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| INTEGRATED CIRCUITS SA5777A Dual air-core gauge driver Product specification Supersedes data of 1997 Feb 24 1999 Sep 20 Philips Semiconductors Philips Semiconductors Product specification Dual air-core gauge driver SA5777A DESCRIPTION The SA5777A is a monolithic driver for controlling air-core (or differential) meters typically used in automotive instrument cluster applications. The circuit interfaces with a microprocessor through a serial bus and directly drives the air-core meter. The SA5777A has 10-bit resolution (0.35 degree) and is guaranteed to be monotonic. Data can be shifted through the part, allowing several SA5777As to be cascaded with only one chip-select line. On-chip current shut down logic protects the circuit from external faults. PIN CONFIGURATION N Package C1- C1+ AGND VBB 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 C2+ C2COM AGND DGND ST CS SCLK FEATURES DATAOUT DATAIN VCC OE * 10-Bit resolution (0.35 degrees) * Exceptional accuracy (0.5 degrees, typical) * High-torque capability * Active differential drivers eliminate back-EMF issues * No RFI/EMI generation issues * Simple serial interface * Simple cascading capability for multiple meters * Internal fault protection * Only one external component required (bypass capacitor) APPLICATION D Package C1- 1 C1+ 2 NC 3 NC 4 NC 5 AGND 6 28 27 26 25 24 23 22 21 20 19 18 17 16 15 C2+ C2NC NC COM AGND NC NC DGND ST NC NC CS SCLK * Instrumentation utilizing air-core meters VBB 7 DATAOUT DATAIN 8 9 NC 10 NC 11 NC 12 VCC 13 OE 14 SL00460 Figure 1. Pin configuration ORDERING INFORMATION DESCRIPTION 16-Pin Plastic Dual In-Line Package (DIP) 28-Pin Plastic Small Outline Package (SO) TEMPERATURE RANGE -40 to +85C -40 to +85C ORDER CODE SA5777AN SA5777AD DWG # SOT38-4 SOT136-1 1999 Sep 20 2 853-1930 022368 Philips Semiconductors Product specification Dual air-core gauge driver SA5777A BLOCK DIAGRAM VBB OE C2+ 7 + - BIT DAC MUX C2- VBB VBB/2 8 7 + - BIT DAC MUX COM C1+ 8 C1- CS VCC DIN SCLK 9-BIT LATCH 9-BIT LATCH FAULT DETECTION ST 10-BIT SHIFT REGISTER 10-BIT SHIFT REGISTER DOUT SL00461 Figure 2. Block diagram Table 1. SA5777A Pin Descriptions for the N Package (Dual In-Line) Pin # 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. DGND AGND COM C2- C2+ Name C1- C1+ AGND VBB DATAOUT DATAIN VCC OE SCLK CS ST Negative output connection to the TAN coil of meter #1. Positive output connection to the TAN coil of meter #1. Ground for VBB supply. Pins 3, 12 and 13 should be connected on the circuit board. Analog supply. Nominally 13.5 V. Serial data output. Output of the internal shift register. When a new data word is shifted in, the old word is shifted out the DATAOUT pin. DATAOUT output is always active. Serial data input. A new data word is serially shifted into the part on the rising edge of SCLK. The data is shifted in MSB first, gauge 1 first. 5 V logic supply. The internal latches and registers are set to zero on the rising edge of this signal. Output drivers are turned off when this input is low. Serial clock input. Data is loaded into the part on the rising edge of SCLK. Data is shifted out of DATAOUT on the falling edge of SCLK. Active high chip select input. When CS is high, the part is enabled to receive a new serial input word. The high-to-low transition of CS loads the new 20-bit word into the DAC registers and updates the output. Status output. This is an open drain output and goes low when the coil output buffers (C1+, C1-, C2+, C2-, COM) have been disabled. The coil outputs may be disabled due to shorted outputs, over-temperature conditions, power-on reset, or by the output enable (OE) pin. Multiple status outputs , ST, may be wire OR'ed together. Ground for VCC supply. Connect to Pins 3 and 13. Ground for VBB supply. Connect to Pins 3 and 12. Output drive for biased coils. This output will be 1/2 of VBB. Negative output connection to the TAN coil of meter #2. Positive output connection to the TAN coil of meter #2. Function 1999 Sep 20 3 Philips Semiconductors Product specification Dual air-core gauge driver SA5777A Table 2. SA5777A Pin Descriptions for the D Package (Small Outline) Pin # 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. DGND NC NC AGND COM NC NC C2- C2+ Name C1- C1+ NC NC NC AGND VBB DATAOUT DATAIN NC NC NC VCC OE SCLK CS NC NC ST Negative output connection to the TAN coil of meter #1. Positive output connection to the TAN coil of meter #1. No connect No connect No connect Ground for VBB supply. Pins 6, 20 and 23 should be connected on the circuit board. Analog supply. Nominally 13.5 V. Serial data output. Output of the internal shift register. When a new data word is shifted in, the old word is shifted out the DATAOUT pin. DATAOUT output is always active. Serial data input. A new data word is serially shifted into the part on the rising edge of SCLK. The data is shifted in MSB first, gauge 1 first. No connect No connect No connect 5 V logic supply. The internal latches and registers are set to zero on the rising edge of this signal. Output drivers are turned off when this input is low. Serial clock input. Data is loaded into the part on the rising edge of SCLK. Data is shifted out of DATAOUT on the falling edge of SCLK. Active high chip select input. When CS is high, the part is enabled to receive a new serial input word. The high-to-low transition of CS loads the new 20-bit word into the DAC registers and updates the output. No connect No connect Status output. This is an open drain output and goes low when the coil output buffers (C1+, C1-, C2+, C2-, COM) have been disabled. The coil outputs may be disabled due to shorted outputs, over-temperature conditions, power-on reset, or by the output enable (OE) pin. Multiple status outputs , ST, may be wire OR'ed together. Ground for VCC supply. Connect to Pins 6 and 23. No connect No connect Ground for VBB supply. Connect to Pins 6 and 20. Output drive for biased coils. This output will be 1/2 of VBB. No connect No connect Negative output connection to the TAN coil of meter #2. Positive output connection to the TAN coil of meter #2. Function ABSOLUTE MAXIMUM RATINGS SYMBOL VBB VCC VIN DGND to AGND TA TJ TSTG PD JA Analog supply Digital supply Digital input voltage, Data In, OE, CS, SCLK Ground difference Ambient operating temperature Junction temperature Storage temperature Power dissipation (TA = DIP and SO packages 25C)1 N, D packages PARAMETER RATING -1 to +23 -1 to +6 -1 to +6 0.5 -40 to +85 150 -65 to +150 1500 90 UNIT V V V V C C C mW C/W NOTE: 1. For power dissipation ratings in still air, derate above 25C at the following rates: N and D packages at 12mW/C 1999 Sep 20 4 Philips Semiconductors Product specification Dual air-core gauge driver SA5777A DC ELECTRICAL CHARACTERISTICS VBB = 7.5 to 18 V; VCC = 4.5 to 5.5 V; TA = -40 to +85C. SYMBOL VBB IIGN ICC VOH VOL VOL Status IOH Status VIH VIL IIH IIL ACC Input high voltage Input low voltage Input high current Input low current Output function accuracy2 PARAMETER Analog supply voltage Analog supply current Logic supply current Output high voltage Output low voltage VIGN = 18 V no load VBB = 18 V with load RC1 = RC2 = RLMIN VCC = 5.5 V Data out IOH = 800 A Data out IOL = 1.5 mA ST, IOL = 2.5 mA ST, VO (ST) = VCC CS, SCLK, DATAIN, OE CS, SCLK, DATAIN, OE CS, SCLK, DATAIN, VIN = 0.7 x VCC CS, SCLK, DATAIN, VIN = 0.3 x VCC RC1 = RC2 = RLMIN C1+, C1-, C2+, C2-, COM ISINK VBB = VBB (MAX) VBB = VBB (MIN) ISOURCE VBB = VBB (MAX) VBB = VBB (MIN) VBB = VBB (MAX) RL = RL (MIN) TA = 85C TA = 25C TA = -40C IOB (Source or Sink) RL = RL (MIN) 85 43 85 43 0.7 x VBB 215 171 138 0.475 x VBB 0.525 x VBB 0.7 x VCC 0.3 x VCC 1 1 1 500 300 500 300 0.8 x VBB VCC - 0.8 0.4 0.8 25 V V A V V A A Degree mA mA mA mA V V TEST CONDITIONS LIMITS MIN 7.5 TYP MAX 18 30 mA 235 1.0 mA UNIT V ISD Output shut-down current VDRIVE RLMIN VBIAS Differential coil drive voltage1 Minimum load resistance Bias voltage3 NOTE: 1. VDRIVE is the maximum voltage that is applied across the coil, it is equal to (C1+) - (C1-) or (C2+) - (C2-). 2. In reference to nominal values in Figure 4. (Based on 7+ bit DAC). 3. Output Angle (0) + tan -1 (C )) - (C-) V BB - V BIAS AC ELECTRICAL CHARACTERISTICS VDD = 7.5 to 18 V; VCC = 4.5 to 5.5 V; TA = -40 to +85C SYMBOL FSCLK TSCLKH TSCLKL TRO TFO TSU THI TCSH TCSL PARAMETER Input frequency SCLK high time SCLK low time Output rise time DO Output fall time DO DI set-up time DI hold time Time before first SCLK rising edge Time after last SCLK falling edge VCC = 5.5 V 0.75 to VCC -1.2 V, CL = 90 pF VCC -1.2 V to 0.75, CL = 90 pF 75 75 75 75 175 175 75 75 TEST CONDITIONS LIMITS MIN TYP MAX 1.60 UNIT MHz ns ns ns ns ns ns ns ns 1999 Sep 20 5 Philips Semiconductors Product specification Dual air-core gauge driver SA5777A FUNCTIONAL DESCRIPTION The SA5777A dual air-core gauge driver logic Block Diagram shows the two 10-bit input shift registers and two 9-bit parallel latches, and two 7+-bit DACs. The MSB is a dummy bit required for compatibility with the SA5775A. The DACs generate output voltages that are offset within the supply rails to give the output buffers enough headroom to operate. With a 14 V supply, the typical output swing is from 1 V to 11.5 V. The MUX generates the two required quadrants by switching the 56 data from the DAC to the appropriate output buffer. The output buffers provide the necessary current to drive the air-core gauge. The output buffers are always connected to the coils and can sink and source sufficient current so that inductive kickback is eliminated during normal operation. The primary function of the SA5777A IC is to generate the transfer function that maps an input code into the correct voltages for linearly controlling the coils of an air-core gauge display (Figure 3). The SA5777A has been implemented using the tangent drive algorithm. Therefore, one coil on each meter will be driven with an output approximating the tangent function, the other coils will be biased at 1/2 VBB. The internal DAC is designed to operate over a 7+ bit (56) data range. An extended range can be achieved by changing the relationship between the bias coil and the driver coil. As the current through the bias coil is reduced, the full scale deflection is increased. Theoretically, this deflection could approach 180, but practical limitations of accuracy, resolution, and torque restrict the full scale range to approximately 112 (Figure 4). This full scale range corresponds to a bias coil voltage of 0.5 x VBB and a full scale tangent voltage of 0.744 x VBB. The DAC has been tailored to maintain the meter accuracy at this maximum deflection. The 0.5 x VBB bias coil voltage is obtained by connecting the bias coils of the two meters in series across VBB. This gives bias stability over temperature. The internal bias generator is used to offset any inaccuracies due to meter mismatches. This circuit receives commands via an internal serial data interface port which is SPI compatible. These parts can be serially cascaded with other SA5777A ICs and/or SA5775A ICs to interface signals in multi-chip systems. The SA5777A has a typical resolution of 0.35 over a full scale deflection of approximately 112 and is guaranteed to be monotonic. The input data is directly proportional to the displayed angle in degrees (Figure NO TAG). Input code 0 gives an output angle of 0, code 319 (decimal) will generate a full scale output of 112.15. Codes higher than decimal 319 will not be loaded into the DAC latches and will leave the coil output buffers unchanged. However, codes greater than 319 can be shifted through the SA5777A intact if other parts are cascaded. The SA5777A is capable of sourcing and sinking up to 100mA per differential driver to control either one or two air-core gauge displays directly. On-chip overcurrent and thermal shut-down logic prevents the chip from overheating due to high current fault conditions. When a shut-down condition is detected, the protection circuit disables the coil output buffers (i.e., C1+, C1-, C2+, C2-, COM). The coil output buffers remain in this condition until the first falling edge of CS that occurs after the die temperature has decreased to about 140C or the overcurrent condition has been removed. During shut-down, the digital portion of this IC continues to operate normally. 14.00 12.00 10.00 8.00 6.00 C+ - C- (VOLTS) 4.00 2.00 0.00 -2.00 -4.00 -6.00 -8.00 -10.00 -12.00 -14.00 31 63 95 127 159 INPUT CODE 191 223 255 287 319 SL00462 Figure 3. Typical output voltage vs input code (VBB = 14 V) 1999 Sep 20 6 Philips Semiconductors Product specification Dual air-core gauge driver SA5777A 0.5 x VBB ASSUMING CODE 0 IS 0: CODE 0 31 63 POSITION -56.097 -45.194 -33.940 -22.685 -11.430 -0.176 11.079 22.333 33.588 44.843 56.097 -56 +56 95 127 159 191 -0.744 x VBB TOTAL SPAN = 112.15 STEP SIZE = 0.35 0.744 x VBB 223 255 287 319 IDEAL ANGLE(DEGREE)=CODE/319*2* ArcTan (0.744/0.5)-ArcTan(0.744/0.5) SL00463 Figure 4. Total span 120 100 80 ANGLE (DEGREES) 60 40 20 0 0 15 31 41 63 79 95 111 127 159 175 143 INPUT CODE 191 207 223 239 255 271 287 303 319 SL00464 Figure 5. Meter position (degrees) vs input code 1999 Sep 20 7 Philips Semiconductors Product specification Dual air-core gauge driver SA5777A CS 20 SCLK CYCLES TCSH 1 SCLK FSCLK 2 19 TSCLKL 20 TSCLKH TCSL 80% DATAIN D19 D18 D1 20% THI TSU D0 DATAOUT D19* D18* D1* D0* TFO TRO GAUGE 2 D0 LSB *DO IS THE PREVIOUSLY LOADED DATA WORD D1 D2 D3 D4 D5 D6 D7 D8 D9 GAUGE 1 D10 D11 D12 D13 D14 D15 D16 D17 D18 D19 MSB MSB LSB SL00465 Figure 6. Serial interface timing Serial Interface The SA5777A is controlled through a serial interface with the following control functions (reference Figure 6): SCLK CS DATAIN DATAOUT Serial input clock. When CS is high, the rising edge of SCLK shifts a new data bit into the SA5777A and the falling edge shifts the data out of DATAOUT. Active high chip select. Enables the SA5777A to receive serial input data. The falling edge of CS loads a new 20-bit data word into the internal DAC registers which updates the tangent coil output buffers (C1+, C1-, C2+, C2-). Serial data input. The data at this pin is shifted into the internal shift register on the rising edge of SCLK. Data is shifted in MSB first, gauge 1 first. Serial data output. This pin is the output of the internal shift register. The data output on this pin is the input data from DATAIN pin delayed by 20 clock cycles. This pin can be used to cascade several SA5777As with one CS line to load all of the SA5777As concurrently. 4. Due to excessive power dissipation (i.e., thermal shut-down). The die temperature must go below 140C before a falling edge on the CS pin will clear this fault condition and allow the coil outputs to go active. Power Moding The SA5777A has a power-on reset capability. On the rising edge of VCC, the internal latches and registers are set to zero and the coil output buffers (C1+, C1-, C2+, C2-, COM) are disabled. Coil Output Buffer Control The coil buffers (C1+, C1-, C2+, C2-, COM) are disabled: 1. With the rising edge of VCC (power-on reset). 2. When OE is taken low or held low. The data registers for the outputs can still be updated while OE is low. When OE is taken high, the current output data value is displayed. A falling edge on CS will be required to activate the outputs if a fault condition has occurred prior to the OE going high. 3. Due to an overcurrent condition on either of the coil output buffers. The coil output buffers will be enabled after the next CS high-to-low transition; assuming OE is high. If the overcurrent condition has not been removed, the outputs will immediately return to their disabled condition. The ST pin will indicate status of the coil outputs. Application Notes The air-core gauge is constructed of two coils would on a cavity at 90 to each other. Inside the cavity there is a disk which is magnetized on its diameter. The currents through the coils generate a resultant magnetic vector that causes the magnetic disc to move until the magnetic fields are aligned. If the ratio of the currents in the two coils follows the tangent function, then the transfer characteristic relating the input data to output angle is linear. Maximum current is when output is at zero and full scale degrees, TA = -40C, and RL = 180. Copper wire has a typical temperature coefficient of 0.4%/C 1999 Sep 20 8 Philips Semiconductors Product specification Dual air-core gauge driver SA5777A DIP16: plastic dual in-line package; 16 leads (300 mil) SOT38-4 1999 Sep 20 9 Philips Semiconductors Product specification Dual air-core gauge driver SA5777A SO28: plastic small outline package; 28 leads; body width 7.5mm SOT136-1 1999 Sep 20 10 Philips Semiconductors Product specification Dual air-core gauge driver SA5777A NOTES 1999 Sep 20 11 Philips Semiconductors Product specification Dual air-core gauge driver SA5777A Data sheet status Data sheet status Objective specification Preliminary specification Product specification Product status Development Qualification Definition [1] This data sheet contains the design target or goal specifications for product development. Specification may change in any manner without notice. This data sheet contains preliminary data, and supplementary data will be published at a later date. Philips Semiconductors reserves the right to make changes at any time without notice in order to improve design and supply the best possible product. This data sheet contains final specifications. Philips Semiconductors reserves the right to make changes at any time without notice in order to improve design and supply the best possible product. Production [1] Please consult the most recently issued datasheet before initiating or completing a design. Definitions Short-form specification -- The data in a short-form specification is extracted from a full data sheet with the same type number and title. For detailed information see the relevant data sheet or data handbook. Limiting values definition -- Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended periods may affect device reliability. Application information -- Applications that are described herein for any of these products are for illustrative purposes only. Philips Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or modification. Disclaimers Life support -- These products are not designed for use in life support appliances, devices or systems where malfunction of these products can reasonably be expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application. Right to make changes -- Philips Semiconductors reserves the right to make changes, without notice, in the products, including circuits, standard cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless otherwise specified. Philips Semiconductors 811 East Arques Avenue P.O. Box 3409 Sunnyvale, California 94088-3409 Telephone 800-234-7381 (c) Copyright Philips Electronics North America Corporation 1999 All rights reserved. Printed in U.S.A. Date of release: 09-99 Document order number: 9397 750 06444 Philips Semiconductors 1999 Sep 20 12 |
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