4/26

BD18378EFV-M

TSZ02201-0W1W0C500020-1-2

© 2015 ROHM Co., Ltd. All rights reserved.

www.rohm.co

m

TSZ22111・15・001

04. Dec. 2015 Rev.004

Block Diagram

Figure 3. Block diagram

Description of Blocks Functionality



Constant current driver

The chip uses a constant current output driver with a provision for individual calibration per channel.

The output device is scaled to give 6 bit output range.

∗

(������������ + ����)

��������

Output currents are timed by the assigned PWM input.

The drivers have a low leakage current to keep the LED in firm OFF condition when the channel is inactive.

Full Scale current setting example table:

12kΩ

50mA

20kΩ

30mA

30kΩ

20mA

60kΩ

10mA



Active pull up circuit

A pull up current can be activated to avoid LED flicker during activated and deactivated state. This can be done by

changing the corresponding bit in the EN_PULL_UP@ON and EN_PULL_UP@OFF registers. Please see also the

description of the WRITE_EN_PULL_UP commands.

Shift Register

Control Logic

PWM Maping/

PWM Fault Detection

16

Over

Temperature

LED Open/

Short

Short to GND

Pull up

Current Mirror

UVLO

BandGap

Weak LED

Supply

48

x12

SDI

CLK

LATCH

SDO

PGND

IREF

CH0-11

SENSE

VCC

PWM0-5

ERR

Iref

CAL

PWM

12

12

6

72

AGND

Constant Current

Driver