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ams AG
The technical content of this austriamicrosystems datasheet is still valid.
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ams AG
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8141 Unterpremstaetten, Austria
Tel: +43 (0) 3136 500 0
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Data sheet
A S 112 1
16- C han ne l L ED D river with D o t C o r r e c t i o n a n d G r e y s c a l e P W M
1 General Description
The AS1121 is a 16-channel, constant current-sink LED driver. Each
of the 16 channels can be individually adjusted by 4096-step grey-
scale PWM brightness control and 64-step constant-current sink (dot
correction).
The dot correction circuitry adjusts the brightness variations between
the AS1121 channels and other LED drivers. Greyscale control and
dot correction circuitry are accessible via the SPI-compatible serial
interface. A single external resistor sets the maximum current value
of all 16 channels.
The open LED detection function indicates a broken or disconnected
LED at one or more of the outputs. The overtemperature protection-
flag indicates that the device is in an overtemperature condition.
2 Key Features
Greyscale PWM Control: 12-Bit (4096 Steps)
Dot Correction: 6-Bit (64 Steps)
Drive Capability (Constant-Current Sink): 0 to 40mA
LED Power Supply Voltage: up to 30V
Supply Voltage Range: 3.1V to 3.6V
SPI-Compatible Serial Interface
An additional power-down pin puts the AS1121 into a 40nA standby-
mode.
The AS1121 is available in a 32-pin TQFN 5x5 mm package.
Figure 1. AS1121 - Block Diagram
26
IREF
24
GSCLK
31
Max OUTn
Current
V
REF
=
1.24V
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Greyscale
Counter
Control
OEN
Status
Open LED Detect,
Overtemperature,
Dot Correction
Data
3
MODE
Te
27
VCC
Over-
temp
Open
LED
Detect
22
XERR
30
GND
AS1121
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Factory set rise- and fall-time for EMI improvement
PWM Clock Rate: up to 10 MHz
Data Transfer Clock Rate: up to 30 MHz
CMOS Level I/O
Diagnostic Features
32-pin TQFN 5x5 mm Package
Output Delay for controlled Inrush Current (factory set, can be
turned off)
3 Applications
The device is ideal for mono-, multi-, and full-color LED displays,
LED signboards, and display backlights.
1 CLK
2 SDI
32 LD
29 PD
Control
Constant Current
Driver
Delay
Greyscale
0 Register 11
12-Bit Greyscale
PWM Control
6-Bit Dot
Correction
0
Dot Correction
Register 5
Input
Shift
Register
Open&Short LED Detection
Control
Greyscale
12 Register 23
6
Dot Correction
Register 11
12-Bit Greyscale
PWM Control
6-Bit Dot
Correction
Constant Current
Driver
5
Delay
OUT1
.
.
.
Open&Short LED Detection
Control
12-Bit Greyscale
PWM Control
6-Bit Dot
Correction
23
Constant Current
Driver
21
Delay
Input
Shift
Register
Greyscale
180 Register191
Dot Correction
90 Register 95
Open&Short LED Detection
SDO
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OUT0
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OUT15
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AS1121
Datasheet - P i n o u t
4 Pinout
Pin Assignments
Figure 2. Pin Assignments (Top View)
IREF 26
GND 30
OEN 31
VCC 27
VCC 25
N/C 28
PD 29
LD 32
CLK
SDI
MODE
OUT0
OUT1
OUT2
OUT3
OUT4
1
2
3
4
5
6
7
8
24 GSCLK
23 SDO
22 XERR
21 OUT15
20 OUT14
18 OUT12
17 OUT11
19 OUT13
AS1121
Thermal
Pad
Pin Descriptions
Table 1. Pin Descriptions
Pin Number
1
2
3
4:11
14:21
22
23
24
26
25, 27
12,13,28
29
30
31
Pin Name
CLK
SDI
MODE
OUT0:OUT7
OUT8:OUT15
XERR
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SDO
GSCLK
IREF
VCC
N/C
PD
GND
OEN
32
LD
Thermal Pad
33
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33
10 OUT6
12 N/C
13 N/C
14 OUT8
15 OUT9
16 OUT10
11 OUT7
Description
Serial Data Shift Clock
Serial Data Input
Mode Select input with internal pulldown
MODE = GND: Selects greyscale mode
(see Setting Greyscale Brightness on page 14)
MODE = V
CC
: Selects dor correction mode
(see Setting Dot Correction on page 13)
Constant-Current Outputs 0:7
Constant-Current Outputs 8:15
Error Output
0 = LED open detection or overtemperature condition is detected.
1 = Normal operation.
Serial Data Output
Greyscale Clock.
Reference clock for greyscale PWM control
Reference Current Terminal
Power Supply Voltage
This pins must not be connected
Power Down
0 = normal operation mode
1 = power down mode
Ground
Blank Outputs
0 = OUTn outputs are controlled by the greyscale PWM control.
1 = OUTn outputs are forced off; the greyscale counter is reset.
Data Latch.
The internal connections are switched by pin MODE.
For LD (MODE = GND), the greyscale register receives new data.
For LD (MODE = V
CC
), the dot correction register receives new data.
Thermal Pad.
This pin must be connected to GND to ensure normal operation.
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OUT5
AS1121
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
Electrical Parameters
VCC to GND
All other pins to GND
VSDO, VXERR to GND
VOUT0 : VOUT15 to GND
Output Current
Electrostatic Discharge
Thermal Information
-0.3
-0.3
-0.3
-0.3
5
V
CC
+ 0.3
V
CC
+ 0.3
30
50
V
V
V
V
mA
Min
Max
Units
Comments
Input Current (latch-up immunity)
Electrostatic Discharge HBM
Junction to ambient thermal resistance
Temperature Ranges and Storage Conditions
Junction Temperature
Storage Temperature Range
Package Body Temperature
Humidity non-condensing
Moisture Sensitive Level
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-100
100
mA
kV
Norm: JEDEC 78
+/- 2
Norm: MIL 883 E method 3015
37
°C/W
For more information about thermal metrics, see
application note
AN01 Thermal Characteristics.
+150
ºC
-55
+150
ºC
+260
ºC
5
85
%
3
Represents a max. floor life time of 168h
Revision 1.01
The reflow peak soldering temperature (body temperature)
specified is in accordance with
IPC/JEDEC J-STD-
020“Moisture/Reflow Sensitivity Classification for Non-
Hermetic Solid State Surface Mount Devices”.
The lead finish for Pb-free leaded packages is matte tin
(100% Sn).
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AS1121
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
V
CC
= +3.1V to +3.6V, Typical values are at T
AMB
= +25°C, V
CC
= 3.3V (unless otherwise specified). All limits are guaranteed. The parameters
with min and max values are guaranteed with production tests or SQC (Statistical Quality Control) methods..
Table 3. Electrical Characteristics
Symbol
T
AMB
T
J
Input Supply
V
CC
Supply Voltage
All outputs off, R
IREF
= 1kΩ
I
CC
Supply Current
All outputs on, R
IREF
= 1kΩ
All outputs off, R
IREF
= 10kΩ
3.1
8.5
15
2
3
Parameter
Operating Temperature Range
Operating Junction Temperature
Condition
Min
-40
-40
Typ
Max
+85
+125
3.6
15
4
20
5
Unit
°C
°C
V
I
Input Current
I
PD
Output
V
OUT
I
COC
Power Down Current
Voltage Applied to Output
(OUT0:OUT15)
Constant Output Current
ΔI
COC
Constant Output Current Error
I
LEAK
ΔI
LNR
Leakage Output Current
Line Regulation
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ΔI
LDR
Load Regulation
Logic Levels
V
IH
V
IL
Te
High-Level Input Voltage
Low-Level Input Voltage
V
OH
V
OL
I
OH
High-Level Output Voltage
Low-Level Output Voltage
High-Level Output Current
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mA
All outputs on, R
IREF
= 10kΩ
V
IN
= V
CC
or GND;
Pins OEN, GSCLK, CLK, SDI, LD, PD
V
IN
= V
CC
; pin MODE
V
IN
= GND; pin MODE
-1
1
50
1
µA
-1
40
nA
1.5
36
30
V
All outputs on, V
OUT
= 1.5V,
R
IREF
= 1kΩ
40
44
mA
V
OUT
= 1.5V, R
IREF
= 1kΩ, OUT0:OUT15
Device to device, average current from
OUT0:OUT15, R
IREF
= 1kΩ
±1
V
OUT
= 1.5V, R
IREF
= 10kΩ, OUT0:OUT15
±1.5
±1
%
Device to device, average current from
OUT0:OUT15, R
IREF
= 10kΩ
All outputs off, V
OUT
= 30V,
R
IREF
= 1kΩ, OUT0:OUT15
±1
20
nA
V
OUT
= 1V, R
IREF
= 1kΩ OUT0:OUT15
V
OUT
= 1.5V to 4V, R
IREF
= 1kΩ,
OUT0:OUT15
V
OUT
= 1.5V to 4V, R
IREF
= 10kΩ,
OUT0:OUT15
0.8 x
V
CC
GND
I
OH
= -1mA, SDO
I
OL
= 1mA, SDO, XERR
V
CC
= 5 V at SDO
-1.0
V
CC
-0.5
0.5
±1
±2.5
V
OUT
= 1V, R
IREF
= 10kΩ OUT0:OUT15
±0.2
±0.1
±0.01
±2.5
±0.4
%/V
±0.4
%/V
V
CC
0.2 x
V
CC
V
V
V
V
mA
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