M5480 LED DISPLAY DRIVER FEATURES SUMMARY ■ 3 1/2 DIGIT LED DRIVER (23 segments) ■ CURRENT GENERATOR OUTPUTS (no resistors required) ■ CONTINUOUS BRIGHTNESS CONTROL ■ SERIAL DATA INPUT ■ NO LOAD SIGNAL REQUIRED ■ WIDE SUPPLY VOLTAGE OPERATION ■ TTL COMPATIBILITY Application Examples: ■ MICROPROCESSOR DISPLAY ■ INDUSTRIAL CONTROL INDICATION ■ RELAY DRIVER ■ INSTRUMENTATION READOUTS Figure 1. Package 28 1 PDIP28 (Plastic Package) DESCRIPTION The M5480 is a monolithic MOS integrated circuit produced with a N-channel silicon gate technology. It utilizes the M5451 die packaged in a 28-pin plastic package making it ideal for a 3 1/2 digit dispaly. A single pin controls the LED dispaly brightness by setting a reference current through a variable resistor connected either to VDD or to a separate supply of 13.2V maximum. The M5480 is a pin-to-pin replacement of the NS MM 5480. REV. 2 April 2004 1/10 M5480 Figure 2. Pin Connections VSS 1 28 OUTPUT BIT 12 OUTPUT BIT 11 2 27 OUTPUT BIT 13 OUTPUT BIT 10 3 26 OUTPUT BIT 14 OUTPUT BIT 9 4 25 OUTPUT BIT 15 OUTPUT BIT 8 5 24 OUTPUT BIT 16 OUTPUT BIT 7 6 23 OUTPUT BIT 17 OUTPUT BIT 6 7 22 OUTPUT BIT 18 OUTPUT BIT 5 8 21 OUTPUT BIT 19 OUTPUT BIT 4 9 20 OUTPUT BIT 20 OUTPUT BIT 3 10 19 OUTPUT BIT 21 OUTPUT BIT 2 11 18 OUTPUT BIT 22 OUTPUT BIT 1 12 17 OUTPUT BIT 23 BRIGHTNESS CONTROL 13 16 DATA IN VDD 14 15 CLOCK IN Figure 3. Block Diagram VDD BRITGHTNESS CONTROL 14 13 OUTPUT BIT 23 OUTPUT BIT 1 17 12 35 OUTPUT BUFFERS 1nF LOAD 35 LATCHES SERIAL DATA 16 CLOCK 15 35 BIT SHIFT REGISTER RESET 1 2/10 M5480 Table 1. Absolute Maximum Ratings Symbol VDD VI VO(off) IO PTOT Tj 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 Total Package Power Dissipation at 25°C 940 mW Total Package Power Dissipation at 85°C 490 mW Junction Temperature 150 °C – 25 to 85 °C – 65 to 150 °C TOP Operating Temperature Range TSTG Storage Temperature Range Note: Stresses in excess of those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions in excess of those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Table 2. Static Electrical Characteristics (Tamb within operating range, VDD = 4.75V to 13.2V, VSS = 0V, unless otherwise specified) Symbol Parameter Test Conditions VDD Supply Voltage.,75 IDD Supply Current VDD = 13.2V VI Input Voltage Logical "0" Level ± 10µA Input Bias Logical "1" Level 4.75 ≤ VDD ≤ 5.25 VDD > 5.25 IB Brightness Input Current (note 2) VB Brightness Input Voltage (pin 13) VO(off) IO IO Typ. Max. Unit 13.2 V 7 mA - 0.3 0.08 V 2.2 VDD V VDD - 2 VDD V 0 0.75 3 4.3 Off State Out. Voltage 13.2 mA V 18 V 10 µA Out. Sink Current (note 3) fclock Note: 1. 2. 3. 4. Input Current = 750µA, Tamb = 25°C Min. Segment OFF VO = 3V Segment ON VO = 1V (note 4) Input Clock Frequency Brightness In. = 0µA 0 Brightness In. = 100µA 2 2,7 Brightness In. = 750µA 12 15 0 Output Matching (note 1) 10 µA 4 mA 25 mA 0.5 MHz ± 20 % Output matching is calculated as the percent variation from I MAX + 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. 3/10 M5480 FUNCTIONAL DESCRIPTION The M5480 is specifically designed to operate 31/ 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 nonmultiplexed, 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 13, to prevent possible oscillations. A block diagram is shown in Figure 3. The output current is typically 20 times greater than the current into pin 13, which is set by an external variable resistor. There is an internal limiting resistor of 400 Ω nominal value. Figure 4 shows the input data format. A start bit of logical "1" precedes the 35 bits of data. At the 36th clock a LOAD signal is generated synchronously with the high state of the clock, which loads the 35 bits of the shift registers into the latches. 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 register, thus allowing continuous operation. Figure 4. Input Data Format 1 36 CLOCK START BIT 1 BIT 34 BIT 35 DATA LOAD (INTERNAL) RESET (INTERNAL) 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 return the chip to its normal operation. Figure 5 shows the timing relationships between Data, and Clock. A maximum clock frequency of 0.5MHz is assumed. Table 3 shows the Output Data Format for the M5480. Because it uses only 23 of the possible 35 outputs, 12 of the bits are "Don’t Care". For applications where a lesser number of outputs are used, it is possible to either increase the cur- 4/10 rent per output, or operate the part at higher than 1V VOUT. The following equation can be used for calculations. Tj = [ (VOUT) (ILED) (No.of segments) + VDD . 7 mA] (132 °C/W) + Tamb where: Tj = junction temperature (150 °C max) VOUT = the voltage at the LED driver outputs ILED = the LED current 132 °C/W = thermal coefficient of the package Tamb = ambient temperature M5480 Figure 5. CLOCK DATA 300ns (min.) Table 3. Serial Data Bus / Outputs Correspondance 5451 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 19 START 5480 X 23 22 21 20 19 X X 18 X 17 16 15 14 13 12 X START 5451 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 START 5480 X X X 11 10 9 8 X X X 7 6 5 4 3 2 1 X START TYPICAL APPLICATION Figure 6. Basic 3 1/2 Digit Interface 23 SEGMENTS M5480 DISPLAY DRIVER CLOCK DATA 5/10 M5480 POWER DISSIPATION OF THE IC The power dissipation of the IC can be limited using different configurations. Figure 8. +VC Figure 7. +VC R ID VD VOUT In this application R must be chosen taking into account the worst operating conditions. R is determined by the maximum number of segments activated. 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, in a first approximation, only on the number of segments activated. Figure 9. V –V –V C DMAX OMIN R = ---------------------------------------------------------------N L MAX D 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. +VC VOUT+ VD In this configuration VOUT + VD is constant. The total power dissipation of the IC depends only on the number of segments activated. 6/10 M5480 PART NUMBERING Table 4. Order Codes Part Number Package Temperature Range M5480 PDIP28 -25 to 85 °C 7/10 M5480 PACKAGE MECHANICAL Table 5. PDIP28 - Mechanical Data millimeters inches Symbol Typ Min Max Typ Min a1 0.63 0.025 b 0.45 0.018 b1 0.23 0.31 b2 Max 0.009 1.27 0.012 0.050 D 52.58 E 15.2 2.070 16.68 0.598 0.657 e 2.54 0.100 e3 48.26 1.900 F 14.1 0.555 i 4.445 0.175 L 3.3 0.130 I L a1 Figure 10. PDIP28 - Package Dimensions b1 b b2 e E e3 D 15 1 14 F 28 Note: Drawing is not to scale 8/10 M5480 REVISION HISTORY Table 6. Revision History Date Revision Description of Changes May-1993 1 First Issue 14-Apr-2004 2 Stylesheet update. No content change. 9/10 M5480 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 express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners © 2004 STMicroelectronics - All rights reserved STMicroelectronics GROUP OF COMPANIES Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States www.st.com 10/10