SAK215 ETC | Alldatasheet
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Pulse Shaper Circuit for Revolution Counters AAA A 8 5 The monolithic integrated circuit SAK215 is designed for use in & revolution counters of cars and for other applications like nih frequency to current converters. By use of suitable external ve 35 * 15° circuitry the revolution counter can be adapted to engines with maxss 4 im twoto eight cylinders. Itis designed for anominal 12 V DC supply. ¢ 4 . __ 038 Fig. 2. shows the operating circuit of a revolution counter with | a eg! 5° FSD = 6000 RPM (two ignition pulses per turn of the crank-shaft) His a i 5 »254-e1 —762—4 at a nominal battery voltage of 12 V. i Fig. 1: SAK215 in mini Dip Dimensioning Hints plastic package similar to TO-116 Coil resistance Ry of the indicating instrument: 20A8 according to DIN 41866 The output transistor must operate in the active range. This is ensured if Weight approximately 0.5 4 Vee = Vz = Vo = (Isp * Pa) Dimensions in mm. is above 1 V. The additional inductive voltage drop at the beginning of a current pulse due to the inductance of the moving coil is ignored in this equation. Pin connections Adjustment resistor Re; for the instrument current: The peak current through the moving coil is given at a pulse 1 Ground, 0 duty factor of 0.7 by 2 Input | 3 Feedback output lop =e 4 Feedback input 07 5 Output where ly is the DC current for full scale deflection. Since the $ eee foroutput cn rent current flowing into pin 5 is equal to the sink current of pin 6 8 Sup oy. Ita ne age Pp the adjustment resistor Rg; can be calculated as pply voltage Ve Vi Re =—2 Isp Series resistor Ry: tocerkast brealar Between pin 7 and pin 1 the circuit behaves like a zener diode. 34 ° The resistor Ry therefore has to be chosen so that adequate 17 | Vet. current for the IC and the moving coil is available even at the a el ae lowest battery voltage: Cit 7] [| a, = Vonm=82V saxo] <= 0 La] Fe mA + leg «FOF By-pass resistor R75: ° In order to ensure proper function of the stabilizing circuit the voltage drop across the by-pass resistor R;/s must be limited to Fig. 2: 7 V at the highest battery voltage. Block diagram and operating circuit of the SAK215, 7V-R Ve max—7.4 V 7 ee el
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° oo Fig. 3: Test circuit for the characteristics
2 ME 4b82721 0003483 811 =
All voltages are referred to pin 1. Absolute Maximum Ratings PO i Supply Voltage Ve see dimensioning hints for Ry and Ryg - Input Voltage V2 +20 v Current through Instrument Coil Is 40 mA —le 40 mA Power Dissipation at T, = 65 °C Prot 500 mw Ambient Operating Temperature Range Ta —25to +65 °c Storage Temperature Range Ts 25 to +125 °c Recommended Operating Conditions Frequency of the Input Pulses f - 10 kHz Pulse Duty Factor of the Output Current tos/Ts - 09 - Timing Resistor Bra 15 100 kQ Resistor for adjusting the Current Ren 100 - a through the Instrument Coil Voltage Drop across Bypass Resistor Vag - 7 Vv Voltage Drop between Pins 5 and 6 Vere 1 - Vv Test Conditions for the Characteristics (see test circuit Fig. 3) : PT ae Supply Voltage Ve 14 v Ambient Operating Temperature Ta 25 °C Input Pulse Amplitude Ve 1.6 Vv input Pulse Duration t 0.5 ms Input Pulse Repetition Frequency f, 250 Hz Characteristics in the Test Circuit Fig. 3 Po simon Fin tym |x| it | Supply Voltage (stabilized) Vr 74 - 8.2 Vv Current Consumption Ua - - 12 mA Input Voltage Range without triggering the Circuit Vo —20 - +0.5 v Trigger Range V2 1.5 - 20 v Trigger Slope dV2/dt positive going Input Impedance ton - | 7 | - ka Pulse Amplitude at Pin 6 Ve 2 - 25 v Output Pulse Duration ts 0.64 - Rig - Cara Output Current Is - le - - ME 4682711 0003484 758 ml 3