CS4121 Low Voltage Precision Air−Core Tach/Speedo Driver The CS4121 is specifically designed for use with air−core meter movements. The IC provides all the functions necessary for an analog tachometer or speedometer. The CS4121 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 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 60 V 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. The CS4121 is compatible with the CS8190, and provides higher accuracy at a lower supply voltage (8.0 V min. as opposed to 8.5 V). It is functionally operational to 6.5 V. http://onsemi.com SO−20L DWF SUFFIX CASE 751D 20 1 DIP−16 NF SUFFIX CASE 648 Features • • • • • • • • 16 Pb−Free Package is Available* Direct Sensor Input High Torque Output Low Pointer Flutter High Input Impedance Overvoltage Protection Accurate to 8.0 V Functional to 6.5 V (typ) Internally Fused Leads in SO−20 Package and DIP−16 1 ORDERING INFORMATION ABSOLUTE MAXIMUM RATINGS Rating Device Package Shipping† CS4121EDWF20 SO−20L 37 Units/Rail CS4121EDWF20G SO−20L (Pb−Free) 37 Units/Rail Value Unit CS4121EDWFR20 SO−20L 1000 Tape&Reel 60 24 V V CS4121ENF16 DIP−16 25 Units/Rail Operating Temperature (TJ) −40 to +105 °C Storage Temperature −40 to +165 °C Junction Temperature −40 to +150 °C †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. 4.0 kV 260 peak 230 peak °C °C Supply Voltage, VCC < 100 ms Pulse Transient Continuous ESD (Human Body Model) Lead Temperature Soldering: Wave Solder (through hole styles only) (Note 1) Reflow: (SMD styles only) (Note 2) DEVICE MARKING INFORMATION See specific marking information and pin connection information on page 4 of this data sheet. Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be affected. 1. 10 seconds maximum. 2. 60 second maximum above 183°C. *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. Semiconductor Components Industries, LLC, 2004 June, 2004 − Rev. 8 1 Publication Order Number: CS4121/D CS4121 BIAS Charge Pump CP+ F/VOUT + − CP− SQOUT VREG + − FREQIN Voltage Regulator GND GND VREG 7.0 V GND GND SINE+ COS+ COS Output − + Func. Gen. + − + − SINE Output SINE− COS− VCC − + High Voltage Protection Figure 1. Block Diagram http://onsemi.com 2 CS4121 ELECTRICAL CHARACTERISTICS (−40°C ≤ TA ≤ 85°C, 8.0 V ≤ VCC ≤ 16 V, unless otherwise specified.) Characteristic Test Conditions Min Typ Max Unit − 50 125 mA 8.0 13.1 16 V Supply Voltage Section ICC Supply Current VCC = 16 V, −40°C, No Load VCC Normal Operation Range − Input Comparator Section Positive Input Threshold − 1.0 2.0 3.0 V Input Hysteresis − 200 500 − mV − −10 −80 A 0 − 20 kHz Input Bias Current (Note 4) 0 V ≤ VIN ≤ 8.0 V Input Frequency Range − Input Voltage Range in series with 1.0 k Output VSAT ICC = 10 mA Output Leakage VCC = 7.0 V Logic 0 Input Voltage −1.0 − VCC V 0 0.15 0.40 V − − 10 A − 1.0 − − V − 6.25 7.00 7.50 V − − − 10 mA − 10 50 mV Voltage Regulator Section Output Voltage Output Load Current Output Load Regulation 0 to 10 mA Output Line Regulation 8.0 V ≤ VCC ≤ 16 V − 20 150 mV Power Supply Rejection VCC = 13.1 V, 1.0 VP/P 1.0 kHz 34 46 − dB Charge Pump Section Inverting Input Voltage − 1.5 2.0 2.5 V Input Bias Current − − 40 150 nA − 1.5 2.0 2.5 V − 0.7 1.1 V VBIAS Input Voltage Non Invert. Input Voltage IIN = 1.0 mA Linearity (Note 3) @ 0, 87.5, 175, 262.5, + 350 Hz −0.10 0.28 +0.70 % F/VOUT Gain @ 350 Hz, CCP = 0.0033 F, RT = 243 k 7.0 10 13 mV/Hz Norton Gain, Positive IIN = 15 A 0.9 1.0 1.1 I/I Norton Gain, Negative IIN = 15 A 0.9 1.0 1.1 I/I 5.5 6.5 7.5 V Function Generator Section (−40°C ≤ TA ≤ 85°C, VCC = 13.1 V unless otherwise noted.) Differential Drive Voltage, (VCOS+ − VCOS−) 8.0 V ≤ VCC ≤ 16 V, = 0° Differential Drive Voltage, (VSIN+ − VSIN−) 8.0 V ≤ VCC ≤ 16 V, = 90° 5.5 6.5 7.5 V Differential Drive Voltage, (VCOS+ − VCOS−) 8.0 V ≤ VCC ≤ 16 V, = 180° −7.5 −6.5 −5.5 V Differential Drive Voltage, (VSIN+ − VSIN−) 8.0 V ≤ VCC ≤ 16 V, = 270° −7.5 −6.5 −5.5 V Differential Drive Current 8.0 V ≤ VCC ≤ 16 V, TA = 25°C − 33 42 mA Zero Hertz Output Angle −1.5 0 1.5 deg Function Generator Error (Note 5) Reference Figures 2, 3, 4, 5 VCC = 13.1 V, TA = 25°C = 0° to 305° − −2.0 0 +2.0 deg Function Generator Error 13.1 V ≤ VCC ≤ 16 V, TA = 25°C −2.5 0 +2.5 deg Function Generator Error 13.1 V ≤ VCC ≤ 11 V, TA = 25°C −1.0 0 +1.0 deg Function Generator Error 13.1 V ≤ VCC ≤ 8.0 V, TA = 25°C −3.0 0 +3.0 deg Function Generator Error 25°C ≤ TA ≤ 85°C −3.0 0 +3.0 deg Function Generator Error 25°C ≤ TA ≤ 105°C −5.5 0 +5.5 deg Function Generator Error −40°C ≤ TA ≤ 25°C −3.0 0 +3.0 deg Function Generator Gain vs F/VOUT, TA = 25°C 60 77 95 °/V 3. Applies to % of full scale (270°). 4. Input is clamped by an internal 12 V Zener. 5. Deviation from nominal per Table 1 after calibration at 0° and 270°. http://onsemi.com 3 CS4121 PIN FUNCTION DESCRIPTION PACKAGE PIN # DIP−16 SO−20L 1 1 CP+ 2 2 SQOUT Buffered square wave output signal. Speed or RPM input signal. PIN SYMBOL FUNCTION Positive input to charge pump. 3 3 FREQIN 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 16 20 CP− Output voltage proportional to input signal frequency. Negative input to charge pump. MARKING DIAGRAM AND PIN CONNECTIONS DIP−16 1 CP+ COS+ COS− VCC F/VOUT VREG GND GND SIN+ SIN− BIAS A WL YY WW = Assembly Location = Wafer Lot = Year = Work Week http://onsemi.com 4 SO−20L CS−4121 AWLYYWW GND GND CP+ SQOUT FREQIN GND GND GND GND COS+ COS− VCC CP− CS−4121 0002SB001 AWLYYWW SQOUT FREQIN 1 16 20 CP− F/VOUT VREG GND GND GND GND SIN+ SIN− BIAS CS4121 TYPICAL PERFORMANCE CHARACTERISTICS FVOUT 2.0 V 2.0 FREQ CCP RT (VREG 0.7 V) 6 5 4 3 2 1 0 −1 −2 −3 −4 −5 −6 −7 7 6 COS F/V Output (V) Output Voltage (V) 7 5 4 3 2 1 SIN 0 45 90 135 180 225 Degrees of Deflection (°) 270 0 315 0 Figure 2. Function Generator Output Voltage vs. Degrees of Deflection 135 180 225 270 Frequency/Output Angle (°) Angle −7.0 V 7.0 V Deviation (°) 1.00 0.75 0.50 0.25 0.00 −0.25 −0.50 (VCOS+) − (VCOS−) −0.75 −1.00 −1.25 −7.0 V −1.50 0 Figure 4. Output Angle in Polar Form 45 90 225 135 180 Theoretical Angle (°) 270 Figure 5. Nominal Output Deviation 45 40 Ideal Angle (°) 35 30 25 20 Ideal Degrees 15 Nominal Degrees 10 5 0 0 5 9 13 315 1.50 1.25 7.0 V SIN VSIN VVCOS VCOS 90 Figure 3. Charge Pump Output Voltage vs. Output Angle (VSINE+) − (VSINE−) ARCTAN 45 17 25 21 Nominal Angle (°) 29 33 37 Figure 6. Nominal Angle vs. Ideal Angle (After Calibrating at 180) http://onsemi.com 5 41 45 315 CS4121 Table 1. Function Generator Output Nominal Angle vs. Ideal Angle (After Calibrating at 270) Ideal Degrees Nominal Degrees Ideal Degrees Nominal Degrees Ideal Degrees Nominal Degrees Ideal Degrees Nominal Degrees Ideal Degrees Nominal Degrees Ideal Degrees Nominal Degrees 0 0 17 17.98 34 33.04 75 74.00 160 159.14 245 244.63 1 1.09 18 18.96 35 34.00 80 79.16 165 164.00 250 249.14 2 2.19 19 19.92 36 35.00 85 84.53 170 169.16 255 254.00 3 3.29 20 20.86 37 36.04 90 90.00 175 174.33 260 259.16 4 4.38 21 21.79 38 37.11 95 95.47 180 180.00 265 264.53 5 5.47 22 22.71 39 38.21 100 100.84 185 185.47 270 270.00 6 6.56 23 23.61 40 39.32 105 106.00 190 190.84 275 275.47 7 7.64 24 24.50 41 40.45 110 110.86 195 196.00 280 280.84 8 8.72 25 25.37 42 41.59 115 115.37 200 200.86 285 286.00 9 9.78 26 26.23 43 42.73 120 119.56 205 205.37 290 290.86 10 10.84 27 27.07 44 43.88 125 124.00 210 209.56 295 295.37 11 11.90 28 27.79 45 45.00 130 129.32 215 214.00 300 299.21 12 12.94 29 28.73 50 50.68 135 135.00 220 219.32 305 303.02 13 13.97 30 29.56 55 56.00 140 140.68 225 225.00 14 14.99 31 30.39 60 60.44 145 146.00 230 230.58 15 16.00 32 31.24 65 64.63 150 150.44 235 236.00 16 17.00 33 32.12 70 69.14 155 154.63 240 240.44 Note: Temperature, voltage and nonlinearity not included. http://onsemi.com 6 CS4121 CIRCUIT DESCRIPTION and APPLICATION NOTES 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 conversion, a bandgap voltage regulator for stable operation, and a function generator with sine and cosine amplifiers to differentially drive the meter coils. From the partial schematic of Figure 7, 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 2.0 V and typical hysteresis of 0.5 V. The output of the comparator, SQOUT, is applied to the charge pump input CP+ through an external capacitor CCP. When the input signal changes state, CCP is charged or discharged through R3 and R4. The charge accumulated on CCP is mirrored to C4 by the Norton Amplifier circuit comprising of Q1, Q2 and Q3. The charge pump output voltage, F/VOUT, ranges from 2.0 V to 6.3 V depending on the input signal frequency and the gain of the charge pump according to the formula: 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. Design Example Maximum meter Deflection = 270° Maximum Input Frequency = 350 Hz 1. Select RT and CCP 970 FREQ CCP RT 270° Let CT = 0.0033 F, find RT RT RT 243 k RT should be a 250 k 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 10 mA. R3 must ensure that the current does not exceed this limit. Choose R3 = 3.3 k The charge current for CCP is FVOUT 2.0 V 2.0 FREQ CCP RT (VREG 0.7 V) 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, , is equal to the F/V gain multiplied by the function generator gain: VREG 0.7 V 1.90 mA 3.3 k CCP must charge and discharge fully during each cycle of the input signal. Time for one cycle at maximum frequency is 2.85 ms. To ensure that CCP is charged, assume that the (R3 + R4) CCP time constant is less than 10% of the minimum input period. T 10% 1 285 s 350 Hz Choose R4 = 1.0 k. Discharge time: tDCHG = R3 × CCP = 3.3 k × 0.0033 F = 10.9 s Charge time: tCHG = (R3 + R4)CCP = 4.3 k. × 0.0033 F = 14.2 s 3. Determine C4 C4 is selected to satisfy both the maximum allowable ripple voltage and response time of the meter movement. AFV AFG, where: AFG 77°V(typ) The relationship between input frequency and output angle is: AFG 2.0 FREQ CCP RT (VREG 0.7 V) or, 970 FREQ CCP RT C4 The ripple voltage at the F/V converter’s output is determined by the ratio of CCP and C4 in the formula: V 270° 970 350 Hz 0.0033 F CCP(VREG 0.7 V) VMAX With C4 = 0.47 F, the F/V ripple voltage is 44 mV. CCP(VREG 0.7 V) C4 http://onsemi.com 7 CS4121 VREG 2.0 V F/VOUT + R3 − 0.25 V + SQOUT FREQIN VC(t) Q3 CP− RT − R4 CCP CP+ C4 + Q1 QSQUARE Q2 − 2.0 V Figure 7. Partial Schematic of Input and Charge Pump T tDCHG tCHG VCC FREQIN 0 VREG SQOUT F to V 0 ICP+ 600 mV VCP+ 0 −0.3 V Figure 8. Timing Diagram of FREQIN and ICP http://onsemi.com 8 CS4121 R3 R4 CCP 0.0033 F ± 30 PPM/°C 3.0 k Speedo Input 1 CP+ 1.0 k CP− F/VOUT SQOUT R2 0.1 F CS4121 C3 GND GND Battery R1 3.9, D1 1.0 A 500 mW 600 PIV GND D2 50 V, 500 mW Zener Trim Resistor RT ± 20 PPM/°C 243 k GND GND COS+ SINE+ COS− SINE− BIAS VCC 0.1 F + 0.47 F VREG FREQIN 10 k C4 C1 COSINE SINE Air Core Gauge 200 Speedometer Notes: 1. For 58% Speed Input TMAX ≤ 5.0/fMAX where TMAX = CCP (R3 + R4) fMAX = maximum speed input frequency 2. The product of C4 and RT have a direct effect on gain and therefore directly affect temperature compensation. 3. CCP Range; 20 pF to 0.2 F. 4. RT Range; 100 k to 500 k. 5. The Ic must be protected from transients above 60 V and reverse battery conditions. 6. Additional filtering on FREQIN lead may be required. 7. Gauge coil connections to the IC must be kept as short as possible (≤ 3.0 inch) for best pointer stability. Figure 9. Speedometer or Tachometer Application http://onsemi.com 9 CS4121 R4 R3 Speedo Input 3.0 k CCP 0.0033 F ± 30 PPM/°C 1.0 k 1 CP+ CP− F/VOUT SQOUT R2 0.1 F CS4121 C3 GND GND Battery R1 3.9, D1 1.0 A 500 mW 600 PIV GND Trim Resistor ± 20 PPM/°C 243 k GND COS+ COS− SINE− BIAS COSINE SINE C1 0.1 F Air Core Gauge 200 C2 RT GND SINE+ VCC D2 50 V, 500 mW Zener 0.47 F VREG FREQIN 10 k C4 + Speedometer 1 CS8441 Air Core Stepper Motor 200 Odometer Notes: 1. The product of C4 and RT have a direct effect on gain and therefore directly affect temperature compensation. 2. CCP Range; 20 pF to 0.2 F. 3. RT Range; 100 k to 500 k. 4. The Ic must be protected from transients above 60 V and reverse battery conditions. 5. Additional filtering on FREQIN lead may be required. 6. Gauge coil connections to the IC must be kept as short as possible (≤ 3.0 inch) for best pointer stability. Figure 10. Speedometer With Odometer or Tachometer Application http://onsemi.com 10 CS4121 PACKAGE DIMENSIONS DIP−16 NF SUFFIX CASE 648−08 ISSUE T NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION L TO CENTER OF LEADS WHEN FORMED PARALLEL. 4. DIMENSION B DOES NOT INCLUDE MOLD FLASH. 5. ROUNDED CORNERS OPTIONAL. −A− 16 9 1 8 B F C L S SEATING PLANE −T− K H G D M J 16 PL 0.25 (0.010) M T A M DIM A B C D F G H J K L M S INCHES MIN MAX 0.740 0.770 0.250 0.270 0.145 0.175 0.015 0.021 0.040 0.70 0.100 BSC 0.050 BSC 0.008 0.015 0.110 0.130 0.295 0.305 0 10 0.020 0.040 MILLIMETERS MIN MAX 18.80 19.55 6.35 6.85 3.69 4.44 0.39 0.53 1.02 1.77 2.54 BSC 1.27 BSC 0.21 0.38 2.80 3.30 7.50 7.74 0 10 0.51 1.01 SO−20L DWF SUFFIX CASE 751D−05 ISSUE G 20 11 X 45 h 1 10 B B 20X 0.25 M T A S B S A L H M E 0.25 10X NOTES: 1. DIMENSIONS ARE IN MILLIMETERS. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M, 1994. 3. DIMENSIONS D AND E DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 PER SIDE. 5. DIMENSION B DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE PROTRUSION SHALL BE 0.13 TOTAL IN EXCESS OF B DIMENSION AT MAXIMUM MATERIAL CONDITION. A B M D 18X e A1 DIM A A1 B C D E e H h L MILLIMETERS MIN MAX 2.35 2.65 0.10 0.25 0.35 0.49 0.23 0.32 12.65 12.95 7.40 7.60 1.27 BSC 10.05 10.55 0.25 0.75 0.50 0.90 0 7 SEATING PLANE C T PACKAGE THERMAL DATA DIP−16 Parameter SO−20L Unit RJC Typical 15 9 °C/W RJA Typical 50 55 °C/W http://onsemi.com 11 CS4121 ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. 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