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PDF AS1122 Data sheet ( Hoja de datos )
| Número de pieza | AS1122 | |
| Descripción | 12-Channel LED Driver | |
| Fabricantes | austriamicrosystems AG | |
| Logotipo |  |
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Datasheet
AS1122
12-Channel LED Driver with Dot Correction and Greyscale PWM
1 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 indi-
cates 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 4x4mm package.
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: 2.7V to 3.6V
Output Delay for controlled Inrush Current (factory set, can be
turned off)
Factory set rise- and fall-time for EMI improvement
Internal PWM Clock: 10 MHz (typ)
Data Transfer Clock Rate: up to 5 MHz
CMOS Level I/O
Diagnostic Features
24-pin QFN 4x4mm Package
3 Applications
The device is ideal for mono-, multi-, and full-color LED displays,
LED signboards, and display backlights.
Figure 1. AS1122 - Typical Application Diagram
www.austriamicrosystems.com/LED-Driver-ICs
Revision 1.00
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1 page  
AS1122
Datasheet - Electrical Characteristics
Timing Characteristics
VDD = +2.7V to +3.6V, TAMB = -40°C to +85ºC. Typical values are at TAMB = +25°C, VDD = 3.3V (unless otherwise specified).
Table 4. Output Timing Characteristics
Symbol
Parameter
Conditions
Min Typ Max
tR_OUT
Rise Time OUT1
20
tF_OUT
Fall Time OUT1
20
tD2
Average Output Delay Time
(can be turned off on request)
25
1. Value can be factory trimmed for EMI improvement.
2. See Figure 24 on page 10.
Unit
ns
ns
ns
Interface Characteristics
VDD = +2.7V to +3.6V, TAMB = -40°C to +85ºC. Typical values are at TAMB = +25°C, VDD = 3.3V (unless otherwise specified).
Table 5. Serial Interface Timing Characteristics
Symbol
Parameter
Conditions
Min Typ Max
fOSC
Oscillator Frequency
8 10 12
fCLK Data Shift Clock Frequency
15
tLOW1
CLK low time during data shift
1
tCAPT1
CLK low time for data capture
1.5 1.8 2.85
tSETUP2
Setup Time
SDI, CLKI
12
tHOLD2
Hold Time
SDI, CLKI
12
tPD_rising2
Delay CLKI to CLKO3
rising CLKI to rising CLKO
2 3.5 8
tPD_falling2
Delay CLKI to CLKO3
rising CLKI to falling CLKO
72 103.5 138
tPD_SDO2
Delay CLKO to SDO3
falling edge CLKO
0.8 1.5
3
tH_CLKO2
High Time of CLKO3
70 100 130
tR_CLK
Rise Time CLK3
CLOAD = 20pF
10
tR_DATA
Rise Time Data3
CLOAD = 20pF
10
1. See Figure 24 on page 10
2. See Figure 36 on page 16 and Figure 37 on page 16
3. Guaranteed by design and not production tested.
Figure 3. Load Circuit for Digital Output Timing Specifications
200µA
IOL
Unit
MHz
MHz
µs
µs
ns
ns
ns
ns
ns
ns
ns
ns
SDO
CLKO
CLOAD
20pF
200µA
IOH
VDD/2
www.austriamicrosystems.com/LED-Driver-ICs
Revision 1.00
5 - 22
5 Page 
AS1122
Datasheet - Detailed Description
Register Access
Before data are accepted by the AS1122, an identifier needs to be send in advance. Only 3 defined identifiers will be recognized, all other bit
combinations will be ignored.
Table 6. Identifier
Identifier
Bit Data Section
76543210
length
Description
Dot Correction Data 1 1 0 0 1 / 0 0 0 1
72 bits
writes Data into Dot Correction Register
PWM Data
1 1 0 0 1/0 0 1 0
144 bits
writes Data into PWM Register
Command Data
1 1 0 0 1/0 1 0 0
8 bits
writes Data into Command Register
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.
Note: Bit3 of the identifier is an global on/off bit. When bit3 of any identifier is set to logic ‘0’ and the OEN bit of the command register (see
Figure 7 on page 14) is ‘0’ (per default), the output channels are immediately turned on.
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 send the whole dataword will be ignored.
Figure 25. Dot Correction Input Timing Diagram
For n devices in a chain only one identifier needs to be send to set all n devices to the same register setting.
Figure 26. Dot Correction for n-devices
www.austriamicrosystems.com/LED-Driver-ICs
Revision 1.00
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| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet AS1122.PDF ] | |
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