negative-voltage power-side switch

Posted on Aug 29, 2012    3635

When you need to quickly connect a negative power supply under logic control, the negative power-side switch in Figure 1 can help. Although originally intended for driving the gates of high-current MOSFETs, the MIC4451 can assume a different role. It provides complementary, low-on-resistance MOSFET switches to connect a system power-supply rail to a negative input voltage or to ground, enabled by a digital signal.

The MIC4451 comprises an input buffer with a small amount of hysteresis and several logic inverter/buffers that ultimately drive a high-current output stage. Figure 2 shows a block diagram of the MIC4451. The on-resistance of the n- and p-channel devices

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