MP4700 – HIGH-BRIGHTNESS BCM, LOW SIDE BUCK WLED DRIVE WLED DRIVER

MP4700 Rev. 1.0

www.MonolithicPower.com

11

10/29/2012

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2012 MPS. All Rights Reserved.

Hiccup Output-Short Protection

Due to the minimal on time limit, the inductor

current will be out of regulation. The MP4700

can detect this failure and shut down for about

2.8ms, and then re-tries the operation. This

hiccup protection can eliminate thermal issues

due to a short-circuit current, and also maintain

normal operation if the protection is mis-

triggered.

Input-Bus

-Voltage Under-Voltage Lockout

(UVLO) Protection

The MP4700 implements UVLO protection for

the input bus voltage. The INUV pin senses the

input bus voltage through a voltage divider. The

IC is locked out until the input bus voltage rises

so that the INUV voltage pin exceeds its UVLO

threshold. This UVLO function protects against

a low input bus voltage. For best results, set the

input bus voltage UVLO point over 1.1 times the

output LED voltage.

Set the input bus UVLO as follows:

INUV _ H

Bus

UVLO

INUV _ L

INUV _ th

R

V_

1

RV



voltage.

VCC Under-Voltage Lockout (UVLO)

Protection

Under-voltage lockout (UVLO) protects the chip

from operating at an insufficient supply voltage.

The UVLO rising threshold is about 7.4V while

its falling threshold is a consistent 6.4V.

Thermal Shutdown Protection

An accurate temperature protection prevents

the chip from operating at exceedingly high

temperatures. When the silicon die temperature

exceeds its upper threshold, it shuts down the

whole chip. When the temperature drops below

its lower threshold, the chip is enabled again.