The CS8121 is a 5V, 1A precision linear regulator with two microprocessor compatible control functions and protection circuitry included on chip. The composite NPN-PNP output pass transistor assures a lower dropout voltage (1.2V @ 1A) without requiring excessive supply current (4mA). The CS8121Õs two logic control functions make this regulator well suited to applications requiring microprocessor- based control at the board or module level. controls the output stage. A high voltage (>2.9V) on the lead turns off the regulatorÕs pass transistor and sends the IC into Sleep mode where it draws only 250µA. sends a signal when the IC is powering up or whenever the output voltage falls out of regulation. The signal is valid down to VOUT = 1V. The CS8121 design optimizes supply rejection by switching the internal bandgap reference from the supply input to the regulator output as soon as the nominal output voltage is achieved. Additional on chip filtering enhances rejection of high frequency transients on all external leads. The CS8121 is fault protected against short circuit, over voltage and thermal runaway conditions.