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AS1112
16-Channel LED Driver with Dot Correction and Greyscale PWM
D a ta s h e e t
1 General Description
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 AS1112 AS1112B Power-Down Yes No TEST pin Connect to GND Connect to VCC
2 Key Features
! ! ! ! ! ! ! ! ! ! !
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. The AS1112 is available in a 32-pin TQFN 5x5 mm package. Figure 1. Block Diagram
1 CLK 26 IREF 24 GSCLK 31 OEN Status Open LED Detect, Overtemperature Flag, Dot Correction Data 3
MODE
3 Applications
The device is ideal for mono-, multi-, and full-color LED displays, LED signboards, and display backlights.
2 SDI
32 LD
29 PD Control Greyscale 0 Register 11 12-Bit Greyscale PWM Control 6-Bit Dot Correction Constant Current Driver 4 Delay x0 OUT0
Max OUTn Current
VREF = 1.24V
Greyscale Counter
Control Input Shift Register
Dot Correction 0 Register 5
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 x1 OUT1
.
. .
Constant Current Driver 21 Delay x15 OUT15
.
Thermal Flag Open LED Detect
Open&Short LED Detection Control 12-Bit Greyscale PWM Control 6-Bit Dot Correction 23
27 VCC
. .
Input Shift Register Greyscale 180 Register191 Dot Correction 90 Register 95
22 XERR 30 GND
Open&Short LED Detection
AS1112
SDO
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AS1112
Datasheet - P i n o u t
4 Pinout
Pin Assignments
Figure 2. Pin Assignments (Top View)
XTEST 25 TEST 25 GND 30 GND 30 OEN 31 OEN 31 IREF 26 IREF 26 VCC 27 VCC 27 N/C 29 N/C 28 N/C 28
PD 29
LD 32
LD 32
CLK SDI MODE OUT0 OUT1 OUT2 OUT3 OUT4
1 2 3 4 5 6 7 8 10 OUT6 12 N/C 13 N/C 14 OUT8 11 OUT7 9 OUT5
24 GSCLK 23 SDO 22 XERR 21 OUT15 20 OUT14 19 OUT13 33 15 OUT9 16 OUT10 18 OUT12 17 OUT11
CLK SDI MODE OUT0 OUT1 OUT2 OUT3 OUT4
1 2 3 4 5 6 7 8 10 OUT6 12 N/C 13 N/C 14 OUT8 11 OUT7 9 33 15 OUT9 16 OUT10
24 GSCLK 23 SDO 22 XERR 21 OUT15 20 OUT14 19 OUT13 18 OUT12 17 OUT11
AS1112
Thermal Pad
AS1112B
Thermal Pad
OUT5
Pin Descriptions
Table 2. Pin Descriptions Pin Number 1 2 3 4:11 14:21 22 23 24 25 26 27 12,13,28 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. Revision 1.06 2 - 18 Pin Name CLK SDI Description
29
30 31
32 33
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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 Input Voltage Range to GND Output Current (DC) Input Voltage Range Output Voltage Range VSDO, VXERR to GND Output Voltage Range VOUT0: VOUT15 to GND ESD Rating Storage Temperature Range Operating Ambient Temperature Range 32-pin TQFN 5x5 mm Package Thermal Impedance -55 -40 -0.3 -0.3 -0.3 Min 0.3 Max 6 90 VCC + 0.3 VCC + 0.3 15 2 +150 +85 23 Units V mA V V V kV C C C/W on 4-Layer PCB 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). JEDEC 22-A114 Human Body Model Comments
Package Body Temperature
+260
C
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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 VCC VOUT VIH VIL IOH IOL ICOC Parameter Supply Voltage Voltage Applied to Output (OUT0:OUT15) High-Level Input Voltage Low-Level Input Voltage High-Level Output Current Low-Level Output Current Constant Output Current VCC = 5 V at SDO VCC = 5 V at SDO, XERR OUT0:OUT15 0.8 x VCC GND -1.0 1.0 80 Conditions Min 3 Typ Max 5.5 15 VCC 0.2 x VCC Unit V V V V mA mA mA
Table 5. AC Characteristics - VCC = 3 V to 5.5 V, TAMB = -40 to 85C (unless otherwise noted) Symbol fCLK fGSCLK tWH0/tWL0 tWH1/tWL1 tWH2 tWH3 tSU0 tSU1 tSU2 tSU3 tSU4 tH0 tH1 tH2 tH3 tH4 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. Hold Time Setup Time Parameter Data Shift Clock Frequency Greyscale Clock Frequency CLK Pulse Duration GSCLK Pulse Duration LD Pulse Duration OEN Pulse Duration Conditions CLK GSCLK CLK = 1/0
1 2
Min
Typ
Max 30 30
Unit MHz MHz ns ns ns ns
16 16 20
GSCLK = 1/0 LD = 1
1 2 3 3
OEN = 1 SDI, CLK CLK, LD
20 12 12
4
MODE, CLK MODE, LD
12 12
ns
4 2
OEN, GSCLK CLK, SDI LD, CLK
3 1
12 12 12
CLK, MODE LD, MODE
4
12 12
ns
4 2
OEN, GSCLK
12
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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 +85C. Typical values are at TAMB = 25C, VCC = 5V (unless otherwise specified). Table 6. Electrical Characteristics Symbol VOH VOL Parameter High-Level Output Voltage Low-Level Output Voltage Condition IOH = -1mA, SDO IOL = 1mA, SDO, XERR VIN = VCC or GND; Pins OEN, TEST, GSCLK, CLK, SDI, LD I Input Current VIN = VCC; pin MODE, PD VIN = GND; pin MODE, PD All outputs off, RIREF = 10k ICC Supply Current All outputs off, RIREF = 1.3k All outputs on, RIREF = 1.3k All outputs on, RIREF = 640 IPD ICOC ILEAK Power Down Current Constant Output Current Leakage Output Current All outputs on, VOUT = 2V, RIREF = 640 All outputs off, VOUT = 15V, RIREF = 640, OUT0:OUT15 VOUT = 2V, RIREF = 640, OUT0:OUT15 VOUT = 2V, RIREF = 480, OUT0:OUT15 ICOC Constant Current Error Device to device, average current from OUT0:OUT15, RIREF = 1920 (20 mA) Device to device, average current from OUT0:OUT15, RIREF = 480 (80 mA) ILNR VOUT = 2V, RIREF = 640 OUT0:OUT15 VOUT = 2V, RIREF = 480 OUT0:OUT15 VOUT = 2 to 4V, RIREF = 640, OUT0:OUT15 VOUT = 2 to 4V, RIREF = 480, OUT0:OUT15 Junction temperature Junction temperature VCC = 5V
1 1
Min VCC 0.5
Typ
Max
Unit V
0.5 -1 1 100 -1 1.2 4 15 30 40 54 61 20 3 3 3 4.5 4.5 4.5 69 1 3 10 20 40
V
A
mA
nA mA nA
%
3 1 1 0.1 0.1 150 125 3.6 0.3
4.5 2.5 %/V 2.5 0.5 %/V 0.5 C C V 0.4 1.28 V V
Line Regulation
ILDR
Load Regulation
TTEF TTWF VLSD VLOD VIREF
Thermal Error Flag Threshold Thermal Warn Flag Threshold LED Short Detection Threshold LED Open Detection Threshold Reference Voltage Output
RIREF = 640
1.20
1.24
1. Specified by design. Not tested.
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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 +85C. Typical values are at TAMB = 25C, VCC = 5V (unless otherwise specified). Table 7. Switching Characteristics Symbol tR0 tR1 tF0 tF1 tPD0 tPD1 Propagation Delay Time tPD2 tPD3 tD Average Output Delay Time Fall Time Rise Time Parameter Conditions SDO OUTn, DC = 3FHEX SOUT OUTn, DC = 3FHEX CLK, SDO
1 2
Min
Typ 8 20 8 20 15 30
Max
Unit ns
ns
OEN, OUT0
2
OUTn, XERR (includes error detection time, see Figure 8 on page 10) GSCLK, OUT0 OUTn, OUTn+1
2 2
ns 1000 30 30 ns
1. See Figure 12 on page 13. 2. See Figure 14 on page 14.
Dissipation Ratings
Table 8. Dissipation Ratings Package Type 32-pin TQFN 5x5 mm Power Rating (TAMB < 25C) 5433mW Derating Factor above 25C 43.47mW/C Power Rating (TAMB = 70C) 3477mW Power Rating (TAMB = 85C) 2825mW
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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 = 25C. Figure 3. Output Current vs. VDS;
90
RIREF = 480
Figure 4. Output Current vs. VDS;
90 80 70
RIREF = 480
80 70
IOUT (mA) .
50 40 30 20
IOUT (mA) .
60
RIREF = 1k
60 50 40 30 20
RIREF = 3.9k RIREF = 1k
RIREF = 3.9k
10 0 0 3 6 9 12 15
10 0 0 0.5 1 1.5
2
2.5
3
VDS (V)
VDS (V)
Figure 5. Output Current vs. REXT
100
Figure 6. Output Current vs. Dot Correction Value
90 80 70
RIREF = 480
IOUT (mA) .
IOUT (mA) .
60 50 40 30
RIREF = 1k
10
20 10 1 0 1 2 3 4 5 6 7 8 9 10 0 0 9 18 27 36 45 54 63
REXT (kOhm)
Dot Correction Value
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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 MODE tH3 LD tSU3 tH3 Greyscale Mode Data Input Cycle Dot Correction Mode Data Input Cycle
SDI
DCn-1 LSB
DCn MSB
DCn LSB tH2 tSU2
GSn MSB
GSn LSB
DCn+1 MSB tSU2
DCn-1 MSB-1
CLK
1
96
1
192
1
2
SDO
DCn-1 MSB
DCn-1 MSB-1
DCn-1 LSB
DCn MSB
X
X
SID MSB
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).
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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. TJ < TTEF Thermal OUTn Voltage Error Flag OUTn > VLOD OUTn < VLOD OUTn > VLOD TJ > TTEF TJ > TTEF TJ < TTEF TJ > TTWF TJ < TTWF OUTn < VLOD Don't Care Don't Care Don't Care Don't Care 0 0 1 1 0 1 Don't Care Don't Care Error Information Thermal Warning Open LED Detect Flag Don't Care Don't Care Don't Care Don't Care 0 1 0 1 Selected Mode Short LED Detect Don't Care Don't Care Don't Care Don't Care OEN Mode XERR 0 0 0 0 1 1 1 1 0 0 0 0 0 0 1 1 1 0 0 0 1 0 1 0 normal open error temp. error open & temp. error normal temp error normal temp. warn Status
O p e n T e m p
Don't Care Don't Care Don't Care Don't Care Don't Care Don't Care 0 1 Don't Care Don't Care Don't Care Don't Care
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 (150C 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 125C 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 1s 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 1s 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.
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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 >1s OEN
GSCLK
SID Error Detection Start
LODn, LSDn
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 0 1 OUT0:OUT15 Normal Operation 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 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. x 31.5 (EQ 1)
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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 0 1 Input Shift Register 192-bit 96-bit Operating Mode Greyscale PWM Mode 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 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 DCn 63 (EQ 3)
MSB 95 DC15.5 ... DC OUT15 90 DC15.0 89 DC14.5 ... DC OUT14:DC OUT1 6 DC1.0 5 DC0.5 ... DC OUT0
LSB 0 DC0.0
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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 VCC MODE
GND
Dot Correction Mode Data Input Cycle n +1
SDI
DCn-1 LSB
DCn MSB tSU0
DCn MSB-1 tWH0
DCn MSB-2
DCn LSB+1
DCn LSB
DCn+1 MSB
DCn+1 MSB-1
CLK
1
2 tWL0
1
95
96
1
2
SDO
DCn-1 MSB
DCn-1 MSB-1
DCn-1 MSB-2
DCn-1 LSB+1
DCn-1 LSB tSU1
DCn MSB tWH2 tH1
DCn MSB-1
DCn MSB-2
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
MSB 191 GS15.11 ... GS OUT15 180 GS15.0 179 GS14.11 ... GS OUT14:GS OUT1 12 GS1.0 11 GS0.11 ... GS OUT0 LSB 0 GS0.0
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.
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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
Dot Correction Mode Data Input Cycle 1st Greyscale Mode Data Input Cycle After Dot Correction Input Following Greyscale Mode Data Input Cycle
MODE
tH3 tSU3 LD tH3 SDI DCn-1 LSB tH2 tSU2 CLK 96 tH0 1 GSn MSB tSU1 GSn LSB GSn+1 MSB GSn+1 LSB
192
1
192
SDO
DCn-1 MSB-1
DCn-1 MSB
x
x
x
SIDn MSB
SIDn MSB-1
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 191 LOD15 ... Open LED Detect 176 LOD0 175 TEF 174 TWF ... 168 X 167 DC15. ... DC Values 72 DC0. 71 X ... 16:31 LOD LSB 0:15 LSD
Overtemperature
Bit # 0:15 16:31 32:71 72:167
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, 125C, typ) 175 Temperature Error Flag (TEF, 150C, 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).
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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 OEN tWH1 GSCLK tPD1 OUT0 Current tPD1 + tD OUT1 Current ... tPD1 + 15 x tD OUT15 Current tPD2 XERR ... ... ... 1 tPD3 n x tD 2 tW1 tPD3 tWL1 3 tH4 tWH3
4096
Greyscale PWM Cycle n+1 tSU4
tPD3
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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 ... OUT0 SIN SDI XERR XERR CLK CLK LD LD GSCLK GSCLK MODE MODE OEN SOUT Controller OEN IREF OEN IREF GND MODE GND VCC CLK SDO VCC XERR VCC LD GSCLK SDI SDO VCC OUT15 ... OUT0 VLED VLED ... OUT15 VLED
100k
AS1112
100nF TEST
AS1112
100nF TEST
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 Where: fGSCLK is the minimum frequency needed for GSCLK; fUPDATE is the update rate of whole cascaded system. fCLK = 193 x fUPDATE x n 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. (EQ 6) (EQ 5)
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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 A A1 b D E D1 E1 Notes:
Min 0.80
Common Dimensions Nom Max Symbol 1.00 0.203 REF 0.23 5.00 BSC 5.00 BSC 3.60 3.60 e L 0.30 L1 P aaa 3.70 3.70 ccc
Min
Nom 0.5 BSC 0.40 45 BSC 0.15 0.10
Max
0.30
0.50 0.10
0.18
3.50 3.50
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.
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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 AS1112-BQFT Description 16-Channel LED Driver with Dot Correction and Greyscale PWM with Active-High TEST Input and Power-Down Mode Delivery Form Tape and Reel Tape and Reel Package 32-pin TQFN 5x5 mm 32-pin TQFN 5x5 mm
Correction AS1112B-BQFT 16-Channel LED Driver with Dotand without and Greyscale PWM with Active-Low XTEST Input Power-Down Mode All devices are RoHS compliant and free of halogene substances.
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Revision 1.06
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AS1112
Datasheet
Copyrights
Copyright (c) 1997-2009, austriamicrosystems AG, Schloss Premstaetten, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered (R). 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
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Revision 1.06
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