BD6583MUV-A 데이터 시트보기 (PDF) - ROHM Semiconductor

부품명

상세내역

일치하는 목록

BD6583MUV-A

White Backlight LED Driver for Medium to Large LCD Panels (Switching Regulator Type)

ROHM Semiconductor 

BD6583MUV-A

Technical Note

●The coil selection

The DC/DC is designed by more than 4.7µH. When L value sets to a lower value, it is possibility that the specific

sub-harmonic oscillation of current mode DC / DC will be happened.

Please do not let L value to 3.3µH or below.

And, L value increases, the phase margin of DC / DC becomes to zero. Please enlarge the output capacitor value when you

increase L value.

Example)

4.7µH

=

output capacitor 2.2µF/50V

1pcs

6.8µH

=

output capacitor 2.2µF/50V

2pcs

10µH

=

output capacitor 2.2µF/50V

3pcs

This value is just examples, please made sure the final judgment is under an enough evaluation.

●Layout

In order to make the most of the performance of this IC, its layout pattern is very important. Characteristics such as efficiency

and ripple and the likes change greatly with layout patterns, which please note carefully.

to Power Supply

CIN

L

CBAT

PWM

Reset

CREG

to Cathode

of LED

to GND

SBD

COUT

VDET

N.C.

Tr

GND

SW

RSENSE

SENSP

TEST

LED6

LED5

LED4

GND

LED3

LED2

to Anode

of each LED

RISET

Fig. 43 Layout

Connect the input bypath capacitor CIN(10µF) nearest to coil L, as shown in the upper diagram.

Wire the power supply line by the low resistance from CIN to VBAT pin. Thereby, the input voltage ripple of the IC can be

reduced. Connect smoothing capacitor CREG of the regulator nearest to between VREG and GND pin, as shown in the upper

diagram. Connect schottky barrier diode SBD of the regulator nearest to between coil L and switching transistor Tr.

And connect output capacitor COUT nearest to between CIN and GND pin. Thereby, the output voltage ripple of the IC can

be reduced.

Connect switching transistor Tr nearest to SW pin. Wire coil L and switching transistor Tr, current sensing resistor RSENSE by the

low resistance. Wiring to the SENSP pin isn't Tr side, but connect it from RSENSE side. Over current value may become low when

wiring from Tr side. Connect RSENSE of GND side isolated to SENS pin. Don’t wire between RSENSE and SNESN pin wiring from

RSENSE pin to GND pin. And RSENSE GND line must be wired directly to GND pin of output capacitor. It has the possibility that

restricts the current drive performance by the influence of the noise when other GND is connected to this GND.

Connect LED current setting resistor RISET nearest to ISET pin. There is possibility to oscillate when capacity is added to ISET

terminal, so pay attention that capacity isn't added. And, RISET of GND side must be wired directly to GND pin.

When those pins are not connected directly near the chip, influence is given to the performance of BD6583MUV-A, and may

limit the current drive performance. As for the wire to the inductor, make its resistance component small so as to reduce electric

power consumption and increase the entire efficiency.

The layout pattern in consideration of these is shown in next page.

www.rohm.com

© 2011 ROHM Co., Ltd. All rights reserved.

16/26

2011.06 - Rev.C

Share Link: