ZLED7022

Low-Voltage Six-Channel LED Driver

Data Sheet

November 9, 2010

© 2010

Zentrum Mikroelektronik Dresden AG - Rev. 1.0

All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without

the prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.

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2.6.

PCC Serial Digital Interface

The ZLED7022 detects the rising edges of the control signal input on the EN/SET pin via an internal counter and decodes the

signal into one of the 14 current level settings given in Table 2.1. The control signal timing can vary (even during a program-

ming cycle), and its frequency can range from high data rates (e.g., 1MHz) to very low rates (e.g., 15kHz). (Also see section

minimum) so that the ZLED7022 latches the programmed current level code into the data register and the current level

becomes active as illustrated in Figure 2.1. The internal counter is then reset to zero to be ready for the next programming

cycle. This process is repeated for the next data sent by the control system for subsequent current level programming. See

section 2.4 regarding the low-current shutdown mode, which is entered when the EN/SET signal remains low for longer than

Figure 2.1

PCC Serial Digital Interface Signal Timing

EN/SET

Data Reg

1

2

n

n= 14

1

n

0

3

Operating Conditions

3.1.

RF Noise Reduction

The ZLED7022 charge pump operates at a fixed frequency of 1MHz (typical) to limit noise and harmonics and prevent genera-

tion of RF interference by the ZLED7022, which could affect operation of local communication devices, such as cell phones.

The soft-start feature also prevents noise transients caused by inrush currents due to charge pump start-up.

The ZLED7022 has significantly lower back-injected noise at the input pin of the charge pump (typically 60mV peak-to-peak),

compared to inductor-based DC/DC boost converter solutions for white LED backlight applications (typically 10 times higher).

3.2.

ZLED7022 Thermal Protection

The ZLED7022 includes an on-board temperature sensing circuit that shuts down the ZLED7022 and turns off its outputs if the

die junction temperature exceeds 160°C (typical).