PCA9901_1

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 01 — 3 December 2009

7 of 27

NXP Semiconductors

PCA9901

One wire single LED driver

8.2.6 RESET command

A single pulse sent to the PCA9901 in less than 1.5 ms causes the PCA9901 to go to

Shutdown mode and to reset its registers to zeroes.

8.3 State machine

002aac605

power-up;

registers reset to zeroes

Shutdown mode

PCA9901 up and running;

registers reset to zeroes

training sequence;

LEDOUT follows CTRL state

TRAINING START

sequence memorized;

LEDOUT off

TRAINING END

RUN

RUN ONCE

RESET

PCA9901 up

and running

time-out detected during

training sequence

sequence

sent by

host

controller

PCA9901 up

and running

sequence is sent (loop)

STOP

PCA9901 up

and running

sequence is sent once

TRAINING END

Bypass mode when

registers still at zeroes

RESET

LEDOUT follows

CTRL state:

LEDOUT = ON

when CRTL = HIGH;

LEDOUT = OFF

when CTRL = LOW

registers reset

to zeroes

no patterns memorized

RUN or RUN ONCE

(1) PCA9901 goes directly to Shutdown mode if a training sequence has not been previously performed.

Fig 6.

State machine of the PCA9901