mic5219-2.8ym5-tr

The MIC5219-2.8YM5-TR from Microchip (formerly Micrel) is a 500 mA peak-output low-dropout linear regulator with a fixed 2.8 V output. It features ultra-low noise performance via a BYP bypass pin (470 pF capacitor to GND reduces output noise to 300 nV/sqrt-Hz), +/-1% output voltage accuracy, and a low 350 mV typical dropout voltage at full load. The 80 uA quiescent current and near-zero shutdown current (<1 uA) make it ideal for battery-powered applications. The CMOS P-MOSFET pass element ensures ground current remains nearly constant regardless of load. Built-in protections include current limiting, thermal shutdown, and reverse-battery protection.

The MIC5219 uses a P-channel MOSFET pass transistor controlled by an error amplifier that compares a fraction of the output voltage (from an internal resistor divider for fixed-voltage versions) against a precision bandgap reference. The error amplifier drives the PMOS gate to regulate the output. A unique BYP pin connects to the reference voltage node through an internal resistor; an external 470 pF capacitor on this pin filters reference noise, achieving ultra-low output noise. The enable pin controls a CMOS/TTL-compatible shutdown circuit that disconnects the pass transistor, reducing supply current to below 1 uA. Current limiting is implemented by sensing the pass transistor current and clamping the gate drive. Thermal shutdown activates at approximately 160 degC with 15 degC hysteresis. The reverse-battery protection circuit prevents damage when input polarity is reversed.

• RF/wireless module 2.8V power supply with ultra-low noise requirement
• Battery-powered portable electronics requiring long standby life
• GSM/GPRS module peak-current supply during transmit bursts
• Audio codec and DAC clean power rail
• 2.8V I/O voltage rail for FPGA/ASIC power sequencing
• USB-powered device regulation