PCA9901_1

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 01 — 3 December 2009

8 of 27

NXP Semiconductors

PCA9901

One wire single LED driver

8.4 Lighting training sequence

Training sequence starts after a TRAINING START command has been issued by the

host controller and ends after a TRAINING END command has been issued.

The LED ON timing is provided when CTRL is HIGH and the LED OFF timing is provided

when CTRL is LOW.

LEDOUT follows CTRL Logic state during the Training sequence: The LED is ON when

CTRL = HIGH, and the LED is OFF when CTRL = LOW.

The sequence is as follows:

Pattern 1 ON – Pattern 1 OFF – Pattern 2 ON – Pattern 2 OFF – Pattern 3 ON –

Pattern 3 OFF

A sequence composed by only 1 or 2 patterns can also be stored by issuing the

registers during the training sequence remain programmed with zeroes; when the state

machine encounters a Zero ON time register, it loops to the beginning of the sequence.

255 ms.

An ON time higher than 255 ms causes the ON counter to saturate at max value

(0xFF).

and 5.1 s.

An OFF time higher than 5.1 s causes the OFF counter to saturate at max value

(0xFF).

ON and OFF timings are stored on the 8-bit registers. The registers are reset to zeroes

when the host controller sends a TRAINING START or RESET command.

TRAINING

START

TRAINING

END

LED OFF

LED OFF

LED OFF

LED ON

LED ON

LED ON

1_ON

1_OFF

2_ON

3_ON

2_OFF

3_OFF

Pattern 1

Pattern 2

Pattern 3

sequence

LEDOUT pin follows CTRL state dring the sequence capture

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1_ON, 2_ON and 3_ON timings: between 1 ms and at least 255 ms (4096 steps).

2_OFF, 2_OFF and 3_OFF timings: between at least 20 ms and 5.1 s (4096 steps).

Fig 7.

Lighting sequence capture