ZLED7012 Datasheet

© 2016 Integrated Device Technology, Inc.

9

April 20, 2016

The current sinks [D3:D0] are controlled by the PCC serial data input on the EN/SET pin. Data is written to an internal data register

that sets the outputs to one of 14 current levels. The Vout pin provides a shared supply voltage for the LEDs. The capacitor across

the C+ and C- pins is the “pump capacitor” used by the charge pump.

2.3.

ZLED7012 Soft-Start Feature

The soft-start feature protects against excessive inrush currents during the start-up of the charge pump circuit. This prevents

potential transient noise effects that can affect initial performance, especially in battery-operated applications toward the end of the

battery life.

2.4.

ZLED7012 Low-Current Shutdown Mode

The ZLED7012 enters a low-current shutdown mode whenever its EN/SET input is held low longer than TOFF (

500μs minimum). In

the low-current shutdown mode, the ZLED7012 draws minimal current (ISHDN=1

μA typical, 2μA maximum) and the internal data

register that controls output current is reset to 0, which disables the outputs.

2.5.

LED Current Control

The ZLED7012’s Pulse Count Control (PCC) serial digital interface is used to enable/disable the LED outputs and set the constant

current level to one of 14 settings using a nearly logarithmic scale (approximately 1.5dB difference between settings) to provide a

linear brightness progression as the current level increases/decreases. See Table 2.1 for the current level settings.

Because [D3:D0] are independent constant current sinks, the voltage at the LED output being driven is determined by the LED’s

forward voltage (VF). This enables accurate LED brightness control and matching by the control system.

Table 2.1

Current Output Settings

Data Level

Current Output per Channel (mA)

1

20.0

2

17.0

3

14.0

4

12.0

5

10.0

6

8.6

7

7.0

8

6.0

9

5.0

10

4.2

11

3.6

12

3.0

13

2.4

14

1.8