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CS8191
CS8191
Precision Air-Core Tach/Speedo Driver with Short Circuit Protection
Description
The CS8191 is specifically designed for use with 4 quadrant air-core meter movements. The IC includes an input comparator for sensing input frequency such as vehicle speed or engine RPM, a charge pump for frequency to voltage conversion, a bandgap reference for stable operation and a function generator with sine and cosine amplifiers that differentially drive the motor coils. The CS8191 has a higher torque output and better output signal symmetry than other competitive parts (CS289, and LM1819). It is protected against short circuit and overvoltage (60V) fault conditions. Enhanced circuitry permits functional operation down to 8V.
Features
s Direct Sensor Input s High Output Torque s Wide Output Voltage Range s High Impedance Inputs s Accurate down to 10V VCC s Fault Protection Overvoltage Short Circuit s Low Voltage Operation
Absolute Maximum Ratings
( 100ms pulse transient) ...........................................VCC = 60V (continuous) ..................................................................VCC = 24V Operating Temperature Range ........................................................-40C to +105C Junction Temperature Range ...........................................................-40C to +150C Storage Temperature Range.............................................................-55C to +165C Electrostatic Discharge (Human Body Model) ...................................................4kV Lead Temperature Soldering Wave Solder (through hole styles only)..................10 sec. max, 260C peak Reflow (SMD styles only)...................60 sec. max above 183C, 230C peak Supply Voltage
Package Options
16 Lead PDIP (internally fused leads)
VCC 1 VREG 2 BIAS 3 Gnd 4 Gnd 5
16 15 14 13 12 11 10 9
F/VOUT CP+ CPGnd Gnd COS+ SINE+ SQOUT
Block Diagram
+ Charge Pump Input Comp. Voltage Regulator VREG COS Output Function Generator + COSHigh Voltage, Short Circuit Protection + + SINE VREG 7.0V Gnd SINE Output + + BIAS CP+ SQOUT FREQIN
F/VOUT CP-
COS- 6 SINE- 7 FREQIN 8
20 Lead SOIC (internally fused leads)
VCC 1 VREG 2 BIAS 3
20 19 18 17 16 15 14 13 12 11
Gnd Gnd COS+
Gnd
F/VOUT CP+ CPNC Gnd Gnd NC COS+ SIN+ SQOUT
SINE+
NC 4 Gnd 5 Gnd 6 NC 7 COS- 8 SIN- 9 FREQIN 10
VCC
Cherry Semiconductor Corporation 2000 South County Trail, East Greenwich, RI 02818 Tel: (401)885-3600 Fax: (401)885-5786 Email: info@cherry-semi.com Web Site: www.cherry-semi.com
Rev 3/9/99
1
A
Company
CS8191
Electrical Characteristics: -40C TA 105C, 8V VCC 16V unless otherwise specified.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
s Supply Voltage Section ICC Supply Current VCC Normal Operation Range s Input Comparator Section Positive Input Threshold Negative Input Threshold Input Hysteresis Input Bias Current * Input Frequency Range Input Voltage Range Output VSAT Output Leakage Logic 0 Input Voltage
*Note: Input is clamped by an internal 12V Zener.
VCC = 16V, -40C, No Load 8.0
70 13.1
125 16.0
mA V
2.4 2.0 200 0V VIN 8V 0 in series with 1k1/2 ICC = 10mA VCC = 7V 2.0 -1
2.7 2.3 400 -2
3.0 1000 10 20 VCC
V V mV A kHz V V A V
0.15
0.40 10
s Voltage Regulator Section Output Voltage Output Load Current Output Load Regulation Output Line Regulation Power Supply Rejection s Charge Pump Section Inverting Input Voltage Input Bias Current VBIAS Input Voltage Non Invert. Input Voltage Linearity* F/VOUT Gain Norton Gain, Positive Norton Gain, Negative
*Note: Applies to % of full scale (270).
6.50 0 to 10 mA 8.0V VCC 16V VCC = 13.1V, 1VP/P 1kHz 34
7.00 10 20 46
7.50 10 50 150
V mA mV mV dB
1.5 1.5 IIN = 1mA @ 0, 87.5, 175, 262.5, + 350Hz @ 350Hz, CT = 0.0033F, RT = 243k1/2 IIN = 15A IIN = -15A -0.10 7 0.9 0.9
2.0 40 2.0 0.7 0.28 10 1.0 1.0
2.5 150 2.5 1.1 +0.70 13 1.1 1.1
V nA V V % mV/Hz I/I I/I
s Function Generator Section: -40 TA 85C, VCC = 13.1V unless otherwise noted. Differential Drive Voltage (VCOS+ - VCOS-) Differential Drive Voltage (VSIN+ - VSIN-) Differential Drive Voltage (VCOS+ - VCOS-) Differential Drive Voltage (VSIN+ - VSIN-) Differential Drive Load 10V VCC 16V Q = 0 10V VCC 16V Q = 90 10V VCC 16V Q = 180 10V VCC 16V Q = 270 10V VCC 16V, -40C 25C 105C 2 7.5 7.5 -8.5 -8.5 178 239 314 -0.08 0.0 +0.08 8.0 8.0 -8.0 -8.0 8.5 8.5 -7.5 -7.5 V V V V 1/2 1/2 1/2 V
Zero Hertz Output Voltage
CS8191
Electrical Characteristics: continued
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
s Function Generator Section: continued Function Generator Error * Reference Figures 1 - 4 Function Generator Error Function Generator Error Function Generator Error Function Generator Error Function Generator Error Function Generator Error Function Generator Gain Q = 0 to 225 Q = 226 to 305 13.1V VCC 16V 13.1V VCC 10V 13.1V VCC 8.0V 25C TA 80C 25C TA 105C 40C TA 25C TA = 25C, Q vs F/VOUT -2 -3 -1 -1 -7 -2 -4 -2 60 0 0 0 0 0 0 0 0 77 +2 +3 +1 +1 +7 +2 +4 +2 95 deg deg deg deg deg deg deg deg /V
*Note: Deviation from nominal per Table 1 after calibration at 0 and 270.
Package Lead Description
PACKAGE LEAD # LEAD SYMBOL FUNCTION
16L PDIP 1 2 3 4, 5, 12, 13 6 7 8 9 10 11 14 15 16
20L SO 1 2 3 5, 6, 15, 16 8 9 10 11 12 13 18 19 20 4, 7, 14, 17 VCC VREG BIAS Gnd COSSINFREQIN SQOUT SIN+ COS+ CPCP+ F/VOUT NC Ignition or battery supply voltage. Voltage regulator output. Test point or zero adjustment. Ground Connections. Negative cosine output signal. Negative sine output signal. Speed or rpm input signal. Buffered square wave output signal. Positive sine output signal. Positive cosine output signal. Negative input to charge pump. Positive input to charge pump. Output voltage proportional to input signal frequency. No connection.
Typical Performance Characteristics
Figure 1: Function Generator Output Voltage vs Degrees of Deflection
7 6 5 4 6
Figure 2: Charge Pump Output Voltage vs Output Angle F/VOUT = 2.0V + 2 FREQ CT RT (VREG - 0.7)
7
COS
5
Output Voltage (V)
1 0 -1 -2 -3 -4 -5 -6 -7 0 45 90 135 180 225 270 315
F/V Output (V) SIN
3 2
4 3
2 1 0 0 45 90 135 180 225 270 315
Degrees of Deflection ()
Frequency/Output Angle ()
3
CS8191
Typical Performance Characteristics: continued
Figure 3: Output Angle in Polar Form
1.50
7V (VSINE+) - (VSINE-)
Figure 4: Nominal Output Deviation
1.25 1.00 0.75 Deviation () 0.50 0.25 0.00 -0.25 -0.50 -0.75 -1.00 -1.25 -1.50 0 45 90
Q 7V
Angle +7V
(VCOS+) - (VCOS-)
Q = ARCTAN
[
VSIN+ VSINVCOS+ VCOS-
]
-7V
135 180 Theoretical Angle ()
225
270
315
Nominal Angle vs. Ideal Angle (After calibrating at 180)
Note: Temperature, voltage and nonlinearity not included.
45 40 35 30 Ideal Angle (Degrees) 25 20
Ideal Degrees
15
Nominal Degrees
10 5 0 1 5 9 13 17 21 25 29 33 37 41 45
Nominal Angle (Degrees)
Table 1: Function Generator Output Nominal Angle vs. Ideal Angle (After calibrating at 270)
Ideal Q Degrees Nominal Q Degrees Ideal Q Nominal Degrees Q Degrees Ideal Q Nominal Degrees Q Degrees Ideal Q Degrees Nominal Q Degrees Ideal Q Nominal Degrees Q Degrees Ideal Q Nominal Degrees Q Degrees
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
0 1.09 2.19 3.29 4.38 5.47 6.56 7.64 8.72 9.78 10.84 11.90 12.94 13.97 14.99 16.00 17.00
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
17.98 18.96 19.92 20.86 21.79 22.71 23.61 24.50 25.37 26.23 27.07 27.79 28.73 29.56 30.39 31.24 32.12
34 35 36 37 38 39 40 41 42 43 44 45 50 55 60 65 70
33.04 34.00 35.00 36.04 37.11 38.21 39.32 40.45 41.59 42.73 43.88 45.00 50.68 56.00 60.44 64.63 69.14 4
75 80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155
74.00 79.16 84.53 90.00 95.47 100.84 106.00 110.86 115.37 119.56 124.00 129.32 135.00 140.68 146.00 150.44 154.63
160 165 170 175 180 185 190 195 200 205 210 215 220 225 230 235 240
159.14 164.00 169.16 174.33 180.00 185.47 190.84 196.00 200.86 205.37 209.56 214.00 219.32 225.00 230.58 236.00 240.44
245 250 255 260 265 270 275 280 285 290 295 300 305
244.63 249.14 254.00 259.16 264.53 270.00 275.47 280.84 286.00 290.86 295.37 299.21 303.02
Note: Temperature, voltage and nonlinearity not included.
CS8191
Circuit Description and Application Notes The CS8191 is specifically designed for use with air-core meter movements. It includes an input comparator for sensing an input signal from an ignition pulse or speed sensor, a charge pump for frequency to voltage conversion, a bandgap voltage regulator for stable operation, and a function generator with sine and cosine amplifiers to differentially drive the motor coils. From the simplified block diagram of Figure 5A, the input signal is applied to the FREQIN lead, this is the input to a high impedance comparator with a typical positive input threshold of 2.7V and typical hysteresis of 0.4V. The output of the comparator, SQOUT, is applied to the charge pump input CP+ through an external capacitor CT. When the input signal changes state, CT is charged or discharged through R3 and R4. The charge accumulated on CT is mirrored to C4 by the Norton Amplifier circuit comprising of Q1, Q2 and Q3. The charge pump output voltage, F/VOUT, ranges from 2V to 6.3V depending on the input signal frequency and the gain of the charge pump according to the formula: F/VOUT = 2.0V + 2 FREQ CT RT (VREG 0.7V) RT is a potentiometer used to adjust the gain of the F/V output stage and give the correct meter deflection. The F/V output voltage is applied to the function generator which generates the sine and cosine output voltages. The output voltage of the sine and cosine amplifiers are derived from the on-chip amplifier and function generator circuitry. The various trip points for the circuit (i.e., 0, 90, 180, 270) are determined by an internal resistor divider and the bandgap voltage reference. The coils are differentially driven, allowing bidirectional current flow in the outputs, thus providing up to 305 range of meter deflection. Driving the coils differentially offers faster response time, higher current capability, higher output voltage swings, and reduced external component count. The key advantage is a higher torque output for the pointer. The output angle, Q, is equal to the F/V gain multiplied by the function generator gain: Q = AF/V AFG, where: /V AFG = 77 (typ) The relationship between input frequency and output angle is: Q = AFG 2 FREQ CT RT (VREG 0.7V) or, Q = 970 FREQ CT RT The ripple voltage at the F/V converterOs output is determined by the ratio of CT and C4 in the formula: AEV = CT(VREG 0.7V) C4
Design Example
Maximum meter Deflection = 270 Maximum Input Frequency = 350Hz 1. Select RT and CT Q = AGEN AEF/V AEF/V = 2 FREQ CT RT (VREG 0.7V) Q = 970 FREQ CT RT Let CT = 0.0033F, Find RT 270 RT = 970 350Hz 0.0033F RT = 243k1/2 RT should be a 250k1/2 potentiometer to trim out any inaccuracies due to IC tolerances or meter movement pointer placement. 2. Select R3 and R4 Resistor R3 sets the output current from the voltage regulator. The maximum output current from the voltage regulator is 10mA, R3 must ensure that the current does not exceed this limit. Choose R3 = 3.3k1/2 The charge current for CT is: VREG 0.7V = 1.90mA 3.3k1/2 C1 must charge and discharge fully during each cycle of the input signal. Time for one cycle at maximum frequency is 2.85ms. To ensure that CT is discharged, assume that the (R3 + R4) CT time constant is less than 10% of the minimum input frequency pulse width. T = 285s Choose R4 = 1k1/2. Charge time: T = R3 CT = 3.3k1/2 0.0033F = 10.9s Discharge time:T = (R3 + R4)CT = 4.3k1/2 0.0033F = 14.2s 3. Determine C4 C4 is selected to satisfy both the maximum allowable ripple voltage and response time of the meter movement. C4 = CT(VREG 0.7V) VRIPPLE(MAX)
Ripple voltage on the F/V output causes pointer or needle flutter especially at low input frequencies. The response time of the F/V is determined by the time constant formed by RT and C4. Increasing the value of C4 will reduce the ripple on the F/V output but will also increase the response time. An increase in response time causes a very slow meter movement and may be unacceptable for many applications. 5
With C4 = 0.47F, the F/V ripple voltage is 44mV. Figure 7 shows how the CS8191 and the CS8441 are used to produce a Speedometer and Odometer circuit.
CS8191
Circuit Description and Application Notes: continued
VREG 2.5V R3 VC(t) + FREQIN
+
F/VOUT
+
F to V RT C4
0.25V
Q3
CP
SQOUT
CT QSQUARE
R4
CP+ Q1 Q2
2.7V
Figure 5A: Partial Schematic of Input and Charge Pump
T PW VCC FREQIN 0 VREG T-PW
SQOUT 0
ICP+
VCP+ 0
Figure 5B: Timing Diagram of FREQIN and ICP
6
CS8191
Speedometer/Odometer or Tachometer Application
Battery
1
CP+ VCC VREG BIAS
F/VOUT16 CP+ 15 CP- 14 C4 + RT
D1 Ground
R1 D2 C1
Battery
1
2 3 4 5 6 7 8
VCC CP+ VREG BIAS
F/VOUT 16 CP+ 15 CP- 14 C4 + RT
D1 Ground
R1 D2 C1
2 3
CS8191
Gnd Gnd COSSINEFREQIN
Gnd 13 Gnd 12 COS+ 11 SINE+ 10 SQOUT 9 R4 CT R3
CS8191
4 Gnd 5 6 7 8
Gnd 13 Gnd 12 COS+ 11 SINE+ 10 SQOUT 9 R4 R3 CT
Gnd COSSINE-
R2 C3
SINE
R2 C3
FREQIN
SINE
Typical Speedometer Input Air Core Gauge Speedometer
Typical Speedometer Input
COSINE
COSINE
Air Core Gauge Speedometer
C2
1
CS8441
Figure 6 R1 - 3.9, 500mW R2 - 10k1/2 R3 - 3k1/2 R4 - 1k1/2 RT - Trim Resistor +/- 20 PPM/DEG. C C1 - 0.1F C2 - With CS-8441 application, 10F C3 - 0.1F C4 - 0.47F CT - 0.0033F, +/- 30 PPM/C D1 - 1A, 600 PIV D2 - 50V, 500mW Zener Note 1: The product of CT and RT have a direct effect on gain and therefore directly effect temperature compensation. Note 2: C4 Range; 20pF to .2F. Note 3: R4 Range; 100k1/2 to 500k1/2.
Air Core Stepper Motor 200W
Odometer
Figure 7
Note 4: The IC must be protected from transients above 60V and reverse battery conditions. Note 5: Additional filtering on the FREQIN lead may be required.
In some cases a designer may wish to use the CS8191 only as a driver for an air-core meter having performed the F/V conversion elsewhere in the circuit. Figure 8 shows how to drive the CS8191 with a DC voltage ranging from 2V to 6V. This is accomplished by forcing a voltage on the F/VOUT lead. The alternative scheme shown in figure 9 uses an external op amp as a buffer and operates over an input voltage range of 0V to 4V.
An alternative solution is to use the CS4101 which has a separate function generator input lead and can be driven directly from a DC source. Figure 8 and 9 are not temperature compensated.
CS8191
100kW VREG 100kW CPBIAS + CP+ 10kW F/VOUT -
CS8191
VIN 0V to 4V DC
100kW
10kW VIN 2V to 6V DC
N/C
BIAS 100kW F/VOUT
Figure 8. Driving the CS8191 from an external DC voltage.
+ 100kW
Figure 9. Driving the CS8191 from an external DC voltage using an Op Amp Buffer.
7
CS8191
Package Specification
PACKAGE DIMENSIONS IN mm (INCHES) PACKAGE THERMAL DATA
D Lead Count 16L PDIP (internally fused leads) 20L SOIC (internally fused leads) Metric Max Min 19.69 18.67 13.00 12.60 English Max Min .775 .735 .512 .496
Thermal Data RQJC typ RQJA typ
16L PDIP* 15 50
20L SOIC* 9 55 uC/W uC/W
*Internally Fused Leads
Plastic DIP (N); 300 mil wide
7.11 (.280) 6.10 (.240)
8.26 (.325) 7.62 (.300) 3.68 (.145) 2.92 (.115)
1.77 (.070) 1.14 (.045)
2.54 (.100) BSC
.356 (.014) .203 (.008)
0.39 (.015) MIN. .558 (.022) .356 (.014) Some 8 and 16 lead packages may have 1/2 lead at the end of the package. All specs are the same.
REF: JEDEC MS-001
D
Surface Mount Wide Body (DW); 300 mil wide
7.60 (.299) 7.40 (.291)
10.65 (.419) 10.00 (.394)
0.51 (.020) 0.33 (.013)
1.27 (.050) BSC
2.49 (.098) 2.24 (.088)
2.65 (.104) 2.35 (.093)
1.27 (.050) 0.40 (.016)
REF: JEDEC MS-013
0.32 (.013) 0.23 (.009) D 0.30 (.012) 0.10 (.004)
Ordering Information
Part Number Description CS8191XNF16 16L PDIP (internally fused leads) CS8191XDWF20 20L SOIC (internally fused leads) CS8191XDWFR20 20L SOIC (internally fused leads) (tape & reel)
Rev. 3/9/99
Cherry Semiconductor Corporation reserves the right to make changes to the specifications without notice. Please contact Cherry Semiconductor Corporation for the latest available information. 8
(c) 1999 Cherry Semiconductor Corporation

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