CS4121

CS4121 CHERRY | Alldatasheet

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Technical content

Features

7.0V VCC COS- COS+ Gnd Gnd FREQIN SQOUT CP+ Input Comp. Ð Gnd CP- Voltage Regulator High Voltage Protection BIAS Charge Pump Func. Gen. Ð Ð Ð Ð Ð n Direct Sensor Input n High Torque Output n Low Pointer Flutter n High Input Impedance n Overvoltage Protection n Accurate to 8V Functional to 6.5V (typ) Package Options

16 Lead PDIP

(internally fused leads)

20 Lead SOIC

(internally fused leads) CS4121 Low Voltage Precision Air-Core Tach/Speedo Driver 1CP+ SQOUT FREQIN Gnd Gnd COS+ COS- VCC CP- F/VOUT VREG Gnd Gnd SINE+ SINE- BIAS 1CP+ SQOUT FREQIN Gnd Gnd Gnd Gnd COS+ 1110 CP- F/VOUT VREG Gnd Gnd Gnd Gnd SIN+ 9COS- SIN- VCC BIAS CS4121

Description

The CS4121 is specifically designed for use with air-core meter move- ments. The IC provides all the func- tions necessary for an analog tachometer or speedometer. The CS4121 takes a speed sensor input and generates sine and cosine relat- ed output signals to differentially drive an air-core meter. Many enhancements have been added over industry standard tachometer drivers such as the CS289 or LM1819. The output uti- lizes differential drivers which elim- inates 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 allow- ing for fewer trims and for use in a speedometer. The CS4121 is compatible with the CS8190, and provides higher accu- racy at a lower supply voltage (8.0V min. as opposed to 8.5V). It is func- tionally operational to 6.5V. Block Diagram Absolute Maximum Ratings Lead Temperature Soldering 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 A Company ¨ Rev 12/4/96

Electrical Characteristics: -40¡C ² TA ² 85¡C, 8.0V ² VCC ² 16V unless otherwise specified. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT CS4121 n Supply Voltage Section ICC Supply Current V CC = 16V, -40¡C, No Load 50 125 mA VCC Normal Operation Range 8.0 13.1 16.0 V n Input Comparator Section Positive Input Threshold 1.0 2.0 3.0 V Input Hysteresis 200 500 mV Input Bias Current * 0V ² V IN ² 8V -10 -80 µA Input Frequency Range 0 20 kHz Input Voltage Range in series with 1k½ -1 V CC V Output VSAT ICC = 10mA 0.15 0.40 V Output Leakage V CC = 7V 10 µA Logic 0 Input Voltage 1 V *Note: Input is clamped by an internal 12V Zener. n Voltage Regulator Section Output Voltage 6.25 7.00 7.50 V Output Load Current 10 mA Output Load Regulation 0 to 10 mA 10 50 mV Output Line Regulation 8.0V ² V CC ² 16V 20 150 mV Power Supply Rejection V CC = 13.1V, 1VP/P 1kHz 34 46 dB n Charge Pump Section Inverting Input Voltage 1.5 2.0 2.5 V Input Bias Current 40 150 nA Vbias Input Voltage 1.5 2.0 2.5 V Non Invert. Input Voltage I IN = 1mA 0.7 1.1 V F/V OUT Gain @ 350Hz, C T = 0.0033µF, RT = 243k½ 7 10 13 mV/Hz Norton Gain, Positive I IN = 15µA 0.9 1.0 1.1 I/I Norton Gain, Negative I IN = 15µA 0.9 1.0 1.1 I/I *Note: Applies to % of full scale (270¡). n Function Generator Section: -40¡C ² TA ² 85¡C, VCC = 13.1V unless otherwise noted. Differential Drive Voltage 8.0V ² V CC ² 16V 5.5 6.5 7.5 V (VCOS+ - VCOS-) Q = 0¡ Differential Drive Voltage 8.0V ² V CC ² 16V 5.5 6.5 7.5 V (VSIN+ - VSIN-) Q = 90¡ Differential Drive Voltage 8.0V ² V CC ² 16V -7.5 -6.5 -5.5 V (VCOS+ - VCOS-) Q = 180¡ Differential Drive Voltage 8.0V ² V CC ² 16V -7.5 -6.5 -5.5 V (VSIN+ - VSIN-) Q = 270¡ Differential Drive Current 8.0V ² V CC ² 16V, TA=25¡C 33 42 mA Zero Hertz Output Angle -1.5 0.0 1.5 deg Function Generator Error * V CC = 13.1V, TA=25¡C -2 0 +2 deg Reference Figures 1,2,3,4 Q = 0¡ to 305¡ *Note: Deviation from nominal per Table 1 after calibration at 0¡ and 270¡.

PACKAGE LEAD # LEAD SYMBOL FUNCTION CS4121 Electrical Characteristics: continued PARAMETER TEST CONDITIONS MIN TYP MAX UNIT Package Lead Description Typical Performance Characteristics 0 45 90 135 180 225 270 315 Output Voltage (V) Degrees of Deflection (°) COS SIN 04 5 90 135 180 225 270 315 F/V Output (V) Frequency/Output Angle (°) Figure 2: Charge Pump Output Voltage vs Output AngleFigure 1: Function Generator Output Voltage vs Degrees of Deflection F/VOUT = 2.0V + 2 FREQ ´ CT ´ RT ´ (VREG - 0.7) n Function Generator Section: continued Function Generator Error 13.1V ² V CC ² 16V, TA=25¡C -2.5 0 +2.5 deg Function Generator Error 13.1V ² V CC ² 11V, TA=25¡C -1 0 +1 deg Function Generator Error 13.1V ² V CC ² 8V, TA=25¡C -3 0 +3 deg Function Generator Error 25¡C ² T A ² 85¡C -3 0 +3 deg Function Generator Error 25¡C ² T A ² 105¡C -5.5 0 +5.5 deg Function Generator Error Ð40¡C ² T A ² 25¡C -3 0 +3 deg Function Generator Gain T A = 25¡C Q vs F/VOUT 60 77 95 ¡/V 16L PDIP* 20L SO* 1 1 CP+ Positive input to charge pump. 22 S Q OUT Buffered square wave output signal. 3 3 FREQ IN 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. 81 0 V CC 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 V REG Voltage regulator output. 15 19 F/V OUT Output voltage proportional to input signal frequency. 16 20 CP- Negative input to charge pump. *Internally Fused Leads

1 1.09 2 2.19 3 3.29 4 4.38 5 5.47 6 6.56 7 7.64 8 8.72 9 9.78 10 10.84 11 11.90 12 12.94 13 13.97 14 14.99 15 16.00 16 17.00 17 17.98 18 18.96 19 19.92 20 20.86 21 21.79 22 22.71 23 23.61 24 24.50 25 25.37 26 26.23 27 27.07 28 27.79 29 28.73 30 29.56 31 30.39 32 31.24 33 32.12 34 33.04 35 34.00 36 35.00 37 36.04 38 37.11 39 38.21 40 39.32 41 40.45 42 41.59 43 42.73 44 43.88 45 45.00 50 50.68 55 56.00 60 60.44 65 64.63 70 69.14 75 74.00 80 79.16 85 84.53 90 90.00 95 95.47 100 100.84 105 106.00 110 110.86 115 115.37 120 119.56 125 124.00 130 129.32 135 135.00 140 140.68 145 146.00 150 150.44 155 154.63 160 159.14 165 164.00 170 169.16 175 174.33 180 180.00 185 185.47 190 190.84 195 196.00 200 200.86 205 205.37 210 209.56 215 214.00 220 219.32 225 225.00 230 230.58 235 236.00 240 240.44 245 244.63 250 249.14 255 254.00 260 259.16 265 264.53 270 270.00 275 275.47 280 280.84 285 286.00 290 290.86 295 295.37 300 299.21 305 303.02 Ideal Q Nominal Ideal Q Nominal Ideal Q Nominal Ideal Q Nominal Ideal Q Nominal Ideal Q Nominal Degrees Q Degrees Degrees Q Degrees Degrees Q Degrees Degrees Q Degrees Degrees Q Degrees Degrees Q Degrees Typical Performance Characteristics: continued CS4121 Nominal Angle vs. Ideal Angle (After calibrating at 180¡) +7VÐ7V (VCOS+) - (VCOS-) Angle -7V Q (VSINE+) - (VSINE-) VSIN+ Ð VSIN- VCOS+ Ð VCOS- Q = ARCTAN [ -1.50 Deviation (°) 0 45 90 135 180 225 270 315 -1.25 -1.00 -0.75 -0.50 -0.25 0.00 0.25 0.50 0.75 1.00 1.25 1.50 Theoretical Angle (°) Figure 4: Nominal Output DeviationFigure 3: Output Angle in Polar Form Ideal Angle (Degrees) Nominal Angle (Degrees) 1 5 9 13 17 21 25 29 33 37 41 45 Ideal Degrees Nominal Degrees Table 1: Function Generator Output Nominal Angle vs. Ideal Angle (After calibrating at 270¡) Note: Temperature, voltage and nonlinearity not included. Note: Temperature, voltage and nonlinearity not included.

The CS4121 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 conver- sion, 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 FREQ IN lead, this is the input to a high impedance comparator with a typical pos- itive input threshold of 2.0V and typical hysteresis of 0.5V. The output of the comparator, SQ OUT, is applied to the charge pump input CP+ through an external capacitor C T. When the input signal changes state, CT is charged or discharged through R3 and R4. The charge accumulat- ed on C T is mirrored to C4 by the Norton Amplifier cir- cuit comprising of Q1, Q2 and Q3. The charge pump out- put voltage, F/V OUT, ranges from 2V to 6.3V depending on the input signal frequency and the gain of the charge pump according to the formula: F/V OUT = 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 genera- tor 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 = A F/V ´ AFG, where: AFG = 77¡ /V (typ) The relationship between input frequency and output angle is: Q = AFG ´ 2 ´ FREQ ´ CT ´ RT ´ (VREG Ð 0.7V) or, Q = 970 ´ FREQ ´ CT ´ RT The ripple voltage at the F/V converterÕs output is deter- mined by the ratio of CT and C4 in the formula: ÆV = Ripple voltage on the F/V output causes pointer or nee- dle 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 unac- ceptable for many applications. Design Example Maximum meter Deflection = 270¡ Maximum Input Frequency = 350Hz 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 RT = RT = 243k½ RT should be a 250k½ potentiometer to trim out any inac- curacies due to IC tolerances or meter movement pointer placement. 2. Select R3 and R4 Resistor R3 sets the output current from the voltage regu- lator. The maximum output current from the voltage reg- ulator is 10mA R3 must ensure that the current does not exceed this limit. Choose R3 = 3.3k½ The charge current for C T is = 1.90mA C1 must charge and discharge fully during each cycle of the input signal. Time for one cycle at maximum frequen- cy is 2.85ms. To ensure that C T is discharged, assume that the (R3 + R4) CT time constant is less than 10% of the minimum input frequency pulse width. T = 285µs Choose R4 = 1k½. Charge time: T = R3 ´ C T = 3.3k½ ´ 0.0033µF = 10.9µs Discharge time:T = (R3 + R4)CT = 4.3k½´ 0.0033µF = 14.2µs 3. Determine C4 C4 is selected to satisfy both the maximum allowable rip- ple voltage and response time of the meter movement. C4 = With C4 = 0.47µF, the F/V ripple voltage is 44mV. Figure 7 shows how the CS4121 and the CS-8441 are used to produce a Speedometer and Odometer circuit. CT(VREG Ð 0.7V) VRIPPLE(MAX) VREG Ð 0.7V 3.3k½ 270¡ 970 ´ 350Hz ´ 0.0033µF CT(VREG Ð 0.7V) Circuit Description and Application Notes

Speedometer/Odometer or Tachometer Application R1 - 3.9, 500mW R2 - 10k½ R3 - 3k½ R4 - 1k½ R T - Trim Resistor +/- 20 PPM/¡C 243k½ C1 - 0.1µF C3 - 0.1µF C4 - 0.47µF C T - 0.0033µF, +/- 30 PPM/¡C D1 - 1A, 600 PIV D2 - 50V, 500mW Zener Note 1: For 58% Speed Input T MAX ² 5/f MAX where TMAX = CT(R3+R4) fMAX = maximum speed input frequency Note 1: The product of C T and RT have a direct effect on gain and therefore directly affect temperature compensation Note 2: C T Range; 20pF to .2µF Note 3: R T Range; 100k½ to 500k½ Note 4: The IC must be protected from transients above 60V and reverse battery conditions Note 5: Additional filtering on FREQ IN lead may be required

1 CP+

+C4 RT COSINE SINE Air Core Gauge 200W Speedometer Gnd Battery Speedo Input CS8441 Air Core Stepper Motor 200W Odometer CP+ +C4 RT COSINE SINE Air Core Gauge 200W Speedometer Gnd Battery Speedo Input R4 CP+ Figure 6 Figure 7 CS4121

D Lead Count Metric English Max Min Max Min 16L PDIP* 19.69 18.67 .775 .735 20L SOIC* 13.00 12.60 .512 .496

Ordering Information

Rev. 12/4/96 Part Number Description CS4121ENF16 16L PDIP (internally fused leads) CS4121EDWF20 20L SOIC (internally fused leads) CS4121EDWFR20 20L SOIC (internally fused leads) (tape & reel) Thermal Data 16L PDIP* 20L SOIC* RQJC typ 15 9 ûC/W RQJA typ 50 55 ûC/W Package Specification PACKAGE DIMENSIONS IN mm (INCHES) PACKAGE THERMAL DATA CS4121 © 1999 Cherry Semiconductor Corporation Cherry Semiconductor Corporation reserves the right to make changes to the specifications without notice. Please contact Cherry Semiconductor Corporation for the latest available information. 1.27 (.050) BSC 7.60 (.299) 7.40 (.291) 10.65 (.419) 10.00 (.394) D 0.32 (.013) 0.23 (.009) 1.27 (.050) 0.40 (.016) REF: JEDEC MS-013 2.49 (.098) 2.24 (.088) 0.51 (.020) 0.33 (.013) 2.65 (.104) 0.10 (.004) Surface Mount Wide Body (DW); 300 mil wide Plastic DIP (N); 300 mil wide 0.39 (.015) MIN. 1.14 (.045) D Some 8 and 16 lead packages may have 1/2 lead at the end of the package. All specs are the same. .203 (.008) .356 (.014) REF: JEDEC MS-001 3.68 (.145) 2.92 (.115) 8.26 (.325) 7.62 (.300) 7.11 (.280) 6.10 (.240) .356 (.014) .558 (.022) *Internally Fused Leads