austriamicrosystems AG is now ams AG The technical content of this austriamicrosystems datasheet is still valid. Contact information: Headquarters: ams AG Tobelbaderstrasse 30 8141 Unterpremstaetten, Austria Tel: +43 (0) 3136 500 0 e-Mail: [email protected] Please visit our website at www.ams.com Da ta s hee t A S11 22 1 2- C h a n n e l L E D D ri v er w it h D o t Co rr e c ti o n a n d G r ey s c a le P W M 2 Key Features 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. 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 am lc s on A te G nt st il 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. al id 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). lv 1 General Description A single external resistor sets the maximum current value of all 12 channels. The AS1122 is available in a 24-pin QFN 4x4mm package. 3 Applications The device is ideal for mono-, multi-, and full-color LED displays, LED signboards, and display backlights. Te ch ni ca Figure 1. AS1122 - Typical Application Diagram www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 1 - 22 AS1122 Datasheet - P i n o u t 4 Pinout Pin Assignments am lc s on A te G nt st il lv al id Figure 2. Pin Assignments (Top View) Pin Descriptions Table 1. Pin Descriptions Pin Name SDI CLKI CLKO SDO OUT0:OUT11 VDD IRQ 15 RST IREF GND NC Thermal Pad Te ch 18 3, 4, 17 25 ni 16 Description Serial Data Input Serial Data Clock Input Serial Data Clock Output Serial Data Output Constant-Current Outputs 0:11 Power Supply Voltage Interrupt Request Output. Open drain pin, can be left open if not used. 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. Reference Current Terminal. A resistor connected to this pin sets the maximum output currents (see Setting Maximum Channel Current on page 15). Ground Not Connected. Connect to GND if not used. Ground. This pin must be connected to GND to ensure normal operation. ca Pin Number 1 2 5 6 7:12, 19:24 13 14 www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 2 - 22 AS1122 Datasheet - A b s o l u t e M a x i m u m R a t i n g s 5 Absolute Maximum Ratings Stresses beyond those listed in Table 2 may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in Electrical Characteristics on page 4 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 2. Absolute Maximum Ratings Min Max Units Comments al id Parameter VCC to GND -0.3 5 V All other pins to GND -0.3 VDD + 0.3 V VSDO to GND -0.3 VDD + 0.3 V VOUT0 : VOUT11 to GND -0.3 30 V 50 mA -100 100 mA Output Current Electrostatic Discharge Electrostatic Discharge HBM Thermal Information Norm: JEDEC 78 am lc s on A te G nt st il Input Current (latch-up immunity) lv Electrical Parameters +/- 2 Junction to ambient thermal resistance kV Norm: MIL 883 E method 3015 37 °C/W For more information about thermal metrics, see application note AN01 Thermal Characteristics. +150 ºC +150 ºC Temperature Ranges and Storage Conditions Junction Temperature Storage Temperature Range -55 Package Body Temperature Humidity non-condensing 5 ºC 85 % 3 Represents a max. floor life time of 168h Te ch ni ca Moisture Sensitive Level +260 The reflow peak soldering temperature (body temperature) specified is in accordance with IPC/JEDEC J-STD020“Moisture/Reflow Sensitivity Classification for NonHermetic Solid State Surface Mount Devices”. The lead finish for Pb-free leaded packages is matte tin (100% Sn). www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 3 - 22 AS1122 Datasheet - E l e c t r i c a l C h a r a c t e r i s t i c s 6 Electrical Characteristics VDD = +2.7V to +3.6V, Typical values are at TAMB = +25°C, VDD = 3.3V (unless otherwise specified). All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality Control) methods. Table 3. Electrical Characteristics Parameter Condition Min TAMB Operating Temperature Range -40 TJ Operating Junction Temperature -40 VDD Supply Voltage 2.7 ICC Supply Current Typ Input Supply 9.5 All outputs on, RIREF = 10kΩ Power Down Current 4 RST = High, TAMB = +25°C °C +125 °C 3.6 V 12 6 Reference Current Resistor VOUT Voltage Applied to Output (OUT0:OUT11) ICOC Constant Output Current ∆ICOC 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 ±0.1 ±1.5 VOUT = 1V, RIREF = 10kΩ OUT0:OUT11 ±0.2 ±1.5 VOUT = 1V to 4V, RIREF = 1kΩ, OUT0:OUT11 ±0.1 ±0.4 VOUT = 1V to 4V, RIREF = 10kΩ, OUT0:OUT11 ±0.01 ±0.4 All outputs on, VOUT = 1V, RIREF = 1kΩ Constant Output Current Error ILEAK Leakage Output Current ∆ILNR Line Regulation ∆ILDR ca Load Regulation ni Logic Levels 38 % nA %/V %/V 0.8 x VDD VDD V Low-Level Input Voltage GND 0.2 x VDD V ch High-Level Input Voltage VOH High-Level Output Voltage VOL Low-Level Output Voltage VLOD LED Open Detection Threshold VIREF Reference Voltage Output Te mA nA am lc s on A te G nt st il RIREF VIL +85 40 Output VIH Unit lv IPD All outputs on, RIREF = 1kΩ Max al id Symbol www.austriamicrosystems.com/LED-Driver-ICs 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 Revision 1.00 1.24 4 - 22 AS1122 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 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 tR_OUT Rise Time OUT tF_OUT Fall Time OUT Min Max Unit 1 20 ns 1 20 ns Average Output Delay Time (can be turned off on request) 2 Typ 25 ns lv 1. Value can be factory trimmed for EMI improvement. 2. See Figure 24 on page 10. al id tD Conditions Interface Characteristics am lc s on A te G nt st il 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 fOSC fCLK tLOW Conditions Min Typ Max Unit Oscillator Frequency 8 10 12 MHz Data Shift Clock Frequency 1 5 MHz 1 µs 2.85 µs 1 CLK low time during data shift 1 CLK low time for data capture tCAPT tSETUP 2 2 tHOLD tPD_rising 2 2 SDI, CLKI 12 ns Hold Time SDI, CLKI 12 ns 3 rising CLKI to rising CLKO 2 3.5 8 ns 3 rising CLKI to falling CLKO 72 103.5 138 ns falling edge CLKO 0.8 1.5 3 ns 70 100 130 ns Delay CLKI to CLKO 2 Delay CLKO to SDO tPD_SDO 2 3 3 High Time of CLKO ca tH_CLKO tR_CLK Rise Time CLK 3 CLOAD = 20pF 10 ns 3 CLOAD = 20pF 10 ns Rise Time Data ni tR_DATA 1.8 Setup Time Delay CLKI to CLKO tPD_falling 1.5 ch 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. Te Figure 3. Load Circuit for Digital Output Timing Specifications 200µA IOL SDO CLKO VDD/2 CLOAD 20pF 200µA IOH www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 5 - 22 AS112 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 7 Typical Operating Characteristics TAMB = +25°C, VDD = 3.0V, VOUT = 1.0V (unless otherwise specified) Figure 4. Constant Output Current vs. Output Voltage Figure 5. Constant Output Current vs. Output Voltage 50 50 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 lv Constant Output Current (mA) 35 al id 45 Icoc = 40mA (1kΩ) 40 15 Icoc = 8mA (4.7kΩ) 10 Icoc = 4mA (10kΩ) 5 am lc s on A te G nt st il Constant Output Current (mA) 45 0 0 1 2 3 4 5 6 7 8 9 10 0 0.25 0.5 Output Voltage (V) Figure 6. Constant Output Current vs. VOUT; REXT = 1kΩ 50 1.25 1.5 1.75 2 Figure 7. Constant Output Current vs. VOUT; REXT = 1kΩ 45 40 35 30 25 20 15 Constant Output Current (mA) Constant Output Current (mA) 1 50 45 -40°C 10 +25°C 5 +85°C 0 40 35 30 25 20 15 -40°C 10 +25°C 5 +85°C 0 1 2 3 4 5 6 7 8 9 ca 0 10 0 0.25 0.5 Output Voltage (V) Constant Output Current (mA) 40.5 Te 40.25 40 39.75 39.5 -40°C +25°C 39.25 1.25 1.5 1.75 2 4.1 ch 40.75 1 Figure 9. ICOC vs. Supply Voltage; REXT = 10kΩ ni 41 0.75 Output Voltage (V) Figure 8. ICOC vs. Supply Voltage; REXT = 1kΩ Constant Output Current (mA) 0.75 Output Voltage (V) +85°C 39 4.06 4.02 3.98 -40°C 3.94 +25°C +85°C 3.9 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 Supply Voltage (V) www.austriamicrosystems.com/LED-Driver-ICs 2.7 2.8 2.9 3 3.1 3.2 3.3 3.4 3.5 3.6 Supply Voltage (V) Revision 1.00 6 - 22 AS112 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 Figure 11. ICOC vs. Temperature; REXT = 10kΩ 42 4.2 41.5 4.15 40.5 40 39.5 39 Vdd = 2.7V Vdd = 3.0V 38.5 Vdd = 3.6V 38 4.1 4.05 4 al id 41 3.95 3.9 Vdd = 2.7V Vdd = 3.0V 3.85 Vdd = 3.6V 3.8 -40 -15 10 35 60 85 -40 -15 Figure 12. ICOC vs. REXT 30 25 20 15 10 5 0 35 30 25 20 15 10 5 2 4 6 8 10 0 9 18 ni ch Constant Output Current (mA) 25 Te 20 15 10 5 0 36 45 54 63 Figure 15. ICOC vs. PWM; REXT = 1kΩ 0.4 Constant Output Current (mA) ca Figure 14. ICOC vs. PWM; REXT = 1kΩ 27 Dot Correction RIREF (kOhm) 30 85 0 0 35 60 40 35 40 35 Figure 13. ICOC vs. Dot Correction; REXT = 1kΩ Constant Output Current (mA) Constant Output Current (mA) 40 10 Ambient Temperature(ΣC) am lc s on A te G nt st il Ambient Temperature(ΣC) lv Constant Output Current (mA) Constant Output Current (mA) Figure 10. ICOC vs. Temperature; REXT = 1kΩ 0.3 0.2 0.1 0 0 500 1000 1500 2000 2500 3000 3500 4000 0 PWM (#) www.austriamicrosystems.com/LED-Driver-ICs 2 4 6 8 10 12 14 16 18 20 PWM (#) Revision 1.00 7 - 22 AS112 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 Figure 16. ∆ICOC vs. Constant Output Voltage; REXT = 1kΩ Figure 17. ∆ICOC vs. Constant Output Voltage; REXT = 10kΩ 2 0.5 0.25 -40°C +25°C +85°C 0 1.5 1.25 1 al id 0.75 1.75 0.75 0.5 -40°C +25°C 0.25 +85°C lv Constant Output Current Error (%) Constant Output Current Error (%) 1 0 0.5 1 1.5 2 2.5 3 3.5 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) am lc s on A te G nt st il Output Voltage (V) Figure 18. ∆ICOC vs. Temperature; REXT = 1kΩ 2 0.75 0.5 0.25 Constant Output Current Error (%) Constant Output Current Error (%) 1 Figure 19. ∆ICOC vs. Temperature; REXT = 10kΩ Vdd = 2.7V Vdd = 3.0V Vdd = 3.6V 0 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 85 -40 Figure 20. Supply Current vs. Temperature; REXT = 1kΩ 10.5 Supply Current (mA) Supply Current (mA) Te 85 5 9 8.5 Vdd = 2.7V Vdd = 3.0V 7.5 60 5.5 9.5 8 35 6 ch 10 10 Figure 21. Supply Current vs. Temperature; REXT = 10kΩ ni 11 -15 Ambient Temperature (ΣC) ca Ambient Temperature (ΣC) 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 85 www.austriamicrosystems.com/LED-Driver-ICs -40 -15 10 35 60 85 Ambient Temperature (°C) Ambient Temperature (ΣC) Revision 1.00 8 - 22 AS112 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 Figure 23. ∆ICOC Matching vs. Dot Correction; REXT = 1kΩ Figure 22. LED Open Detection Threshold vs. Temperature 2 1.75 0.5 1.5 0.3 0.2 Vdd = 2.7V 0.1 Vdd = 3.0V 1.25 1 al id 0.4 ICOC Matching (%) 0.75 0.5 0.25 Vdd = 3.6V 0 0 -40 -15 10 35 60 85 0 9 18 27 36 45 54 63 Dot Correction Te ch ni ca am lc s on A te G nt st il Ambient Temperature(°C) lv LED Open Detection Threshold (V) 0.6 www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 9 - 22 AS1122 Datasheet - D e t a i l e d D e s c r i p t i o n 8 Detailed Description 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. al id 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 (see Figure 24). The internal LD signal is triggered after the clk is low for a time tCAPT 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. lv 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. Te ch ni ca am lc s on A te G nt st il Figure 24. PWM Cycle Timing Diagram www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 10 - 22 AS1122 Datasheet - D e t a i l e d D e s c r i p t i o n 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 Bit 7 6 5 4 3 2 1 0 Data Section length 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 Description al id Identifier am lc s on A te G nt st il lv 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. ca Figure 25. Dot Correction Input Timing Diagram ni For n devices in a chain only one identifier needs to be send to set all n devices to the same register setting. Te ch Figure 26. Dot Correction for n-devices www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 11 - 22 AS1122 Datasheet - D e t a i l e d D e s c r i p t i o n PWM Data 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 send the whole dataword will be ignored. am lc s on A te G nt st il lv al id Figure 27. PWM 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 28. PWM Data for n-devices 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 send the whole dataword will be ignored. Te ch ni ca Figure 29. Command Input Timing Diagram www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 12 - 22 AS1122 Datasheet - D e t a i l e d D e s c r i p t i o n For n devices in a chain only one identifier needs to be send to set all n devices to the same register setting. al id Figure 30. Command Data for n-devices lv 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). am lc s on A te G nt st il 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 (IMAX). The output current for each OUTn channel can be calculated as: IOUTn = IMAX x Where: DCn 63 (EQ 1) 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 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 (see Figure 31) and 8-bit for the identifier. Channel data is put on one by one, and the data is clocked in with the MSB first. ca Figure 31. Dot Correction Data Packet Format ni The Dot Correction data is only valid if the exact identifier byte was send. Otherwise the data will be ignored. Setting Greyscale Brightness (PWM) Te ch 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 2) Where: GSn is the programmed greyscale value for OUTn (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. www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 13 - 22 AS1122 Datasheet - D e t a i l e d D e s c r i p t i o n 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 (see Figure 32) plus the 8-bit for the identifier. al id Figure 32. PWM Data Packet Format The PWM data is only valid if the exact identifier byte was send. Otherwise the data will be ignored. lv 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. Bit Bit Name am lc s on A te G nt st il Table 7. Command Register Format 7:5 - 4 Read SID 3 OPEN Test 2 Over Temperature Power down 1 Display One Time 0 OEN Default Access Bit Description 000 n/a 0 W 0: normal operation 1: read Status Information Register (SID) 0 W 0: no test is running 1: start OPEN test 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. 0 W 0: The PWM is running endless 1: The PWM is running for one cycle 0 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 The complete status information data packet is shown in Figure 33. Te ch ni ca Figure 33. Command Packet Format www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 14 - 22 AS1122 Datasheet - D e t a i l e d D e s c r i p t i o n 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. al id 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. The complete status information data packet is shown in Figure 34. lv Figure 34. Status Information Data Packet Format am lc s on A te G nt st il Note: 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. 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 lachted 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 need information. Figure 35. Reading of the Status Information Register ca Setting Maximum Channel Current IMAX = VIREF x 31.5 (EQ 3) RIREF ch ni 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 (1.27V 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: Where: Te VIREF = 1.27V; RIREF = User-selected external resistor. www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 15 - 22 AS1122 Datasheet - D e t a i l e d D e s c r i p t i o n Timing for Cascading of n-devices With the rising edge of CLKI the data will 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%. am lc s on A te G nt st il lv al id Figure 36. Clock Handling with 5MHz Data-Clock Te ch ni ca Figure 37. Clock Handling with 2MHz Data-Clock www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 16 - 22 AS1122 Datasheet - D e t a i l e d D e s c r i p t i o n Scrambled PWM General Due to the possibility to interrupt a running PWM cycle the AS1122 is useing a scrambled PWM. The advantage is, that 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 (see Figure 38). al id 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. Te ch ni ca am lc s on A te G nt st il lv Figure 38. Classic PWM vs. scrambled PWM www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 17 - 22 AS1122 Datasheet - D e t a i l e d D e s c r i p t i o n PWM scheme of AS1122 The AS1122 uses a scrambled PWM scheme. Meaning the PWM value is divide into sup-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 shows some examples how different PWM settings are distributed over one PWM cycle. am lc s on A te G nt st il lv al id Figure 39. Different PWM Outputs of AS1122 Te ch ni ca The PWM clock is generated internally and is running with fOSZ (10MHz typ.). For a PWM value of 20 the OUT channel is high for 20 PWM-clock pulses (20 x 100ns) and stays then low for 4076 PWM-clock pulses (4076 x 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. www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 18 - 22 AS1122 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 9 Package Drawings and Markings am lc s on A te G nt st il lv al id Figure 40. 24-pin QFN 4x4mm Marking Table 8. Packaging Code YYWWXZZ YY WW X ZZ manufacturing week plant identifier free choice / traceability code Te ch ni ca last two digits of the current year www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 19 - 22 AS1122 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 Te ch ni ca am lc s on A te G nt st il lv al id Figure 41. 24-pin QFN 4x4mm Package www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 20 - 22 AS1122 Datasheet - O r d e r i n g I n f o r m a t i o n 10 Ordering Information The device is available as the standard products shown in Table 9. Table 9. Ordering Information Description Delivery Form Package AS1122-BQFT AS1122 12-Channel LED Driver with Dot Correction and Greyscale PWM Tape and Reel 24-pin QFN 4x4mm AS1122B-BQFT* AS1122B 12-Channel LED Driver with Dot Correction and Greyscale PWM without Output Delay Tape and Reel 24-pin QFN 4x4mm *) on request Note: All products are RoHS compliant and austriamicrosystems green. Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect Technical Support is found at http://www.austriamicrosystems.com/Technical-Support Te ch ni ca am lc s on A te G nt st il For further information and requests, please contact us mailto:[email protected] or find your local distributor at http://www.austriamicrosystems.com/distributor al id Marking lv Ordering Code www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 21 - 22 AS1122 Datasheet Copyrights Copyright © 1997-2012, austriamicrosystems AG, Tobelbaderstrasse 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. All products and companies mentioned are trademarks or registered trademarks of their respective companies. al id Disclaimer lv 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. ca am lc s on A te G nt st il 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. Headquarters ni Contact Information ch austriamicrosystems AG Tobelbaderstrasse 30 A-8141 Unterpremstaetten, Austria Te 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 www.austriamicrosystems.com/LED-Driver-ICs Revision 1.00 22 - 22