Micrel, Inc.

MIC4043

Functional Description

reference, and a pass transistor in a single package.

The operation of the MIC4043 is similar to conventional

shunt regulators such as the industry standard ’431. In a

closed loop system, the MIC4043 maintains the desired

feedback voltage at the FB pin by sinking current onto the

SNK pin proportional to the error voltage at the FB pin.

The ratio of sink current to error voltage is the

transconductance of the device.

Reference

The MIC4043 uses a high-side reference. External

voltage dividers providing feedback to the MIC4043 will

be inverted when compared to those used with ’431-

equivalent devices.

Behavior

The external feedback voltage is compared to the internal

high-side 1.245V reference.

amplifier provides no drive to the sink transistor. If the

amplifier drives the pass transistor which sinks current to

ground.

October 10, 2014

7

Revision 2.0