CS8190 CS8190 Precision Air-Core Tach/Speedo Driver with Return to Zero Description The CS8190 is specifically designed for use with air-core meter movements. The IC provides all the functions necessary for an analog tachometer or speedometer. The CS8190 takes a speed sensor input and generates sine and cosine related output signals to differentially drive an air-core meter. Many enhancements have been added over industry standard Features tachometer drivers such as the CS289 or LM1819. The output utilizes differential drivers which eliminates the need for a zener reference and offers more torque. The device withstands 60V transients which decreases the protection circuitry required. The device is also more precise than existing devices allowing for fewer trims and for use in a speedometer. ■ Direct Sensor Input ■ High Output Torque ■ Low Pointer Flutter ■ High Input Impedance ■ Overvoltage Protection ■ Return to Zero Absolute Maximum Ratings Supply Voltage (<100ms pulse transient) .........................................VCC = 60V (continuous)..............................................................VCC = 24V Operating Temperature .............................................................Ð40¡C to +105¡C Storage Temperature..................................................................Ð40¡C to +165¡C Junction Temperature .................................................................Ð40¡C to+150¡C ESD (Human Body Model) .............................................................................4kV Lead Temperature Soldering Wave Solder(through hole styles only).............10 sec. max, 260¡C peak Reflow (SMD styles only).............60 sec. max above 183¡C, 230¡C peak Block Diagram BIAS + F/VOUT Ð CP+ Charge Pump SQOUT 16 Lead PDIP (internally fused leads) + VREG Voltage Regulator Ð 1 16 2 15 F/VOUT FREQIN 3 14 VREG Gnd 4 13 Gnd Gnd 5 12 Gnd COS+ 6 11 SINE+ COS- 7 10 SINE- VCC 8 9 BIAS 20 Lead SOIC (internally fused leads) CP+ 1 Gnd Gnd VREG 7.0V Gnd Gnd COS+ Ð Ð + COS Output + Func. Gen. SINE+ SINE Output + + Ð Ð COS- VCC CP- CP+ SQOUT CP- Input Comp. FREQIN Package Options SINEHigh Voltage Protection 20 CP- SQOUT 2 19 F/VOUT FREQIN VREG 3 18 Gnd 4 17 Gnd Gnd 5 16 Gnd Gnd 6 15 Gnd Gnd 7 14 Gnd COS+ 8 13 COS- 9 12 SIN- VCC 10 11 BIAS SIN+ Cherry Semiconductor Corporation 2000 South County Trail, East Greenwich, RI 02818 Tel: (401)885-3600 Fax: (401)885-5786 Email: [email protected] Web Site: www.cherry-semi.com Rev. 11/21/96 1 A ¨ Company CS8190 Electrical Characteristics: -40¡C ² TA ² 85¡C, 8.5V ² VCC ² 15V unless otherwise specified. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT ■ Supply Voltage Section ICC Supply Current VCC = 16V, -40¡C, No Load VCC Normal Operation Range 50 125 mA 8.5 13.1 16.0 V 1.0 2.0 3.0 V 200 500 ■ Input Comparator Section Positive Input Threshold Input Hysteresis Input Bias Current * 0V ² VIN ² 8V -10 Input Frequency Range Input Voltage Range in series with 1k½ Output VSAT ICC = 10mA Output Leakage VCC = 7V Low VCC Disable Threshold µA 0 20 KHz -1 VCC V 0.15 0.40 V 10 µA 8.0 8.5 V 7.0 Logic 0 Input Voltage mV -80 1 V * Note: Input is clamped by an internal 12V Zener. ■ Voltage Regulator Section Output Voltage 6.25 7.00 7.50 V 10 mA 10 50 mV 20 150 mV Output Load Current Output Load Regulation 0 to 10 mA Output Line Regulation 8.5V ² VCC ² 16V Power Supply Rejection VCC = 13.1V, 1Vp/p 1kHz 34 46 dB 1.5 2.0 2.5 V 40 150 nA 1.5 2.0 2.5 V 0.7 1.1 V -0.10 0.28 +0.70 % 7 10 13 mV/Hz ■ Charge Pump Section Inverting Input Voltage Input Bias Current VBIAS Input Voltage Non Invert. Input Voltage IIN = 1mA Linearity* @ 0, 87.5, 175, 262.5, + 350Hz F/VOUT Gain @ 350Hz, CT = 0.0033µF, RT = 243k½ Norton Gain, Positive IIN = 15µA 0.9 1.0 1.1 I/I Norton Gain, Negative IIN = 15µA 0.9 1.0 1.1 I/I * Note: Applies to % of full scale (270¡) ■ Function Generator Section: -40¡ ² TA ² 85¡C, VCC = 13.1V unless otherwise noted. Return to Zero Threshold TA = 25¡C 5.2 6.0 7.0 V Differential Drive Voltage (VCOS+ - VCOS-) 8.5V ² VCC ² 16V Q = 0¡ 5.5 6.5 7.5 V Differential Drive Voltage (VSIN+ - VSIN-) 8.5V ² VCC ² 16V Q = 90¡ 5.5 6.5 7.5 V Differential Drive Voltage (VCOS+ - VCOS-) 8.5V ² VCC ² 16V Q = 180¡ -7.5 -6.5 -5.5 V Differential Drive Voltage (VSIN+ - VSIN-) 8.5V ² VCC ² 16V Q = 270¡ -7.5 -6.5 -5.5 V Differential Drive Current 8.5V ² VCC ² 16V 33 42 mA -1.5 0.0 1.5 deg Zero Hertz Output Angle 2 PARAMETER TEST CONDITIONS MIN TYP MAX UNIT -2 0 +2 deg ■ Function Generator Section: continued Function Generator Error * Reference Figures 1 - 4 VCC = 13.1V Q = 0¡ to 305¡ Function Generator Error 13.1V ² VCC ² 16V -2.5 0 +2.5 deg Function Generator Error 13.1V ² VCC ² 11V -1 0 +1 deg Function Generator Error 13.1V ² VCC ² 9V -3 0 +3 deg Function Generator Error 25¡C ² TA ² 80¡C -3 0 +3 deg Function Generator Error 25¡C ² TA ² 105¡C -5.5 0 +5.5 deg Function Generator Error Ð40¡C ² TA ² 25¡C -3 0 +3 deg Function Generator Gain TA = 25¡C, Q vs F/VOUT 60 77 95 ¡/V * Note: Deviation from nominal per Table 1 after calibration at 0 and 270¡. Package Lead Description PACKAGE LEAD # LEAD SYMBOL FUNCTION 16L 20L 1 1 CP+ Positive input to charge pump. 2 2 SQOUT Buffered square wave output signal. 3 3 FREQIN Speed or rpm input signal. 4, 5, 12, 13 4 - 7, 14 - 17 Gnd Ground Connections. 6 8 COS+ Positive cosine output signal. 7 9 COS- Negative cosine output signal. 8 10 VCC Ignition or battery supply voltage. 9 11 BIAS Test point or zero adjustment. 10 12 SIN- Negative sine output signal. 11 13 SIN+ Positive sine output signal. 14 18 VREG Voltage regulator output. 15 19 F/VOUT Output voltage proportional to input signal frequency. 16 20 CP- Negative input to charge pump. Typical Performance Characteristics Figure 1: Function Generator Output Voltage vs Degrees of Deflection Figure 2: Charge Pump Output Voltage vs Output Angle F/VOUT = 2.0V + 2 FREQ ´ CT ´ RT ´ (VREG - 0.7V) 7 7 6 5 6 COS 3 2 5 F/V Output (V) Output Voltage (V) 4 1 0 -1 -2 -3 4 3 2 -4 -5 1 SIN -6 -7 0 45 90 135 180 225 270 0 315 0 Degrees of Deflection (°) 45 90 135 180 225 Frequency/Output Angle (°) 3 270 315 CS8190 Electrical Characteristics: continued CS8190 Typical Performance Characteristics continued Figure 4: Nominal Output Deviation Figure 3: Output Angle in Polar Form 1.50 7V 1.25 (VSINE+) - (VSINE-) 1.00 Q Deviation (°) 0.75 Angle +7V Ð7V 0.50 0.25 0.00 -0.25 -0.50 -0.75 (VCOS+) - (VCOS-) -1.00 -1.25 -1.50 Q = ARCTAN [ VSIN+ Ð VSINVCOS+ Ð VCOS- ] 0 45 90 135 180 Theoretical Angle (°) -7V 225 270 315 Nominal Angle vs. Ideal Angle (After calibrating at 180¡) Note: Temperature, voltage, and nonlinearity not included. 45 40 35 Ideal Angle (Degrees) 30 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 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 Ideal Q Nominal Degrees Q Degrees 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 Ideal Q Nominal Degrees Q Degrees 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 Note: Temperature, voltage, and nonlinearity not included. 4 Ideal Q Degrees Nominal Q Degrees 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 Ideal Q Nominal Degrees Q Degrees 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 Ideal Q Nominal Degrees Q Degrees 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 The CS8190 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 2.0V and typical hysteresis of 0.5V. 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: The CS8190 has an undervoltage detect circuit that disables the input comparator when VCC falls below 8.0V(typical). With no input signal the F/V output voltage decreases and the needle moves towards zero. A second undervoltage detect circuit at 6.0V(typical) causes the function generator to generate a differential SIN drive voltage of zero volts and the differential COS drive voltage to go as high as possible. This combination of voltages (Figure 1) across the meter coil moves the needle to the 0¡ position. Connecting a large capacitor(> 2000µF) to the VCC lead (C2 in Figure 6) increases the time between these undervoltage points since the capacitor discharges slowly and ensures that the needle moves towards 0¡ as opposed to 360¡. The exact value of the capacitor depends on the response time of the system,the maximum meter deflection and the current consumption of the circuit. It should be selected by breadboarding the design in the lab. Design Example Maximum meter Deflection = 270¡ Maximum Input Frequency = 350Hz F/VOUT = 2.0V + 2 ´ FREQ ´ CT ´ RT ´ (VREG Ð 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: AFG = 77¡/V (typ) The relationship between input frequency and output angle is: 1. Select RT and CT Q = AGEN ´ ÆF/V ÆF/V = 2 ´ FREQ ´ CT ´ RT ´ (VREG Ð 0.7V) Q = 970 ´ FREQ ´ CT ´ RT Let CT = 0.0033µF, Find RT 270¡ RT = 970 ´ 350Hz ´ 0.0033µF RT = 243k½ RT should be a 250k½ 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 = 3.3k½ The charge current for CT is: Q = AFG ´ 2 ´ FREQ ´ CT ´ RT ´ (VREG Ð 0.7V) VREG Ð 0.7V = 1.90mA 3.3k½ or, Q = 970 ´ FREQ ´ CT ´ RT The ripple voltage at the F/V converterÕs output is determined by the ratio of CT and C4 in the formula: ÆV = 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. CT(VREG Ð 0.7V) C4 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. T = 285µs Choose R4 = 1k½. Charge time: T = R3 ´ CT = 3.3k½ ´ 0.0033µF = 10.9µs Discharge time:T = (R3 + R4)CT = 4.3k½ ´ 0.0033µF = 14.2µs 5 CS8190 Circuit Description and Application Notes CS8190 Circuit Description and Application Notes: continued The last component to be selected is the return to zero capacitor C2. This is selected by increasing the input signal frequency to its maximum so the pointer is at its maximum deflection and removing the power from the circuit. C2 should be large enough to ensure that the pointer always returns to the 0¡ position rather than 360¡ under all operating conditions. Figure 7 shows how the CS8190 and the CS8441 are used to produce a Speedometer and Odometer circuit. 3. Determine C4 C4 is selected to satisfy both the maximum allowable ripple voltage and response time of the meter movement. C4 = CT(VREG Ð 0.7V) VRIPPLE(MAX) With C4 = 0.47µF, the F/V ripple voltage is 44mV. VREG 2.0V R3 CT SQOUT 0.25V R4 Q3 Q1 QSQUARE Q2 Figure 5A: Partial Schematic of Input and Charge Pump T PW T-PW VCC FREQIN 0 VREG 0 ICP+ VCP+ 0 Figure 5B: Timing Diagram of FREQIN and ICP 6 RT C4 2.0V SQOUT CPÐ CP+ + Ð F to V Ð VC(t) + Ð FREQIN F/VOUT + CS8190 Speedometer/Odometer or Tachometer Application 1 CP+ 2 SQOUT CT C3 Battery 3 FREQIN 4 Gnd 5 Gnd 6 COS+ 7 COS- 8 C4 + C1 CP+ CP+ 2 SQOUT R2 C3 4 Gnd Gnd 12 5 Gnd SINE+ 11 6 COS+ 7 COS- 8 VCC Gnd 13 SINE- 10 VCC Battery BIAS 9 C2 + RT Gnd 13 Gnd 12 SINE+ 11 SINE- 10 BIAS 9 C1 COSINE SINE SINE Gnd Gnd Air Core Gauge 200W C4 VREG 14 D1 R1 D2 COSINE CP- 16 F/VOUT 15 3 FREQIN D1 R1 D2 1 CT Speedo Input RT VREG 14 CS8190 R2 R4 R3 CP- 16 F/VOUT 15 CS8190 R4 R3 Speedo Input Speedometer Air Core Gauge 200W Speedometer C2 Figure 6 1 CS8441 R1 - 3.9, 500mW R2 - 10k½ R3 - 3k½ R4 - 1k½ RT - Trim Resistor ±20 PPM/DEG. C C1 - 0.1µF C2 1. Stand alone Speedo or Tach with return to Zero, 2000µF 2. With CS8441 application, 10µF C3 - 0.1µF C4 - 0.47µF CT - 0.0033µF, ±30 PPM/¡C D1 - 1A, 600 PIV D2 - 50V, 500mW Zener Air Core Stepper Motor 200W Odometer Figure 7 Note 4: R4 Range; 100k½ to 500k½. Note 5: The IC must be protected from transients above 60V and reverse battery conditions. Note 6: Additional filtering on the FREQIN lead may be required. Note 1: C2 (> 2000µF) is needed if return to zero function is required. Note 2: The product of C4 and R4 have a direct effect on gain and therefore directly effect temperature compensation. Note 3: C4 Range; 20pF to .2µF. In some cases a designer may wish to use the CS8190 only as a driver for an air-core meter having performed the F/V conversion elsewhere in the circuit. 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 shows how to drive the CS8190 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. CS8190 100kW VREG 100kW VIN 0V to 4V DC CS8190 + 10kW VIN 2V to 6V DC N/C CP+ - - 10kW F/VOUT - CP- 100kW BIAS + 100kW 100kW BIAS F/VOUT Figure 9. Driving the CS8190 from an external DC voltage using an Op Amp Buffer. Figure 8. Driving the CS8190 from an external DC voltage. 7 CS8190 Package Specification PACKAGE THERMAL DATA PACKAGE DIMENSIONS IN mm (INCHES) D Lead Count 16L PDIP* 20L SOIC* Metric Max Min 19.69 18.67 13.00 12.60 Thermal Data RQJC typ RQJA typ English Max Min .775 .735 .512 .496 16L PDIP* 15 50 20L SOIC* 9 55 ûC/W ûC/W *Internally Fused Leads Plastic DIP (N); 300 mil wide 7.11 (.280) 6.10 (.240) 8.26 (.325) 7.62 (.300) 1.77 (.070) 1.14 (.045) 2.54 (.100) BSC 3.68 (.145) 2.92 (.115) .356 (.014) .203 (.008) 0.39 (.015) MIN. .558 (.022) .356 (.014) REF: JEDEC MS-001 D Some 8 and 16 lead packages may have 1/2 lead at the end of the package. All specs are the same. 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) 1.27 (.050) 0.40 (.016) 2.65 (.104) 2.35 (.093) 0.32 (.013) 0.23 (.009) D REF: JEDEC MS-013 0.30 (.012) 0.10 (.004) Ordering Information Part Number Description CS8190ENF16 16L PDIP (internally fused leads) CS8190EDWF20 20L SOIC (internally fused leads) CS8190EDWFR20 20L SOIC (internally fused leads) (tape & reel) Rev. 11/21/96 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 © 1999 Cherry Semiconductor Corporation