A Product Line of Diodes Incorporated PAM2861 1A LED DRIVER WITH INTERNAL SWITCH Description Pin Assignments The PAM2861 is a continuous mode inductive step-down converter, Top View designed for driving single or multiple series connected LEDs TSOT25 efficiently from a voltage source higher than the LED voltage. The device operates from an input supply between 6V and 40V and provides an externally adjustable output current of up to 1A. Depending upon supply voltage and external components, this can provide up to 30 watts of output power. The PAM2861 includes the output switch and a high-side output current sensing circuit, which uses an external resistor to set the nominal average output current. Output current can be adjusted below the set value, by applying an external control signal to the VSET pin. The VSET pin will accept either a DC voltage or a PWM waveform. The soft-start time can be increased using an external capacitor from the VSET pin to ground. Applying a voltage of 0.2V or lower to the VSET pin turns the output off and switches the device into a low current standby state. Features Simple Low Parts Count Applications Internal 40V NDMOS Switch Low voltage halogen replacement LEDs 1A Output Current Low voltage industrial lighting Single Pin On/Off and Brightness Control Using DC Voltage or LED back-side lighting PWM Illuminated signs Soft-Start High Efficiency (up to 97%) Wide Input Voltage Range: 6V to 40V Output Shutdown Open LED Protection Short LED Protection Up to 1MHz Switching Frequency Inherent Open-Circuit LED Protection Typical 5% Output Current Accuracy Pb-free TSOT25 and SOT89-5 Packages 1 of 12 July 2013 PAM2861 Diodes Incorporated www.diodes.com Document number: DSxxxxx Rev. 1 - 1 A Product Line of Diodes Incorporated PAM2861 Typical Applications Circuit Pin Descriptions Pin Pin Function Number Name Drain of NDMOS switch. 1 LX Ground (0V) 2 GND Multi-function On/Off and brightness control pin: Leave floating for normal operation. Drive to voltage below 0.2V to turn off output current Drive with DC voltage (0.3V < VSET< 2.5V) to adjust output current from 12% to 100% of I nom OUT 3 VSET Drive with PWM signal from open-collector or open-drain transistor, to adjust output current. Adjustment range 1% to 100% of I nom for f < 500Hz OUT Connect a capacitor from this pin to ground to increase soft-start time. (Default soft-start time = 0.1ms. Additional soft-start time is approx.1.5ms/1nF) Connect resistor RS from this pin to VIN to define nominal average output current 4 ISENSE I nom = 0.1/Rs OUT Input voltage (6V to 40V). Decouple to ground with 10 F or higher X7R ceramic capacitor close to device. 5 VIN 2 of 12 July 2013 PAM2861 Diodes Incorporated www.diodes.com Document number: DSxxxxx Rev. 1 - 1