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Datasheet: AS1109 8-Bit LED Driver with Diagnostics

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A S 110 9
Constant-Current, 8-Bit LED Driver with Diagnostics

1 General Description 2 Key Features

The AS1109 is designed to drive up to 8 LEDs through a fast serial 8 Constant-Current Output Channels
interface and features 8 output constant current drivers and an on-
Excellent Output Current Accuracy
chip diagnostic read-back function.
The high clock-frequency (up to 50MHz), adjustable output current, - Between Channels: ±2%
and flexible serial interface makes the device perfectly suited for - Between AS1109 Devices: ±2%
high-volume transmission applications. Output Current Per Channel: 0.5 to 100mA
Output current is adjustable (up to 100mA/channel) using an external
Controlled In-Rush Current
resistor (REXT).
The serial interface with Schmitt trigger inputs includes an integrated Over-Temperature, Open-LED, Shorted-LED
shift register. Additionally, an internal data register stores the Diagnostics Functions
currently displayed data.
Low-Current Test Mode
The device features integrated diagnostics for over-
temperature, open-LED, and shorted-LED conditions. Integrated Global Fault Monitoring

registers store global fault status information during load as well as Low Shutdown Mode Current: 3µA
the detailed temperature/open-LED/shorted-LED diagnostics results.
Fast Serial Interface: up to 50MHz
The AS1109 also features a low-current diagnostic mode to minimize
display flicker during fault testing. Cascaded Configuration
With an operating temperature range from -40 to +125°C the Fast Output Drivers Suitable for PWM
AS1109 is also ideal for industrial applications.
16-pin SOIC-150, 16-pin QFN (4x4mm) and 16-pin QSOP-150
The AS1109 is available in a 16-pin SOIC-150, a 16-pin QFN
(4x4mm) and the 16-pin QSOP-150 package. Package

3 Applications
The device is ideal for fixed- or slow-rolling displays using static or
multiplexed LED matrix and dimming functions, large LED matrix
displays, mixed LED display and switch monitoring, displays in
elevators, public transports (underground, trains, buses, taxis,
airplanes, etc.), large displays in stadiums and public areas, price
indicators in retail stores, promotional panels, bar-graph displays,
Figure 1. Main Diagram and Pin Assignments industrial controller displays, white good panels, emergency light
indicators, and traffic signs.

+VLED

GND 1 16 VDD
SDI 2 15 REXT
OUTN0 OUTN1 OUTN2 OUTN3 OUTN4 OUTN5 OUTN6 OUTN7
CLK 3 14 SDO
LD 4 13 OEN
SDI
AS1109 SDO AS1109
OUTN0 5 12 OUTN7
OUTN1 6 11 OUTN6
OUTN2 7 10 OUTN5
CLK LD OEN REXT GND VDD
OUTN3 8 9 OUTN4

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AS1109
Datasheet

4 Pin Assignments
Figure 2. Pin Assignments (Top View)

SDI GND VDD REXT

GND 1 16 VDD 16 15 14 13

SDI 2
CLK 1 12 SDO
15 REXT
CLK 3 14 SDO
LD 2 11 OEN
LD 4 13 OEN AS1109
OUTN0 5
AS1109 12 OUTN7
16-pin QFN
OUTN0 3 (4x4mm) 10 OUTN7
OUTN1 6 11 OUTN6
OUTN2 7 10 OUTN5 OUTN1 4 9 OUTN6

OUTN3 8 9 OUTN4 5 6 7 8

OUTN5
OUTN4
OUTN3
OUTN2
16-pin QSOP-150
16-pin SOIC-150

4.1 Pin Descriptions

Table 1. Pin Descriptions
Pin Number
16-pin QSOP-150 16-pin QFN
Pin Name Description
16-pin SOIC-150 (4x4mm)

1 15 GND Ground
2 16 SDI Serial Data Input
Serial Data Clock. The rising edge of the CLK signal is used to clock data into and at
3 1 CLK the falling edge out of the AS1109 shift register. In error mode, the rising edge of the CLK
signal is used to switch error modes.
4 2 LD Serial Data Load. Data is transferred to the data register at the rising edge of this pin.
Output Current Drivers. These pins are used as LED drivers or for input sense for
5:12 3:10 OUTN0:7
diagnostic modes.
Output Enable. The active-low pin OEN signal can always enable output drivers to sink
current independent of the AS1109 mode.
13 11 OEN
0 = Output drivers are enabled.
1 = Output drivers are disabled.
Serial Data Output. In normal mode SDO is clocked out 8.5 clock cycles after SDI is
clocked in.
14 12 SDO In global error detection mode this pin indicates the occurrence of a global error.
0 = Global error mode returned an error.
1 = No errors.
External Resistor Connection. This pin connects through the external resistor (REXT)
15 13 REXT
to GND, to setup the load current.
16 14 VDD Positive Supply Voltage

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AS1109
Datasheet - A b s o l u t e M a x i m u m R a t i n g s

5 Absolute Maximum Ratings

Stresses beyond those listed in Table 2 may cause permanent damage to the device. These are stress ratings only, and functional operation of
the device at these or any other conditions beyond those indicated in Electrical Characteristics on page 4 is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
Table 2. Absolute Maximum Ratings
Parameter Min Max Units Comments
Electrical Parameters
VDD to GND -0.3 7 V
Input Voltage -0.4 VDD + 0.4 V
Output Voltage -0.4 15 V
GND Pin Current 1000 mA
Input Current (latch-up immunity) -100 100 mA Norm: JEDEC 78
Electrostatic Discharge
Electrostatic Discharge HBM 2 kV Norm: MIL 883 E method 3015
Temperature Ranges and Storage Conditions
33 ºC/W on PCB, 16-pin SOIC-150 package
Thermal Resistance ΘJA 113 ºC/W on PCB, 16-pin QSOP-150 package
32 ºC/W on PCB, 16-pin QFN (4x4mm) package
Storage Temperature Range -55 +150 ºC
The reflow peak soldering temperature (body
temperature) specified is in accordance with IPC/
JEDEC J-STD-020“Moisture/Reflow Sensitivity
Package Body Temperature +260 ºC Classification for Non-Hermetic Solid State Surface
Mount Devices”.
The lead finish for Pb-free leaded packages is matte tin
(100% Sn).
Humidity non-condensing 5 85 %
QFN and QSOP 1 Represents a maximum floor life time of unlimited
Moisture Sensitive Level Moisture Sensitive 3 Represents a maximum floor life of 168h
Layer (SOIC)

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AS1109
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s

6 Electrical Characteristics
VDD = +3.0V to +5.5V, Typical values measured at VDD = 5V, TAMB = 25°C (unless otherwise specified).

Table 3. Electrical Characteristics

Symbol Parameter Condition Min Typ Max Unit
TAMB Operating Temperature Range Device fully functional up to 125°C -40 +85 °C
VDD Supply Voltage 3.0 5.5 V
VDS Output Voltage OUTN0:7 0 15.0 V
IOUT OUTN0:7, VDD = 5V (see Figure 8) 0.5 100
IOH Output Current SDO -1.0 mA
IOL SDO 1.0

VIH 0.7 x VDD +

High Level VDD 0.3
Input Voltage CLK, OEN, LD, SDI V
VIL 0.3 x
Low Level -0.3 VDD
IDS(OFF) Output Leakage Current OEN = 1, VDS = 15.0V 0.5 µA
VOL IOL = +1.0mA 0.4
Output
SDO VDD - V
VOH Voltage IOH = -1.0mA 0.4V

IAV(LC1) Device-to-Device Average Output Current VDS = 0.5V, VDD = Const., 24.5 25.26 26 mA
from OUTN0 to OUTN7 REXT = 744Ω
Current Skew VDS ≥ 0.5V, VDD = Const.,
ΔIAV(LC1) ±0.9 ±3 %
(Between Channels) REXT = 744Ω

IAV(LC2) Device-to-Device Average Output Current VDS = 0.6V, VDD > 3.3V, 49.50 50.52 51.55 mA
from OUTN0 to OUTN7 REXT = 372Ω
Current Skew VDS ≥ 0.6V, VDD = Const.,
ΔIAV(LC2) ±0.8 ±2 %
(Between Channels) REXT = 372Ω

IAV(LC3) Device-to-Device Average Output Current VDS = 0.8V, VDD = 5.0V, 98 101 104 mA
from OUTN0 to OUTN7 REXT = 186Ω

ΔIAV(LC3) Current Skew VDS ≥ 0.8V, VDD = Const.,

(Between Channels) ±0.5 ±2 %
REXT = 186Ω
ILC Low-Current Diagnosis Mode VDS = 0.8V, VDD = 5.0V 0.4 0.6 0.8 mA

IPD VDS = 0.8V, VDD = 5.0V,

Power Down Supply Current 3 20 µA
REXT = 372Ω, OUTN0:7 = On

%/ΔVDS Output Current vs. VDS within 1.0 and 3.0V ±0.1 %/V
Output Voltage Regulation

%/ΔVDD Output Current vs. VDD within 3.0 and 5.0V ±1 %/V
Supply Voltage Regulation
RIN(UP) Pullup Resistance OEN 250 500 800 kΩ
RIN(DOWN) Pulldown Resistance LD 250 500 800 kΩ
*
VTHL Open Error Detection Threshold Voltage No load 0.25 0.35 0.45 V

*
VDD = 3.0V, no load 1.2 1.3 1.4
VTHH Short Error Detection Threshold Voltage V
VDD = 5.0V, no load 2.0 2.2 2.4
TOV1 Overtemperature Threshold Flag 150 ºC

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AS1109
Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s

Table 3. Electrical Characteristics (Continued)

Symbol Parameter Condition Min Typ Max Unit
IDD(OFF)0 REXT = Open‚ OUTN0:7 = Off 1.3 2
IDD(OFF)1 REXT = 744Ω‚ OUTN0:7 = Off 3.0 3.68
Off
IDD(OFF)2 REXT = 372Ω‚ OUTN0:7 = Off 4.7 5.37
IDD(OFF)3 Supply Current REXT = 186Ω, OUTN0:7 = Off 8.1 8.73 mA
IDD(ON)1 REXT = 744Ω‚ OUTN0:7 = On 4.5 5
IDD(ON)2 On REXT = 372Ω‚ OUTN0:7 = On 7.5 8
IDD(ON)3 REXT = 186Ω‚ OUTN0:7 = On 13.7 15

6.1 Switching Characteristics

VDD = 3.0 to 5.5V, VDS = 0.8V, VIH = VDD, VIL = GND, REXT = 372Ω, VLOAD = 4.0V, RLOAD = 64Ω, CLOAD = 10pF; guaranteed by design.
Table 4. Switching Characteristics
Symbol Parameter Conditions Min Typ Max Unit
tP1 Propagation Delay Time CLK - SDO 5 10
tP2 Propagation Delay Time (Without Staggered LD - OUTNn 100 200 ns
tP3 Output Delay) OEN - OUTNn 100 200
tP4 Propagation Delay Time 10 ns
tW(CLK) CLK 15
tW(L) Pulse Width LD 15 ns
tW(OE) OEN (@IOUT < 60mA) 200
* Maximum CLK Rise Time 500 ns
tR
* Maximum CLK Fall Time 500 ns
tF
tOR Output Rise Time of VOUT (Turn Off) 100 200 ns
tOF Output Fall Time of VOUT (Turn On) 100 300 ns
tSU(D) Setup Time for SDI 5 ns
tH(D) Hold Time for SDI 5 ns
tSU(L) Setup Time for LD 5 ns
tH(L) Hold Time for LD 5 ns
tTESTING Minimum OEN Time for Error Detection 2000 ns
tSTAG Staggered Output Delay 20 40 ns
tSU(OE) Output Enable Setup Time 20 ns
tGSW(ERROR) Global Error Switching Setup Time 10 ns
tSU(ERROR) Global Error Detection Setup Time 10 ns
tP(I/O) Propagation Delay Global Error Flag 5 ns
tSW(ERROR) Switching Time Global Error Flag 10 ns
fCLK Maximum Clock Frequency 30 50 MHz
(Cascade Operation)
tP3,ON Low-Current Test Mode Turn ON 3 5 µs
Propagation Delay Time Turn OFF 0.05 0.1 µs
tTP3,OFF
External Resistor Reaction Time Change from REXT1 = 372Ω, IOUT1 0.5 1 µs
tREXT2,1 = 50.52mA to REXT2 = 37.2kΩ,
IOUT2 < 1mA
External Resistor Reaction Time Change from REXT1 = 37.2kΩ, 0.5 1 µs
tREXT2,1 IOUT1 = 0.5mA to REXT2 = 372Ω,
IOUT2 > 25mA
*
If multiple AS1109 devices are cascaded and tr or tf is large, it may be critical to achieve the timing required for data transfer between two
cascaded LED drivers.

Note: All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality
Control) methods.

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AS1109
Datasheet - Ty p i c a l O p e r a t i n g C h a r a c t e r i s t i c s

7 Typical Operating Characteristics

Figure 3. Output Current vs. REXT, Figure 4. Relative Output Current Error vs. VDD,
VDD = 5V; VOUT = 0.8V, TAMB = 25°C Iout/Iout@VDD = 5V - 1, TAMB = 25°C
100 2

Relative Output Current Error (%)

1.5

1
IOUT (mA) .

0.5
REXT = 744Ω;
VDS = 0.5V
10 0

.
-0.5 REXT = 186Ω;
REXT = 372Ω; VDS = 0.8V
VDS = 0.6V
-1

-1.5

1 -2
100 1000 10000 3 3.5 4 4.5 5 5.5
REXT (Ohm) VDD (V)
Figure 5. Output Current vs. VDS; Figure 6. Output Current vs. VDS;
VDD = 5V, TAMB = 25°C VDD = 5V, TAMB = 25°C
160 160
REXT = 127Ω REXT = 127Ω
140 140

120 REXT = 150Ω 120 REXT = 150Ω

IOUT (mA) .

IOUT (mA) .

100 100
REXT = 186Ω REXT = 186Ω
80 80
REXT = 251Ω REXT = 251Ω
60 60
REXT = 372Ω REXT = 372Ω
40 40

20 REXT = 744Ω 20 REXT = 744Ω

0 0
0 2 4 6 8 10 12 14 0 0.2 0.4 0.6 0.8 1 1.2 1.4
VDS (V) VDS (V)

Figure 7. Relative IOUT Error vs. Temperature Figure 8. Output Current vs. VDD
VDD = 5V, Iout/Iout@25°C - 1, TAMB = 25°C
1 160
Relative Output Current Error (%)

VDS = 1V
REXT = 372Ω; 140
VDS = 0.6V
0.5 120 VDS = 0.9V
IOUT (mA) .

100 VDS = 0.8V

REXT = 186Ω;
0 VDS = 0.8V 80
.

VDS = 0.7V
60
VDS = 0.6V
-0.5 REXT = 744Ω; 40
VDS = 0.5V
20 VDS = 0.5V

-1 0
-50 -25 0 25 50 75 100 3 3.5 4 4.5 5 5.5
Temperature (°C) VDD (V)

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AS1109
Datasheet - D e t a i l e d D e s c r i p t i o n

8 Detailed Description
The AS1109 is designed to drive up to 8 LEDs through a fast serial interface and 8 constant-current output drivers. Furthermore, the AS1109
provides diagnostics for detecting open- or shorted-LEDs, as well as over-temperature conditions for LED display systems, especially LED traffic
sign applications.
The AS1109 contains an 8-bit shift register and an 8-bit data register, which convert serial input data into parallel output format. At AS1109 output
stages, eight regulated current sinks are designed to provide uniform and constant current with excellent matching between ports for driving
LEDs within a wide range of forward voltage variations. External output current is adjustable from 0.5 to 100mA using an external resistor for
flexibility in controlling the brightness intensity of LEDs. The AS1109 guarantees to endure 15V maximum at the outputs.
The serial interface is capable of operating at a minimum of 30 MHz, satisfying the requirements of high-volume data transmission.
Using a multiplexed input/output technique, the AS1109 adds additional functionality to pins SDO, LD and OEN. These pins provide highly useful
functions (open- and shorted-LED detection, over-temperature detection), thus reducing pin count. Over-temperature detection will work on-the-
run, whereas the open- and shorted-LED detection can be used on-the-run or in low-current diagnostic mode (see page 14).

Figure 9. AS1109 - Block Diagram

+VLED

OUTN0 OUTN1 OUTN2 OUTN3 OUTN4 OUTN5 OUTN6 OUTN7

8-Bit Open Detec- 8-Bit Short

Temperature
Detection
tion & Error Reg- Detection & Error AS1109
REXT ister Register
Current
Generators

OEN

LD 8-Bit Data
Register Detailed
Error Global Error
Detection Detection

CLK 8-Bit Shift

Register
SDI
Control Logic

SDO

Indicates 8 Bit Path

8.1 Serial Interface

Data accesses are made serially via pins SDI and SDO. At each CLK rising edge, the signal present at pin SDI is shifted into the first bit of the
internal shift register and the other bits are shifted ahead of the first bit. The MSB is the first bit to be clocked in. In error-detection mode the shift
register will latch-in the corresponding error data of temperature-, open-, and short-error register with each falling edge of LD.

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AS1109
Datasheet - D e t a i l e d D e s c r i p t i o n

The 8-bit data register will latch the data of the shift register at each rising edge of LD. This data is then used to drive the current generator output
drivers to switch on the corresponding LEDs as OEN goes low.

8.2 Timing Diagrams

This section contains timing diagrams referenced in other sections of this data sheet.

Figure 10. Normal Mode Timing Diagram

tW(CLK)

CLK 50% 50% 50%

tSU(D) tH(D)

SDI 50% 50%

SDO 50%

tP1

tW(L)

LD 50% 50%

tSU(L) tH(L)

OEN OEN Low = Output Enabled

OUTNx High = Output Off

OUTNx 50%
OUTNx Low = Output On

tP2

Figure 11. Output Delay Timing Diagram

tW(OE)
OEN 50% 50%

tP3 tP3
90% 90%
OUTN0 50% 10% 50%
10%

tOF tOR
tSTAG tSTAG

OUTN1 50% 50%

7XtSTAG 7XtSTAG

OUTN7 50% 50%

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AS1109
Datasheet - D e t a i l e d D e s c r i p t i o n

Figure 12. Data Input Timing Diagram

OEN tW(OE)
tSU(L tSU(OE)

LD 8 CLK Pulses tW(L)

CLK

tSU(D)

Data Bit Data Bit Data Bit Data Bit Data Bit Data Bit Data Bit Data Bit
SDI Don’t Care
7 6 5 4 3 2 1 0

tH(D)

Old Data Old Data Old Data Old Data Old Data Old Data Old Data Old Data Don’t Care
SDO
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

tP1

Figure 13. Data Input Example Timing Diagram

Time = 0 1 2 3 4 5 6 7

CLK

SDI D7 D6 D5 D4 D3 D2 D1 D0

LD

OEN

Off
OUTN0
On

Off
OUTN1
On

Off
OUTN2 On

OUTN3 Off
On

OUTN4 Off
On

Off
OUTN5 On

Off
OUTN6 On

Off
OUTN7 On

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AS1109
Datasheet - D e t a i l e d D e s c r i p t i o n

Figure 14. Switching Global Error Mode Timing Diagram

OEN tTESTING

tGSW(ERROR)

tGSW(ERROR)
LD tSU(ERROR)
tP(I/O) tP(I/O) tP(I/O)

tGSW(ERROR)
CLK

SDI TFLAG(IN) OFLAG(IN) SFLAG(IN)

SDO Don’t Don’t Don’t

TFLAG OFLAG SFLAG
Care Care Care

tP4 tSW(ERROR) tSW(ERROR)

Acquisition of Error
Status

8.3 Error-Detection Mode

Acquisition of the error status occurs at the rising edge of OEN. Error-detection mode is started on the rising edge of LD when OEN is high. The
CLK signal must be low when entering error detection mode. Error detection for open- and shorted-LEDs can only be performed for LEDs that
are switched on during test time. To switch between error-detection modes clock pulses are needed (see Table 5).
Note: To test all LEDs, a test pattern that turns on all LEDs must be input to the AS1109.

8.4 Global Error Mode

Global error mode is entered when error-detection mode is started. Clock pulses during this period are used to select between temperature,
open-LED, and shorted-LED tests, as well as low-current diagnostic mode and shutdown mode (see Table 5). In global error mode, an error flag
(TFLAG, OFLAG, SFLAG) is delivered to pin SDO if any errors are encountered.
Table 5. Global Error Mode Selections
Clock Output Port Error-Detection Mode Global Error Flag/Shutdown Condition
Pulses
TFLAG = SDO = 1: No over-temperature warning.
0 Don't Care Over-Temperature Detection
TFLAG = SDO = 0: Over-temperature warning.
OFLAG = SDO = 1: No open-LED error.
1 Enabled Open-LED Detection
OFLAG = SDO = 0: Open-LED error.
SFLAG = SDO = 1: No shorted-LED error.
2 Enabled Shorted-LED Detection
SFLAG = SDO = 0: Shorted-LED error.
3 Don't Care Low-Current Diagnostic Mode
SDI = 1: Wakeup
4 Don't Care Shutdown Mode
SDI = 0: Shutdown

Note: For a valid result SDI must be 1 for the first device.

If there are multiple AS1109s in a chain, the error flag will be gated through all devices. To get a valid result at the end of the chain, a logic 1 must
be applied to the SDI input of the first device of the chain. If one device produces an error this error will show up after n*tP(I/O) + tSW(ERROR) at
pin SDO of the last device in the chain. This means it is not possible to identify which device in the chain produced the error. Therefore, if a global
error occurs, the detailed error report can be run to identify which AS1109, or LED produced the error.
Note: When no error has occurred, the detailed error report can be skipped, setting LD and subsequently OEN low.

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AS1109
Datasheet - D e t a i l e d D e s c r i p t i o n

8.5 Error Detection Functions

8.5.1 Open-LED Detection
The AS1109 open-LED detection is based on the comparison between VDS and VTHL. The open LED status is aquired at the rising edge of
OEN and stored internally. While detecting open-LEDs the output port must be turned on. Open LED detection can be started with 1 clock pulse
during error detection mode while the output port is turned on.

Note: LEDs which are turned off at test time cannot be tested.
Table 6. Open LED Detection Modes
Effective Output Detected Open-LED
Output Port State Meaning
Point Conditions Error Status Code
On VDS < VTHL 0 Open Circuit
On VDS > VTHL 1 Normal

8.5.2 Shorted-LED
The AS1109 shorted-LED detection is based on the comparison between VDS and VTHH. The shortened LED status is acquired at the rising
edge of OEN and stored internally. While detecting shorted-LEDs the output port must be turned on. Shorted-LED detection can be started with
2 clock pulses during error detection mode while the output port is turned on.
For valid results, the voltage at OUTN0:OUTN7 must be lower then VTHH under low-current diagnostic mode operating conditions. This can be
achieved by reducing the VLED voltage or by adding additional diodes, resistors or LED’s.

Note: LEDs which are turned off at test time cannot be tested.

Table 7. Shorted LED Detection Modes

Effective Output Detected Shorted-LED
Output Port State Meaning
Point Conditions Error Status Code
On VDS > VTHH 0 Short Circuit
On VDS < VTHH 1 Normal

8.5.3 Overtemperature
Thermal protection for the AS1109 is provided by continuously monitoring the device’s core temperature. The overtemperature status is aquired
at the rising edge of OEN and stored internally.
Table 8. Overtemperature Modes
Effective Output Detected Overtemperature
Output Port State Meaning
Point Conditions Status Code
Don’t Care Temperature > TOV1 0 Overtemperature Condition
Don’t Care Temperature < TOV1 1 Normal

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AS1109
Datasheet - D e t a i l e d D e s c r i p t i o n

8.6 Detailed Error Reports

The detailed error report can be read out after global error mode has been run. On the falling edge of LD, the detailed error report of the selected
test is latched into the shift register and can be clocked out with n*8 clock cycles (n is the number of AS1109s in a chain) via pin SDO. At the
same time new data can be written into the shift register, which will load on the next rising edge of pin LD. This data will show at the output
drivers, at the falling edge of OEN.

8.6.1 Detailed Temperature Warning Report

The detailed temperature warning report can be read out immediately after global error mode has been run. Bit0 of the 8bit data word represents
the temperature flag of the chip.

Figure 15. Detailed Temperature Warning Report Timing Diagram

Global Flag Readout Detailed Error Report Readout

OEN
tH(L)
tGSW(ERROR)

LD

t(SU)ERROR tP4
CLK

Don’t
SDI DBit7 DBit6 DBit5 DBit4 DBit3 DBit2 DBit1 DBit0
Care
New Data Input

TFLAG Don’t
SDO Undefined TBit0
Care

tP4 Temperature Error Report Output

tP1
For detailed timing information see Timing Diagrams on page 8.

Detailed Temperature Warning Report Example

Consider a case where five AS1109s are cascaded in one chain. The detailed error report lists the temperatures for each device in the chain:
IC1:[70°] IC2:[85°] IC3:[66°] IC4:[160°] IC5:[76°]
In this case, IC4 is overheated and will generate a global error, and therefore 5*8 clock cycles are needed to write out the detailed temperature
warning report, and optionally read in new data. The detailed temperature warning report would look like this:
XXXXXXX1 XXXXXXX1 XXXXXXX1 XXXXXXX0 XXXXXXX1
The 0 in the detailed temperature warning report indicates that IC4 is the device with the over-temperature condition.

Note: In an actual report there are no spaces in the output.

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AS1109
Datasheet - D e t a i l e d D e s c r i p t i o n

8.6.2 Detailed Open-LED Error Report

The detailed open-LED error report can be read out immediately after global error mode has been run.

Figure 16. Detailed Open-LED Error Report Timing Diagram

Global Flag Readout Detailed Error Report Readout

OEN

tTESTING
tH(L)

LD tSU(ERROR)

tGSW(ERROR) tP4
tGSW(ERROR)
CLK

tGSW(ERROR)
Don’t
SDI DBit7 DBit6 DBit5 DBit4 DBit3 DBit2 DBit1 DBit0
Care
Acquisition of

tSW(ERROR)
Error Status

New Data Input

Don’t
SDO TFlag OFlag OBit7 OBit6 OBit5 OBit4 OBit3 OBit2 OBit1 OBit0
Care
tP4 Open Error Report Output tP1
For detailed timing information see Timing Diagrams on page 8.

Detailed Open-LED Error Report Example

Consider a case where five AS1109s are cascaded in one chain. A 1 indicates a LED is on, a 0 indicates a LED is off, and an X indicates an open
LED. The open-LED test is only applied to LEDs that are turned on. This test is used with a test pattern where all LEDs are on at test time.
IC1:[11111111] IC2:[111XX111] IC3:[11111111] IC4:[1X111111] IC5:[11111111]
IC2 has two open LEDs and IC4 has one open LED switched on due to input. 5*8 clock cycles are needed to write the entire error code out. The
detailed error report would look like this:

Input Data: 1 1 1 1 1 1 1 1 11111111 11111111 11111111 11111111

LED Status: 1 1 1 1 1 1 1 1 111XX111 11111111 1X111111 11111111
Failure Code: 1 1 1 1 1 1 1 1 11100111 11111111 10111111 11111111

Comparing this report with the input data indicates that IC2 is the device with two open LEDs at position 4 and 5 and IC4 with an open LED at
second position. For such a test it is recommended to enter low-current diagnostic mode first (see Low-Current Diagnostic Mode on page 14) to
reduce onscreen flickering.

Note: In an actual report there are no spaces in the output.

LEDs turned off during test time cannot be tested.

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AS1109
Datasheet - D e t a i l e d D e s c r i p t i o n

8.6.3 Detailed Shorted-LED Error Report

The detailed shorted-LED error report can be read out immediately after global error mode has been run (see Global Error Mode on page 10).

Figure 17. Detailed Shorted-LED Error Report Timing Diagram

Global Flag Readout Detailed Error Report Readout

OEN

tTESTING

LD tSU(ERROR) tH(L)

tGSW(ERROR) tP4

CLK tGSW(ERROR)

tGSW(ERROR)
Don’t
Acquisition of Error

DBit7 DBit6 DBit5 DBit4 DBit3 DBit2 DBit1 DBit0

SDI Care
Status

tSW(ERROR)
New Data Input

Don’t
SDO FLAG OFLAG
TTFLAG SFLAG SBit7 SBit6 SBit5 SBit4 SBit3 SBit2 SBit1 SBit0
Care

tP4 Shorted-LED Error Report Output tP1

For detailed timing information see Timing Diagrams on page 8.

Detailed Shorted-LED Error Report Example

Consider a case where five AS1109s are cascaded in one chain. A 1 indicates a LED is on, a 0 indicates a LED is off, and an X indicates a
shorted LED. This test is used with a test pattern where all LEDs are on at test time. Additionally, this test should be run after starting low-current
diagnostic mode (see Low-Current Diagnostic Mode on page 14).
IC1:[11111XX1] IC2:[11111111] IC3:[11111111] IC4:[111X1111] IC5:[11111111]
IC2 has two shorted LEDs and IC4 has one shorted LED switched on due to input. 5*8 clock cycles are needed to write the entire error code out.
The detailed error report would look like this:

Input Data: 1 1 1 1 1 1 1 1 11111111 11111111 11111111 11111111

LED Status: 1 1 1 1 1 X X 1 11111111 11111111 111X1111 11111111
Failure Code: 1 1 1 1 1 0 0 1 11111111 11111111 11101111 11111111

Showing IC1 as the device with two shorted LEDs at position 6 and 7, and IC4 with one shorted LED at position 4.

Note: In an actual report there are no spaces in the output. LEDs turned off during test time cannot be tested.

8.6.4 Low-Current Diagnostic Mode

To run the open- or shorted-LED test, a test pattern must be used that will turn on each LED to be tested. This test pattern will cause a short
flicker on the screen while the test is being performed. The low-current diagnostic mode can be initiated prior to running a detailed error report to
reduce this on-screen flickering.
Note: Normally, displays using such a diagnosis mode require additional cables, resistors, and other components to reduce the current. The
AS1109 has this current-reduction capability built-in, thereby minimizing the number of external components required.

Low-current diagnostic mode can be initiated via 3 clock pulses during error-detection mode. After the falling edge of LD, a test pattern displaying
all 1s can be written to the shift register which will be used for the next error-detection test.
On the next falling edge of OEN, current is reduced to ILC. With the next rising edge of OEN the current will immediately increase to normal
levels and the detailed error report can be read out entering error-detection mode.

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AS1109
Datasheet - D e t a i l e d D e s c r i p t i o n

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

Global Flag Readout 2µs Low-Current Diagnosis Mode

Load Internal all 1s Test

OEN Pattern
(optional) tTESTING

tSU(ERROR) tH(L)
LD

tGSW(ERROR) tP4 tH(L)

CLK

tGSW(ERROR) tGSW(ERROR)

tSW(ERROR)
SDI
Re-entering Error Detection
Mode

TFLAG OFLAG SFLAG

Don’t
SDO Care

tP1 Normal Operation Current

For detailed timing information see Timing Diagrams on page 8.

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

OEN

LD tSU(ERROR)

CLK

1 = Wakeup
SDI
0 = Shutdown

1 = Wakeup
SDO TFLAG OFLAG SFLAG
0 = Shutdown

tP4 tSU(D)

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AS1109
Datasheet - A p p l i c a t i o n I n f o r m a t i o n

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 Data1 Data2 Data3

SDI Data2 Data3 Data4

T/O or S Error Code Data0 T/O or S Error Code T/O or S Error Code
SDO GEF GEF
Data0 Data1 Data2

Clock for Error Clock for Error

Mode 0x/1x/2x Mode 0x/1x/2x
CLK
1024x 1024x 1024x

Rising Edge of OEN Rising Edge of OEN

OEN Acquisition of Error Status Acquisition of Error Status

Falling Edge of LD; Error Register is copied Falling Edge of LD; Error Register is copied
LD into Shift Register into Shift Register

Current ≤ 100mA

GEF = Global Error Flag

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Datasheet - A p p l i c a t i o n I n f o r m a t i o 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

2µs Low-Current Diagnosis Mode

Display Data0 Data1

SDI Data1 Data2

O or S Error Code of
SDO GEF GEF Temperature Error Code
All 1s Test Patern
3x Clocks Low- Clock for Error Mode
Current Mode 1x/2x
CLK 1024x 1024x

OEN Rising Edge of OEN

Acquisition of Error Status

Falling Edge of LD; Error Register is cop-

LD ied into Shift Register
Load Internal All 1s Test Pattern

Current ≤ 100mA ≤ 100mA

≤ 0.8mA
GEF = Global Error Flag

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

2µs Low-Current Diagnosis Mode

Display Data1 Data2

SDI External all 1s Test Pattern Data2 Data3

T/O or S Error Code O or S Error Code

SDO GEF GEF Temperature Error Code
Data0 from Test Pattern
3x Clocks
Low-Current Clock for Error
Mode Mode 1x/2x
CLK 1024x 1024x 1024x

OEN Rising Edge of OEN

Acquisition of Error Status

LD Falling Edge of LD; Error Register is cop-

ied into Shift Register

Current
≤ 100mA ≤ 100mA

≤ 0.8mA
GEF = Global Error Flag

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AS1109
Datasheet - A p p l i c a t i o n I n f o r m a t i o n

9.2 Cascading Devices

To cascade multiple AS1109 devices, pin SDO must be connected to pin SDI of the next AS1109 (see Figure 23). At each rising edge of CLK the
LSB of the shift register will be written into the shift register SDI of the next AS1109 in the chain. Data at the SDI pin is clocked in at the rising
edge of the CLK pulse and is clocked out at the SDO pin 8.5 clock cycles later at the falling edge of the CLK pulse.
Note: When n*AS1109 devices are in one chain, n*8 clock pulses are needed to latch-in the input data.

Figure 23. Cascading AS1109 Devices

SDI
SDI AS1109 #1 SDO SDI AS1109 #2 SDO SDI AS1109 #n-1 SDO

CLK LD OEN CLK LD OEN CLK LD OEN

CLK
LD

OEN

9.3 Constant Current

In LED display applications, the AS1109 provides virtually no current variations from channel-to-channel and from AS1109-to-AS1109. This is
mostly due to 2 factors:
While IOUT ≥ 50mA, the maximum current skew is less than ±2% between channels and less than ±2% between AS1109 devices.

In the saturation region, the characteristics curve of the output stage is flat (see Figure 5 on page 6). Thus, the output current can be kept
constant regardless of the variations of LED forward voltages (VF).

9.4 Adjusting Output Current

The AS1109 scales up the reference current (IREF) set by external resistor (REXT) to sink a current (IOUT) at each output port. As shown in
Figure 3 on page 6 the output current in the saturation region is extremely flat so that it is possible to define it as target current (IOUT TARGET).
IOUT TARGET can be calculated by:
VREXT = 1.253V (EQ 1)
IREF = VREXT/REXT (if the other end of REXT is connected to ground) (EQ 2)
IOUT TARGET = IREF*15 = (1.253V/REXT)*15 (EQ 3)
Where:
REXT is the resistance of the external resistor connected to pin REXT.
VREXT is the voltage on pin REXT.
The magnitude of current (as a function of REXT) is around 100mA at 186Ω, 50.52mA at 372Ω and 25.26mA at 744Ω. Figure 3 on page 6
shows the relationship curve between the IOUT TARGET of each channel and the corresponding external resistor (REXT).

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AS1109
Datasheet - A p p l i c a t i o n I n f o r m a t i o n

9.5 Package Power Dissipation

The maximum allowable package power dissipation (PD) is determined as:
PD(MAX) = (TJ-TAMB)/RTH(J-A) (EQ 4)
When 8 output channels are turned on simultaneously, the actual package power dissipation is:
PD(ACT) = (IDD*VDD) + (IOUT*Duty*VDS*8) (EQ 5)
Therefore, to keep PD(ACT) ≤ PD(MAX), the allowable maximum output current as a function of duty cycle is:
IOUT = {[(TJ-TAMB)/RTH(J-A)]-(IDD*VDD)}/VDS/Duty/8 (EQ 6)
Where:
TJ = 150ºC

9.6 Delayed Outputs

The AS1109 has graduated delay circuits between outputs. These delay circuits can be found between OUTNn and constant current block.
The fixed delay time is 20 ns (typ) where OUTN0 has no delay, OUTN1 has 20ns delay, OUTN2 has 40ns delay ... OUTN7 has 140ns delay. This
delay prevents large inrush currents, which reduce power supply bypass capacitor requirements when the outputs turn on (see Figure 12 on
page 9)

9.7 Switching-Noise Reduction

LED drivers are frequently used in switch-mode applications which normally exhibit switching noise due to parasitic inductance on the PCB.

9.8 Load Supply Voltage

Considering the package power dissipation limits (see EQ 4:6), the AS1109 should be operated within the range of
VDS = 0.4 to 1.0V.
For example, if VLED is higher than 5V, VDS may be so high that PD(ACT) > PD(MAX) where VDS = VLED - VF. In this case, the lowest possible
supply voltage or a voltage reducer (VDROP) should be used. The voltage reducer allows
VDS = (VLED -VF) - VDROP.

Note: Resistors or zener diodes can be used as a voltage reducer as shown in Figure 24.

Figure 24. Voltage Reducer using Resistor (Left) and Zener Diode (Right)

Voltage Supply Voltage Supply

VLED
} VDROP
VDROP { VLED
VF VDS
VF VDS

AS1109
AS1109

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AS1109
Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s

10 Package Drawings and Markings

The product is available in a 16-pin SOIC-150, 16-pin QSOP-150, and 16-pin QFN 4x4mm package.

Figure 25. 16-pin SOIC-150 Package

AS1109B
YYWWRZZ

Symbol Min Nom Max Symbol Min Nom Max

A - - 1.75 R1 0.07 -
A1 0.10 - 0.25 h 0.25 - 0.50
A2 1.25 - - Θ 0º - 8º
b 0.31 - 0.51 Θ1 5º - 15º
c 0.17 - 0.25 Θ2 0º - -
D - 9.90 BSC - aaa - 0.10 -
E - 6.00 BSC - bbb - 0.20 -
E1 - 3.90 BSC - ccc - 0.10 -
e - 1.27 BSC - ddd - 0.25 - Notes:
L 0.40 - 1.27 eee - 0.10 - 1. Dimensioning & tolerancing conform
L1 - 1.40 REF - fff - 0.15 - to ASME Y14.5M-1994.
L2 - 0.25 BSC - ggg - 0.15 - 2. All dimensions are in millimeters.
R 0.07 - - N 16 Angles are in degrees.

Marking: YYWWRZZ.

YY WW R ZZ
Last two digits of the current year Manufacturing Week Plant identifier Traceability code

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AS1109
Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s

Figure 26. 16-pin QSOP-150 Package

AS1109B
YYWWRZZ

Symbol Min Nom Max

A - - 1.75
A1 0.10 - 0.25
A2 1.24 - -
b 0.20 - 0.30
c 0.15 - 0.25
D 4.90 BSC
E 6.00 BSC
E1 3.91 BSC
e 0.635 BSC
L 0.41 - 1.27
L1 1.04 REF
L2 0.25 BSC
R 0.08 - -
R1 0.08 - -
h 0.25 - 0.51
Θ 0º - 8º
Θ1 5º - 15º
Θ2 0º - -
aaa - 0.10 -
bbb - 0.20 -
ccc - 0.10 -
Notes:
ddd - 0.18 -
1. Dimensioning & tolerancing conform to ASME Y14.5M-1994. eee - 0.10 -
2. All dimensions are in millimeters. Angles are in degrees. fff - 0.15 -
3. Datums A & B to be determined at Datum H. N 16

Marking: YYWWRZZ.

YY WW R ZZ
Last two digits of the current year Manufacturing Week Plant identifier Traceability code

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AS1109
Datasheet - P a c k a g e D r a w i n g s a n d M a r k i n g s

Figure 27. 16-pin QFN 4x4mm Package

AS
1109B
YYWW
QZZ

Symbol Min Nom Max

A 0.70 0.75 0.80
A1 0 0.02 0.05
A3 0.20 REF
L 0.45 0.55 0.65
b 0.25 0.30 0.35
D 4.00 BSC
E 4.00 BSC
e 0.65 BSC
D2 2.00 2.15 2.25
E2 2.00 2.15 2.25
aaa - 0.15 -
Notes:
bbb - 0.10 -
1. Dimensioning & tolerancing conform to ASME Y14.5M-1994. ccc - 0.10 -
2. All dimensions are in millimeters. Angles are in degrees. ddd - 0.05 -
3. Coplanarity applies to the exposed heat slug as well as the terminal. eee - 0.08 -
4. Radius on terminal is optional. fff - 0.10 -
5. N is the total number of terminals. N 16

Marking: YYWWQZZ.

YY WW Q ZZ
Last two digits of the current year Manufacturing Week Plant identifier Traceability code

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AS1109
Datasheet - O r d e r i n g I n f o r m a t i o n

11 Ordering Information
The device is available as the standard products shown in Table 9.

Table 9. Ordering Information

Ordering Code Marking Description Delivery Form Package
AS1109-BSOU AS1109B Constant-Current, 8-Bit LED Driver with Diagnostics Tubes 16-pin SOIC-150
AS1109-BSOT AS1109B Constant-Current, 8-Bit LED Driver with Diagnostics Tape and Reel 16-pin SOIC-150
AS1109-BSSU AS1109B Constant-Current, 8-Bit LED Driver with Diagnostics Tubes 16-pin QSOP-150
AS1109-BSST AS1109B Constant-Current, 8-Bit LED Driver with Diagnostics Tape and Reel 16-pin QSOP-150
AS1109-BQFR AS1109B Constant-Current, 8-Bit LED Driver with Diagnostics Tray 16-pin QFN (4x4mm)
AS1109-BQFT AS1109B Constant-Current, 8-Bit LED Driver with Diagnostics Tape and Reel 16-pin QFN (4x4mm)

Note: All products are RoHS compliant.

Buy our products or get free samples online at www.ams.com/ICdirect

Technical Support is available at www.ams.com/Technical-Support

For further information and requests, email us at sales@ams.com

(or) find your local distributor at www.ams.com/distributor

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AS1109
Datasheet - O r d e r i n g I n f o r m a t i o n

Copyrights
Copyright © 1997-2012, ams AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®. All rights
reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the
copyright owner.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.

Disclaimer
Devices sold by ams AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. ams AG makes no
warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described
devices from patent infringement. ams AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior
to designing this product into a system, it is necessary to check with ams AG for current information. This product is intended for use in normal
commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability
applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing
by ams AG for each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard
production flow, such as test flow or test location.
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www.ams.com/LED-Driver-ICs/AS1109 Revision 1.21 24 - 24