PCA9901_1

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 01 — 3 December 2009

9 of 27

NXP Semiconductors

PCA9901

One wire single LED driver

8.5 TRAINING START and TRAINING END commands waveforms

002aac607

TRAINING START command

1.5 ms minimum

PCA9901 leaves Shutdown mode

and is ready for capture within 1.5 ms (max).

All registers are set to zeroes.

first LED ON timing

last LED OFF timing

Training sequence

TRAINING END command

1.5 ms minimum

PCA9901 goes to Shutdown mode

Fig 8.

TRAINING START and TRAINING END commands

8.6 RUN ONCE, RUN, STOP and RESET commands waveforms

002aac608

RUN ONCE command

1.5 ms minimum

PCA9901 goes to Shutdown mode immediately

if LED is OFF (counting LED OFF time).

programmed

sequence

runs once

LEDOUT = OFF

PCA9901 goes to Shutdown mode

RUN command

1.5 ms minimum

programmed sequence

runs in loop

STOP command

PCA9901 goes to Shutdown mode

once the current LED ON time

has been performed.

or

PCA9901 leaves

Shutdown mode

LED on

RESET command

All registers set to zeroes;

PCA9901 goes to

Shutdown mode.

1.5 ms minimum

PCA9901 leaves

Shutdown mode

Fig 9.

RUN ONCE, RUN, STOP and RESET commands

8.7 Bypass mode

A Bypass mode allows the PCA9901 LEDOUT pin to be directly driven by the CTRL logic

state.

A TRAINING START command followed immediately by a TRAINING END command

enters the Bypass mode. Once the TRAINING END command has been issued, the

LEDOUT output follows the CTRL logic state (LED ON when CTRL = HIGH, LED OFF

when CTRL = 0). Sending a RESET command exits the Bypass mode.

The Bypass mode allows the microcontroller to directly control the LED and blink it or

dim it.