Packaging:  REEL
Std Packaging Qty:  3,000



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$0.2400 USD (each)
3000+ $0.2400


Qty in Stock : 0
Factory Stock : 0
Factory Lead-Time: 21 Weeks
Min. Order Qty: 3,000
Multiple of: 3,000
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Product Highlight

  • Reference Voltage: 1.245 V
  • Operating Temp Range: -40 to +85 °C

The MIC4043 is a shunt regulator optimized for secondary-side regulation in low-voltage power supplies. Featuring a output stage guaranteed to swing within 400 mV of ground, the MIC4043 can be used in power supplies operating down to 1.5 V, even with optoisolators requiring greater than 1.2 V of headroom.

The MIC4043 normally drives the LED of an optically isolated feedback circuit. The MIC4043 monitors a resistively-divided output voltage and sinks error current through the optoisolator’s LED (secondary side); the optoisolator’s transistor (primary side) provides this signal to the controller’s feedback input. The MIC4043 is also practical for other voltage-monitoring applications requiring an open-collector output.

The MIC4043 replaces conventional ’431-type shunt regulators to allow low-voltage applications where there is inadequate headroom for a 2.5 V regulator in series with an optoisolator. Replacing ’431-type devices requires only a minor change to the way that the resistive-divider values are calculated.


  • Ideal for 1.8 V switching converters
  • Low-voltage operation
  • 400 mV maximum saturation over operating temperature range
  • Easy to use
  • voltage in, current out
  • 2% voltage tolerance over operating temperature range


  • Optically isolated low-volage power supplies
  • Low-voltage discrete regulator control 

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