ams AS1112 16-channel led driver with dot correction and greyscale pwm Datasheet

AS1112
D a ta s h e e t
16-Channel LED Driver with Dot Correction and
Greyscale PWM
1 General Description
2 Key Features
!
The AS1112 is a 16-channel, constant current-sink LED
driver. Each of the 16 channels can be individually
adjusted by 4096-step greyscale PWM brightness control and 64-step constant-current sink (dot correction).
!
The dot correction circuitry adjusts the brightness variations between the AS1112 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 & short LED detection function indicates a
broken, shorted or disconnected LED at one or more of
the outputs. The overtemperature flag indicates that the
device is in an overtemperature condition.
Table 1. Standard Products
Model
Power-Down
TEST pin
AS1112
Yes
Connect to GND
AS1112B
No
Connect to VCC
16 Channels
Greyscale PWM Control: 12-Bit (4096 Steps)
!
Dot Correction: 6-Bit (64 Steps)
!
Drive Capability (Constant-Current Sink): 0 to 80mA
!
LED Power Supply Voltage: Up to 15V
!
Supply Voltage Range: 3.0 to 5.5 V
!
SPI-Compatible Serial Interface
!
Controlled In-Rush Current
!
Data Transfer & PWM Clock Rate: up to 30 MHz
!
CMOS Level I/O
!
Diagnostic Features
- LED Open/Short Detection
- Overtemperature Flag
!
32-pin TQFN 5x5 mm Package
An additional power-down pin puts the AS1112 into a
40nA standby-mode.
3 Applications
The AS1112 is available in a 32-pin TQFN 5x5 mm
package.
The device is ideal for mono-, multi-, and full-color LED
displays, LED signboards, and display backlights.
Figure 1. Block Diagram
1 CLK
26
IREF
Max OUTn
Current
2 SDI
Greyscale
Counter
Control
Greyscale
0 Register 11
12-Bit Greyscale
PWM Control
Dot Correction
0 Register 5
6-Bit Dot
Correction
Input
Shift
Register
Greyscale
12 Register 23
12-Bit Greyscale
PWM Control
Dot Correction
Register 11
6-Bit Dot
Correction
6
.
MODE
Open
LED
Detect
22
Constant Current
Driver
Input
Shift
Register
Delay
x1
OUT1
.
.
.
Open&Short LED Detection
.
.
Control
Constant Current
Driver
21
Greyscale
180 Register191
12-Bit Greyscale
PWM Control
Dot Correction
90 Register 95
6-Bit Dot
Correction
XERR
30
GND
OUT0
5
3
Thermal
Flag
Delay
x0
Open&Short LED Detection
Control
Status
Open LED Detect,
Overtemperature
Flag, Dot
Correction Data
27
Constant Current
Driver
4
Control
OEN
VCC
29 PD
VREF =
1.24V
24
GSCLK
31
32 LD
Delay
x15
OUT15
Open&Short LED Detection
23
AS1112
www.austriamicrosystems.com
SDO
Revision 1.06
1 - 18
AS1112
Datasheet - P i n o u t
4 Pinout
Pin Assignments
Figure 2. Pin Assignments (Top View)
XTEST 25
IREF 26
N/C 28
VCC 27
N/C 29
GND 30
LD 32
OEN 31
TEST 25
IREF 26
N/C 28
VCC 27
PD 29
GND 30
LD 32
OEN 31
CLK
1
24 GSCLK
CLK
1
24 GSCLK
SDI
2
23 SDO
SDI
2
23 SDO
MODE
3
22 XERR
MODE
3
OUT0
4
21 OUT15
OUT0
4
OUT1
5
20 OUT14
OUT1
5
OUT2
6
19 OUT13
OUT2
6
OUT3
7
18 OUT12
OUT3
7
OUT4
8
17 OUT11
OUT4
8
AS1112
Thermal
Pad
33
22 XERR
AS1112B
21 OUT15
Thermal
Pad
20 OUT14
19 OUT13
18 OUT12
33
17 OUT11
16 OUT10
15 OUT9
14 OUT8
13 N/C
11 OUT7
OUT5
12 N/C
9
10 OUT6
16 OUT10
15 OUT9
14 OUT8
13 N/C
11 OUT7
OUT5
12 N/C
9
10 OUT6
Pin Descriptions
Table 2. Pin Descriptions
Pin Number
1
2
3
4:11
14:21
22
23
24
25
26
27
12,13,28
29
30
31
32
33
Pin Name
CLK
SDI
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 12).
MODE
MODE = VCC: Selects dot correction mode (see Setting Dot Correction on page 11).
OUT0:OUT7 Constant-Current Outputs 0:7
OUT8:OUT15 Constant-Current Outputs 8:15
Error Output
0 = LED open detection or overtemperature condition is detected.
XERR
1 = Normal operation.
Serial Data Output
SDO
Greyscale Clock. Reference clock for greyscale PWM control
GSCLK
Test Pin This pin must be connected to GND (AS1112) to ensure normal operation.
TEST
Test Pin This pin must be connected to VCC (AS1112B) to ensure normal operation.
XTEST
Reference Current Terminal
IREF
Power Supply Voltage
VCC
This pin must not be connected.
N/C
Power Down input with internal pulldown (AS1112)
0 = normal operation mode
PD
1 = powerdown mode
Not Connected (AS1112B)
N/C
Ground
GND
Blank Outputs
0 = OUTn outputs are controlled by the greyscale PWM control.
OEN
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.
LD
For LD (MODE = VCC), the dot correction register receives new data.
Thermal Pad Thermal Pad. This pin must be connected to GND to ensure normal operation.
www.austriamicrosystems.com
Revision 1.06
2 - 18
AS1112
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 3 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 Recommended Operating Conditions on page 4 is not implied. Exposure to absolute maximum rating conditions for extended periods may
affect device reliability.
Table 3. Absolute Maximum Ratings
Parameter
Min
Max
Units
Input Voltage Range to GND
0.3
6
V
Output Current (DC)
90
mA
Input Voltage Range
-0.3
VCC +
0.3
V
Output Voltage Range
VSDO, VXERR to GND
-0.3
VCC +
0.3
V
Output Voltage Range
VOUT0: VOUT15 to GND
-0.3
15
V
2
kV
ESD Rating
Comments
JEDEC 22-A114 Human Body Model
Storage Temperature Range
-55
+150
ºC
Operating Ambient
Temperature Range
-40
+85
ºC
23
ºC/W
on 4-Layer PCB
ºC
The reflow peak soldering temperature (body
temperature) specified is in accordance with
IPC/JEDEC J-STD-020D “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).
32-pin TQFN 5x5 mm Package
Thermal Impedance
Package Body Temperature
www.austriamicrosystems.com
+260
Revision 1.06
3 - 18
AS1112
Datasheet - R e c o m m e n d e d O p e r a t i n g C o n d i t i o n s
6 Recommended Operating Conditions
Table 4. DC Characteristics
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
VCC
Supply Voltage
5.5
V
VOUT
Voltage Applied to Output
(OUT0:OUT15)
15
V
VIH
High-Level Input Voltage
0.8 x
VCC
VCC
V
VIL
Low-Level Input Voltage
GND
0.2 x
VCC
V
IOH
High-Level Output Current
VCC = 5 V at SDO
-1.0
mA
IOL
Low-Level Output Current
VCC = 5 V at SDO, XERR
1.0
mA
ICOC
Constant Output Current
OUT0:OUT15
3
80
mA
Max
Unit
30
MHz
30
MHz
Table 5. AC Characteristics – VCC = 3 V to 5.5 V, TAMB = -40 to 85°C (unless otherwise noted)
Symbol
Parameter
Conditions
fCLK
Data Shift Clock Frequency
CLK
fGSCLK
Greyscale Clock Frequency
GSCLK
1
tWH0/tWL0
CLK Pulse Duration
CLK = 1/0
tWH1/tWL1
GSCLK Pulse Duration
GSCLK = 1/0
tWH2
LD Pulse Duration
LD = 1
tWH3
OEN Pulse Duration
OEN = 1
SDI, CLK
tSU1
CLK, LD
Setup Time
2
1
tSU0
tSU2
Min
2
3
3
ns
16
ns
20
ns
20
ns
12
MODE, CLK
4
4
MODE, LD
tSU4
OEN, GSCLK
tH0
CLK, SDI
tH1
LD, CLK
Hold Time
16
12
tSU3
tH2
Typ
12
12
2
12
3
12
1
12
CLK, MODE
4
4
tH3
LD, MODE
tH4
OEN, GSCLK
ns
12
ns
12
2
12
1. See Figure 10 on page 12.
2. See Figure 14 on page 14.
3. See Figure 12 on page 13.
4. See Figure 7 on page 8.
www.austriamicrosystems.com
Revision 1.06
4 - 18
AS1112
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
7 Electrical Characteristics
VCC = +3.0 to +5.5V, TAMB = -40 to +85ºC. Typical values are at TAMB = 25°C, VCC = 5V (unless otherwise specified).
Table 6. Electrical Characteristics
Symbol
Parameter
Condition
Min
VOH
High-Level Output Voltage
IOH = -1mA, SDO
VCC 0.5
VOL
Low-Level Output Voltage
IOL = 1mA, SDO, XERR
VIN = VCC or GND; Pins OEN, TEST,
GSCLK, CLK, SDI, LD
I
Input Current
Supply Current
Max
0.5
-1
-1
All outputs off, RIREF = 10kΩ
1.2
3
All outputs off, RIREF = 1.3kΩ
4
10
All outputs on, RIREF = 1.3kΩ
15
20
All outputs on, RIREF = 640Ω
30
40
Power Down Current
ICOC
Constant Output Current
All outputs on, VOUT = 2V,
RIREF = 640Ω
ILEAK
Leakage Output Current
All outputs off, VOUT = 15V,
RIREF = 640Ω, OUT0:OUT15
20
VOUT = 2V, RIREF = 640Ω,
OUT0:OUT15
±3
±4.5
VOUT = 2V, RIREF = 480Ω,
OUT0:OUT15
±3
±4.5
Device to device, average current
from OUT0:OUT15, RIREF = 1920Ω
(20 mA)
±3
±4.5
Device to device, average current
from OUT0:OUT15,
RIREF = 480Ω (80 mA)
±3
±4.5
VOUT = 2V, RIREF = 640Ω
OUT0:OUT15
±1
±2.5
VOUT = 2V, RIREF = 480Ω
OUT0:OUT15
±1
±2.5
VOUT = 2 to 4V, RIREF = 640Ω,
OUT0:OUT15
±0.1
±0.5
VOUT = 2 to 4V, RIREF = 480Ω,
OUT0:OUT15
±0.1
±0.5
ΔILNR
ΔILDR
Constant Current Error
Line Regulation
Load Regulation
40
TTEF
Thermal Error Flag Threshold
Junction temperature
TTWF
Thermal Warn Flag Threshold
Junction temperature
VLSD
LED Short Detection
Threshold
VLOD
LED Open Detection
Threshold
VIREF
Reference Voltage Output
61
mA
nA
69
mA
nA
%
%/V
%/V
1
150
ºC
1
125
ºC
3.6
V
VCC = 5V
RIREF = 640Ω
µA
1
IPD
ΔICOC
V
1
100
54
Unit
V
VIN = VCC; pin MODE, PD
VIN = GND; pin MODE, PD
ICC
Typ
1.20
0.3
0.4
V
1.24
1.28
V
1. Specified by design. Not tested.
www.austriamicrosystems.com
Revision 1.06
5 - 18
AS1112
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
Switching Characteristics
VCC = +3.0 to +5.5V, TAMB = -40 to +85ºC. Typical values are at TAMB = 25°C, VCC = 5V (unless otherwise specified).
Table 7. Switching Characteristics
Symbol
Parameter
Conditions
tR0
tR1
Rise Time
tF1
8
OUTn, DC = 3FHEX
20
SOUT
8
OUTn, DC = 3FHEX
20
1
tPD0
CLK, SDO
tPD1
OEN, OUT0
Propagation Delay Time
tPD2
2
Average Output Delay
Time
OUTn, OUTn+1
Unit
ns
ns
30
ns
2
GSCLK, OUT0
Max
15
OUTn, XERR (includes error detection
time, see Figure 8 on page 10)
tPD3
tD
Typ
SDO
tF0
Fall Time
Min
1000
2
30
2
30
ns
1. See Figure 12 on page 13.
2. See Figure 14 on page 14.
Dissipation Ratings
Table 8. Dissipation Ratings
Package Type
Power Rating
(TAMB < 25ºC)
Derating Factor
above 25ºC
Power Rating
(TAMB = 70ºC)
Power Rating
(TAMB = 85ºC)
32-pin TQFN 5x5 mm
5433mW
43.47mW/ºC
3477mW
2825mW
www.austriamicrosystems.com
Revision 1.06
6 - 18
AS1112
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
8 Typical Operating Characteristics
VDD = 5V, TAMB = 25ºC.
Figure 3. Output Current vs. VDS;
Figure 4. Output Current vs. VDS;
90
90
RIREF = 480Ω
80
80
70
70
60
60
50
IOUT (mA) .
IOUT (mA) .
RIREF = 480Ω
RIREF = 1kΩ
40
30
20
50
RIREF = 1kΩ
40
30
20
RIREF = 3.9kΩ
10
RIREF = 3.9kΩ
10
0
0
0
3
6
9
12
15
0
0.5
1
VDS (V)
1.5
2
2.5
3
VDS (V)
Figure 5. Output Current vs. REXT
Figure 6. Output Current vs. Dot Correction Value
90
100
80
RIREF = 480Ω
IOUT (mA) .
IOUT (mA) .
70
10
60
50
40
30
RIREF = 1kΩ
20
10
1
0
0
1
2
3
4
5
6
7
8
9
10
0
REXT (kOhm)
www.austriamicrosystems.com
9
18
27
36
45
54
63
Dot Correction Value
Revision 1.06
7 - 18
AS1112
Datasheet - D e t a i l e d D e s c r i p t i o n
9 Detailed Description
Serial Interface
The AS1112 features a versatile 3-pin (CLK, SDI, and SDO) serial interface, which can be connected to microcontrollers or digital signal processors in various configurations.
The rising edge of the CLK signal shifts data from pin SDI to the internal register. After all data is clocked in, the serial
data is latched into the internal registers at the rising edge of the LD signal.
Note: All data is clocked in with the MSB first.
Multiple AS1112 devices can be cascaded by connecting the SDO pin of one device with pin SDI of the next device
(see Figure 15 on page 15). The SDO pin can also be connected to the microcontroller to receive status information
from the AS1112. The serial data format is 96-bit or 192-bit wide, depending on mode of the device (see LD on page 2).
Figure 7. Serial Data Input Timing Diagram
Dot Correction Mode
Data Input Cycle
Greyscale Mode
Data Input Cycle
Dot Correction Mode
Data Input Cycle
MODE
tH3
tSU3
tH3
LD
SDI
DCn-1
LSB
DCn
MSB
DCn
LSB
tH2
CLK
SDO
1
DCn-1
MSB
DCn-1
MSB-1
96
DCn-1
LSB
GSn
MSB
GSn
LSB
tSU2
tSU2
1
DCn
MSB
DCn-1
MSB-1
DCn+1
MSB
192
X
X
1
SID
MSB
2
X
Error Information Output
The open-drain output pin XERR indicates if the device is in one of the two error conditions: overtemperature flag or
open LED detect. During normal operation, the internal transistor connected to pin XERR is turned off and the voltage
on XERR is pulled up to VCC through an external pullup resistor.
If an overtemperature or open LED condition is detected, the internal transistor is switched on, and XERR is pulled to
GND. Because XERR is an open-drain output, multiple AS1112 devices can be ORed together and pulled up to VCC
with a single pullup resistor (see Figure 15 on page 15). This reduces the number of signals needed to report a system
error.
To differentiate the overtemperature flag from the open LED detect flag from pin XERR, the open LED detect flag can
be masked out by setting OEN = 1 (see Table 9).
www.austriamicrosystems.com
Revision 1.06
8 - 18
AS1112
Datasheet - D e t a i l e d D e s c r i p t i o n
Table 9. XERR Truth Table
Error Condition
Temp.
O
p
e
n
T
e
m
p
TJ < TTEF
TJ > TTEF
Thermal
OUTn Voltage Error
Flag
Error Information
Thermal
LED
Warning Open
Detect
Flag
Selected Mode
Short
LED
Detect
Status
OEN Mode XERR
OUTn > VLOD
0
Don't Care
0
Don't Care
0
0
1
normal
OUTn < VLOD
0
Don't Care
1
Don't Care
0
0
0
open error
OUTn > VLOD
1
Don't Care
0
Don't Care
0
0
0
temp. error
OUTn < VLOD
1
Don't Care
1
Don't Care
0
0
0
open &
temp. error
TJ > TTEF
Don't Care
0
Don't Care Don't Care Don't Care
1
0
1
normal
TJ < TTEF
Don't Care
1
Don't Care Don't Care Don't Care
1
0
0
temp error
TJ > TTWF
Don't Care
Don't Care
0
Don't Care Don't Care
1
1
1
normal
TJ < TTWF
Don't Care
Don't Care
1
Don't Care Don't Care
1
1
0
temp. warn
Overtemperature Error/Warning Flags
The AS1112 provides a overtemperature circuit to indicate that the device is in an overtemperature condition. If the
device junction temperature (TJ) exceeds the threshold temperature (150°C typ), the overtemperature circuit trips and
pulls XERR to ground. The overtemperature flag status can be read out from the AS1112 status register.
To prevent an overtemperature condition the AS1112 offers an temperature warning flag at 125°C typical. This flag can
be used to take precautions (e.g. start an external cooling) against a overtemperature condition.
Open LED Detection
The AS1112 integrated open LED detection circuit reports an error if any of the 16 LEDs is open or disconnected from
the circuit. The open LED detection circuit trips when the error detection is activated (see Table 9) and the voltage at
OUTn is less than VLOD.
Note: The voltage at each OUTn is sampled 1µs after being switched on. Please refer to Figure 8.
The open LED detection circuit also pulls XERR to GND when tripped. The open LED status of each channel can also
be read out from the AS1112 status information data (SID) during a greyscale data input cycle.
Shorted LED Detection
The AS1112 integrated shorted LED detection circuit detects if any of the 16 LEDs is short-circuited. The shorted LED
detection circuit trips when the error detection is activated and the voltage at OUTn is higher than VLSD.
Note: The voltage at each OUTn is sampled 1µs after being switched on. Please refer to Figure 8.
The shorted LED status of each channel can only be read out from the AS1112 status information data (SID) during a
greyscale data input cycle.
www.austriamicrosystems.com
Revision 1.06
9 - 18
AS1112
Datasheet - D e t a i l e d D e s c r i p t i o n
Figure 8. Error Detection Timing (GS=FFFFHEX, DC=3FHEX)
LD
>1µs
OEN
GSCLK
SID
LODn, LSDn
Error
Detection
Start
LODn+1, LSDn+1
Error
Detection
End
Note: The rising edge of LD latches new data into the internal registers depending on the logic level of the pin
MODE. If the pin MODE is tied GND, the greyscale registers are updated. If the pin MODE is tied to VCC, the
dot correction registers are updated.
Delay Between Outputs
The AS1112 uses graduated delay circuits between OUTn outputs. These circuits are contained in the constant-current
driver block of the AS1112 (see Figure 1 on page 1). The average-delay time is 30ns (typ).
The maximum delay is 450ns (typ) from OUT0 to OUT15. The delay scheme works by switching on and switching off
each output channel. Thus the on/off time of each channel is the same regardless of the delay. These delays prevent
large inrush currents and switching noise that can reduce bypass capacitance when the outputs are switched on.
OUTn Enable
All OUTn channels can be collectively switched off with one signal. When OEN is set to 1, all OUTn channels are disabled, regardless of the device logic operations. The greyscale counter is also reset when OEN is set to 1.
When OEN is set to 0, all OUTn channels are in normal operation.
Table 10. Pin OEN Truth Table
OEN
OUT0:OUT15
0
Normal Operation
1
Disabled
Setting Maximum Channel Current
The maximum output current per channel is programmed by a single resistor, RIREF, which is placed between pin IREF
and GND. The voltage on pin IREF is set by an internal band gap VIREF (1.24V typ). The maximum channel current is
equivalent to the current flowing through RIREF multiplied by a factor of 31.5. The maximum output current is calculated
as:
IMAX =
VIREF
x 31.5
(EQ 1)
RIREF
Where:
VIREF = 1.24V;
RIREF = User-selected external resistor.
Figure 5 on page 7 shows the maximum output current IOUT versus RIREF, where RIREF is the value of the resistor
between IREF terminal to GND, and IOUT is the constant output current of OUT0:OUT15.
www.austriamicrosystems.com
Revision 1.06
10 - 18
AS1112
Datasheet - D e t a i l e d D e s c r i p t i o n
Power Dissipation
To ensure proper operation of the device, the total power dissipation of the AS1112 must be below the power dissipation rating of the device package. Total power dissipation is calculated as:
PD = (VCC x ICC) + (VOUT x IMAX x n x
DCn
dPWM)
63
(EQ 2)
Where:
VCC is the device supply voltage;
ICC is the device supply current;
VOUT is the device OUTn voltage when driving LED current;
IMAX is the LED current adjusted by RIREF;
DCn is the maximum dot correction value for OUTn;
n is the number of OUTn driving LED at the same time;
dPWM is the duty cycle defined by pin OEN or the greyscale PWM value.
Operating Modes
The AS1112 operates in two modes (see Table 11). Greyscale operating mode (see Figure 12 on page 13) and the shift
registers are in reset state at power-up.
Table 11. Operating Modes
Mode
Input Shift Register
Operating Mode
0
192-bit
Greyscale PWM Mode
1
96-bit
Dot Correction Data Input Mode
Setting Dot Correction
The AS1112 can perform independent fine-adjustments to the output current of each channel, i.e., dot correction. Dot
correction is used to adjust brightness deviations of LEDs connected to the output channels (OUT0:OUT15).
The device powers up with the following default seetings: DC = 63 and GS = 4095.
The 16 channels can be individually programmed with a 6-bit word. The channel output can be adjusted in 64 steps
from 0 to 100% of the maximum output current (IMAX). The output current for each OUTn channel can be calculated as:
IOUTn = IMAX x
DCn
63
(EQ 3)
Where:
IMAX is the maximum programmable output current for each output;
DCn is the programmed dot correction value for output (DCn = 0 to 63);
n = 0 to 15
Dot correction data are simultaneously entered for all channels. The complete dot correction data format consists of 16
x 6-bit words, which forms a 96-bit serial data packet (see Figure 9). Channel data is put on one by one, and the data
is clocked in with the MSB first.
Figure 9. Dot Correction Data Packet Format
MSB
LSB
95
DC15.5
...
90
89
DC15.0
DC14.5
DC OUT15
www.austriamicrosystems.com
...
DC OUT14:DC OUT1
Revision 1.06
6
5
DC1.0
DC0.5
0
...
DC0.0
DC OUT0
11 - 18
AS1112
Datasheet - D e t a i l e d D e s c r i p t i o n
Figure 10. Dot Correction Data Input Timing Diagram
Dot Correction Mode
Data Input Cycle n
Dot Correction Mode
Data Input Cycle n +1
VCC
MODE
GND
SDI
DCn-1
LSB
DCn
MSB
DCn
MSB-1
tSU0
CLK
DCn
MSB-2
DCn
LSB+1
DCn
LSB
DCn+1
MSB
DCn+1
MSB-1
tWH0
1
2
1
95
96
1
2
tWL0
DCn-1
MSB
SDO
DCn-1
MSB-1
DCn-1
MSB-2
DCn-1
LSB+1
DCn-1
LSB
DCn
MSB-1
DCn
MSB
tWH2
tSU1
DCn
MSB-2
tH1
LD
Setting Greyscale Brightness
The brightness of each channel output can be adjusted using a 12 bits-per-channel PWM control scheme which results
in 4096 brightness steps, from 0% to 100% brightness. The brightness level for each output is calculated as:
%Brightness =
GSn
x 100
4095
(EQ 4)
Where:
GSn is the programmed greyscale value for OUTn (GSn = 0 to 4095);
n = 0 to 15 greyscale data for all outputs.
The device powers up with the following default seetings: GS = 4095 and DC = 63.
The input shift register shifts greyscale data into the greyscale register for all channels simultaneously. The complete
greyscale data format consists of 16 x 12 bit words, which forms a 192-bit wide data packet (see Figure 11).
Note: The data packet must be clocked in with the MSB first.
Figure 11. Greyscale Data Packet Format
LSB
MSB
191
GS15.11
...
180
179
GS15.0
GS14.11
GS OUT15
...
GS OUT14:GS OUT1
12
11
GS1.0
GS0.11
0
...
GS0.0
GS OUT0
When pin MODE is tied to GND, the AS1112 enters greyscale data input mode. The device switches the input shift register to 192-bit width. After all data is clocked in, the rising edge of the LD signal latches the data into the greyscale register (see Figure 12).
All greyscale data in the input shift register is replaced with status information data (SID) after latching into the greyscale register.
www.austriamicrosystems.com
Revision 1.06
12 - 18
AS1112
Datasheet - D e t a i l e d D e s c r i p t i o n
Figure 12. Greyscale Data Input Timing Diagram
1st Greyscale Mode
Data Input Cycle After Dot Correction Input
Dot Correction Mode
Data Input Cycle
Following Greyscale Mode
Data Input Cycle
MODE
tH3
tSU3
LD
tH3
GSn
MSB
DCn-1
LSB
SDI
GSn
LSB
tH2
tSU2
CLK
SDO
1
DCn-1
MSB
DCn-1
MSB-1
x
GSn+1
LSB
tSU1
tH0
96
GSn+1
MSB
192
x
1
SIDn
MSB-1
SIDn
MSB
x
192
SIDn
MSB-2
SIDn
LSB
SIDn
MSB
Status Information Data (SID)
The AS1112 contains an integrated status information register, which can be accessed in greyscale mode (MODE =
GND). Once the LD signal latches the data into the greyscale register, the input shift register data is replaced with status information data (see Figure 13).
Open, shorted LED, temperature warning and overtemperature flags as well as the dot-correction registers can be
read out at pin SDO. The status information data packet is 192 bits wide. Bits 191:176 and 31:16 contain the open LED
detection status of each channel (either 191:176 or 31:16 can be used for readout). Bit 175 contains the thermal error
flag status. Bit 174 contains the temperature warning flag. Bits 167:72 contain the data of the dot-correction register. Bit
15:0 contains the LED shorted flags. The remaining bits are reserved. The complete status information data packet is
shown in Figure 13.
Figure 13. Status Information Data Packet Format
MSB
LSB
191
LOD15
...
Open LED
Detect
Bit #
0:15
16:31
32:71
72:167
176
175
174
LOD0
TEF
TWF
...
168
167
X
DC15.
Overtemperature
...
72
71
DC0.
X
...
16:31
0:15
LOD
LSD
DC Values
Description
LED Short Detection, LSD
LED Open Detection (Optional, same as bits 176:191), LOD
Undefined
Dot Correction Readback (16 x 6 Bit)
Bit #
Description
168:173
Undefined
174
Temperature Warning Flag (TWF, 125ºC, typ)
175
Temperature Error Flag (TEF, 150ºC, typ)
176:191
LED Open Detection, LOD
Greyscale PWM Operation
The falling edge of the OEN signal initiates a greyscale PWM cycle. The first GSCLK pulse after the falling edge of
OEN increments the greyscale counter by one and switches on any OUTn whose greyscale value does not equal zero.
Each subsequent rising edge of GSCLK increments the greyscale counter by one.
The AS1112 compares the greyscale value of each OUTn channel with the greyscale counter value. All OUTn whose
greyscale values equal the counter values are switched off. A OEN = 1 signal after 4096 GSCLK pulses resets the
greyscale counter to zero and completes a greyscale PWM cycle (see Figure 14).
www.austriamicrosystems.com
Revision 1.06
13 - 18
AS1112
Datasheet - D e t a i l e d D e s c r i p t i o n
Figure 14. Greyscale PWM Cycle Timing Diagram
Greyscale
PWM
Cycle n+1
Greyscale PWM
Cycle n
OEN
tWL1
tWH1
GSCLK
tH4
tSU4
tWH3
2
1
3
4096
tW1
tPD1
tPD3
tPD3
OUT0
Current
n x tD
tPD3
tPD1 + tD
OUT1
Current
...
...
...
...
tPD1 + 15 x tD
OUT15
Current
tPD2
XERR
www.austriamicrosystems.com
Revision 1.06
14 - 18
AS1112
Datasheet - D e t a i l e d D e s c r i p t i o n
Serial Data Transfer Rate
Figure 15 shows a cascaded arrangement AS1112 devices connected to a controller, building a basic module of an
LED display system.
Figure 15. Cascaded Configuration
VCC
VLED
VLED
VLED
...
100kΩ
OUT0
VLED
...
OUT15
OUT0
...
OUT15
SIN
SDI
SDO
XERR
SDI
SDO
VCC
VCC
XERR
XERR
CLK
VCC
VCC
CLK
LD
LD
GSCLK
CLK
100nF
AS1112
LD
AS1112
100nF
GSCLK
TEST
GSCLK
TEST
MODE
GND
MODE
GND
MODE
OEN
SOUT
OEN
OEN
IREF
IREF
Controller
6
The maximum number of cascading AS1112 devices depends on the application system and is in the range of 40
devices. The minimum frequency needed can be calculated by the following equations:
fGSCLK = 4096 x fUPDATE
(EQ 5)
Where:
fGSCLK is the minimum frequency needed for GSCLK;
fUPDATE is the update rate of whole cascaded system.
fCLK = 193 x fUPDATE x n
(EQ 6)
Where:
fCLK is the minimum frequency needed for CLK and SIN;
fUPDATE is the update rate of whole cascaded system;
n is the number of cascaded of AS1112 devices.
www.austriamicrosystems.com
Revision 1.06
15 - 18
AS1112
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 device is available in an 32-pin TQFN 5x5 mm package.
Figure 16. 32-pin TQFN 5x5 mm Package
Symbol
Min
A
0.80
A1
b
0.18
D
E
D1
E1
3.50
3.50
Common Dimensions
Nom
Max
Symbol
1.00
0.203
REF
0.23
5.00
BSC
5.00
BSC
3.60
3.60
3.70
3.70
Nom
0.5
BSC
Max
0.30
0.40
0.50
e
L
0.30
Min
L1
0.10
P
45°
BSC
aaa
0.15
ccc
0.10
Notes:
1. Dimensioning and tolerancing conform to ASME Y14.5 M-194.
2. All dimensions are in millimeters while angle is in degrees.
3. Dimension b applies to metallized terminal and is measured between 0.25mm and 0.30mm from the terminal tip.
Dimension L1 represents terminal full back from package edge up to 0.1mm is acceptable.
4. Coplanarity applies to the exposed heat slug as well as the terminal
5. Radius on terminal is optional.
www.austriamicrosystems.com
Revision 1.06
16 - 18
AS1112
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 12.
Table 12. Ordering Information
Model
Description
Delivery Form
Package
AS1112-BQFT
16-Channel LED Driver with Dot Correction and Greyscale PWM
with Active-High TEST Input and Power-Down Mode
Tape and Reel
32-pin TQFN
5x5 mm
LED Driver with Dot Correction and Greyscale PWM
AS1112B-BQFT 16-Channel
with Active-Low XTEST Input and without Power-Down Mode
Tape and Reel
32-pin TQFN
5x5 mm
All devices are RoHS compliant and free of halogene substances.
www.austriamicrosystems.com
Revision 1.06
17 - 18
AS1112
Datasheet
Copyrights
Copyright © 1997-2009, austriamicrosystems AG, Schloss Premstaetten, 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 austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing
in its Term of Sale. austriamicrosystems 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.
austriamicrosystems 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 austriamicrosystems 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
austriamicrosystems 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.
The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However,
austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to
personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or
consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the
technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of
austriamicrosystems AG rendering of technical or other services.
Contact Information
Headquarters
austriamicrosystems AG
Tobelbaderstrasse 30
A-8141 Unterpremstaetten - Graz, Austria
Tel: +43 (0) 3136 500 0
Fax: +43 (0) 3136 525 01
For Sales Offices, Distributors and Representatives, please visit:
http://www.austriamicrosystems.com/contact-us
www.austriamicrosystems.com
Revision 1.06
18 - 18