MICROCHIP LR8K4-G Adjustable Linear Voltage Regulator, 20mA, TO-252AA-3

The MICROCHIP LR8K4-G is a high-voltage, low-output current, adjustable linear voltage regulator designed for demanding applications. It features an exceptionally wide operating input voltage range from 13.2V to 450V, making it ideal for circuits where a stable, precise voltage must be derived from a high-voltage source. The output voltage is user-adjustable from 1.2V up to 440V, provided the input voltage remains at least 12V greater than the desired output.

Voltage adjustment is achieved using two external resistors, R1 and R2, configured in a standard application circuit. The IC regulates the voltage difference between its V_OUT and ADJ pins to a nominal 1.20V. This reference voltage is then amplified by the external resistor ratio. A typical internal bias current of 10µA at the ADJ pin adds a constant offset, calculated as 10µA multiplied by R2, to the final output voltage.

Reliability and Protection

Built-in protection features ensure robust operation. The device incorporates both output current limiting and internal junction temperature limiting. The output current is typically limited to 20mA, which also safely restricts the short-circuit current to this level in the event of a fault. The thermal shutdown activates at a minimum junction temperature of 125°C, safeguarding the component from overheating.

Applications

This regulator is perfectly suited for industrial control systems, motor drive control circuits, and general power management tasks where high input voltages are present and a low, stable output current is required. Its 5% output voltage tolerance and surface-mount TO-252AA-3 (DPAK) package make it a reliable and compact choice for modern electronic designs, operating reliably across a temperature range of -40°C to +85°C.