UC2904

The UC1904 Quad Supply Monitor will respond to under- and over-voltage conditions on up to four continuously monitored voltage levels. Four independent positive voltages can be monitored or, alternatively, two of the sense inputs are preset to monitor -5V and -12V supplies. The device also monitors Over-Current and Line Sense inputs, both with precision input thresholds.

Four open collector outputs on the UC1904 give the following responses: 1. The OV/OC output is a latched over-voltage, or over-current response. 2. A Power Good signal responds low with any fault detection on power-up a programmable delay is used to hold this output low for a system Power On Reset signal. 3. The PWRW output responds only to a Line Sense input, for early warning of power failures. 4. The last open collector, the ON/OFF output, generates a delayed supply OFF control signal in response to an OFF input command, under-voltage condition, or line fault detection.

The OV-UV fault window is adjustable with a programming input. The thresholds are centered around the precision 2.5V reference, with a scaled hysteresis for precise, glitch free operation. In the positive mode of operation, the fault windows at each of the sense inputs can be independently scaled using external resistors and the 2.5V reference output.

An Auto Restart function couples with the under-voltage and line sensing circuits to allow controlled power supply start-up and shutdown. This device will operate over a supply range of 4.75V to 18V. The device is available in a DIP, SOIC, or PLCC outline. This device is ESD protected on all pins.