The IMP38C4x and IMP38HC4x are fixed frequency, high performance, bipolar 384x pin-compatible current-mode PWM controllers imported from BiCMOS devices, but feature improved processing and circuit design. Among the significant improvements are zero current cross-conduction/shoot-through, reduced start-up and operating current, low current detection delays, higher frequency operation, all providing a trimmed 1% reference voltage and output voltage swing. The IMP38C4x and IMP38HC4x output drive stages have zero-cross conduction current. A proprietary output state machine monitors each output MOSFET and ensures zero cross conduction current for the design. This is an industry first for 384x PWM devices. Undervoltage lockout (UVL) performance has been improved. When the supply voltage is lower than the startup voltage, the internal circuit puts the output into a low impedance state. The output will sink 20mA still below 1.3V, well below the threshold voltage of the external MOSFET. Even when VDD drops to zero volts, the output pin does not rise above about 1.3V because the output UVLO circuit is powered through the output pin. The leakage current from the external power MOSFET will not force the PWM output to rise, in turn the external MOSFET. The current-sense propagation delay time is 35ns typical, 65ns maximum, a 75% reduction compared to other 38xx implementations. The output stage driver is 0.5A for the IMP38C4x devices. The IMP38HC4x family of high drivers are rated for 1.0A peak current drivers. Like the traditional 384x controllers, the IMP38C4x and IMP38HC4x controllers use a current-mode architecture for excellent load regulation, pulse-through current limiting and output MOSFET protection. All versions can operate up to 20 volts. For maximum application flexibility, start-up voltages range from 14.5V to 8.4V. Start-up current has been reduced to 120µA maximum and operating current has been reduced to 1.5mA maximum. The IMP38C4x/IMP38HC4x are available in 8-pin and 14-pin DIP and SO packages as well as 8-pin MicroSO packages. 14-pin devices provide independent controller power pin output driver power. This configuration maximizes application flexibility and performance. The 14-pin package also consumes more power. The devices in the compact 8-pin package do not have separate output driver power connections. The IMP38C4x and IMP38HC4x families operate over the -40°C to +85°C temperature range.