M5481 LED DISPLAY DRIVER FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 2 DIGIT LED DRIVER (14 segments) CURRENT GENERATOR OUTPUTS registor required) CONTINUOU BRIGHTNESS CONTROL SERIAL DATA INPUT DATA ENABLE WIDE SUPPLY VOLTAGE OPERATION TLL COMPATIBILITY APPLICATION EXAMPLES MICROPROCESSOR DISPLAYS INDUSTRIAL CONTROL INDICATOR RELAY DRIVER INSTRUMENTATION READOUTS (no DIP20 (Plastic package) ORDER CODE: M5481 B7 DESCRIPTION The M5481 is a monolithic MOS integrated circuit produced with a N-channel silicon gate technology. It uses the M5450 die packaged in a 20-pin plastic package copper frame, making it ideal for a 1-digit display. A single pin controls the LED display brightness by setting a reference current through a variable resistor connected either to VDD or to a separate supply of 13.2V maximum. The M5481 is a pin-to-pin replacement of the NS MM 5481. PIN CONNECTIONS Output Bit 8 1 20 Output Bit 9 Output Bit 7 2 19 Output Bit 9 Output Bit 6 3 18 Output Bit 9 Output Bit 5 4 17 Output Bit 9 Output Bit 4 5 16 Output Bit 3 6 15 Output Bit 9 VSS Output Bit 2 7 14 Output Bit 9 Output Bit 1 8 13 Data Enable Brightness Control 9 12 10 11 Data In Clock VDD Version 4.1 April 2000 1/8 1 M5481 1 - BLOC DIAGRAM Figure 1. VDD Brightness Control 10 Output Bit 14 Output Bit 1 14 8 100kΩ 35 Output Buffers 9 1nF Load 35 Latches Data Enable 13 Serial Data 12 Clock 11 35-Bit Shift Register Reset 15 2 - ABSOLUTE MAXIMUM RATINGS Symbol VDD Vi Vo(off) Io Parameter Value Unit Supply Voltage -0.3 to 15 V Input Voltage -0.3 to 15 V Off-state Output Voltage 15 V Output Sink Current 40 mA 1.5 800 mW 150 °C Total package power Dissipation Ptot Tj at 25°C t 85°C Junction Temperature W Toper Operating Temperature Range -25, +85 °C Tstg Staorage Temperature Range -65, +150 °C Stresses exceeding those listed under “Absolute Maximum Ratings” may cause permanent damage to the device and affect its reliability. 2/8 2 M5481 3 - STATIC ELECTRICAL CHARACTERISTICS (Tamb within operational range, VDD=4.75V to 13.2V, VSS=0V, unless otherwise specified) Symbol VDD Supply Voltage Idd Supply Current Vi Input Voltages Logical “0” Level Logical “1” Level IB Brightness Input Current (Note 2) VB Brightness Input Voltage (pin9) Vo(off) Io fclock Io Note Note Note Note Parameter 1 2 3 4 Test Conditions Min Typ Max Unit 13.2 V 7 mA -0.3 2.2 VDD2 0.8 VDD VDD V V V 0 0.75 mA 3 4.3 V 13.2 V 10 µA 10 4 25 µA mA mA 0.5 MHz ±20 % 4.5 VDD=13.2V +10µA Input Bias 4.75≤VDD≤5.25 VDD>5.25 Input Curren=750µA Tamb=25°C Off-state Output Voltage Output Sink Current (Note 3) Segment OFF Segment ON Input Clock Frequency Output Matching (Note 1) Vo=3V Vo=1V (Note 4) Brightness In.=0µA Brightness In.=100µA Brightness In.=750µA 0 2 12 0 2.7 15 Output matching is calculated as the percent variation from Imax+Imin/2 With a fixed resistor on the brightness input some variation in brightness will occur from one device to another. Absolute maximum for each output should be limited to 40mA. the Vo voltage should be regulated by the user. 4 - FUNCTIONAL DESCRIPTION The M5481 uses the M5450 die which is packaged to operate 2-digit alphanumeric displays with minimal interface with the display and the data source. Serial data transfer from the data source to the display driver is accomplished with 2 signals, serial data and clock. using a format of a leading “1” followed by the 35 data bits allows data transfer without an additional load signal. The 35 data bits are latched after the 36th bit is complete, thus providing non-multiplexed, direct drive to the display. Outputs change only if the serial data bits differ from the previous time. Display brightness is determined by control of the output current for LED displays. A 1nF capacitor should be connected to brightness control (pin 9) to prevent possible oscillations. A bloc diagram is shown on Figure 1. The output current is typically 20 times greater than the current into pin 9, which is set by an external variable resistor. The latter is an internal limiting resistor of 400Ω nominal value. Figure 2 shows the input data format. A start bit of logical “1” precedes the 35 bits of data. At the 36th clock a LOAD is generated synchronously with the high state of the clock, which loads the 35 bits of the shift registers into the latches. 3/8 M5481 Figure 2. Input Data Format 1 36 CLOCK START BIT 1 BIT 34 BIT 35 DATA LOAD (INTERNAL) RESET (INTERNAL) The following equation can be used for calculations. Tj=[(Vout)(ILED)(No. of segments)+VDDx7mA] x(80°C/W)+Tamb where: Tj=junction temperature (150°Cmax) Vout= voltage at the LED driver outputs ILED= LED current 80°C/W=thermal coefficient of the package Tamb=ambiant temperature At the low state of the clock a RESET signal is generated which clears all the shift registers for the next set of data. The shift registers are static master slave configurations. There is no clear for the master portion of the first shift register, thus allowing continuous operation. There must be a complete set of 36 clocks or the shift registers will not clear. When power is first applied to the chip an internal power ON reset signal is generated which resets all registers and all latches. The START bit and the first clock reset the chip to its normal operation. Figure 3 shows the timing relationships between Data, Clock and DATA ENABLE. A maximum clock frequency of 0.5MHz is assumed. Figure 4 shows the Output Data Format for the M5481. Because it uses only 14 of the possible 35 outputs, 21 of the bits are “Don’t Cares”. For applications where a lesser number of outputs are used it is possible to either increase the current per output or operate the part at higher than 1V Vout. Figure 3. CLOCK DATA 300ns (min.) DATA ENABLE 100ns (min.) Figure 4. Serial Bus/Outputs Correspondance 5450 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 START 5481 X X X X 13 X X X X X 12 11 10 9 X X X START 5450 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 START 5481 X 8 7 6 5 X X X X 4 3 2 1 X X X X START 4/8 M5481 5 - TYPICAL APPLICATION BASIC electronically tuned TV system. LED DISPLAY 14 SEGMENTS M5481 DISPLAY DRIVER KEYBOARD PROCESSOR PLL SYNTHESIZER 6 - POWER DISSIPATION OF THE IC The power dissipation of the IC can be limited using different configurations. +V C V –V –V C DMAX OMIN R = ---------------------------------------------------------------N xI MAX D R ID VD V OUT In this application R must be chosen by taking into account the worst operating conditions. R is determined by the maximum number of segments activated. The worst case condition for the device is when roughly half of the maximum number of segments are activated. It must be checked that the total power dissipation does not exceed the absolute maximum ratings of the device. In critical cases more resistors can be used in conjunction with groups of segments. In this case the current variation in the single resistor is reduced and Ptot limited. 5/8 M5481 +V C +VC V OUT +V D In this configuration the drop on the serial connected diodes is quite stable if the diodes are properly chosen. The total power dissipation of the IC depends only, in first approximation, on the number of segments activated. 6/8 In this configuration VOUT+VD is constant. the total power dissipation of the IC depends only on the number of segments activated. M5481 7 - PACKAGE MECHANICAL DATA 20 Pins — Plastic Dip e4 R1 N N N K1 I K K2 A a1 b B b1 C L R1 e Z F e3 E D Tie Bar Center 11 20 10 1 R2 Dimensions A a1 B b b1 C D E e e3 e4 F I L N R1 R2 K K1 K2 Z Min. 3.25 1.39 0.381 0.20 5.20 24.9 7.8 2.29 22.60 7.36 6.22 3.42 3.17 Millimeters Typ. 3.30 0.508 0.457 0.254 5.33 25.15 8.5 2.54 22.86 7.62 6.35 3.68 3.30 7d 0.152 0.762 1.524 0.762 0.762 1.27 Max. 3.35 Min. 0.128 1.65 0.533 0.30 5.46 25.4 9.1 2.79 23.11 7.87 6.50 3.93 3.42 0.055 0.015 0.008 0.205 0.980 0.307 0.090 0.890 0.290 0.245 0.135 0.125 1.34 Inches Typ. 0.130 0.020 0.018 0.010 0.210 0.990 0.335 0.100 0.900 0.300 0.250 0.145 0.130 7d 0.006 0.030 0.060 0.030 0.030 0.050 Max. 0.132 0.065 0.021 0.012 0.215 1.000 0.358 0.110 0.910 0.310 0.255 0.155 0.135 0.053 7/8 M5481 Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without the express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics 2000 STMicroelectronics - All Rights Reserved. I2C Purchase of Components by STMicroelectronics conveys a license under the Philips I2C Patent. Rights to use these components in an I2C system is granted provided that the system conforms to the I2C Standard Specification as defined by Philips. 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