LD1970 16 Segment x 12 Grid VFD Driver with Key Scan LD1970 16 SEGMENT X 12 GRID VFD DRIVER with KEYSCAN Ver. 4.0 / Dec. 2012 This document is a general product description and is subject to change without notice. LDT Inc. does NOT assume any responsibility for use of circuits described. 1 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Description LD1970 is a Vacuum Fluorescent Display (VFD) Controller driven on a 1/4 to 1/12 duty factor. 16 segment output lines, 4 grid output lines, 8 segment/grid output drive lines, one display memory, control circuit and key scan circuit are all incorporated into a single chip to build a highly reliable peripheral device for a single chip micro computer. Serial data is fed to LD1970 via a three-line serial interface. It is housed in a 48QFN, 44LQFP & 44MQFP package. Device name Package Type LD1970 48 QFN, 44LQFP, 44MQFP Features CMOS Technology Low Power Consumption Key Scanning (16X2) Matrix Multiple Display Modes (16 segments, 12 digits to 24 segments, 4 digits) 8-Step Dimming Circuitry LED Ports Provide (4 channels, 20mA max.) Serial Interface for Clock, Data Input, Data Output, Strobe Pins No External Resistors Needed for Driver Outputs Available in 48 QFN , 44LQFP, 44MQFP Device name LD1970 Package Type 48 QFN (include 4NC), 44LQFP, 44MQFP Power / Ground VDD1, VDD2, VEE / VSS(2) DI / DO / AIO DI:3 EA, DO:1EA, AIO:1EA FIP Output 34 EA (LED1~4, K1,K2,SG1~24, GR1~4) Applications Microcomputer Peripheral Devices Digital Audio/Video System : CD/MD/VCD/DVD players Car Audio VCR Electric scale meter P.O.S Electronic equipment with instructional display ORDERING INFORMATION Device name Segment Grid Key Scanning PKG Type LD1970-QFN 16~ 24 Segment 12~4Grid 16X2 matrix 48QFN LD1970-LQFP 16~24 Segment 12~4Grid 16X2 matrix 44LQFP LD1970-MQFP 16~24 Segment 12~4Grid 16X2 matrix 44MQFP 2 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Pin Description Pin No. Pin name Type Description QFN LQFP,MQFP 1~4 1~4 Oscillator I/O Pin A resistor is connected to this pin to determine the oscillation frequency. 5 5 LED1 ~ LED4 O OSC I/O DOUT O Data Output Pin (N-Channel, Open-Drain) This pin outputs serial data at the falling edge of the shift clock (starting from the lower bit) 7 6 DIN (Schmitt Trigger) I Data Input Pin This pin inputs serial data at the rising edge of the shift clock (starting from the lower bit) 8 7 CLK (Schmitt Trigger) I Clock Input Pin This pin reads serial data at the rising edge and outputs data at the falling edge of the shift clock 9 8 STB (Schmitt Trigger) I Serial Interface Strobe Pin The data input after the STB has fallen is processed as a command. When this pin is “HIGH”, CLK is ignored. 10 9 K1, K2 I Key Data Input Pins The data inputted to these pins is latched at the end of the display cycle. 11,12 10,11 VSS G Logic Ground Pin 13,48 12,44 VDD1, VDD2 P(+) Logic Positive Power Pin 47,14 43, 13 SG1/KS1 ~ SG16/KS16 O High-Voltage Segment Output Pins, Also acts as the Key Source. 15~32 14~29 VEE P(-) 33 30 SG17/GR12 ~ SG24/GR5 O High-Voltage Segment/Grid Output Pins 34~41 31~38 GR1~GR4 O High-Voltage Grid Output Pins 43~46 39~42 LED Output Pin Pull-Down Level / Negative Power Pin 3 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan LED Driver DIN CLK STB DOUT K1 K2 OSC SG24/GR5 SG23/GR6 SG22/GR7 SG21/GR8 Segment Driver Grid Driver Key Scan Output Control VDD2 VSS VEE OSC Grid Driver POR SG20/GR9 SG19/GR10 SG18/GR11 SG17/GR12 SG16/KS16 SG15/KS15 SG14/KS14 SG13/KS13 SG12/KS12 SG11/KS11 SG10/KS10 SG9/KS9 SG8/KS8 SG7/KS7 SG6/KS6 SG5/KS5 SG1/KS1 SG2/KS2 SG3/KS3 SG4/KS4 LED1 LED2 LED3 LED4 GR1 GR2 GR3 GR4 VDD1 Block Diagram 4 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan GR2 GR3 GR4 NC SG24/GR5 SG23/GR6 SG22/GR7 SG21/GR8 SG20/GR9 44 43 42 41 40 39 38 37 SG17/GR12 4 33 VEE OSC 5 32 SG16/KS16 NC 6 31 SG15/KS15 DOUT 7 30 NC DIN 8 29 SG14/KS14 CLK 9 28 SG13/KS13 STB 10 27 SG12/KS12 K1 11 26 SG11/KS11 K2 12 25 SG10/KS10 LD1970 [ 48 QFN] 15 16 17 18 19 20 21 22 23 24 SG2/KS2 SG3/KS3 NC SG4/KS4 SG5/KS5 SG6/KS6 SG7/KS7 SG8/KS8 SG9/KS9 LED4 45 34 SG1/KS1 3 GR1 SG18/GR11 Logic Power LED3 46 35 14 2 VDD1 SG19/GR10 VDD2 LED2 47 36 13 1 VSS LED1 Grid Power 48 VSS Pin Configuration 48 QFN 5 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan VDD1 Pin Configuration 44 LQFP & 44MQFP VDD2 LD1970 [44LQFP/44MQFP] 6 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan I/O Pins Schematic Diagram VDD Input pins: CLK, STB, DIN VDD Input pins: K1, K2 VDD Output pin: DOUT VDD Output pins: SGn, GRn VEE VDD Output pins: LED1~LED4 7 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Absolute Maximum Ratings (Unless otherwise stated, Ta=25°C, GND=0V) Parameters Symbol Ratings Unit Logic Supply Voltage VDD -0.3 ~ +7.0 V Driver Supply Voltage VEE VDD+0.3 ~ VDD-40 V Logic Input Voltage VI -0.3 ~ VDD+0.3 V VFD Driver Output Voltage VO VEE-0.3 ~ VDD+0.3 V LED Driver Output Current IOLED ± 20 mA VFD Drive Output Current IOVFD -40 @ Grid, -15 @ Segment mA Operating Temperature Topr -40 ~ 85 °C Storage Temperature Tstg -65 ~ 150 °C Recommended Operating Range (Unless otherwise stated, Ta=25°C, GND=0V) Ratings Parameters Symbol Unit Min. Typ. Max. Logic Supply Voltage VDD 3.0 5.0 5.5 V High-Level Input Voltage VIH 0.7*VDD - VDD V Low-Level Input Voltage VIL 0 - 0.3*VDD V Driver Supply Voltage VEE VDD-35 - 0 V 8 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Electrical Characteristics (Unless otherwise stated, VDD=5.0V, GND=0V, VEE=VDD-35V, Ta=25°C) Parameters Symbol Test Conditions Min. Typ. Max. Unit High-Level Output Voltage VOHLED IOHLED=-12mA LED1 ~ LED4 VDD-1 - - V Low-Level Output Voltage VOLLED IOHLED=+15mA LED1 ~ LED4 - - 1 V Low-Level Output Voltage VOLDOUT IOLDOUT=4mA DOUT - - 0.4 V High-Level Output Current IOHSG VO=VDD-2V SG1/KS1~SG16/KS16 -3 - - mA High-Level Output Current IOHGR VO=VDD-2V GR1~GR4 SG17/GR12~SG24/GR5 -15 - - mA Oscillation Frequency fOSC R=82KΩ 350 500 650 KHz Schmitt-Trigger Transfer Voltage(+) VT+ VDD=5V DIN, CLK, STB 2.7 3.0 3.3 V Schmitt-Trigger Transfer Voltage(-) VT- VDD=5V DIN, CLK, STB 0.7 1.0 1.3 V Hysteresis Voltage Vhys VDD=5V DIN, CLK, STB 1.4 2.0 - V Input Current II VI=VDD or VSS - - ±1 uA Dynamic Current Consumption IDDdyn Under no load Display Off - - 5 mA 9 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Electrical Characteristics (Unless otherwise stated, VDD=3.3V, GND=0V, VEE=VDD-35V, Ta=25°C) Parameters Symbol Test Conditions Min. Typ. Max. Unit High-Level Output Voltage VOHLED IOHLED=-6mA LED1 ~ LED4 VDD-1 - - V Low-Level Output Voltage VOLLED IOHLED=+15mA LED1 ~ LED4 - - 1 V Low-Level Output Voltage VOLDOUT IOLDOUT=4mA DOUT - - 0.4 V High-Level Output Current IOHSG VO=VDD-2V SG1/KS1~SG16/KS16 -1.5 - - mA High-Level Output Current IOHGR VO=VDD-2V GR1~GR4 SG17/GR12~SG24/GR5 -6 - - mA Oscillation Frequency fOSC R=82KΩ 350 500 650 KHz Schmitt-Trigger Transfer Voltage(+) VT+ VDD=3.3V DIN, CLK, STB 1.8 2.0 2.2 V Schmitt-Trigger Transfer Voltage(-) VT- VDD=3.3V DIN, CLK, STB 0.2 0.4 0.6 V Hysteresis Voltage Vhys VDD=3.3V DIN, CLK, STB 1.0 1.6 - V Input Current II VI=VDD or VSS - - ±1 uA Dynamic Current Consumption IDDdyn Under no load Display Off - - 3 mA 10 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Switching Characteristic Waveform fOSC Internal OSC PWSTB STB PWCLK PWCLK tsetup thold tCLK-STB CLK DIN tPLZ tPZL DOUT tTHZ tTZH2 90% GRn 10% tTHZ tTZH1 90% SEGn 10% fOSC = Oscillation Frequency PW STB (Strobe Pulse Width) ≥ 1us PW CLK (Clock Pulse Width) ≥ 400ns tCLK-STB (Clock-Strobe Time) ≥ 1us tsetup (Data Setup Time) ≥ 100ns thold (Data Hold Time) ≥ 100ns tPZL (Propagation Delay Time) ≤ 100ns tPLZ (Propagation Delay Time) ≤ 400ns tTHZ (Grid Fall Time) ≤ 150us tTHZ (Segment Fall Time) ≤ 150us tTZH1 (Segment Rise Time) < 2.0us(VDD=5.0V) tTZH2 (Grid Rise Time) ≤ 0.5us(VDD=5.0V) tTZH1 (Segment Rise Time) < 4.0us(VDD=3.3V) tTZH2 (Grid Rise Time) ≤ 1.2us(VDD=3.3V) 11 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Functional Description Commands Commands determine the display mode and status of LD1970. A command is the first byte (b0 to b7) inputted to LD1970 via the DIN pin after STB pin has changed from “High” to “Low” state. If for some reason the STB pin is set to “High” while data or commands are being transmitted, the serial communication is initialized, and the data/commands being transmitted are considered invalid. Command 1 : Display Mode Setting command LD1970 provides 8 display mode settings as shown in the diagram below : As stated earlier a command is the first one byte(b0 to b7) transmitted to LD1970 via the DIN pin when STB pin is “Low”. However, for this command, the bits 5 to 6 (b4 to b5) are ignored, bits 7 & 8 (b6 to b7) are given a value of “0”. The Display Mode Setting command determines the number of segments and grids to be used(1/4 to 1/12 duty, 16 to 24 segments). When this command is executed, the display is forcibly turned off, the key scanning stops. A display command “ON” must be executed in order to resume display. If the same mode setting is selected, no command execution is taken place, therefore nothing happens. When Power is turned “ON”, the 12-grid, 16-segment mode is selected. MSB 0 LSB 0 00 : Command1 - Don’t Care - b3 b2 b1 b0 Display Mode Settings 0000 : 4Grid, 24Segment 0001 : 5Grid, 23Segment 0010 : 6Grid, 22Segment 0011 : 7Grid, 21Segment 0100 : 8Grid, 20Segment 0101 : 9Grid, 19Segment 0110 : 10Grid, 18Segment 0111 : 11Grid, 17Segment 1XXX : 12Grid, 16Segment 12 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Display Mode and Memory Address Data transmitted from an external device to LD1970 via the serial interface are stored in the Display Memory and are assigned addresses. The Memory Addresses of LD1970 are given below in the 8bits unit. SG1 SG4 SG5 SG8 SG9 SG12 SG13 SG16 SG17 SG20 SG21 SG24 00HL 00HH 01HL 01HH 02HL 02HH Grid1 03HL 03HH 04HL 04HH 05HL 05HH Grid2 06HL 06HH 07HL 07HH 08HL 08HH Grid3 09HL 09HH 0AHL 0AHH 0BHL 0BHH Grid4 0CHL 0CHH 0DHL 0DHH 0EHL 0EHH Grid5 0FHL 0FHH 10HL 10HH 11HL 11HH Grid6 12HL 12HH 13HL 13HH 14HL 14HH Grid7 15HL 15HH 16HL 16HH 17HL 17HH Grid8 18HL 18HH 19HL 19HH 1AHL 1AHH Grid9 1BHL 1BHH 1CHL 1CHH 1DHL 1DHH Grid10 1EHL 1EHH 1FHL 1FHH 20HL 20HH Grid11 21HL 21HH 22HL 22HH 23HL 23HH Grid12 b0 b3 b4 b7 xxHL xxHH Lower 4bits Higher 4bits 13 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Command 2 : Data Setting command The Data Setting command executes the Data Write or Data Read Modes for LD1970. The Data Setting Command, the bits 5 and 6 (b4, b5) are ignored, bit 7 (b6) is given the value of “1” while bit 8 (b7) is given the value of “0”. Please refer to the diagram below. When Power is turned “ON”, the bit 4 to bit1 (b3 to b0) are given the value of “0”. MSB 0 LSB 1 01 : Command2 - Don’t Care - b3 b2 b1 b0 Data Write Mode Setting 00 : Write data to display mode 01 : Write data to LED Port 10 : Read Key Scan data 11 : Don’t care Address Increment Mode Settings (Display Mode) 0 : Increment address after data has been written 1 : Fixes address Mode Setting 0 : Normal operation mode 1 : Test mode (user don’t use) 14 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan LD1970 Key Matrix & Key Input Data Storage Memory LD1970 Key Matrix consists of 16 x 2 array as shown below. K1 SG16/KS16 SG15/KS15 SG14/KS14 SG13/KS13 SG12/KS12 SG11/KS11 SG10/KS10 SG9/KS9 SG8/KS8 SG7/KS7 SG6/KS6 SG5/KS5 SG4/KS4 SG3/KS3 SG2/KS2 SG1/KS1 K2 Each data inputted by each key are stored as follows. They are read by a READ command, starting from the least significant bit. When the most significant bit of the data (SG16, b7) has been read, the least significant bit if the next data (SG1, b0) is read. K1 K2 K1 K2 K1 K2 K1 K2 SG1/KS1 SG2/KS2 SG3/KS3 SG4/KS4 SG5/KS5 SG6/KS6 SG7/KS7 SG8/KS8 SG9/KS9 SG10/KS10 SG11/KS11 SG12/KS12 SG13/KS13 SG14/KS14 SG15/KS15 SG16/KS16 b0 b2 b1 b3 b4 b5 b6 Reading Sequence b7 15 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan LED Display LD1970 provides 4 LED Display Terminals, namely LED1 to LED4. Data is written to the LED Port starting from the least significant bit (b0) of the port using a Write Command. Each bit starting from the least significant (b0) activates a specific LED Display Terminal – b0 corresponds LED1 Display,b1 activates LED2 and so forth. Since there are only 4 LED Display Terminals, bit5 to bit8 (b4 ~ b7) are not used and therefore ignored. This means that b4 to b7 does not in anyway activate any LED Display and they are totally ignored. When a bit (b0 ~ b3) in the LED Port is “1”, the corresponding LED is Off. Conversely, when the bit is “0”, the LED Display is turned On. For example, Bit1 (as designated by b0) has the value of “1”, then this means that LED1 is Off. It must be noted that when power is turned on, bit1 to bit4 (b0 to b3) are given the value of “0” (All LEDs are turned On). Please refer to the diagram below. MSB - LSB - - - b3 b2 b1 Don’t Care b0 LED1 LED2 LED3 LED4 16 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Command 3 : Address Setting command The display memory is addressed by Address Setting command. The valid address range is from “00h” to “23h”. If the address is set to 24h or higher, the data is ignored until a valid address is set. When the power is turned On, the address is set at “00h”. Please refer to the diagram below. MSB 1 LSB 1 b5 b4 b3 b2 b1 b0 11 : Command 3 Address : 00h to 23h 17 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Command 4 : Display Control command The Display Control command is used to turn On or Off a display. It is also used to set the pulse width. Please refer to the diagram below. When the power is turned On, a 1/16 pulse width is selected and the display is turned Off (the key scanning is stopped). MSB 1 LSB 0 10 : Command 4 - - Don’t Care b3 b2 b1 b0 Dimming Quantity Setting : 000 : Pulse Width = 1/16 001 : Pulse Width = 2/16 010 : Pulse Width = 4/16 011 : Pulse Width = 10/16 100 : Pulse Width = 11/16 101 : Pulse Width = 12/16 110 : Pulse Width = 13/16 111 : Pulse Width = 14/16 Display Setting 0 : Display Off (key scan continues) 1 : Display On 18 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Scanning and Display Timing The key scanning and display timing diagram is given below. One cycle of key scanning consists of 2 frames. The data of the 16 x 2 matrix is stored in the Memory. Tdisplay=500us Key Scan Data SGn G1 G2 G3 Gn 1Frame = Tdisplay x (n+1) Note : Tdisplay is the width of segment only 19 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Serial Communication Format The following diagram shows the LD1970 serial communication format. The DOUT pin is an N-channel open drain output pin, therefore , it is highly recommended that an external pull-up resistor (1㏀ ~ 10㏀) must be connected to DOUT. Reception (Data/Command Write) If data continues STB DIN CLK 2 1 3 7 8 Transmission (Data Read) STB DIN b0 b1 b2 b3 b4 b5 b6 CLK b7 Twait DOUT b0 Data Read Command Set b1 b6 b7 b0 b1 b6 b7 Data Reading Starts Where : Twait (waiting time) ≥ 1us It must be noted that when the data is read, the waiting time (Twait) between the rising of the 8 th clock that has set the command and the falling of the 1st clock that has the data is greater or equal to 1us. 20 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Serial Communication Example Serial communication timing diagram for initialization setting STB CLK DIN Command2 Command3 data1 data2 Command1 Command4 Where : Command1 : Display Mode Setting Command2 : Data Setting Command Command3 : Address Setting Command Data1 to n : Transfer Display Data (36 byte max.) Command4 : Display Control Command Transmission diagram for new Data on specific addresses. STB CLK DIN Command2 Command3 data command3 data Where : Command2 : Data Setting Command Command3 : Address Setting Command Data : Display Data Transmission diagram for LED Data setting diagram. STB CLK DIN Command2 data Where : Command2 : Data Setting Command LED Data : 4 LED (LED1 to LED4) Display Data 21 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Recommended Software Programming Flow Chart START Delay 200ms SET Test Mode initial (Command 4Bh, Parameter 00h) SET Command2 (Write Data) SET Command3 Clear Display Memory (See Note5) Initial Setting SET Command1 SET Command4 (88h ~ 8Fh : Display On) Main Program SET Command2 (Read key & Write Data Included) SET Command3 Main Loop SET Command1 SET Command4 Note : 1. Command1 : Display Mode Setting END 2. Command2 : Data Setting Command 3. Command3 : Address Setting Command 4. Command4 : Display Control Command 5. When IC Power is applied for the first time, the contents of the Display Memory are not defined. Thus, it is strongly suggested that the contents of the Display Memory must be cleared during the initial setting. 22 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan Application Circuit LD1970 Note : The capacitor(0.1uF) connected between the GND and the VDD pins must be located as close as possible to the LD1970 chip. 23 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan PACKAGE INFORMATION 48 QFN Package (Bode Size : 6mm x 6mm; Pitch : 0.4mm; THK Body: 0.75mm) Unit : mm NOTES ALL DIMENSIONS REFER TO JEDEC STANDARD MO-220 (VJJE) 24 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan 44-Pin LQFP Package (Bode Size : 10mm x 10mm; Pitch : 0.8mm; THK Body: 1.40mm) Unit : mm 25 Ver 4.0 LD1970 16 Segment x 12 Grid VFD Driver with Key Scan 44-Pin MQFP Package (Bode Size : 10mm x 10mm; Pitch : 0.8mm; THK Body: 2.10mm) Unit : mm 26 Ver 4.0