al8807 Diodes, Inc., al8807 Datasheet - Page 14

• Manufacturer Part Number: al8807
• Description: High Efficiency Low Emi 30v 1a Buck Led Driver
• Manufacturer: Diodes, Inc.

Applications Information
Recommendations for minimising radiated EMI and other transients and thermal considerations are:
A Typical application for the AL8807 is an LED MR16 lamp (schematic shown in Figure 37).
An evaluation board for the AL8807 (named the AL8807EV2) for MR16 is available on request from your local Diodes’ sales
representative. This board follows Diodes’ recommendations for low EMI. Images of the top layer and bottom layers are
shown in Figure 38.
AL8807
Document Number: DS35281 Rev. 3 - 2
1.
2.
3.
4.
5.
6.
The decoupling capacitor (C1) has to be placed as close as possible to the V
The freewheeling diode’s (D1) anode, the SW pin and the inductor have to be placed as close as possible to each
other to avoid ringing.
The Ground return path from C1 must be a low impedance path with the ground plane as large as possible
The LED current sense resistor (R1) has to be placed as close as possible to the V
The majority of the conducted heat from the AL8807 is through the GND pin 2. A maximum earth plane with thermal
vias into a second earth plane will minimise self-heating
To reduce emissions via long leads on the supply input and LEDs low RF impedance capacitors (C2 and C5) should
be used at the point the wires are joined to the PCB
(cont.)
Fig. 38 Recommended MR16 PCB Layout
Fig. 37 MR16 Circuit Schematic
HIGH EFFICIENCY LOW EMI 30V 1A BUCK LED DRIVER
www.diodes.com
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IN
pin and D1 Cathode
IN
and SET pins.
AL8807
© Diodes Incorporated
November 2011