AS1109-BSSU-Z Datasheet AS1109-BQFR, AS1109-BSOU, AS1109-BQFT | P16-P18

www.ams.com/LED-Driver-ICs/AS1109 Revision 1.21 15 - 24

AS1109

Datasheet - Detailed Description

Figure 18. Switching into Low-Current Diagnostic Mode Timing Diagram

8.7 Shutdown Mode

The AS1109 features a shutdown mode which can be entered via 4 clock pulses during error-detection mode. To enable the shutdown mode a 0

must be placed at SDI after the rising edge of the 3rd clock pulse.

To disable shutdown mode a 1 must be placed at SDI after the 3rd clock pulse. The shutdown/wakeup information will be latched through if

multiple AS1109 devices are in a chain. At the rising edge of the 4th clock pulse the shutdown bit will be read out and the AS1109 will shutdown

or wakeup.

Note: In shutdown mode the supply current drops down to typically 3µA.

Figure 19. Shutdown Mode Timing Diagram

OFLAGTFLAG SFLAG

Don’t

Care

Re-entering Error Detection

Mode

tTESTING

Global Flag Readout

SDI

OEN

CLK

SDO

Load Internal all 1s Test

Pattern

(optional)

tH(L)

tP4

tSW(ERROR)

tP1

tSU(ERROR)

Normal Operation Current

For detailed timing information see Timing Diagrams on page 8.

tGSW(ERROR)

2µs Low-Current Diagnosis Mode

tH(L)

SDI

OEN

CLK

SDO

1 = Wakeup

0 = Shutdown

1 = Wakeup

0 = Shutdown

OFLAGTFLAG SFLAG

tP4

tSU(ERROR)

tSU(D)

www.ams.com/LED-Driver-ICs/AS1109 Revision 1.21 16 - 24

AS1109

Datasheet - Application Information

9 Application Information

9.1 Error Detection

The AS1109 features two types of error detection. The error detection can be used on-the-fly, for active LEDs, without any delay, or by entering

into low-current diagnosis mode.

9.1.1 Error Detection On-The-Fly

Error detection on-the-fly will output the status of active LEDs during operation. Without choosing an error mode this will output the temperature

flag at every input/output cycle. Triggering one clock pulse for open or two clock pulses for short detection during error detection mode outputs

the detailed open- or short-error report with the next input/output cycle (see Figure 20). LEDs that are turned off cannot be tested and their digits

at the error output must be ignored.

Figure 20. Normal Operation with Error Detection During Operation – 128 Cascaded AS1109s

Display

SDI

SDO

CLK

OEN

Current

Data1

Data2 Data3

T/O or S Error Code

Data1

T/O or S Error Code Data0

Data0

T/O or S Error Code

Data2

1024x

Clock for Error

Mode 0x/1x/2x

Rising Edge of OEN

Acquisition of Error Status

Falling Edge of LD; Error Register is copied

into Shift Register

≤ 100mA

GEFGEF

GEF = Global Error Flag

Falling Edge of LD; Error Register is copied

into Shift Register

Clock for Error

Mode 0x/1x/2x

Rising Edge of OEN

Acquisition of Error Status

Data2

Data3

Data4

www.ams.com/LED-Driver-ICs/AS1109 Revision 1.21 17 - 24

AS1109

Datasheet - Application Information

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

1024x1024x

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

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

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

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P21 P22-P24 P25-P25

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LED Display Drivers AS1109-BSSU-Z QSOP16 LF TUB

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