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AS1109

Datasheet - Application In form atio n

9.1.2 Error Detection with Low-Current Diagnosis Mode

This unique feature of the AS1109 uses an internal all 1s test pattern for a flicker free diagnosis of all LEDs. This error detection mode can be

started anytime, and does not require any SDI input (see Figure 21).

Figure 21. Low-Current Diagnosis Mode with Internal All 1s Test Pattern – 128 Cascaded AS1109s

Low-current diagnosis mode is started with 3 clock pulses during error detection mode. After the three pulses of CLK, a pulse of LD loads the

internal all 1s test pattern. Then OEN should be enabled for 2µs for testing. With the rising edge of OEN the test of the LEDs is stopped and

while LD is high the desired error mode can be selected with the corresponding clock pulses.

With the next data input the detailed error code will be clocked out at SDO.

Note:

See Figure 22 for the use of an external test pattern.

Figure 22. Low-Current Diagnosis Mode with External Test Pattern – 128 Cascaded AS1109s

GEF

1024x

1024x

Data0

Data1

Rising Edge of OEN

Acquisition of Error Status

Falling Edge of LD; Error Register is cop-

ied into Shift Register

GEF

O or S Error Code of

All 1s Test Patern

Temperature Error Code

Load Internal All 1s Test Pattern

≤ 100mA

≤ 100mA

2µs Low-Current Diagnosis Mode

3x Clocks Low-

Current Mode

Clock for Error Mode

1x/2x

Display

SDI

SDO

CLK

OEN

LD

Current

≤ 0.8mA

GEF = Global Error Flag

Data1

Data2

Temperature Error Code

Data2

Data1

GEF

GEF

T/O or S Error Code

Data0

Rising Edge of OEN

Acquisition of Error Status

Display

SDI

SDO

CLK

OEN

LD

1024x

1024x

3x Clocks

Low-Current

Mode

Clock for Error

Mode 1x/2x

Falling Edge of LD; Error Register is cop-

ied into Shift Register

O or S Error Code

from Test Pattern

1024x

GEF = Global Error Flag

2µs Low-Current Diagnosis Mode

≤ 100mA

≤ 100mA

Current

≤ 0.8mA

Data2

Data3

External all 1s Test Pattern