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 Datas h eet A S 11 0 8 4- D i g i t L E D D i sp l a y D r i ve r 2 Key Features The device includes an integrated BCD code-B/HEX decoder, multiplex scan circuitry, segment and display drivers, and a 32-bit memory. Internal memory stores the LED settings, eliminating the need for continuous device reprogramming. Every segment can be individually addressed and updated separately. Only one external resistor (RSET) is required to set the current through the LED display. LED brightness can be controlled by analog or digital means. The device can be programmed to use the internal code-B/HEX decoder to display numeric digits or to directly address each segment. am lc s on A te G nt st il 10MHz SPI-, QSPI-, Microwire-Compatible Serial I/O Individual LED Segment Control Segment Blinking Control (can be synchronized across multiple drivers) Hexadecimal- or BCD-Code/No-Decode Digit Selection 3µA Low-Power Shutdown Current (typ; data retained) Extremely Low Operating Current 0.5mA in Open-Loop Digital and Analog Brightness Control Display Blanked on Power-Up Drive Common-Cathode LED Displays Supply Voltage Range: +2.7 to +5.5V Software Reset Optional External Clock SOIC 20-pin package al id The AS1108 is a compact display driver for 7-segment numeric displays of up to 4 digits. The device can be programmed via SPI, QSPI, and Microwire as well as a conventional 4-wire serial interface. lv 1 General Description The AS1108 features an extremely low shutdown current of typically 3µA, and an operational current of less than 500µA. The number of digits can be programmed, the device can be reset by software, and an external clock is also supported. Additionally, segment blinking can be synchronized across multiple drivers. 3 Applications The AS1108 provides several test modes for easy application debugging. The AS1108 is ideal for bar-graph displays, instrumentpanel meters, LED matrix displays, dot matrix displays, set-top boxes, white goods, professional audio equipment, medical equipment, industrial controllers and panel meters. The device is available in a SOIC 20-pin package. ni ca Figure 1. AS1108 - Typical Application Diagram VDD Te ch 9.53kΩ I/O I/O SCK Microprocessor +5V 4 Digits ISET DIG0 to DIG3 DIN LOAD/CSN AS1108 CLK 8 Segments SEG A to G SEP DP GND GND 4-Digit Microprocessor Display www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 1 - 20 AS1108 Datasheet - P i n o u t 4 Pinout Pin Assignments Figure 2. Pin Assignments (Top View) DIN 2 19 SEG DP DIG 0 3 18 SEG E GND 4 17 SEG C DIG 2 5 DIG 3 6 AS1108 15 ISET 14 SEG G 13 SEG B LOAD/CSN 9 12 SEG F am lc s on A te G nt st il GND 7 DIG 1 8 CLK 10 Pin Descriptions 16 VDD al id 20 SEG D lv DOUT 1 11 SEG A Table 1. Pin Descriptions Pin Number Pin Name 1 DOUT 2 DIN 3, 5, 6, 8 DIG 0:DIG 3 4, 7 GND 9 ca ni CLK ch 10 LOAD/CSN Description Serial-Data Output. The data into pin DIN is valid at pin DOUT 16.5 clock cycles later. This pin is used to daisy-chain several AS1108 devices and is never high-impedance. Serial-Data Input. Data is loaded into the internal 16-bit shift register on the rising edge of pin CLK. Digit Drive Lines. 4 four-digit drive lines that sink current from the display common cathode. The AS1108 pulls the digit outputs to VDD when turned off. Ground. Both GND pins must be connected. Load-Data Input. The last 16 bits of serial data are latched on the rising edge of this pin. Chip-Select Input (AS1108 SPI-enabled only). Serial data is loaded into the shift register while this pin is low. The last 16 bits of serial data are latched on the rising edge of this pin. Serial-Clock Input. 10MHz maximum rate. Data is shifted into the internal shift register on the rising edge of this pin. Data is clocked out of DOUT on the falling edge of this pin. On the AS1108 SPI-enabled, the CLK input is active only while pin LOAD/CSN is low. Seven Segment and Decimal Point Drive Lines. 8 seven-segment drives and decimal point drive that source current to the display. When a segment driver is turned off it is pulled to GND. Set Segment Current. Connect to VDD through RSET to set the peak segment current (see Selecting RSET Resistor Value and Using External Drivers on page 14). Positive Supply Voltage. Connect to +2.7 to +5.5V supply. SEG A:SEG G, SEG DP 15 ISET 16 VDD Te 11, 12, 13, 14, 17, 18, 19, 20 www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 2 - 20 AS1108 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 Section 6 Electrical Characteristics on page 4 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Min Max Units VDD to GND -0.3 7 V All other pins to GND -0.3 VDD + 0.3 (max 7V) V DIG 0:DIG 3 Sink Current 500 mA SEG A:SEG G, SEG DP 100 mA Electrical Parameters am lc s on A te G nt st il Current Latch-Up Immunity ±200 mA Digital outputs 1000 V All other pins 1000 V 941 mW +150 ºC Electrostatic Discharge Notes lv Parameter al id Table 2. Absolute Maximum Ratings All pins except AS1108 pin 11: ±180 mA Norm: JEDEC 78 Norm: MIL 883 E method 3015 Continuous Power Dissipation (TA = +85°C) Wide SOIC Derate 11.8mW/ºC above +70ºC Temperature Ranges and Storage Conditions Storage Temperature Range -55 Package Body Temperature (Wide SOIC) Humidity ºC 85 % Non-condensing 3 Represents a max. floor life time of 168h Te ch ni ca Moisture Sensitive Level 5 +260 The reflow peak soldering temperature (body temperature) specified is in accordance with IPC/ JEDEC J-STD-020 “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). www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 3 - 20 AS1108 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 5.5V, RSET = 9.53kΩ±1%, TAMB = TMIN to TMAX (unless otherwise specified). All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC (Statistical Qualification Control) methods. Table 3. Electrical Characteristics Symbol Conditions Typ TAMB Min 0 Operating Temperature Range Operating Supply Voltage VDD 2.7 5.0 Shutdown Supply Current IDDSD All digital inputs at VDD or GND, TAMB = +25ºC Operating Supply Current IDD All segments and decimal point on; ISEG = -40mA. Display Scan Rate fOSC 4 digits scanned 1000 Digit Drive Sink Current IDIGIT VOUT = 0.65V 320 Unit °C 5.5 V 10 µA 1 mA lv RSET = open circuit. Max +70 al id Parameter 330 1600 2600 am lc s on A te G nt st il Segment Drive Source Current ISEG Segment Drive Current Matching ∆ISEG VDD = 5.0V, VOUT = (VDD -1V) -30 Hz mA -40 -45 3.0 mA % Digit Drive Source Current IDIGIT Digit off, VDIGIT = (VDD - 0.3V) -2 mA Segment Drive Sink Current ISEG Segment off, VSEG = 0.3V 5 mA Slow Segment Blink Period (ON phase, Internal Oscillator) tSLOWBLINK 0.64 1 1.65 s Fast Segment Blink Period (ON phase, Internal Oscillator) tFASTBLINK 0.32 0.5 0.83 s 49.9 50 50.1 % Fast or Slow Segment Blink Duty Cycle (Guaranteed by design) Table 4. Logic Inputs/Outputs Characteristics Symbol IIH, IIL VIH Logic Low Input Voltage VIL ca Parameter Input Current DIN, CLK, LOAD/CSN Logic High Input Voltage ni Output High Voltage VOL ∆VI VDD = 5.0V ± 10% VDD = 3.0V ± 10% DOUT, ISOURCE = -1mA, VDD = 5.0V ± 10% DOUT, ISOURCE = -1mA, VDD = 3.0V ± 10% DOUT, ISINK = 1.6mA DIN, CLK, LOAD/CSN Min -1 0.7 x VDD Typ Max 1 0.8 0.6 Unit µA V V VDD - 1 V VDD - 0.5 0.4 1 V V Te ch Output Low Voltage Hysteresis Voltage VOH Conditions VIN = 0V or VDD www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 4 - 20 AS1108 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 Table 5. Timing Characteristics (see Figure 10 on page 8) Conditions Min 100 50 50 tCSS 25 tCSH tDS tDH tDO tLDCK tCSW tDSPD 0 25 0 CLOAD = 50pF Typ Max ns 25 ns ns ns ns ns ns ms lv 50 50 Unit ns ns ns al id Symbol tCP tCH tCL 2.25 Te ch ni ca am lc s on A te G nt st il Parameter CLK Clock Period CLK Pulse Width High CLK Pulse Width Low CSMFall-to-CLK Rise Setup Time (AS1108 SPI-programmed) CLK Rise-to -LOAD/CSN Rise Hold Time DIN Setup Time DIN Hold Time Output Data Propagation Delay LOAD Rising Edge-to-Next Clock Rising Edge Minimum LOAD/CSN Pulse High Data-to-Segment Delay www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 5 - 20 AS1108 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 VDD = 5V, RSET = 9.53kΩ, TAMB = 25ºC (unless otherwise specified). Figure 3. Scan Frequency vs.Temperature Figure 4. Scan Frequency vs. VDD 1980 1960 al id 1940 1960 1920 FOSC (Hz) 1920 1900 1880 1860 1900 lv FOSC (Hz) 1940 1840 1880 1820 1860 -20 am lc s on A te G nt st il 1800 -40 0 20 40 60 80 2 3 4 VDD (V) TAMB (°C) Figure 5. ISEG vs. Temperature 50 VDD = 5V, VOUT = 4V 35 40 30 25 ISEG (mA) ISEG (mA) 60 50 40 VDD = 2.7V, VOUT = 2V 20 VOUT = 1.7V 30 VOUT = 4V 20 15 VDD = 2.7V, VOUT = 2.4V 10 VOUT = 2.4V 10 5 0 0 -40 -20 0 20 40 60 2 80 2.5 3 3.5 ca Figure 7. ISEG vs. VOUT 40 20 ISEG (mA) ISEG (mA) Te 6 RSET = 10kΩ RSET = 20kΩ 20 15 RSET = 20kΩ 10 15 10 5.5 VDD = 2.7V 30 25 5 25 RSET = 10kΩ ch 35 4.5 Figure 8. ISEG vs. VOUT ni 50 4 VDD (V) TAMB (°C) 45 6 Figure 6. ISEG vs. VDD VDD = 5V, VOUT = 2.4V 45 5 RSET = 40kΩ 5 RSET = 40kΩ 5 0 0 0 0.5 1 1.5 2 2.5 3 3.5 VOUT (V) 4 4.5 www.austriamicrosystems.com/LED-Driver-ICs/AS1108 0 5 0.5 1 1.5 2 2.5 VOUT (V) Revision 2.13 6 - 20 AS1108 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 9. ISEG vs. RSET 60 VOUT = 2.4V 50 30 VOUT = 4V al id ISEG (mA) 40 VOUT = 2V 20 VDD = 5V 10 0 10 20 VDD = 2.7V 30 40 50 60 70 lv VOUT = 1.7V 0 80 Te ch ni ca am lc s on A te G nt st il RSET (k Ω) www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 7 - 20 AS1108 Datasheet - D e t a i l e d D e s c r i p t i o n 8 Detailed Description Serial-Addressing Format Programming the AS1108 is accomplished by writing to the device’s internal registers (see Digit- and Control-Registers on page 9) via the 4-wire serial interface. A programming sequence consists of 16-bit packages as depicted in Table 6. al id The data is shifted into the internal 16-bit register with the rising edge of the CLK signal. With the rising edge of the LOAD/CSN signal the data is latched into a digit- or control-register. The LOAD/CSN signal must go high after the 16th rising clock edge. The LOAD/CSN signal can also come later but this must happen just before the next rising edge of CLK, otherwise the data will be lost. The contents of the internal shift register are applied 16.5 clock cycles later to pin DOUT. The data is clocked out at the falling edge of CLK. lv The first 4 bits (D15:D12) are “don't care” settings, bits D11:D8 contain the register address, and bits D7:D0 contain the data. The first bit is D15, the most significant bit (MSB). The exact timing is shown in Figure 10. Table 6. 16-Bit Serial Data Format D14 X D13 X D12 X Initial Power-Up D11 D10 D9 D8 D7 Register Address (see Table 7) MSB D6 D5 D4 D3 Data D2 D1 am lc s on A te G nt st il D15 X D0 LSB On initial power-up, the AS1108 registers are reset to their default values, the display is blanked, and the device goes into shutdown mode. All registers should be programmed for normal operation at this time. Note: The default settings enable only scanning of one digit; the internal decoder is disabled and the Intensity Control Register (see page 12) is set to the minimum values. Figure 10. Interface Timing LOAD/ CSN tCSW tCSH tCP tCSS tCL CLK tLDCK tCH ca tDH tDS DIN D1 ni D14 D0 tDO Te ch DOUT D15 www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 8 - 20 AS1108 Datasheet - D e t a i l e d D e s c r i p t i o n Shutdown Mode The AS1108 features a shutdown mode, consuming only 10µA (max) current. Shutdown mode is entered via a write to the Shutdown Register (see Table 8). At that point, all segment current sources are pulled to ground and all digit drivers are connected to VDD, so that all segments are blanked. Note: During shutdown mode the Digit-Registers maintain their data. al id Shutdown mode can either be used as a means to reduce power consumption or for generating a flashing display (repeatedly entering and leaving shutdown mode). For minimum supply current in shutdown mode, logic input should be at GND or VDD (CMOS logic level). The device needs typically 250µs to exit shutdown mode, and during shutdown mode the AS1108 is fully programmable. Only the display test mode (see page 11) overrides shutdown mode. lv When entering or leaving shutdown mode, the Feature Register is reset to its default values (all 0s) when Shutdown Register bit D7 (page 10) = 0. When bit D7 = 1, the Feature Register is left unchanged when entering or leaving shutdown mode. am lc s on A te G nt st il Note: If the AS1108 is used with an external clock, Shutdown Register bit D7 should be set to 1 when writing to the Shutdown Register. Digit- and Control-Registers The AS1108 contains four Digit-Registers and six control-registers, which are listed in Table 7. All registers are selected using a 4-bit address word, and communication is done via the serial interface. Digit Registers – These registers are realized with an on-chip 32-bit memory. Each digit can be controlled directly without rewriting the whole register contents. Control Registers – These registers consist of decode mode, display intensity, number of scanned digits, shutdown, display test and features selection registers. Table 7. Register Address Map Register HEX Code No-Op Digit 0 Digit 1 Digit 2 Page D15:D12 D11 D10 D9 D8 0xX0 X 0 0 0 0 13 0xX1 X 0 0 0 1 N/A 0xX2 X 0 0 1 0 N/A 0xX3 X 0 0 1 1 N/A 0xX4 X 0 1 0 0 N/A 0xX9 X 1 0 0 1 10 Intensity Control 0xXA X 1 0 1 0 12 Scan Limit 0xXB X 1 0 1 1 12 Shutdown X 1 1 0 0 10 0xXD X 1 1 0 1 N/A Feature 0xXE X 1 1 1 0 13 0xXF X 1 1 1 1 11 ni 0xXC N/A ch Decode-Mode ca Digit 3 Address Te Display Test www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 9 - 20 AS1108 Datasheet - D e t a i l e d D e s c r i p t i o n Shutdown Register (0xXC) The Shutdown Register controls AS1108 shutdown mode (see Shutdown Mode on page 9). Table 8. Shutdown Register Format (Address (HEX) = 0xXC)) HEX Code Shutdown Mode, Reset Feature Register to Default Settings Shutdown Mode, Feature Register Unchanged Normal Operation, Reset Feature Register to Default Settings Normal Operation, Feature Register Unchanged Register Data D7 D6 D5 D4 D3 D2 D1 D0 0x00 0 X X X X X X 0 0x80 1 X X X X 0x01 0 X X X X 0x81 1 X X X X al id Mode X 0 X X 1 X X 1 lv Decode Enable Register (0xX9) X am lc s on A te G nt st il The Decode Enable Register sets the decode mode. BCD/HEX decoding (either BCD code – characters 0:9, E, H, L, P, and -, or HEX code – characters 0:9 and A:F) is selected by bit D2 (page 13) of the Feature Register. The Decode Enable Register is used to select the decode mode or no-decode for each digit. Each bit in the Decode Enable Register corresponds to its respective display digit (i.e., bit D0 corresponds to digit 0, bit D1 corresponds to digit 1 and so on). Table 10 lists some examples of the possible settings for the Decode Enable Register bits. Note: A logic high enables decoding and a logic low bypasses the decoder altogether. When decode mode is used, the decoder looks only at the lower-nibble (bits D3:D0) of the data in the Digit-Registers, disregarding bits D6:D4. Bit D7 sets the decimal point (SEG DP) independent of the decoder and is positive logic (bit D7 = 1 turns the decimal point on). Table 10 lists the code-B font; Table 11 lists the HEX font. When no-decode mode is selected, data bits D7:D0 of the Digit-Registers correspond to the segment lines of the AS1108. Table 12 shows the 1:1 pairing of each data bit and the appropriate segment line. Table 9. Decode Enable Register Format (Address (HEX) = 0xX9)) Decode Mode HEX Code No decode for digits 3:0 Code-B/HEX decode for digit 0. No decode for digits 3:1 Code-B/HEX decode for digits 3:0 0x00 0x01 0xFF D7 X X X D6 X X X Register Data D5 D4 D3 D2 X X 0 0 X X 0 0 X X 1 1 D1 0 0 1 D0 0 1 1 F 1 0 0 0 1 1 G 0 0 1 1 1 1 Figure 11. Standard 7-Segment LED Intensity Control and Inter-Digit Blanking ch ni ca A F B G C E D DP Table 10. Code-B Font Te 7-Segment Character 0 1 2 3 4 5 D7 † Register Data D6:D4 X X X X X X D3 0 0 0 0 0 0 www.austriamicrosystems.com/LED-Driver-ICs/AS1108 D2 0 0 0 0 1 1 On Segments = 1 D1 0 0 1 1 0 0 D0 0 1 0 1 0 1 Revision 2.13 DP † A 1 0 1 1 0 1 B 1 1 1 1 1 0 C 1 1 0 1 1 1 D 1 0 1 1 0 1 E 1 0 1 0 0 0 10 - 20 AS1108 Datasheet - D e t a i l e d D e s c r i p t i o n Table 10. Code-B Font (Continued) D7 6 7 8 9 E H L P Blank † D6:D4 X X X X X X X X X X D3 0 0 1 1 1 1 1 1 1 1 D2 1 1 0 0 0 0 1 1 1 1 On Segments = 1 D1 1 1 0 0 1 1 0 0 1 1 D0 0 1 0 1 0 1 0 1 0 1 DP † A 1 1 1 1 0 1 0 0 1 0 B 0 1 1 1 0 0 1 0 1 0 C 1 1 1 1 0 0 1 0 0 0 The decimal point is enabled by setting bit D7 = 1. 0 1 2 3 4 5 6 7 8 9 A b C d E F Register Data D7 † D6:D4 X X X X X X X X X X X X X X X X D3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 F 1 0 1 1 0 1 1 1 1 0 D2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 G 1 0 1 1 1 1 1 0 1 0 On Segments = 1 D1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 D0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 DP † A 1 0 1 1 0 1 1 1 1 1 1 0 1 0 1 1 B 1 1 1 1 1 0 0 1 1 1 1 0 0 1 0 0 C 1 1 0 1 1 1 1 1 1 1 1 1 0 1 0 0 D 1 0 1 1 0 1 1 0 1 1 0 1 1 1 1 0 E 1 0 1 0 0 0 1 0 1 0 1 1 1 1 1 1 F 1 0 0 0 1 1 1 0 1 1 1 1 1 0 1 1 G 0 0 1 1 1 1 1 0 1 1 1 1 0 1 1 1 The decimal point is enabled by setting bit D7 = 1. ca † E 1 0 1 0 0 1 1 1 1 0 am lc s on A te G nt st il Table 11. HEX Font 7-Segment Character D 1 0 1 1 0 1 0 1 0 0 al id Register Data † lv 7-Segment Character Table 12. No-Decode Mode Data Bits and Corresponding Segment Lines D7 DP ni Corresponding Segment Line D6 A D5 B D4 C D3 D D2 E D1 F D0 G ch Display-Test Register (0xXF) The AS1108 can operate in two modes: normal mode and display test mode. In display test mode all LEDs are switched on at maximum brightness (duty cycle is 15/16). The device remains in display-test mode until the DisplayTest Register is set for normal operation. Te Note: All settings of the Digit- and Control-Registers are maintained. Table 13. Display-Test Register Format (Address (HEX) = 0xXF)) Mode Normal Operation Display Test Mode www.austriamicrosystems.com/LED-Driver-ICs/AS1108 D7 X X D6 X X Revision 2.13 D5 X X Register Data D4 D3 X X X X D2 X X D1 X X D0 0 1 11 - 20 AS1108 Datasheet - D e t a i l e d D e s c r i p t i o n Intensity Control Register (0xXA) The brightness of the display can be controlled by digital means using the Intensity Control Register and by analog means using RSET (see Selecting RSET Resistor Value and Using External Drivers on page 14). Display brightness is controlled by an integrated pulse-width modulator which is controlled by the lower-nibble of the Intensity Control Register. The modulator scales the average segment-current in 16 steps from a maximum of 31/32 down to 1/32 of the peak current set by RSET. HEX Code D7 X X X X X X X X X X X X X X X X Register Data D4 D3 X 0 X 0 X 0 X 0 X 0 X 0 X 0 X 0 X 1 X 1 X 1 X 1 X 1 X 1 X 1 X 1 D5 X X X X X X X X X X X X X X X X D2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 D1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 am lc s on A te G nt st il 0xX0 0xX1 0xX2 0xX3 0xX4 0xX5 0xX6 0xX7 0xX8 0xX9 0xXA 0xXB 0xXC 0xXD 0xXE 0xXF D6 X X X X X X X X X X X X X X X X D0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 lv Duty Cycle AS1108 1/32 (min on) 3/32 5/32 7/32 9/32 11/32 13/32 15/32 17/32 19/32 21/32 23/32 25/32 27/32 29/32 31/32 (max on) al id Table 14. Intensity Register Format (Address (HEX) = 0xXA)) Scan-Limit Register (0x0B) The Scan-Limit Register controls which of the digits are to be displayed. When all 4 digits are to be displayed, the update frequency is typically 1600Hz. If the number of digits displayed is reduced, the update frequency is increased. The frequency can be calculated using 8fOSC/N, where N is the number of digits. Since the number of displayed digits influences the brightness, RSET should be adjusted accordingly. Table 16 lists the maximum allowed current when fewer than 4 digits are used. Note: To avoid differences in brightness this register should not be used to blank parts of the display (leading zeros). ca Table 15. Scan-Limit Register Format (Address (HEX) = 0xXB)) HEX Code Display digit 0 only (see Table 16) Display digits 0:1 (see Table 16) Display digits 0:2 (see Table 16) Display digits 0:3 0xX0 0xX1 0xX2 0xX3 ch ni Scan Limit D7 X X X X D6 X X X X D5 X X X X Register Data D4 D3 X X X X X X X X D2 0 0 0 0 D1 0 0 1 1 D0 0 1 0 1 Table 16. Maximum Segment Current for 1-, 2-, or 3-Digit Displays Te Number of Digits Displayed 1 2 3 www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Maximum Segment Current (mA) 10 20 30 Revision 2.13 12 - 20 AS1108 Datasheet - D e t a i l e d D e s c r i p t i o n Feature Register (0xXE) The Feature Register is used for switching the device into external clock mode, applying an external reset, selecting code-B or HEX decoding, enabling or disabling blinking, enabling or disabling the SPI-compatible interface, setting the blinking rate, and resetting the blink timing. Note: At power-up the Feature Register is initialized to 0. D7 D6 D5 D4 D3 D2 D1 blink_ start sync blink_ freq_sel blink_en spi_en decode_sel reg_res Table 18. Feature Register Bit Descriptions (Address (HEX) = 0xXE)) D3 D4 D5 D6 lv ch D7 am lc s on A te G nt st il D2 ca D1 clk_en ni D0 D0 Feature Register Enables and disables various device features. Bit Name Default Access Bit Description External clock select. clk_en 0 R/W 0 = Internal oscillator is used for system clock. 1 = Pin CLK of the serial interface operates as system clock input. Resets all control registers except the Feature Register. 0 = Reset Disabled. Normal operation. reg_res 0 R/W 1 = All control registers are reset to default state (except the Feature Register) identically after power-up. Note: The Digit Registers maintain their data. Selects display decoding. decode_sel 0 = Enable Code-B decoding (see Table 10 on page 10). 0 R/W 1 = Enable HEX decoding (see Table 11 on page 11). Enables the SPI-compatible interface. spi_en 0 R/W 0 = Disable SPI-compatible interface. 1 = Enable the SPI-compatible interface. Enables blinking. blink_en 0 = Disable blinking. 0 R/W 1 = Enable blinking. Sets blink with low frequency (with the internal oscillator enabled): blink_freq_sel 0 = Blink period typically is 1 second (0.5s on, 0.5s off). 0 R/W 1 = Blink period is 2 seconds (1s on, 1s off). Synchronizes blinking on the rising edge of pin LOAD/CSN. The multiplex and blink timing counter is cleared on the rising edge of pin sync 0 R/W LOAD/CSN. By setting this bit in multiple AS1108 devices, the blink timing can be synchronized across all the devices. Start Blinking with display enabled phase. When bit D4 (blink_en) is set, bit D7 determines how blinking starts. blink_start 0 R/W 0 = Blinking starts with the display turned off. 1 = Blinking starts with the display turned on. Addr: 0xXE Bit al id Table 17. Feature Register Summary No-Op Register (0xX0) Te The No-Op Register is used when multiple AS1108 devices are cascaded in order to support displays with more than 4 digits. The cascading must be done in such a way that all DOUT pins are connected to DIN of the next AS1108 (see Figure 12 on page 16). The LOAD/CSN and CLK signals are connected to all devices. For example, if five devices are cascaded, in order to perform a write operation to the fifth device, the write-command must be followed by four no-operation commands. When the LOAD/CSN signal goes high, all shift registers are latched. The first four devices will receive no-operation commands and only the fifth device will receive the intended operation command, and subsequently update its register. www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 13 - 20 AS1108 Datasheet - Ty p i c a l A p p l i c a t i o n 9 Typical Application Supply Bypassing and Wiring In order to achieve optimal performance the AS1108 should be placed very close to the LED display to minimize effects of electromagnetic interference and wiring inductance. al id Furthermore, a 10µF electrolytic and a 0.1µF ceramic capacitor should be connected between pins VDD and GND to avoid power supply ripple (see Figure 12 on page 16). Note: Both GND pins must be connected to ground. Selecting RSET Resistor Value and Using External Drivers lv Brightness of the display segments is controlled via RSET. The current that flows between VDD and ISET defines the current that flows through the LEDs. am lc s on A te G nt st il Segment current is about 200 times the current in ISET. Typical values for RSET for different segment currents, operating voltages, and LED voltage drop (VLED) are given in Tables 19 - 23. The maximum current the AS1108 can drive is 40mA. If higher currents are needed, external drivers must be used, in which case it is no longer necessary that the device drive high currents. In cases where the device drives only a few digits, Table 16 specifies the maximum currents, and RSET must be set accordingly. Note: The display brightness can also be logically controlled (see Selecting RSET Resistor Value and Using External Drivers on page 14). Table 19. RSET vs. Segment Current and LED Forward Voltage, VDD = 2.7V VLED(V) ISEG (mA) 1.5 5kΩ 6.9kΩ 10.7kΩ 22.2kΩ 40 30 20 10 2.0 4.4kΩ 5.9kΩ 9.6kΩ 20.7kΩ Table 20. RSET vs. Segment Current and LED Forward Voltage, VDD = 3.3V ISEG (mA) VLED(V) 2.0 6.4kΩ 8.8kΩ 13.3kΩ 27.7kΩ 1.5 6.7kΩ 9.1kΩ 13.9kΩ 28.8kΩ 2.5 5.7kΩ 8.1kΩ 12.6kΩ 26kΩ ni ca 40 30 20 10 Table 21. RSET vs. Segment Current and LED Forward Voltage, VDD = 3.6V 1.5 7.5kΩ 10.18kΩ 15.6kΩ 31.9kΩ ch ISEG (mA) Te 40 30 20 10 VLED(V) 2.0 7.2kΩ 9.8kΩ 15kΩ 31kΩ 2.5 6.6kΩ 9.2kΩ 14.3kΩ 29.5kΩ 3.0 5.5kΩ 7.5kΩ 13kΩ 27.3kΩ Table 22. RSET vs. Segment Current and LED Forward Voltage, VDD = 4.0V ISEG (mA) 40 30 1.5 8.6kΩ 11.6kΩ 2.0 8.3kΩ 11.2kΩ www.austriamicrosystems.com/LED-Driver-ICs/AS1108 VLED(V) 2.5 7.9kΩ 10.8kΩ Revision 2.13 3.0 7.6kΩ 9.9kΩ 3.5 5.2kΩ 7.8kΩ 14 - 20 AS1108 Datasheet - Ty p i c a l A p p l i c a t i o n Table 22. RSET vs. Segment Current and LED Forward Voltage, VDD = 4.0V (Continued) ISEG (mA) 1.5 17.7kΩ 36.89kΩ 20 10 2.0 17.3kΩ 35.7kΩ VLED(V) 2.5 16.6kΩ 34.5kΩ 3.0 15.6kΩ 32.5kΩ 3.5 13.6kΩ 29.1kΩ VLED (V) 1.5 11.35kΩ 15.4kΩ 23.6kΩ 48.9kΩ 40 30 20 10 2.0 11.12kΩ 15.1kΩ 23.1kΩ 47.8kΩ 2.5 10.84kΩ 14.7kΩ 22.6kΩ 46.9kΩ Table 24. Package Thermal Data 4.0 9.9kΩ 13.1kΩ 20.2kΩ 42kΩ Te ch ni ca 20 Wide SOIC Thermal Resistance (ΘJA) +85°C/W 3.5 10.2kΩ 13.6kΩ 21.1kΩ 43.8kΩ am lc s on A te G nt st il Package 3.0 10.49kΩ 14.4kΩ 22kΩ 45.4kΩ lv ISEG (mA) al id Table 23. RSET vs. Segment Current and LED Forward Voltage, VDD = 5.0V www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 15 - 20 AS1108 Datasheet - Ty p i c a l A p p l i c a t i o n 4x8 LED Dot Matrix Driver The application example in Figure 12 shows the AS1108 as a 4x8 LED dot matrix driver. The LED columns have common cathodes and are connected to the DIG0:3 outputs. The rows are connected to the segment drivers. Each of the 32 LEDs can be addressed separately. The columns are selected via the digits as listed in Table 7 on page 9. al id The Decode Enable Register (see page 10) must be set to ‘00000000’ as described in Table 9 on page 10. Single LEDs in a column can be addressed as described in Table 12 on page 11, where bit D0 corresponds to segment G and bit D7 corresponds to segment DP. Note: For a multiple-digit dot matrix, multiple AS1108 devices must be cascaded. Figure 12. Application Example as LED Dot Matrix Driver Diode Arrangement 4x8 LED Dot Matrix lv 4x8 LED Dot Matrix SEG G SEG F SEG E SEG D SEG C SEG B SEG A SEG DP SEG D SEG C SEG B SEG A SEG DP am lc s on A te G nt st il SEG G SEG F SEG E SEG A:G DIG0:3 SEG DP DOUT SEG A:G DIG0:3 SEG DP AS1108 VDD DIN MicroProcessor AS1108 VBAT 9.53kΩ LOAD/CSN CLK LOAD/CSN VBAT 9.53kΩ CLK ISET GND GND ISET GND ni ca GND VDD DIN Cascading Drivers ch If more than 4 digits or 32 LEDs are needed, it is recommended to use the AS1106/AS1107, although several AS1108 devices can be cascaded. Te The example in Figure 4 drives 2 dot matrix digits using a 4-wire microprocessor interface. All Scan-Limit Registers should be set to the same value so that one display will not appear brighter than the other. For example, to display 6 digits, set both Scan-Limit Registers to display 3 digits so that both displays have a 1/3 duty cycle per digit. If 5 digits are needed, set both Scan-Limit Registers to display 3 digits and leave one digit unconnected. Otherwise, if one driver is set to display 3 digits and the other to display 2 digits one display will appear brighter because its duty cycle per digit will be 1/2 and the other display’s duty cycle will be 1/3. Note: Refer to No-Op Register (0xX0) on page 13 for additional information. www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 16 - 20 AS1108 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 am lc s on A te G nt st il lv al id Figure 13. SOIC 20-pin Marking Table 25. Packaging Code YYWWRZZ YY WW manufacturing week Q ZZ plant identifier free choice / traceability code Te ch ni ca last two digits of the current year www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 17 - 20 AS1108 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 14. SOIC 20-pin Package www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 18 - 20 AS1108 Datasheet - O r d e r i n g I n f o r m a t i o n 11 Ordering Information The AS1108 is available as the standard products shown in Table 26. Table 26. Ordering Information Marking Description Temperature Range Delivery Form Package AS1108WL AS1108WL 4-Digit LED Display Driver 0 to +70ºC Tubes SOIC 20-pin AS1108WL-T AS1108WL 4-Digit LED Display Driver 0 to +70ºC Tape and Reel SOIC 20-pin al id Ordering Code lv 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 www.austriamicrosystems.com/LED-Driver-ICs/AS1108 Revision 2.13 19 - 20 AS1108 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 am lc s on A te G nt st il 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. ni ca 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 ch Headquarters 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/AS1108 Revision 2.13 20 - 20