AS3685A datasheet(13/25 Pages) AMSCO

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AS3685A/AS3685B

Datasheet

www.austriamicrosystems.com/

AS3685

(ptr)

Revision 2.2

12 - 24

7.2.2 AS3685B Current Setting

The current through the LED (ILED) can be set in several steps using the following waveforms:

Figure 16 – AS3685B Current Setting Method A

For method A, the current is started after a certain time after the first rising edge of EN1. The AS3685B chooses

method A, if EN1 is high at the first rising edge of EN2.

Figure 17 – AS3685B Current Setting Method B

For method B, the current is started after the second rising edge of EN2. The AS3685B chooses method B, if

EN1 is low at the first rising edge of EN2.

Any high or low level duration for EN1 or EN2 should not be shorter than tPULSEWIDTH.

The actual number of pulses on the pin EN1 (applies for methods A and B) define the mode and the current

settings for the AS3685B:

Table

9 – AS3685B Current Settings

H-L-H Pulses on EN1

Mode

ILED

(for RISET = 14.2kΩ)

ILED

(for RISET = 10kΩ)

ILED/IISET

EN1=EN2=0

Off

0mA

(Off)

Indicator

4.7mA average

(=150mA with

1/32 duty cycle

1) )

6.7mA

(=214mA with

1/32 duty cycle

1))

52.2

(=ITORCH2ISET/32)

41mA

60mA

448

85mA

120mA

929

129mA

180mA

1410

Torch

173mA

250mA

1891

Flash

217mA

310mA

2371

EN2

EN1

Set current with

number of pulses

off

Flash/Strobe/Indicatior function

dependent on number of pulses

ILED

typ. 64µs

Current can be increased

if required

Define

Method A

min.

tPULSEWIDTH

EN2

EN1

Set current with

number of pulses

off

Flash/Strobe/Indicatior function

dependent on number of pulses

ILED

typ. 64µs

Current can be

increased if required

no time limit

Define

Method B

min tPULSEWIDTH

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