IMP38HC4x

The IMP38C4x and IMP38HC4x are fixed frequency, high performance, current-mode PWM controllers that are pin compatible with bipolar 384x devices but feature improvements resulting from IMP's BiCMOS processing and circuit design. Notable among the improvements are zero cross-conduction/shoot-through current, reduced start-up and operating current, lower current-sense delay, higher frequency operation, full supply voltage swing of IMP38HC4x at the output and a 1% trimmed voltage reference.

IMP38C4x and IMP38HC4x output driver stage has zero cross-conduction current. A proprietary output state-machine monitors each output MOSFET and guarantees by design zero cross-conduction current. This is an industry first for 384x PWM devices.

Under-voltage lockout (UVL) performance of IMP38HC4x has been improved. When the power supply voltage is below the startup voltage, internal circuitry puts the output into a low impedance state. The output will sink 20mA and remain below 1.3V, well below the turn-on threshold voltage of the external MOSFET. Even when VDD drops to zero volts, the out pin of IMP38HC4x will not rise above approximately 1.3V because the output UVLO circuit is