AS3688 datasheet(52/72 Pages) AMSOSRAM

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AS3688

austriami crosyst ems

Datasheet, Confidential

www.austriamicrosystems.com (ptr,tje)

Revision 1.1.1 / 20060707

50 - 70

GPIO driving cap

Addr: 20h

This register enables low current mode for GPIOs.

Bit

Bit Name

Default

Access

Description

gpio0_low_curr

R/W

Defines the driving capability of pin GPIO0.

0 = Iout

1 = Iout /4

gpio1_low_curr

R/W

Defines the driving capability of pin GPIO1.

0 = Iout

1 = Iout /4

gpio2_low_curr

R/W

Defines the driving capability of pin GPIO2.

0 = Iout

1 = Iout /4

7:3

N/A

7.6 LED Test

Figure

30 – LED Function Testing

The AS3688 supports the verification of the functionality of the connected LEDs (open and shorted LEDs can be

detected). This feature is especially useful in production test to verify the correct assembly of the LEDs, all its

connectors and cables. It can also be used in the field to verify if any of the LEDs is damaged. A damaged LED

can then be disabled (to avoid unnecessary currents).

The current sources, charge pump, dcdc converter and the internal ADC are used to verify the forward voltage of

the LEDs. If this forward voltage is within the specified limits of the LEDs, the external circuitry is assumed to

operate.

7.6.1 Function Testing for single LEDs connected to the Charge Pump

For any current source connected to the charge pump (usually RGB{1,2,3}, CURR{30,31,32,33,41,42,43}) where

only one LED is connected between the charge pump and the current sink (see Figure 1) use:

Table

19 – Function Testing for LEDs connected to the Charge Pump

Step

Action

Example Code

Switch on the charge pump and set it into manual 1:2

mode (to avoid automatic mode switching during

measurements)

Reg 23h <- 14h (cp_mode = 1:2, manual)

Reg 00h <- 04h (cp _on = 1)

4.7µF

CPOUT

2.2µF

ADC

Baseband

Processor

Interface

Detect Open LEDs

Detect Shorted LEDs

From DCDC

Step Up

Converter

From Charge

Pump

DCDC_FB

I(step_up_vtuning)

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