Datasheet SA5777A Datasheet (Philips)

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INTEGRATED CIRCUITS

SA5777A

Dual air–core gauge driver

Product specification Supersedes data of 1997 Feb 24

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1999 Sep 20

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Philips Semiconductors Product specification

SA5777ADual air-core gauge driver

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.

FEATURES

•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

•Instrumentation utilizing air-core meters

PIN CONFIGURATION

C1–

C1+

GND

DATA

OUT

C1– C1+

2 3

NC NC

4 5

GND

OUT

NC NC NC

11 12

NC NC

N Package

D Package

C2+

C2-

COM

GND

CLK

C2+ C2-

26 25

COM

GND

21 20

GND

18 17 16

CLK

SL00460

Figure 1. Pin configuration

ORDERING INFORMATION

DESCRIPTION TEMPERATURE RANGE ORDER CODE DWG #

16-Pin Plastic Dual In-Line Package (DIP) 28-Pin Plastic Small Outline Package (SO)

1999 Sep 20 853-1930 022368

-40 to +85°C

SA5777AN SOT38-4 SA5777AD SOT136-1

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Philips Semiconductors Product specification

SA5777ADual air-core gauge driver

BLOCK DIAGRAM

7 + – BIT

DAC

MUX

C2+

C2–

V D

CC IN

CLK

7 + – BIT

DAC

9-BIT LATCH

10-BIT

SHIFT REGISTER

MUX

9-BIT LATCH

10-BIT

SHIFT REGISTER

Figure 2. Block diagram

Table 1. SA5777A Pin Descriptions for the N Package (Dual In-Line)

Pin # Name Function

1. C1– Negative output connection to the TAN coil of meter #1.

2. C1+ Positive output connection to the TAN coil of meter #1.

3. A

GND

4. V DATA

DATAINSerial data input. A new data word is serially shifted into the part on the rising edge of S

7. V

8. OE Output drivers are turned off when this input is low.

10.

CLK

CS Active high chip select input. When CS is high, the part is enabled to receive a new serial input word. The high-to-low

ST Status output. This is an open drain output and goes low when the coil output buffers (C1+, C1–, C2+, C2–, COM) have

11.

12. D

13. A

GND GND

14. COM Output drive for biased coils. This output will be 1/2 of VBB.

15. C2– Negative output connection to the TAN coil of meter #2.

16. C2+ Positive output connection to the TAN coil of meter #2.

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

OUT

DATA

pin. DATA

OUT

output is always active.

OUT

first, gauge 1 first. 5 V logic supply. The internal latches and registers are set to zero on the rising edge of this signal.

Serial clock input. Data is loaded into the part on the rising edge of S edge of S

CLK

transition of CS loads the new 20-bit word into the DAC registers and updates the output.

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.

VBB/2

FAULT

DETECTION

. The data is shifted in MSB

CLK

. Data is shifted out of DATA

CLK

COM

C1+

C1–

SL00461

OUT

on the falling

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Philips Semiconductors Product specification

SA5777ADual air-core gauge driver

Table 2. SA5777A Pin Descriptions for the D Package (Small Outline)

Pin # Name Function

1. C1– Negative output connection to the TAN coil of meter #1.

2. C1+ Positive output connection to the TAN coil of meter #1.

3. NC No connect

4. NC No connect

5. NC No connect

6. A

GND

7. V DATA

DATAINSerial data input. A new data word is serially shifted into the part on the rising edge of S

10. NC No connect

11. NC No connect

12. NC No connect

13. V

14. OE Output drivers are turned off when this input is low. S

15.

16.

CLK

CS Active high chip select input. When CS is high, the part is enabled to receive a new serial input word. The high-to-low

17. NC No connect

18. NC No connect

ST Status output. This is an open drain output and goes low when the coil output buffers (C1+, C1–, C2+, C2–, COM) have

19.

20. D

GND

21. NC No connect

22. NC No connect

23. A

GND

24. COM Output drive for biased coils. This output will be 1/2 of VBB.

25. NC No connect

26. NC No connect

27. C2– Negative output connection to the TAN coil of meter #2.

28. C2+ Positive output connection to the TAN coil of meter #2.

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

OUT

the DATA

first, gauge 1 first.

5 V logic supply. The internal latches and registers are set to zero on the rising edge of this signal.

Serial clock input. Data is loaded into the part on the rising edge of S edge of S

pin. DATA

OUT

CLK

output is always active.

OUT

. The data is shifted in MSB

CLK

. Data is shifted out of DATA

CLK

transition of CS loads the new 20-bit word into the DAC registers and updates the output.

Ground for VCC supply. Connect to Pins 6 and 23.

Ground for VBB supply. Connect to Pins 6 and 20.

on the falling

OUT

ABSOLUTE MAXIMUM RATINGS

SYMBOL PARAMETER RATING UNIT

to A T T T

GND

STG D

GND

NOTE:

1. For power dissipation ratings in still air, derate above 25°C at the following rates: N and D packages at 12mW/°C

1999 Sep 20

Analog supply -1 to +23 V Digital supply -1 to +6 V Digital input voltage, Data In, OE, CS, S

CLK

-1 to +6 V

Ground difference ±0.5 V Ambient operating temperature –40 to +85 Junction temperature 150 Storage temperature –65 to +150

Power dissipation (TA = 25°C)

N, D packages 1500 mW

DIP and SO packages 90

°C °C °C

°C/W

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Philips Semiconductors Product specification

SYMBOL

PARAMETER

TEST CONDITIONS

UNIT

SYMBOL

PARAMETER

TEST CONDITIONS

UNIT

SA5777ADual air-core gauge driver

DC ELECTRICAL CHARACTERISTICS

VBB = 7.5 to 18 V; VCC = 4.5 to 5.5 V; TA = –40 to +85°C.

LIMITS

MIN TYP MAX

IGN

VOL Status ST, IOL = 2.5 mA 0.8 V IOH Status ST, VO (ST) = V V

DRIVE

LMIN

BIAS

NOTE:

1. V

DRIVE

2. In reference to nominal values in Figure 4. (Based on 7+ bit DAC).

Output Angle (0) + tan

Analog supply voltage 7.5 18 V

Analog supply current

= 18 V no load

IGN

VBB = 18 V with load

RC1 = RC2 = R

LMIN

235

Logic supply current VCC = 5.5 V 1.0 mA Output high voltage Data out IOH = 800 µA VCC – 0.8 Output low voltage Data out IOL = 1.5 mA 0.4 V

25 µA

1 µA 1 µA

±1 Degree

Input high voltage CS, S Input low voltage CS, S Input high current CS, S Input low current CS, S Output function accuracy

, DATAIN, VIN = 0.7 x V

CLK

, DATAIN, VIN = 0.3 x V

CLK

RC1 = RC2 = R

, DATAIN, OE 0.7 x V

CLK

, DATAIN, OE 0.3 x V

CLK

CC CC

LMIN

C1+, C1–, C2+, C2–, COM

Output shut-down current

Differential coil drive voltage

Minimum load resistance

Bias voltage

SINK

SOURCEVBB

VBB = V

BB (MAX)

VBB = V

BB (MIN)

= V

BB (MAX)

VBB = V

BB (MIN)

VBB = V

BB (MAX)

RL = R

L (MIN)

TA = 85°C TA = 25°C

TA = –40°C

IOB (Source or Sink)

RL = R

L (MIN)

85 43 85 43

0.7 x V 215

171 138

0.475 x V

500 300 500 300

0.8 x V

0.525 x V

is the maximum voltage that is applied across the coil, it is equal to (C1+) – (C1–) or (C2+) – (C2–).

(C ))–(C–)

–1

–V

BIAS

V V

mA mA mA mA

Ω Ω Ω

AC ELECTRICAL CHARACTERISTICS

VDD = 7.5 to 18 V; VCC = 4.5 to 5.5 V; TA = –40 to +85°C

LIMITS

MIN TYP MAX

CLK

CLKH

CLKL

TRO Output rise time DO 0.75 to VCC –1.2 V, CL = 90 pF 75 ns TFO Output fall time DO VCC –1.2 V to 0.75, CL = 90 pF 75 ns TSU DI set-up time 75 ns THI DI hold time 75 ns T

CSH

CSL

1999 Sep 20

Input frequency 1.60 MHz S

high time 175 ns

CLK

low time VCC = 5.5 V 175 ns

CLK

Time before first S Time after last S

rising edge 75 ns

CLK

falling edge 75 ns

CLK

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Philips Semiconductors Product specification

SA5777ADual air-core gauge driver

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 V

. 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 V tangent voltage of 0.744 x V

. The DAC has been tailored to

and a full scale

maintain the meter accuracy at this maximum deflection. The 0.5 x

bias coil voltage is obtained by connecting the bias coils of the

two meters in series across V

. 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 140°C or the overcurrent condition has been removed. During shut-down, the digital portion of this IC continues to operate normally.

C+ – C– (VOLTS)

–10.00

–12.00

–14.00

14.00

12.00

10.00

8.00

6.00

4.00

2.00

0.00

–2.00

–4.00

–6.00

–8.00

31 63 95 127 159 191 223 255 287 319

INPUT CODE

SL00462

Figure 3. Typical output voltage vs input code (VBB = 14 V)

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Philips Semiconductors Product specification

SA5777ADual air-core gauge driver

–0.744 x V

120

100

0.5 x V

+56°–56°

TOTAL SPAN = 112.15° STEP SIZE = 0.35°

0.744 x V

Figure 4. Total span

ASSUMING CODE 0 IS 0°:

CODE

31 63

95 127 159 191 223 255 287 319

IDEAL ANGLE(DEGREE)=CODE/319*2* ArcTan (0.744/0.5)–ArcTan(0.744/0.5)

POSITION

–56.097 –45.194 –33.940 –22.685 –11.430

–0.176

11.079

22.333

33.588

44.843

56.097

SL00463

ANGLE (DEGREES)

01531 637995111127143

Figure 5. Meter position (degrees) vs input code

159 175 191 207 223 239 255 271 287 30341

INPUT CODE

319

SL00464

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Philips Semiconductors Product specification

SA5777ADual air-core gauge driver

20 S

CYCLES

CLK

TSU

THI

80%

20%

CLKL

CLKH

DATA

CLK

CSH

1 2 19 20

D19 D18 D1 D0

CLK

DATA

OUT

D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17 D18 D19

LSB

*DO IS THE PREVIOUSLY LOADED DATA WORD

D19* D18* D1* D0*

TFO TRO

GAUGE 2 GAUGE 1

MSB LSB MSB

SL00465

Figure 6. Serial interface timing

Serial Interface

The SA5777A is controlled through a serial interface with the following control functions (reference Figure 6):

CLK

Serial input clock. When CS is high, the rising edge of S the data out of DATA

OUT

CS 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–).

DATA

Serial data input. The data at this pin is shifted into the internal shift register on the rising edge of S

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 DATA

OUT

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.

Power Moding

The SA5777A has a power-on reset capability. On the rising edge of V

, the internal latches and registers are set to zero and the coil

output buffers (C1+, C1–, C2+, C2–, COM) are disabled.

shifts a new data bit into the SA5777A and the falling edge shifts

CLK

. Data is shifted in MSB

CLK

4. Due to excessive power dissipation (i.e., thermal shut-down). The die temperature must go below 140°C before a falling edge on the CS pin will clear this fault condition and allow the coil outputs to go active.

Coil Output Buffer Control

The coil buffers (C1+, C1–, C2+, C2–, COM) are disabled:

1. With the rising edge of V

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.

1999 Sep 20

(power-on reset).

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, T

= –40°C, and RL = 180.

Copper wire has a typical temperature coefficient of 0.4%/C

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Philips Semiconductors Product specification

SA5777ADual air–core gauge driver

DIP16: plastic dual in-line package; 16 leads (300 mil) SOT38-4

1999 Sep 20

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Philips Semiconductors Product specification

SA5777ADual air–core gauge driver

SO28: plastic small outline package; 28 leads; body width 7.5mm SOT136-1

1999 Sep 20

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Philips Semiconductors Product specification

SA5777ADual air–core gauge driver

NOTES

1999 Sep 20

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Philips Semiconductors Product specification

SA5777ADual air–core gauge driver

Data sheet status

Objective specification

Preliminary specification

Product specification

Product status

Development

Qualification

Production

Definition

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.

[1]

[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

 Copyright Philips Electronics North America Corporation 1999

Date of release: 09-99

Document order number: 9397 750 06444

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1999 Sep 20