Issue 3 – August 2009

www.diodes.com

© Diodes Incorporated, 2009

AP8800EV2 USER GUIDE

DESCRIPTION

The AP8800EV2, Figure 1, is a PCB constructed using an FR4 base for evaluating the AP8800 LED

driver with internal switch in MSOP-8L package. The evaluation board can be used to drive an

external choice of LEDs; the total forward voltage across the LEDs depending on the number and

type connected. [1]

The operating voltage for the evaluation board ranges from 8V to 28V maximum.

Higher voltage means lower supply current.

The nominal current for the evaluation board is set at 300mA with a 0R33 sense resistor, R1.

Test point CTRL provides a connection point for DC or PWM dimming and shutdown.

Note: The evaluation board does not have reverse polarity protection

Warning: with 300mA output, the connected LED will be hot and very bright

Figure 1: AP8800EV2 Evaluation Board

AP8800 DEVICE DESCRIPTION

The AP8800 is a step-down DC/DC converter designed to drive LEDs with a constant current. The

device can drive up to thirteen LEDs, depending largely on the forward voltage of the LEDs, in series

from a voltage source of 8V to 28V. Series connection of the LEDs provides identical LED currents

resulting in uniform brightness and eliminates the need for ballast resistors. The AP8800 switches at

frequencies up to 500KHz. This allows the use of small size external components, hence minimizing

the PCB area needed.

input pins. Dimming is achieved by applying either a DC voltage or a PWM signal at the CTRL input

pin. An input voltage of 0.2V or lower at CTRL shuts down the output at SW and puts the device into

a low-current standby state.

The device includes the output switch and a current sense circuit, which requires an external sense

resistor to set the nominal current up to 300mA.