1 TC7211AM BUS COMPATIBLE 4-DIGIT CMOS DECODER/DRIVER 2 FEATURES GENERAL DESCRIPTION ■ The TC7211AM (LCD Decoder/driver) is a CMOS direct drive, 4-digit, 7-segment display decoder and driver. The TC7211AM drives conventional LCDs. An RC oscillator, divider chain, backplane driver, and 28-segment outputs are provided on a single CMOS chip. The segment drivers supply square waves of the same frequency as the backplane, but in-phase for an OFF segment and out-ofphase for an ON segment. The net DC voltage applied between driver segment and backplane is near zero maximizing display lifetime. The four bit binary input is decoded into the seven segment alphanumeric code known as "Code B". The "Code B" output format results in a 0 to 9,—, E, H, L, P or blank display. True BCD or binary inputs will be correctly decoded to the seven segment display format. ■ ■ ■ ■ ■ ■ 4-Digit Non-Multiplexed 7-Segment LCD Outputs With Backplane Driver Input and Digit Select Data Latches RC Oscillator On-Chip Generates Backplane Drive Signal Eliminates DC Bias Which Degrades LCD Life Backplane Input/Output Pin Permits Synchronization of Cascaded Slave Device to a Master Backplane Signal Binary and BCD Inputs Decoded to Code B (0 to 9, —, E, H, L, P, Blank) Pin Compatible and Functionally Equivalent to ICM7211AM 3 4 PIN CONFIGURATIONS ORDERING INFORMATION V+ 1 E1 2 39 G1 3 38 B1 F1 4 37 A1 BP 5 36 OSCILLATOR A2 6 35 GND B2 7 34 CHIP SELECT 2 (CS2) C2 8 33 CHIP SELECT 1 (CS1) D2 9 32 DIGIT SELECT 2 (DS2 E2 10 G2 11 F2 Part No. Driver Type Input Package Code Output Config. TC7211AMIPL LCD 40-Pin Code B Plastic DIP Data and Digit Select Latches 40 D1 C1 5 6 31 DIGIT SELECT 1 (DS1 TC7211AM (LCD) 30 B3 12 29 B2 A3 13 28 B1 B3 14 27 B0 C3 15 26 F4 D3 16 25 G4 E3 17 24 E4 G3 18 23 D4 F3 19 22 C4 A4 20 21 B4 DATA INPUTS 7 8 TC7211AM-4 11/14/96 TELCOM SEMICONDUCTOR, INC. 6-7 BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER TC7211AM FUNCTIONAL BLOCK DIAGRAM D4 SEGMENT OUTPUTS TC7211AM 1 V+ DATA INPUTS B0 B1 B2 B3 D2 SEGMENT OUTPUTS D1 SEGMENT OUTPUTS a 7 WIDE DRIVER 7 WIDE DRIVER 7 WIDE DRIVER 7 WIDE DRIVER 7 WIDE LATCH ENABLE 7 WIDE LATCH ENABLE 7 WIDE LATCH ENABLE 7 WIDE LATCH ENABLE PROGRAMMABLE 4-TO-7 DECODER PROGRAMMABLE 4-TO-7 DECODER PROGRAMMABLE 4-TO-7 DECODER PROGRAMMABLE 4-TO-7 DECODER 35 GND 27 28 29 30 g D3 SEGMENT OUTPUTS 4-BIT LATCH ENABLE DIGIT SELECT INPUTS 31 DS1 32 DS2 2-BIT LATCH 2-TO-4 DECODER ENABLE CS1 CS2 33 34 OSCILLATOR INPUT ENABLE ONE SHOT OSCILLATOR (16 kHz FREERUNNING) 36 ÷128 BACK– PLANE DRIVER ENABLE BACKPLANE (INPUT/OUTPUT) ENABLE DETECTOR 6-8 TELCOM SEMICONDUCTOR, INC. BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER 1 TC7211AM ABSOLUTE MAXIMUM RATINGS* Supply Voltage ........................................................ +6.5V Input Voltage, Any Terminal (Note 2) .................................... V+ +0.3V, GND –0.3V Power Dissipation TA ≤ 70°C (Note 1) ................... 1.23W Operating Temperature Range ................ –20°C to +85°C Storage Temperature Range ................. –65°C to +150°C Lead Temperature (Soldering, 10 sec) ................. +300°C *Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. NOTES: 1. This limit refers to that of the package and will not be realized during normal operation. 2. Due to the SCR structure inherent in the CMOS process, connecting any terminal to voltages greater than V+ or less than GND may cause destructive latch-up. For this reason, it is recommended that inputs from external sources not operating on the same power supply not be applied to the device before its supply is established, and, in multiple supply systems, the supply to the TC7211AM be turned on first. 2 3 TYPICAL CHARACTERISTICS: All parameters measured with V+ = 5V, TA = 25°C Symbol Parameter VSUP IOP IOSCI tRFS tRFB fOSC fBP Operating Voltage Range Operating Current Oscillator Input Current Segment Rise/Fall Time Backplane Rise/Fall Time Oscillator Frequency Backplane Frequency Test Conditions Min Typ Max Unit Display Blank Pin 36 CL = 200 pF CL = 5000 pF Pin 36 Floating Pin 36 Floating 3 — — — — — — 5 10 ±2 0.5 1.5 16 125 6 50 ±10 — — — — V µA µA µsec µsec kHz Hz 3 — — — — — — ±0.01 5 ±0.01 — 1 ±1 — ±1 V V µA pF µA — 200 — pF — — 0 — — — — — nsec nsec nsec µsec 4 Input Characteristics VIH VIL IILK CIN IBPLK Logic “1” High Input Voltage Logic “0” Low Input Voltage Input Leakage Current Input Capacitance BP Input Current Leakage BP Input Capacitance CBPI Pins 27–34 Pins 27–34 Measured at Pin 5 With Pin 36 at GND All Devices 5 AC Characteristics Symbol Parameter Test Conditions tCSA tDS tDH tICS Chip Select Active Pulse Width Data Setup Time Data Hold Time Inter-Chip Select Time (Note 1) 200 100 10 2 6 NOTE: 1. Other chip select (CS) is either held at logic zero or both CS1 and CS2 driven together. 7 8 TELCOM SEMICONDUCTOR, INC. 6-9 BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER TC7211AM TIMING DIAGRAMS CS1 (CS2) tCSA tICS , , ,, CS2 (CS1) DATA AND DIGIT SELECT CODE tDS tDH DON’T CARE Figure 1: BUS Interface Timing Diagram OSCILLATOR FREQUENCY 128 CYCLES BACKPLANE INPUT/OUTPUT 64 CYCLES 64 CYCLES OFF SEGMENTS ON SEGMENTS Figure 2: LCD Display Waveforms 6-10 TELCOM SEMICONDUCTOR, INC. BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER 1 TC7211AM INPUT DEFINITIONS In this table, V+ and GND are considered to be normal operating input logic levels. For lowest power consumption, input signals should swing over the full supply. Input B0 Pin No. Condition Function V+ 27 B1 28 B2 29 B3 30 OSC 36 DS1 31 = Logic “1” GND = Logic “0” V+ = Logic “1” GND = Logic “0” V+ = Logic “1” GND = Logic “0” V+ = Logic “1” GND = Logic “0” Floating or with external capacitor GND V+ = Logical One DS2 32 GND = Logical Zero CS1 33 V+ = Inactive CS2 34 GND = Active Ones (Least Significant) Twos Data Input Bits 3 Fours Eights (Most Significant) Oscillator input. Disables BP output devices, allowing segments to be synchronized to an external signal input at the BP terminal (pin 5) DS2, DS1 = 00 Selects D4 DS2, DS1 = 01 Selects D3 Digit Select Inputs DS2, DS1 = 10 Selects D2 DS2, DS1 = 11 Selects D1 When both CS1 and CS2 are LOW, the data and digit select input latches are open or enabled. On the rising of CS1 or CS2, data is latched, decoded and stored in the output drive latches. OUTPUT DEFINITIONS A1 B1 C1 D1 E1 F1 G1 A2 B2 C2 D2 E2 F2 G2 Pin No. 37 38 39 40 2 4 3 6 7 8 9 10 12 11 Function A Segment Drive B C D E F G A Segment Drive B C D E F G Output Digit 1 (LSD) A3 B3 C3 D3 E3 F3 G3 A4 B4 C4 D4 E4 F4 G4 Digit 2 Pin No. 13 14 15 16 17 19 18 20 21 22 23 24 26 25 Function A Segment Drive B C D E F G A Segment Drive B C D E F G Digit 3 6 Digit 4 (MSD) 7 DIGIT ASSIGNMENT D4 D3 D2 4 5 Output pins are defined by the alphabetical segment assignment and numerical digital assignment. Output 2 D1 A G F E B 8 C D TELCOM SEMICONDUCTOR, INC. 6-11 BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER TC7211AM TYPICAL CHARACTERISTICS Backplane Frequency vs Supply Voltage Operating Supply Current vs Supply Voltage 180 30 LCD DEVICES DISPLAY BLANK PIN 36 OPEN 25 TA = +25°C TA= –20°C 150 120 15 BP (Hz) 20 IOP (µA) COSC = 0 pF (PIN 36 OPEN) TA= +25°C 90 COSC = 22 pF 60 10 TA= +70°C 5 30 COSC = 220 pF 0 1 2 3 4 5 V+ VOLTS 6 7 0 1 2 3 4 5 + V VOLTS 6 7 BASIC OPERATION The TC7211AM drives 4-digit, 7-segment LCDs. This device contains 28 individual segment drivers, a backplane driver, a self-contained oscillator, and a divider chain to generate the backplane signal. The 28 CMOS segment drivers and backplane driver contain ratioed N- and P-channel transistors for identical ON resistance. The equal resistances eliminate the DC output driver component resulting from unequal rise and fall times. This ensures maximum LCD life. The backplane output driver can be disabled by grounding the OSCILLATOR input (pin 36). The 28 output segment drivers can therefore be synchronized directly to an input signal at the backplane (BP) terminal (pin 5). Several slave devices may be cascaded to the backplane output of a master device. The backplane signal may also be derived from an external source. These features permit interfacing to single backplane LCDs with characters in multiples of four. Each slave’s backplane input represents a 200pF capacitive load to the master backplane driver (comparable to one additional segment). The number of slave devices drivable by a master device is therefore set by the larger display backplane capacitive load. The master backplane output will drive the display backplane of 16 one-half-inch characters with rise and fall times under 5 µsec. This represents a system with three slave devices and a fourth master device driving the backplane. 6-12 If more than four devices are slaved together, the backplane signal should be derived externally and all TC7211AM devices slaved to it. The external drive signal must drive a high capacitive load with 1µsec to 2 µsec rise and fall times. The backplane frequency is normally 125 Hz. At lower display ambient temperatures, the frequency may be reduced to compensate for display response time. The on-chip RC oscillator free-runs at approximately 16 kHz. A divide-by 128 circuit provides the 125 Hz backplane frequency. The oscillator frequency may be reduced by connecting an external capacitor between the oscillator terminal and V+. (See typical operating characteristics curves.) The free-running oscillator may be overridden (if desired) by an external clock. The backplane driver, however, must not be disabled during the external clock’s negative or lOW portion, as this will result in a DC drive component being applied to the LCD, limiting the LCD’s life. To prevent backplane driver disabling, the oscillator input should be driven from the positive supply to no less than one-fifth the supply voltage above ground. A backplane disable signal will not be sensed if the driving signal remains above ground by one-fifth the supply voltage. An alternate method for externally driving the oscillator permits the oscillator input to swing the full supply voltage range. The oscillator input signal duty cycle is skewed so the LOW TELCOM SEMICONDUCTOR, INC. BUS COMPATIBLE, 4-DIGIT CMOS DECODER/DRIVER 1 TC7211AM portion duration is less than 1 µsec. The backplane disable sensing circuit will not respond to such a short signal. Table 1. Binary Codes Versus Character Displayed B3 D8 D7 D6 D5 D4 D3 D2 D1 8-DIGIT LCD BACKPLANE BACKPLANE SLAVE +5V 28 SEGMENTS HIGH ORDER V+ GND OSC BCD/BINARY DATA CS2 DS2 B3– B0 CS1 DS1 BP 4 4 BACKPLANE MASTER 28 +5V V+ SEGMENTS HIGH ORDER GND CS2 DS2 B3– OSC B0 CS1 DS1 BP 4 CHIP SELECT TC7211AM DIGIT SELECT Figure 3. TC7211AM Driving an 8-Digit LCD Display in Master/Slave Configuration 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 Binary Input B2 B1 B0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Input Configuration and Output Codes The TC7211AM accepts a 4-bit, true binary (positive level = logic “1”) input at pin 27 (LSB) through pin 30 (MSB). The binary input is decoded to the 7-segment output known as Code B. The output display format is 0 to 9, —, E, H, L, P and blank display (see Table 1). Segment assignments are shown in Figure 4. The TC7211AM will correctly decode binary and BCD true codes to a 7-segment output. The TC7211AM is designed to interface with a data bus and display data under microprocessor control. Four data inputs (pins 27–30) and two digit select input bits (pins 31 and 32) are written into input buffer latches. The rising edge of either chip select causes data to be latched, decoded and stored in the selected digit output data latch. The 2-bit digit code selects the appropriate output digit latch. The 4-bit display data word is decoded to the "Code B" 7-segment output format. For applications where bus compatibility is not required, refer to the TC7211AM (LCD) 4-digit decoder driver data sheet. This device is designed to accept multiplexed BCD/ binary input data for display under the control of four separate digit select control signals. Character Displayed (Code B) 0 1 2 3 4 5 6 7 8 9 — E H L P Blank 2 3 4 A G F E B C 5 D Figure 4. Segment Assignment Special Order Decoder Option The TC7211AM is mask programmed to give the 16 combinations of 7-segment output codes. For large volume orders (50K pieces minimum), custom decoder options are available. Contact TelCom Semiconductor for details. 6 7 8 TELCOM SEMICONDUCTOR, INC. 6-13