Datasheet

AS1122
12-Channel LED Driver with Dot
Correction and Greyscale PWM
General Description
The AS1122 is a 12-channel, constant current-sink LED driver.
Each of the 12 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 AS1122 channels and other LED drivers. Greyscale
control and dot correction circuitry are accessible via a simple
SPI-compatible serial interface.
The open LED detection function indicates a broken or
disconnected LED at one or more of the outputs. The
overtemperature flag indicates that the device is in an
overtemperature condition.
A single external resistor sets the maximum current value of all
12 channels.
The AS1122 is available in a 24-pin QFN 4 × 4mm package.
Ordering Information and Content Guide appear at end of
datasheet.
Key Benefits & Features
The benefits and features of the AS1122, 12-Channel LED Driver
with Dot Correction and Greyscale PWM, are listed below:
Figure 1:
Added Value of Using AS1122
Benefits
Features
• High resolution LED brightness control
12-bit (4096 steps) Greyscale PWM Control
• Independent fine tuning of LED current of each
channel to adjust brightness deviation
6-bit (64 steps) Dot Correction
• Suitable for high-power LEDs
Drive capability up to 40mA
• Multiple white LEDs in series per channel
LED Power Supply up to 30V
• Inrush current control
Delayed enabling of each output channel
Applications
The device is ideal for mono-color, multi-color, and full-color
LED displays, LED signboards, and display backlights.
ams Datasheet
[v1-02] 2015-May-22
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AS1122 − General Description
Block Diagram
The functional blocks of this device for reference are shown
below:
Figure 2:
Functional Blocks of AS1122
SDI
CLKO
Identifier
2.7V to 3.6V
Control
VDD
CIN
GS
Input
Shift
Register
CLKI
Greyscale
Register
12-Bit PWM
Control
Dot Correction
Register
6-Bit Dot
Correction
Constant Current
Driver
Delay_0
OUT0..3
OUT0..3
Command
Register
Control
IRQ
RST
IREF
Control
Logic
CLK
Counter
DC
Input
Shift
Register
MAX OUTn
Current
Greyscale
Register
12-Bit PWM
Control
Dot Correction
Register
6-Bit Dot
Correction
Constant Current
Driver
Delay_1
OUT4..7
OUT4..7
Command
Register
Control
PWM
Counter
Control
Comm
Input
Shift
Register
Greyscale
Register
12-Bit PWM
Control
Dot Correction
Register
6-Bit Dot
Correction
Constant Current
Driver
Delay_2
OUT8..11
OUT8..11
Command
Register
GND
SDO
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AS1122 − Pin Assignments
Pin Assignments
OUT11
OUT10
OUT9
OUT8
OUT7
OUT6
Figure 3:
Pin Assignments (Top View)
24
23
22
21
20
19
SDI 1
18 GND
CLKI 2
17 NC
AS1122
NC 3
16 IREF
QFN 24-pin
4mm x 4mm
NC 4
15 RST
Exposed pad: GND
CLKO 5
14 IRQ
25
8
9
10
11
OUT1
OUT2
OUT3
OUT4
13 VDD
12
OUT5
7
OUT0
SDO 6
Figure 4:
Pin Descriptions
Pin Number
Pin Name
1
SDI
Serial Data Input
2
CLKI
Serial Data Clock Input
5
CLKO
Serial Data Clock Output
6
SDO
Serial Data Output
7:12, 19:24
OUT0: OUT11
13
VDD
Power Supply Voltage
14
IRQ
Interrupt Request Output:
Open drain pin, can be left open if not used.
RST
Reset Input:
Pull this pin to high to reset all registers (set to default values) and to put
the device into shutdown.
Connect this pin to GND for normal operation.
15
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[v1-02] 2015-May-22
Description
Constant-Current Outputs 0:11
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AS1122 − Pin Assignments
Pin Number
Pin Name
16
IREF
Reference Current Terminal:
A resistor connected to this pin sets the maximum output currents.
18
GND
Ground
3,4,17
NC
25
Exp Pad
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Description
Not Connected:
Connect to GND if not used.
Ground:
This pin must be connected to GND to ensure normal operation.
ams Datasheet
[v1-02] 2015-May-22
AS1122 − Absolute Maximum Ratings
Absolute Maximum Ratings
Stresses beyond those listed in Absolute Maximum Ratings 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 is not implied. Exposure to absolute maximum
rating conditions for extended periods may affect device
reliability.
Figure 5:
Absolute Maximum Ratings
Symbol
Parameter
Min
Max
Units
Comments
Electrical Parameters
VCC to GND
-0.3
5
V
All other pins to GND
-0.3
VDD + 0.3
V
VOUT0: VOUT11 to GND
-0.3
30
V
50
mA
100
mA
Norm: JEDEC JESD78D Nov 2011
kV
Norm: JEDEC JESD22-A114F
Output Current
Input Current
(latch-up immunity)
-100
Electrostatic Discharge
ESDHBM
Electrostatic Discharge HBM
±2
Temperature Ranges and Storage Conditions
TAMB
Operating Temperature
Range
-40
85
°C
TJ
Operating Junction
Temperature
-40
125
°C
RTHJA
Junction to Ambient
Thermal Resistance
37
°C/W
150
°C
150
°C
260
°C
85
%
TJ
Junction Temperature
TSTRG
Storage Temperature Range
TBODY
Package Body Temperature
RHNC
Humidity non-condensing
MSL
Moisture Sensitivity Level
-55
5
3
Norm IPC/JEDEC J-STD-020 (1)
Represents a max. floor life time
of 168h
Note(s) and/or Footnote(s):
1. The reflow peak soldering temperature (body temperature) is specified according IPC/JEDEC J-STD-020 “Moisture/Reflow Sensitivity
Classification for Nonhermetic Solid State Surface Mount Devices”. The lead finish for Pb-free leaded packages is “Matte Tin” (100% Sn)
ams Datasheet
[v1-02] 2015-May-22
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AS1122 − Electrical Characteristics
All limits are guaranteed. The parameters with min and max
values are guaranteed with production tests or SQC (Statistical
Quality Control) methods.
Electrical Characteristics
Figure 6:
Electrical Characteristics of AS1122
Symbol
Parameter
Condition
Min
Typ
Max
Unit
3.6
V
Input Supply
VDD
Supply Voltage
ICC
Supply Current
IPD
Power Down
2.7
All outputs ON, RIREF = 1kΩ
9.5
12
All outputs ON, RIREF = 10kΩ
4
6
RST = High, TAMB = 25°C
40
mA
nA
Output
RIREF
Reference Current
Resistor
VOUT
Output Voltage
OUT0:OUT11
ICOC
Constant Output
Current (1)
All outputs ON, VOUT = 1V,
RIREF = 10kΩ
ΔICOC
ILEAK
ΔILNR
ΔILDR
Constant Output
Current Error
Leakage Output
Current
1
10
kΩ
30
V
40
42
mA
VOUT = 1V, RIREF = 1kΩ,
OUT0:OUT11
±0.8
2
VOUT = 1V, RIREF = 10kΩ,
OUT0:OUT11
±1.5
4
Device to device, average
current from OUT0:OUT11,
VOUT = 1V, RIREF = 1kΩ
±0.5
Device to device, average
current from OUT0:OUT11,
VOUT = 1V, RIREF = 10kΩ
±0.6
All outputs OFF, VOUT = 30V,
RIREF = 1kΩ, OUT0:OUT11
20
VOUT = 1V, RIREF = 1kΩ
OUT0:OUT11
38
%
±0.1
nA
±1.5
Line Regulation
%/V
VOUT = 1V, RIREF = 10kΩ
OUT0:OUT11
±0.2
±1.5
VOUT = 1V to 4V, RIREF = 1kΩ,
OUT0:OUT11
±0.1
±0.4
%/mA
Load Regulation
VOUT = 1V to 4V, RIREF = 10kΩ,
OUT0:OUT11
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±0.01
±0.4
ams Datasheet
[v1-02] 2015-May-22
AS1122 − Electrical Characteristics
Symbol
Parameter
Condition
Min
Typ
Max
Unit
Logic Levels
VIH
High-Level Input
0.8 ×
VDD
VDD
V
VIL
Low-Level Input
GND
0.2 ×
VDD
V
VOH
High-Level Output
VOL
Low-Level Output
VLOD
Open Detection
Threshold
VIREF
Reference Voltage
IOH = -1mA, SDO, CLKO
VDD 0.5
V
IOL = 1mA, SDO, CLKO
0.5
V
IOL = 3mA, IRQ
0.5
V
0.3
0.4
V
1.27
1.30
V
RIREF = 1kΩ
1.24
Electrical Characteristics: VDD = +2.7V to +3.6V, Typical values are at TAMB = 25°C, VDD = 3.3V (unless otherwise
specified).
Note(s) and/or Footnote(s):
I max – I min
1. I coc = --------------------------- × 100
I max + I min
ams Datasheet
[v1-02] 2015-May-22
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AS1122 − Typical Operating Characteristics
Typical Operating
Characteristics
Figure 7:
Constant Output Current vs. Output Voltage
50
50
45
Icoc = 40mA (1kΩ)
40
Constant Output Current (mA)
Constant Output Current (mA)
45
35
30
25
Icoc = 20mA (2kΩ)
20
15
Icoc = 8mA (4.7kΩ)
10
Icoc = 4mA (10kΩ)
5
0
Icoc = 40mA (1kΩ)
40
35
30
25
Icoc = 20mA (2kΩ)
20
15
10
Icoc = 8mA (4.7kΩ)
5
Icoc = 4mA (10kΩ)
0
0
1
2
3
4
5
6
7
8
9
10
0
0.25
0.5
Output Voltage (V)
0.75
1
1.25
1.5
1.75
2
Output Voltage (V)
Constant Output Current vs. Output Voltage: These graphs are showing the behavior of different Constant
Output Current settings versus the Output Voltage. VDD = 3.0V, TAMB = 25°C
50
50
45
45
Constant Output Current (mA)
Constant Output Current (mA)
Figure 8:
Constant Output Current vs. Output Voltage (cont.)
40
35
30
25
20
15
-40°C
10
+25°C
5
+85°C
0
40
35
30
25
20
15
-40°C
10
+25°C
5
+85°C
0
0
1
2
3
4
5
6
7
Output Voltage (V)
8
9
10
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
Output Voltage (V)
Constant Output Current vs. Output Voltage: These graphs are showing the behavior of the 40mA Constant
Output Current settings versus the Output Voltage over temperature. VDD = 3.0V, RIREF = 1kΩ
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[v1-02] 2015-May-22
AS1122 − Typical Operating Characteristics
Figure 9:
Constant Output Current vs. Supply Voltage
4.04
REXT = 1kΩ
40.75
Constant Output Current (mA)
Constant Output Current (mA)
41
40.5
40.25
40
39.75
39.5
-40°C
+25°C
39.25
+85°C
39
REXT = 10kΩ
4.03
4.02
4.01
-40°C
+25°C
+85°C
4
2.7 2.8 2.9
3
3.1 3.2 3.3 3.4 3.5 3.6
2.7
2.8
2.9
Supply Voltage (V)
3
3.1
3.2
3.3
3.4
3.5
3.6
Supply Voltage (V)
Constant Output Current vs. Supply Voltage: These graphs are showing the behavior of the Constant Output
Current versus the Supply Voltage over temperature.
VOUT = 1.0V, RIREF = 1kΩ (left graph, ICOC = 40mA), RIREF = 10kΩ (right graph, ICOC = 4mA)
Figure 10:
Constant Output Current vs. Temperature
4.1
REXT = 1kΩ
Constant Output Current (mA)
Constant Output Current (mA)
41
40.5
40
39.5
Vdd = 2.7V
Vdd = 3.0V
REXT = 10kΩ
4.05
4
3.95
Vdd = 2.7V
Vdd = 3.0V
Vdd = 3.6V
Vdd = 3.6V
39
3.9
-40
-15
10
35
Ambient Temperature(°C)
60
85
-40
-15
10
35
60
85
Ambient Temperature(°C)
Constant Output Current vs. Temperature: These graphs are showing the behavior of the Constant Output
Current versus the Temperature for different Supply Voltages.
VOUT = 1.0V, RIREF = 1kΩ (left graph, ICOC = 40mA), RIREF = 10kΩ (right graph, ICOC = 4mA)
ams Datasheet
[v1-02] 2015-May-22
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AS1122 − Typical Operating Characteristics
Figure 11:
Constant Output Current vs. PWM
0.4
Constant Output Current (mA)
Constant Output Current (mA)
40
35
30
25
20
15
10
0.3
0.2
0.1
5
0
0
0
500 1000 1500 2000 2500 3000 3500 4000
0
PWM (#)
2
4
6
8
10
12
14
16
18
20
PWM (#)
Constant Output Current vs. PWM: These graphs are showing the behavior of the Constant Output Current
versus the PWM bit setting.
VOUT = 1.0V, RIREF = 1kΩ, VDD = 3.0V, TAMB = 25°C
Figure 12:
Constant Output Current Error vs. Output Voltage
2
Constant Output Current Error (%)
Constant Output Current Error (%)
1
REXT = 1kΩ
0.75
0.5
0.25
-40°C
+25°C
+85°C
0
1.75
REXT = 10kΩ
1.5
1.25
1
0.75
0.5
-40°C
+25°C
0.25
+85°C
0
0.5
1
1.5
2
2.5
3
3.5
Output Voltage (V)
4
4.5
5
0.2 0.6 1 1.4 1.8 2.2 2.6 3 3.4 3.8 4.2 4.6 5
Output Voltage (V)
Constant Output Current Error vs. PWM: These graphs are showing the Error of the Constant Output Current
versus the Output Voltage over temperature.
VDD = 3.0V, RIREF = 1kΩ (left graph, ICOC = 40mA), RIREF = 10kΩ (right graph, ICOC = 4mA)
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[v1-02] 2015-May-22
AS1122 − Typical Operating Characteristics
Figure 13:
Constant Output Current Error vs. Temperature
2
Constant Output Current Error (%)
Constant Output Current Error (%)
1
REXT = 1kΩ
0.75
0.5
0.25
Vdd = 2.7V
Vdd = 3.0V
Vdd = 3.6V
0
REXT = 10kΩ
1.75
1.5
1.25
1
0.75
0.5
Vdd = 2.7V
Vdd = 3.0V
0.25
Vdd = 3.6V
0
-40
-15
10
35
60
-40
85
Ambient Temperature (°C)
-15
10
35
60
85
Ambient Temperature (°C)
Constant Output Current Error vs. Temperature: These graphs are showing the Error of the Constant Output
Current versus temperature for different Supply Voltages.
VOUT = 1.0V, RIREF = 1kΩ (left graph, ICOC = 40mA), RIREF = 10kΩ (right graph, ICOC = 4mA)
Figure 14:
Supply Current vs. Temperature
11
6
REXT = 1kΩ
10.5
5
Supply Current (mA)
10
Supply Current (mA)
REXT = 10kΩ
5.5
9.5
9
8.5
8
Vdd = 2.7V
Vdd = 3.0V
7.5
4.5
4
3.5
3
Vdd = 2.7V
Vdd = 3.0V
2.5
Vdd = 3.6V
Vdd = 3.6V
7
2
-40
-15
10
35
60
Ambient Temperature (°C)
85
-40
-15
10
35
60
85
Ambient Temperature (°C)
Supply Current vs. Temperature: These graphs are showing the Supply Current versus Temperature for different
Supply Voltages.
VOUT = 1.0V, RIREF = 1kΩ (left graph, ICOC = 40mA), RIREF = 10kΩ (right graph, ICOC = 4mA)
ams Datasheet
[v1-02] 2015-May-22
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AS1122 − Typical Operating Characteristics
Figure 15:
Constant Output Current vs. Reference Current Resistor
40
Constant Output Current (mA)
Constant Output Current vs.
Reference Current Resistor: This graph
is showing the Constant Output Current
versus Reference Current Resistor.
VOUT = 1.0V, VDD = 3.0V, TAMB = 25°C
35
30
25
20
15
10
5
0
0
2
4
6
8
10
RIREF (kOhm)
Figure 16:
Constant Output Current vs. Dot Correction
40
Constant Output Current (mA)
Constant Output Current vs. Dot
Correction: This graph is showing the
Constant Output Current versus Dot
Correction.
VOUT = 1.0V, VDD = 3.0V, TAMB = 25°C,
RIREF = 1kΩ
35
30
25
20
15
10
5
0
0
9
18
27
36
45
54
63
Dot Correction
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[v1-02] 2015-May-22
AS1122 − Typical Operating Characteristics
Figure 17:
LED Open Detection Threshold vs. Temperature
0.6
LED Open Detection Threshold (V)
LED Open Detection Threshold vs.
Temperature: This graph is showing the
LED Open Detection Threshold versus
Temperature for different Supply
Voltages.
0.5
0.4
0.3
0.2
Vdd = 2.7V
0.1
Vdd = 3.0V
Vdd = 3.6V
0
-40
-15
10
35
60
85
Ambient Temperature(°C)
Figure 18:
Constant Output Current Matching vs. Dot Correction
Constant Output Current Matching vs.
Dot Correction: This graph is showing
the Matching of the Constant Output
Current versus Dot Correction.
VOUT = 1.0V, VDD = 3.0V, TAMB = 25°C,
RIREF = 1kΩ
2
1.75
ICOC Matching (%)
1.5
1.25
1
0.75
0.5
0.25
0
0
9
18
27
36
45
54
63
Dot Correction
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[v1-02] 2015-May-22
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AS1122 − Detailed Description
Detailed Description
Timing Characteristics
Figure 19:
Output Timing Characteristics
Symbol
Parameter
Condition
Min
Typ
Max
Unit
tR_OUT
Rise Time OUT (1)
20
ns
tF_OUT
Fall Time OUT (1)
20
ns
Average Output Delay
Time
25
ns
tD (2)
Timing Characteristics: VDD = 2.7V to 3.6V, TAMB = -40°C to 85°C. Typical values are at TAMB = 25°C, VDD = 3.3V
(unless otherwise specified).
Note(s) and/or Footnote(s):
1. Value can be factory trimmed for EMI improvement.
2. Can be turned OFF on request.
Figure 20:
Serial Interface Timing Characteristics
Symbol
Parameter
Condition
Min
Typ
Max
Unit
10
12
MHz
5
MHz
1
μs
2.85
μs
fOSC
Oscillator Frequency
8
fCLK
Data Shift Clock
Frequency
1
tLOW
CLK low time during
data shift
tCAPT
CLK low time for data
capture
tSETUP
Setup Time
SDI, CLKI
12
ns
tHOLD
Hold Time
SDI, CLKI
12
ns
tPD_rising
Delay CLKI to CLKO (1)
rising CLKI to rising CLKO
2
3.5
8
ns
tPD_falling
Delay CLKI to CLKO (1)
rising CLKI to falling CLKO
72
103.5
138
ns
tPD_SDO
Delay CLKO to SDO (1)
falling edge CLKO
0.8
1.5
3
ns
tH_CLKO
High Time of CLKO (1)
70
100
130
ns
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1.5
1.8
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[v1-02] 2015-May-22
AS1122 − Detailed Description
Symbol
Parameter
Condition
Min
Typ
Max
Unit
tR_CLK
Rise Time CLK (1)
CLOAD = 20pF
10
ns
tR_DATA
Rise Time Data (1)
CLOAD = 20pF
10
ns
Timing Characteristics: VDD = 2.7V to 3.6V, TAMB = -40°C to 85°C. Typical values are at TAMB = 25°C, VDD = 3.3V
(unless otherwise specified).
Note(s) and/or Footnote(s):
1. Guaranteed by design and not production tested.
Figure 21:
Load Circuit for Digital Output Timing Specifications
200µA
IOL
SDO
CLKO
VDD/2
CLOAD
20pF
200µA
IOH
ams Datasheet
[v1-02] 2015-May-22
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AS1122 − Detailed Description
Timing Diagrams
Serial Interface
The AS1122 features a 4-pin (CLKI, CLKO, SDI, and SDO) serial
interface, which can be connected to microcontrollers or digital
signal processors.
The rising edge of the CLKI signal shifts data from pin SDI to the
internal register. After all data are clocked in, the serial data are
latched into the internal registers at the rising edge of the
internal LD signal. The internal LD signal is triggered after the
clk is low for a time t CAPT and all Data are clocked in.
With the first 8 clk-cycles an 8 bit identifier needs to be send to
the device to distinguish between Status Information, Dot
Correction, PWM or command data.
After the internal LD signal the internal counter is set to 0 again
and the data are latched into the register according to the prior
identifier. If the LD triggers and the counter has no valid value
(80 bit for Dot-Correction, 152 bit for PWM data or 16 bit for
command data), the counter is set to 0 but the data will be
ignored.
With the falling edge of the CLKO the data is shifted to SDO.
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AS1122 − Detailed Description
Figure 22:
PWM Cycle Timing Diagram
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[v1-02] 2015-May-22
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A S 1 1 2 2 − Detailed Description
Register Access
Before data are accepted by the AS1122, an identifier needs to be sent in advance. Only 3 defined identifiers will be
recognized, all other bit combinations will be ignored.
Figure 23:
Identifier
Bit
7
6
5
4
3 (1)
2
1
0
Data
Section
Length
Dot Correction
1
1
0
0
1/0
0
0
1
72 bits
Dot Correction Register
PWM
1
1
0
0
1/0
0
1
0
144 bits
PWM Register
Command
1
1
0
0
1/0
1
0
0
8 bits
Command Register
Identifier
Description
Note(s) and/or Footnote(s):
1. Bit3 of the identifier is a global ON/OFF bit. When bit3 of any identifier is set to logic ‘0’ and the OEN bit of the command register is ‘0’ (per default), the output channels are immediately turned ON.
The identifier maps the input register to the identified register and all data on pin SDI will be clocked into this
register. This selection is valid as long as no internal LD signal is triggered. When data is latched into the device the
identifier selection is reset and for the next data word a new identifier needs to be send. Every identifier requires a
certain data section length. If this length is not corresponding with the identifier, the data will be ignored.
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AS1122 − Detailed Description
Dot Correction (DC)
The AS1122 offers a 6 bit (64 steps) Dot Correction per Output
channel. After sending the 8 bit identifier for access to the DC
register the device is waiting for 72 bits to receive. If more or
less bits are sent the whole dataword will be ignored.
Figure 24:
Dot Correction Input Timing Diagram
CLKI
SDI
CLKO
SDO
1
2
8
1
2
72
ID7
ID6
ID0
DC
MSB
DC
MSB-1
DC
LSB
1
2
8
1
2
72
ID7
ID6
ID0
1
71
72
1
71
72
DC
MSB
DC
MSB-1
DC
LSB
For n devices in a chain only one identifier is needed to set all
n devices to the same register setting.
Figure 25:
Dot Correction for N Devices
CLKI
1
SDI
CLKO
SDO
2
8
2
Identifier
ams Datasheet
[v1-02] 2015-May-22
2
Dot Correction
Identifier
1
1
8
1
2
71
72
Data Device n
71
72
1
2
Dot Correction
1
2
Dot Correction
71
72
Data Device n-1
71
Device n
72
1
2
Dot Correction
1
2
Dot Correction
71
72
1
2
71
72
1
2
71
72
Data Device n-2
71
Device n-1
72
Dot Correction
Device n-2
Page 19
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AS1122 − Detailed Description
PWM Data (Greyscale)
To set the PWM, 12 bit (4096 steps) per Output channel can be
used. After sending the 8 bit identifier for access to the PWM
Data register the device is waiting for 144 bits to receive. If more
or less bits are sent the whole dataword will be ignored.
Figure 26:
PWM Input Timing Diagram
CLKI
SDI
CLKO
SDO
1
2
8
1
2
144
ID7
ID6
ID0
GS
MSB
GS
MSB-1
GS
LSB
1
2
8
1
2
144
ID7
ID6
ID0
1
143
144
1
143
144
GS
MSB
GS
MSB-1
GS
LSB
For N devices in a chain only one identifier needs to be set all
n devices to the same register setting.
Figure 27:
PWM Data for N Devices
CLKI
1
SDI
CLKO
SDO
2
8
Identifier
1
2
Identifier
Page 20
Document Feedback
1
2
PWM Greyscale
8
1
2
143
144
Data Device n
143
144
1
2
PWM Greyscale
1
2
PWM Greyscale
143
144
Data Device n-1
143
Device n
144
1
2
PWM Greyscale
1
2
PWM Greyscale
143
144
1
2
143
144
1
2
143
144
Data Device n-2
143
Device n-1
144
PWM Greyscale
Device n-2
ams Datasheet
[v1-02] 2015-May-22
AS1122 − Detailed Description
Command Data
The AS1122 offers a command register for setting the
configuration of the device. The command register is again
accessible via an identifier and is 8 bits long. If more or less bits
are sent the whole dataword will be ignored.
Figure 28:
Command Input Timing Diagram
CLKI
SDI
CLKO
1
2
8
ID7
ID6
ID0
1
2
8
SDO
ID7
ID6
1
2
3
Un defined
do n´t care
1
2
3
4
5
6
7
8
Re ad
SID
Open
Test
Over
Temp
Di spla y
1x
OEN
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
ID0
Un defin ed
do n´t care
Re ad
SID
Open
Test
Over
Temp
Di spla y
1x
OEN
Figure 29:
Command Data for N Devices
CLKI
1
SDI
CLKO
SDO
2
8
1
Identifier
1
2
Identifier
ams Datasheet
[v1-02] 2015-May-22
2
Command
8
1
2
7
8
Data Device n
7
1
2
Command
8
1
Command
2
7
8
Data Device n-1
7
Device n
8
1
2
Command
1
2
Command
7
8
1
2
7
8
1
2
7
8
Data Device n-2
7
Device n-1
8
Command
Device n-2
Page 21
Document Feedback
AS1122 − Detailed Description
Typical Operating Characteristics
Setting Dot Correction
The AS1122 can perform independent fine-adjustments to the
output current of each channel. Dot correction is used to adjust
brightness deviations of LEDs connected to the output
channels (OUT0:OUT11).
The device powers up with the following default settings:
DC = 0 and GS = 0.
The 12 channels can be individually programmed with a 6-bit
word for Dot Correction. The channel output can be adjusted
in 64 steps from 0% to 100% of the maximum output current
(I MAX). The output current for each OUTn channel can be
calculated as:
(EQ1)
DC n
I OUTn = I MAX × ----------63
Where:
• I MAX is the maximum programmable output current for
each output;
• DC n is the programmed dot correction value for output
(DCn = 0 to 63);
• n = 0 to 11
Dot correction data are simultaneously entered for all channels.
The complete dot correction data format consists of 12 x 6-bit
words, which forms a 72-bit serial data packet and 8-bit for the
identifier. Channel data is put on one by one, and the data is
clocked in with the MSB first.
Figure 30:
Dot Correction Data Packet Format
The Dot Correction data is only valid if the exact identifier byte
was sent. Otherwise the data will be ignored.
Page 22
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ams Datasheet
[v1-02] 2015-May-22
AS1122 − Detailed Description
Setting Greyscale Brightness (PWM)
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:
(EQ2)
GS n
%Brightness = ------------ × 100
4095
Where:
• GSn is the programmed greyscale value for output
(GSn = 0 to 4095);
• n = 0 to 11 greyscale data for all outputs.
• The device powers up with the following default settings:
GS = 0 and DC = 0
The input shift register shifts greyscale data into the greyscale
register for all channels simultaneously. The complete greyscale
data format consists of 12 x 12 bit words, which forms a 144-bit
wide data packet plus the 8 bit for the identifier.
Figure 31:
PWM Data Packet Format
The PWM data is only valid if the exact identifier byte was send.
Otherwise the data will be ignored.
ams Datasheet
[v1-02] 2015-May-22
Page 23
Document Feedback
AS1122 − Detailed Description
Command Data
In the command register of the AS1122 some configuration of
the device can be done. After sending the correct identifier the
8 bits of the command register are accessible.
Figure 32:
Command Register Format
Bit
Bit Name
Default
Access
7:5
-
000
n/a
Bit Description
4
Read SID
0
W
0: normal operation
1: read Status Information Register (SID)
3
OPEN Test
0
W
0: no test is running
1: start OPEN test
2
Over Temperature
Power Down
0
W
0: If an overtemperature condition
occurs the OUTn are NOT switched OFF
automatically.
1: If an overtemperature condition
occurs the OUTn are switched OFF
automatically.
1
Display ON Time
0
W
0: The PWM is running endless
1: The PWM is running for one cycle
W
0: This bit must be ‘0’ as well as bit3 of
the last valid identifier to turn ON all
channels.
1: all channels are OFF
0
OEN
0
Figure 33:
Command Packet Format
06%
,GHQWLILHU
XQGHILQHG
5HDG6,'
23(1
7HVW
2YHU7HPS
3RZHU'RZQ
'LVSOD\
217LPH
/6%
2(1
'RQWFDUH
Page 24
Document Feedback
ams Datasheet
[v1-02] 2015-May-22
AS1122 − Detailed Description
Status Information Data (SID)
The AS1122 contains an integrated status information register.
After latching the correct identifier with a 16 bit data word the
input shift register data is replaced with status information
data.
With the next 16 clock cycles the Open LED information, the
Overtemperature-Warning and -Error flag as well as the
power-ON reset (POR) flag can be read out at pin SDO. The status
information data packet is 16 bits wide. Bits 11:0 contain the
open LED detection status of each channel. Bit 12 is the
overtemperature-warning flag, bit 13 is the
overtemperature-error flag and bit 14 indicates if the POR was
triggered.
Figure 34:
Status Information Data Packet Format
Note(s) and/or Footnote(s):
1. Bit14 (POR) is set to ‘1’ after start-up and after triggering a power-ON reset due to a supply voltage drop. Must be set to ‘0’ manually.
ams Datasheet
[v1-02] 2015-May-22
Page 25
Document Feedback
AS1122 − Detailed Description
Readback the Status Information Data
To read out the SID the read bit in the command data needs to
be set to “1”. After the new command data is latched into the
device the SID is shifted to the SDO register and will be shifted
out with the next running clk cycles on CLKI. After keeping the
clk low for the time tlow, the device is reset again and can be
programmed with needed information.
Figure 35:
Reading of the Status Information Register
CLKI
1
SDI
2
8
Identifier
1
2
7
Command Dat a
8
Device n
1
2
Command Data
7
8
1
2
1
2
7
8
1
7
8
1
2
3
4
5
15
16
1
15
16
1
3
2
4
5
15
16
15
16
Device n-1
Internal LD
CLKO
SDO
1
2
Identifier
8
1
2
7
8
1
2
Command Dat a
7
Device n
8
Command Data
Device n-1
2
X
3
X
4
Temp
Error
5
Temp
Warn
LED o pen Test resul ts
3
2
X
X
SI D register device n-1
4
Temp
Error
5
Temp
Warn
LED o pen Test resul ts
SI D register device n
Setting Maximum Channel Current
The maximum output current per channel is programmed by a
single resistor R IREF, which is placed between pin I REF and GND.
The voltage on pin IREF is set by an internal band gap V IREF
(1.27V 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:
(EQ3)
V IREF
I MAX = --------------- × 31.5
R IREF
Where:
• V IREF = 1.27V;
• R IREF = User-selected external resistor.
Page 26
Document Feedback
ams Datasheet
[v1-02] 2015-May-22
AS1122 − Detailed Description
Timing for Cascading of N Devices
With the rising edge of CLKI the data will be shifted from SDI
into the device. The rising edge of CLKI is shifted through the
devices to CLKO. After a factory fixed high-time (100ns) the
falling edge of CLKO is triggered and the data are shifted out
via SDO. This ensures a synchronous timing between CLKO and
SDO. The CLK period (frequency) will stay the same only the
duty cycle will be changed.
The fixed high-time will vary with ±30%.
Figure 36:
Clock Handling with 5MHz Data-Clock
tHOLD
CLKI
5MHz
SDI
100ns
100ns
100ns
100ns
tSETUP
DATA1
DATA2
tPD_RISING
100ns (fixed)
CLKO
5MHz
DATA3
tPD_SDO
100ns
100ns (fixed)
100ns
tPD_FALLING
SDO
DATA1
DATA2
Figure 37:
Clock Handling with 2MHz Data-Clock
tHOLD
CLKI
2MHz
SDI
250ns
SDO
ams Datasheet
[v1-02] 2015-May-22
250ns
250ns
tSETUP
DATA1
DATA2
tPD_RISING
CLKO
2MHz
250ns
DATA3
tPD_SDO
100ns
(fixed)
100ns
(fixed)
400ns
400ns
tPD_FALLING
DATA1
DATA2
Page 27
Document Feedback
AS1122 − Detailed Description
Scrambled PWM
Due to the possibility to interrupt a running PWM cycle the
AS1122 is using a scrambled PWM. The scrambled PWM will
cause less error as the classical PWM when data is updated
during a running PWM cycle.
As an example, we take a look on a system with a 8-bit PWM and
three LEDs. The PWM for the red LED is set to 4, for green to 2
and for blue to 6. In the classical approach the red, green and
blue channels are high according to their PWM setting.
If this PWM cycle would be interrupted at the 4th clock, the red
and the blue LED would be as bright as if the PWM setting were
8. The green LED also would be much brighter than desired.
In the scrambled PWM the ON-times are divided evenly over
the whole PWM cycle. So if the running PWM cycle is
interrupted, the failure is less effective.
Figure 38:
Classic PWM vs. Scrambled PWM
Greyscale
CLK
Classic PWM
1
2
3
4
5
6
7
8
Time
red
LED
Time
green
LED
Time
blue
LED
Scrambled PWM
Time
red
LED
Time
green
LED
Time
blue
LED
Time
Page 28
Document Feedback
ams Datasheet
[v1-02] 2015-May-22
AS1122 − Detailed Description
PWM Scheme of AS1122
The AS1122 uses a scrambled PWM scheme. Meaning the PWM
value is divide into sub-periods (32 bits wide) and than evenly
distributed over the whole PWM cycle. If the PWM setting can
not be divided by 32, the rest is added at the beginning of the
PWM cycle.
Figure 39:
Different PWM Outputs of AS1122
SDI
0
OUTn
PWM = 2
2
OUTn
PWM = 20
OUTn
PWM = 36
4095
4094
OUTn
PWM = 64
2
4076
20
4
0
2028
32
32
2016
1008
OUTn
PWM = 2048
20
2032
32
64 blocks á 32 pulses long
OUTn
PWM = 4080
2040
OUTn
PWM = 4095
15
4095
4094
4
1008
4076
2028
1008
32
32
2016
64 blocks á 32 pulses long
2040
2040
15
4095
Note: not in scale
The PWM clock is generated internally and is running with f OSC
(10MHz typ.). For a PWM value of 20 the OUT channel is high for
20 PWM-clock pulses (20 × 100ns) and stays then low for 4076
PWM-clock pulses (4076 × 100ns). After one PWM cycle (4096
pulses) the cycle is repeated endless until the output channels
is turned OFF or updated with new PWM data.
ams Datasheet
[v1-02] 2015-May-22
Page 29
Document Feedback
AS1122 − Application Information
Application Information
Figure 40:
Typical Application Circuit
VLED
OUT0
AS1122
CLKI
uC
OUT0
OUT11
SDI
SDO
SDI
CLKO
CLKI
QFN24 4x4mm
RST
IRQ
GND
IREF
AS1122
CIN
SDO
SDI
CLKO
CLKI
QFN24 4x4mm
RST
VDD
OUT0
OUT11
GND
IREF
SDO
AS1122
CIN
CLKO
QFN24 4x4mm
RST
VDD
IRQ
OUT11
VDD
IRQ
GND
IREF
CIN
Typical Application: This figure shows the typical application circuit of n devices AS1122 connected in a chain.
Page 30
Document Feedback
ams Datasheet
[v1-02] 2015-May-22
AS1122 − Package Drawings & Markings
Package Drawings & Markings
Figure 41:
24-Pin QFN 4 × 4mm Package
RoHS
Green
Note(s) and/or Footnote(s):
1. Dimensions & toleranceing confirm to ASME Y14.5M-1994.
2. All dimensions are in millimeters. Angles are in degrees.
3. Dimension b applies to metallized terminal and is measured between 0.25mm and 0.30mm from terminal tip. Dimension L1
represents terminal full back from package edge up to 0.15mm is acceptable.
4. Coplanarity applies to the exposed heat slug as well as the terminal.
5. Radius on terminal is optional.
6. N is the total number of terminals.
ams Datasheet
[v1-02] 2015-May-22
Page 31
Document Feedback
AS1122 − Package Drawings & Mark ings
Figure 42:
24-Pin QFN 4 × 4mm Marking
AS1122
YYWWXZZ
@
Figure 43:
Packaging Code YYWWXZZ
YY
WW
X
ZZ
@
Last two digits of the
manufacturing year
Manufacturing week
Plant identifier
Free choice /
traceability code
Sublot identifier
Page 32
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ams Datasheet
[v1-02] 2015-May-22
AS1122 − Ordering & Contact Information
Ordering & Contact Information
The device is available as the standard products shown in
Figure 44.
Figure 44:
Ordering Information
Ordering Code
Marking
AS1122-BQFT
AS1122
Description
12-Channel LED Driver
with Dot Correction and
Greyscale PWM
Delivery Form
Package
Tape and Reel
24-pin QFN 4 × 4mm
Buy our products or get free samples online at:
www.ams.com/ICdirect
Technical Support is available at:
www.ams.com/Technical-Support
Provide feedback about this document at:
www.ams.com/Document-Feedback
For further information and requests, e-mail us at:
[email protected]
For sales offices, distributors and representatives, please visit:
www.ams.com/contact
Headquarters
ams AG
Tobelbaderstrasse 30
8141 Unterpremstaetten
Austria, Europe
Tel: +43 (0) 3136 500 0
Website: www.ams.com
ams Datasheet
[v1-02] 2015-May-22
Page 33
Document Feedback
AS1122 − RoHS Compliant & ams Green Statement
RoHS Compliant & ams Green
Statement
RoHS: The term RoHS compliant means that ams AG products
fully comply with current RoHS directives. Our semiconductor
products do not contain any chemicals for all 6 substance
categories, including the requirement that lead not exceed
0.1% by weight in homogeneous materials. Where designed to
be soldered at high temperatures, RoHS compliant products are
suitable for use in specified lead-free processes.
ams Green (RoHS compliant and no Sb/Br): ams Green
defines that in addition to RoHS compliance, our products are
free of Bromine (Br) and Antimony (Sb) based flame retardants
(Br or Sb do not exceed 0.1% by weight in homogeneous
material).
Important Information: The information provided in this
statement represents ams AG knowledge and belief as of the
date that it is provided. ams AG bases its knowledge and belief
on information provided by third parties, and makes no
representation or warranty as to the accuracy of such
information. Efforts are underway to better integrate
information from third parties. ams AG has taken and continues
to take reasonable steps to provide representative and accurate
information but may not have conducted destructive testing or
chemical analysis on incoming materials and chemicals. ams AG
and ams AG suppliers consider certain information to be
proprietary, and thus CAS numbers and other limited
information may not be available for release.
Page 34
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ams Datasheet
[v1-02] 2015-May-22
AS1122 − Copyrights & Disclaimer
Copyrights & Disclaimer
Copyright ams AG, Tobelbader Strasse 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.
Devices sold by ams AG are covered by the warranty and patent
indemnification provisions appearing in its General Terms of
Trade. ams AG makes no warranty, express, statutory, implied,
or by description regarding the information set forth herein.
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
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. This product is provided by ams AG “AS IS”
and any express or implied warranties, including, but not
limited to the implied warranties of merchantability and fitness
for a particular purpose are disclaimed.
ams 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 ams AG rendering of technical or other services.
ams Datasheet
[v1-02] 2015-May-22
Page 35
Document Feedback
AS1122 − Document Status
Document Status
Document Status
Product Preview
Preliminary Datasheet
Datasheet
Datasheet (discontinued)
Page 36
Document Feedback
Product Status
Definition
Pre-Development
Information in this datasheet is based on product ideas in
the planning phase of development. All specifications are
design goals without any warranty and are subject to
change without notice
Pre-Production
Information in this datasheet is based on products in the
design, validation or qualification phase of development.
The performance and parameters shown in this document
are preliminary without any warranty and are subject to
change without notice
Production
Information in this datasheet is based on products in
ramp-up to full production or full production which
conform to specifications in accordance with the terms of
ams AG standard warranty as given in the General Terms of
Trade
Discontinued
Information in this datasheet is based on products which
conform to specifications in accordance with the terms of
ams AG standard warranty as given in the General Terms of
Trade, but these products have been superseded and
should not be used for new designs
ams Datasheet
[v1-02] 2015-May-22
AS1122 − Revision Information
Revision Information
Changes from 1.00 to current revision 1-02 (2015-May-22)
Page
1.00 to 1-01 (2015-May-21)
Content of austriamicrosystems datasheet was converted to latest ams design (including
update of all graphics)
Added benefits to Figure 1
1
Updated Figure 6
6
Updated Figure 23
18
Updated Setting Greyscale Brightness (PWM)
23
Updated Figure 43 (Packaging Code)
32
Updated Figure 44 (Ordering Information)
33
1-01 (2015-May-21) to 1-02 (2015-May-22)
Updated Setting Greyscale Brightness (PWM)
23
Note(s) and/or Footnote(s):
1. Page and figure numbers for the previous version may differ from page and figure numbers in the current revision.
2. Correction of typographical errors is not explicitly mentioned.
ams Datasheet
[v1-02] 2015-May-22
Page 37
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AS1122 − Content Guide
Content Guide
Page 38
Document Feedback
1
1
1
2
General Description
Key Benefits & Features
Applications
Block Diagram
3
5
6
8
Pin Assignments
Absolute Maximum Ratings
Electrical Characteristics
Typical Operating Characteristics
14
14
16
16
18
19
20
21
22
22
23
24
25
26
26
27
28
29
Detailed Description
Timing Characteristics
Timing Diagrams
Serial Interface
Register Access
Dot Correction (DC)
PWM Data (Greyscale)
Command Data
Typical Operating Characteristics
Setting Dot Correction
Setting Greyscale Brightness (PWM)
Command Data
Status Information Data (SID)
Readback the Status Information Data
Setting Maximum Channel Current
Timing for Cascading of N Devices
Scrambled PWM
PWM Scheme of AS1122
30
31
33
34
35
36
37
Application Information
Package Drawings & Markings
Ordering Information
RoHS Compliant & ams Green Statement
Copyrights & Disclaimer
Document Status
Revision Information
ams Datasheet
[v1-02] 2015-May-22
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