M5481B7

M5481 LED DISPLAY DRIVER FEATURES SUMMARY ■ 2 DIGIT LED DRIVER (14 segments) 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. CURRENT GENERATOR OUTPUTS (no registor required) ■ ■ CONTINUOUS BRIGHTNESS CONTROL ■ SERIAL DATA INPUT ■ DATA ENABLE ■ WIDE SUPPLY VOLTAGE OPERATION ■ TLL COMPATIBILITY ■ APPLICATION EXAMPLES ■ MICROPROCESSOR DISPLAYS ■ INDUSTRIAL CONTROL INDICATOR ■ RELAY DRIVER ■ INSTRUMENTATION READOUTS Figure 1. Package c u d e t le o r P PDIP20 (Plastic package) b O - 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 ) s ( ct so ) s t( u d o r P e Figure 2. Pin Connections t e l o bs O Output Bit 8 Output Bit 7 1 20 Output Bit 9 2 19 Output Bit 10 Output Bit 6 3 18 Output Bit 11 Output Bit 5 4 17 Output Bit 12 Output Bit 4 5 16 Output Bit 13 Output Bit 3 6 15 VSS Output Bit 2 7 14 Output Bit 1 8 13 Output Bit 14 Data Enable Brightness Control 9 12 Data In 10 11 Clock VDD REV. 2 April 2004 1/10 M5481 Figure 3. Block Diagram VDD Brightness Control 10 Output Bit 14 Output Bit 1 14 8 100k 9 35 Output Buffers 1nF Load 35 Latches Data Enable 13 Serial Data 12 35-Bit Shift Register Reset 11 Clock 15 e t le Table 1. Absolute Maximum Ratings Symbol Parameter VDD – 0.3 to 15 V 15 V 40 mA Total Package Power Dissipation at 25°C 1.5 W Total Package Power Dissipation at 85°C 800 mW Junction Temperature 150 °C – 25 to 85 °C – 65 to 150 °C o r P e t e l o bs V (s) ct du Output Sink Current PTOT TSTG – 0.3 to 15 Off State Output Voltage IO TOP Unit Input Voltage VO(off) o r P Value Supply Voltage VI Tj o s b O - c u d ) s t( Operating Temperature Range Storage Temperature Range Note: Stresses exceeding those listed under “Absolute Maximum Ratings” may cause permanent damage to the device and affect its reliability. O 2/10 M5481 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 IDD Supply Current VDD = 13.2V VI Input Voltage Logical "0" Level ± 10µA Input Bias 4.75 ≤ VDD ≤ 5.25 Logical "1" Level VDD > 5.25 IB Brightness Input Current (note 2) VB Brightness Input Voltage (pin 9) VO(off) IO Input Current = 750µA, Tamb = 25°C Max. Unit 4.5 Typ. 13.2 V 7 mA - 0.3 0.8 V 2.2 VDD V VDD - 2 VDD V 0 0.75 3 4.3 Off State Out. Voltage mA V 13.2 V 10 µA 10 µA Out. Sink Current (note 3) Segment OFF VO = 3V Segment ON VO = 1V (note 4) Brightness In. = 0µA fclock IO Note: 1. 2. 3. 4. Min. 0 Brightness In. = 100µA 2 2,7 Brightness In. = 750µA 12 15 Input Clock Frequency Output Matching (note 1) mA mA 0.5 MHz ± 20 % c u d 0 ) s t( 4 25 o r P 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. o s b O - 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 ) s ( ct u d o r P e t e l o e t le be connected to brightness control (pin 9) to prevent possible oscillations. A block diagram is shown on Figure 3. 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 4 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. s b O 3/10 M5481 Figure 4. Input Data Format 1 36 CLOCK START BIT 1 BIT 34 BIT 35 DATA LOAD (INTERNAL) RESET (INTERNAL) Tj = [(Vout) (ILED) (No. of segments) + VDD x 7mA] 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 5 shows the timing relationships between Data, Clock and DATA ENABLE. A maximum clock frequency of 0.5MHz is assumed. Table 3 shows the Output Data Format for the M5481. Because it uses only 14 of the possible outputs, 21 of the bits (including bit 35 which was already unused in the M5450) 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. The following equation can be used for calculations. c u d Figure 5. e t le o r P o s b O - ) s ( ct CLOCK DATA u d o 300ns (min.) r P e DATA ENABLE t e l o s b O ) s t( 100ns (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 18 START 5481 X X X X X 14 13 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 4/10 M5481 TYPICAL APPLICATION Figure 6. BASIC electronically tuned TV system LED DISPLAY 14 SEGMENTS M5481 DISPLAY DRIVER KEYBOARD PLL SYNTHESIZER PROCESSOR c u d POWER DISSIPATION OF THE IC The power dissipation of the IC can be limited using different configurations. Figure 7. +VC ) s ( ct R u d o ID VD t e l o r P e VOUT s b O e t le ) s t( o r P In this application R must be chosen taking into account the worst operating conditions. R is determined by the maximum number of segments activated. o s b O - 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. 5/10 M5481 Figure 8. Figure 9. +VC +VC VOUT+ VD 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. ) s ( ct u d o r P e t e l o s b O 6/10 c u d ) s t( In this configuration VOUT+VD is constant. the total power dissipation of the IC depends only on the number of segments activated. o s b O - e t le o r P M5481 PART NUMBERING Table 4. Order Codes Part Number Package M5481 B7 Temperature Range PDIP -25 to 85 °C c u d e t le ) s ( ct ) s t( o r P o s b O - u d o r P e t e l o s b O 7/10 M5481 PACKAGE MECHANICAL Table 5. PDIP20 - Mechanical Data Symbol Typ 3.25 millimeters Min 3.30 0.508 A a1 B b b1 C D E e e3 e4 F I L N R1 R2 K K1 K2 Z 1.39 0.381 0.20 5.20 24.9 7.8 2.29 22.60 7.36 6.22 3.42 3.17 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 Typ 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 e t le 1.34 Figure 10. PDIP20 - Package Dimensions c u d K A e F e3 E D Tie Bar Center 20 11 1 10 R2 Note: Drawing is not to scale b1 C L B Z s b O 8/10 a1 b R1 t e l o I K2 r P e ) s t( 0.053 N K1 u d o 0.065 0.021 0.012 0.215 1.000 0.358 0.110 0.910 0.310 0.255 0.155 0.135 o r P e4 N N ) s ( ct Max 0.132 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 R1 o s b O - inches Min 0.130 0.020 M5481 REVISION HISTORY Table 6. Revision History Date Revision Description of Changes October-2000 1 First Issue 14-Apr-2004 2 Stylesheet update. No content change. c u d e t le ) s ( ct ) s t( o r P o s b O - u d o r P e t e l o s b O 9/10 M5481 c u d e t le ) s ( ct ) s t( o r P o s b O - u d o r P e t e l o 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. s b O 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