AL5809-60P1-7

The Diodes Incorporated AL5809-60P1-7 is a 60V linear constant current LED driver designed to provide a simple and cost-effective solution for driving LED strings. The output current is set by a single external resistor connected to the ISET pin, with the current determined by ILED = 1.2V / RSET. The device features a built-in negative temperature coefficient of -40mV/C at the ISET pin, which gradually reduces LED current at elevated temperatures to protect the LEDs from thermal damage. The wide 2.8V to 60V operating range supports long LED strings. The compact PowerDI-123 package minimizes board space while providing good thermal performance. Thermal shutdown at 155C provides additional protection.

The AL5809-60P1-7 operates as a linear constant current regulator: 1) Current Regulation: An internal bandgap reference generates a 1.2V reference at the ISET pin. An external resistor RSET from ISET to GND sets the LED current: ILED = 1.2V / RSET. An internal current mirror amplifies this reference current to drive the LED string. 2) Temperature Compensation: The negative temperature coefficient of -40mV/C reduces the ISET reference voltage as temperature increases, automatically decreasing LED current to prevent thermal overstress. 3) Linear Regulation: The device operates as a series pass element, dropping excess voltage across its internal transistor. The dropout voltage is the minimum headroom required for regulation, typically 1.8V. 4) Thermal Protection: When junction temperature reaches 155C, the thermal shutdown circuit disables the output to prevent device damage.

• LED signage and channel letter lighting with long series strings
• Automotive interior LED lighting with thermal protection
• Constant current bias for sensor bridge circuits