PPMIC BU

www.belling.com.cn

BL9582 Rev 1.2

Belling Proprietary Information. Unauthorized Photocopy and Duplication Prohibited

2/2010

©2010 Belling All Rights Reserved

15

BL9582

32V, 1.4A Step-down

High Brightness LED Driver with Internal Switch

temperature decreases (140 ), the IC

℃

recovers again.

Layout considerations

Careful PCB layout is critical to achieve

low switching losses and stable operation.

Use a multilayer board whenever possible

for better noise immunity. Minimize ground

noise by connecting high-current ground

returns, the input bypass-capacitor ground

lead, and the output-filter ground lead to a

single point (star ground configuration).

LX pin

The LX pin of the device is a fast switching

node, so PCB tracks should be kept as

short as possible. To minimize ground

'bounce', the ground pin of the device

should be soldered directly to the ground

plane.

Coil and decoupling capacitors and

current sense resistor

It is particularly important to mount the coil

and the input decoupling capacitor as close

to the device pins as possible to minimize

parasitic resistance and inductance, which

will degrade efficiency. It is also important

to minimize any track resistance in series

with no other currents flowing in these

tracks. It is important that the cathode

current of the Schottky diode does not flow

give an apparent higher measure of current

than is actual because of track resistance.

ADJ pin

The ADJ pin is a high impedance input, so

when left floating, PCB traces to this pin

should be as short as possible to reduce

noise pickup. ADJ pin can also be

connected to a voltage between 1.2V~5V.

In this case, the internal circuit will clamp

the output current at the value which is set

by ADJ=1.2V.

High voltage traces

Avoid running any high voltage traces

close to the ADJ pin, to reduce the risk of

leakage due to board contamination. Any

such leakage may raise the ADJ pin

voltage and cause excessive output

current. A ground ring placed around the

ADJ pin will minimize changes in output

current under these conditions.