AS3687 datasheet(26/55 Pages) AMSCO

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AS3687/87XM

Datasheet

www.austriamicrosystems.com/AS3687

1v3-4

25 - 54

Figure

15 – LED Pattern Generator AS3687/87XM for pattern_color = 0

any current sink

1 23 4 56 78 9 ... 32

12 3 4 56

At this time a delay of 0s,1s,2s,...,8s,16s,24s,32s,40s,48s,56s

can be programmed

78 9...

Defined by bit in the setup register pattern_data

in this example the code is 101110011...

31.25ms

(250ms if pattern_slow=1)

To select the different current sinks to be controlled by the LED pattern generator, see the ‘xxxx’_mode registers

(where ‘xxxx’ stands for the to be controlled current sink, e.g. curr1_mode for CURR1 current sink). See also the

descirption of the different current sinks.

To allow the generator of a color patterns set the bit pattern_color to ‘1’. Then the pattern can be connected to

CURR30-32 as follows:

Figure

16 – LED Pattern Generator AS3687/87XM for pattern_color = 1

CURR1/CURR30

CURR2/CURR31

CURR6/CURR32,33

36 9

... 30

...

100ms

(800ms if pattern_slow=1)

... 29

... 28

14 7

25 8

36 9

14 7

25 8

...

Defined by bit in the setup register pattern_data

in this example the code is 111110001011111000110111...

At this time a delay of 0s,1s,2s,...,8s,16s,24s,32s,40s,48s,56s

can be programmed

Only those current sinks will be controlled, where the ‘xxxx’_mode register is configured for LED pattern.

If the register bit pattern_slow is set, all pattern times are increased by a factor of eigth. (bit duration: 250ms if

pattern_color=0 / 800ms if pattern_color=1, delays between pattern up to 24s).

7.3.3.1 Soft Dimming for Pattern

The internal pattern generator can be combined with the internal pwm dimming modulator to obtain as shown in

the following figure:

Figure

17 – Softdimming Architecture for the AS3687/87XM (softdim_pattern=1 and pattern_color = 1)

Pattern

Generator

Dimming

Ramp

Gen

up down

PWM

Modulator

Zero

Detect

Flip Flop

set

reset

out

Flip Flop

set

reset

out

Flip Flop

set

reset

out

CURR1/CURR30

CURR2/CURR31

CURR6/CURR32,33

controls current sources (on/off) for

current source where

currX_mode = LED pattern

With the AS3687/87XM smooth fade-in and fade-out effects can be automatically generated.

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