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Part: CS289
Category:
Analog & Mixed-Signal Processing
Description: 20ma Air-core Tachometer Drive Circuit
Company: ON Semiconductor
Datasheet: Download CS289 datasheet File size : 243 kB
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CS289
CS289
Description
The CS289 is specifically designed for use with air-core meter movements. The IC has charge pump circuitry for frequency-to-voltage conversion, a shunt regulator for stable
DE SI GN
20mA Air-Core Tachometer Drive Circuit
Features
s Single Supply Operation s On-Chip Regulation s 20mA Output Drive Capability
operation, a function generator, and sine and cosine amplifiers. The buffered sine and cosine outputs will typically sink or source 20mA.
RE CO MM EN DE D
Supply Voltage (VCC) .....20V Operating Temperature ...40°C to +100°C Junction Temperature.........40°C to 150°C Storage Temperature........65°C to +150°C 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
AR CH IV FO E R N
Absolute Maximum Ratings Block Diagram
EW
Package Options
14L PDIP
VZ
1
Pwr Gnd VCC VCOS VREG SQIN SQOUT F/VOUT
Pwr Gnd
VCC
VCOS
VREG
SQIN
SQOUT
F/V OUT
VSINE NC VBIAS CP CP+ Gnd
NO T
Regulator
Charge Pump
VSINE VBIAS Gnd
20L SOIC Wide
VZ 1 VCC VCOS VREG Gnd Gnd Gnd Gnd SQIN SQOUT F/VOUT
DE VI CE
Function Generator
+
Gnd Gnd Gnd CP CP+
VZ
VSINE
VBIAS
Cp
CP+
Gnd
NC
ON Semiconductor 2000 South County Trail, East Greenwich, RI 02818 Tel: (401)8853600 Fax: (401)8855786 N. American Technical Support: 800-282-9855 Web Site: www.onsemi.com
December, 2001 - Rev. 4
1
CS289
Electrical Characteristics: (VCC = 13.1V, -30°C TA 85°C)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Supply Current (Note 2)
VCC = 15.0V VCC = 13.1V VCC = 11.3V IREG = 4.3mA IREG = 0 to 5mA T = 25°C ISQ OUT = 5mA, ISQ IN = 500µA ISQ OUT = 16V, VSQ IN = 0V CP+ = 0, T = 25°C VSQIN = 0 (zero input), = 0° VCOS = 0 (Note 1), = 270° 1.8 6.3 -1.5 -0.55 3.8 -3.8 0.1 7.7
54 60 60 8.5 0.10 2.0 0.20 1 2.1 7.1
65 65 9.3 0.20 4.0 0.55 10 15 2.4 7.9 1.5
mA mA mA V V mA V µA nA V % V V V mA mA V V mA mA V
Regulated Voltage Regulation Signal Input Current Saturation Voltage Leakage Current Input Current F to V Output
Linearity Vsine at = 0° MAX Vsine+ MAX VsineCoil Drive Current
EO vs. Frequency VCOS = 0 (Note 1), = 270°, T = 25°C VSQ IN = 0 (zero input), = 0° VCOS = 0 (Note 1), =90° VCOS = 0 (Note 1), = 270° VCOS = 0 (Note 1), = 90°, T = 25°C VCOS = 0 (Note 1), = 270° VSQ IN = 0 (zero input), = 0° Vsine = 0 (Note 1), = 180° VSQ IN = 0 (zero input), = 0° Vsine = 0 (Note 1), = 180°
0.00 4.5 -4.5 20 20
0.55 5.8 -5.8 25 25 5.8 -5.8 25 25 5.85
MAX VCOS+ MAX VCOSCoil Drive Current
3.8 -3.8
4.5 -4.5 20 20
External Voltage Ref.
4.98
5.40
Note 1: Vsine measured Vsine to VZ. VCOS measured VCOS to VZ. All other voltages specified are measured to ground. Note 2: Max PWR dissipation VCC X ICC - (V2 Isine + V12 ICOS).
Package Pin Description
PACKAGE PIN # PIN SYMBOL FUNCTION
20L SO 1 2 3 4, 5, 6, 7, 14, 15, 16, 17 8 9 10 11
14L PDIP 1 2 4 7 5 6 3 8 VZ Vsine VBIAS Gnd CP CP+ NC F/VOUT External Zener reference. Sine output signal. Test pin or "0" calibration pin. Analog Ground connection. Negative input to charge pump. Positive input to charge pump. No Connection Output voltage proportional to input signal frequency.
2
CS289
Package Pin Description: continued
PACKAGE PIN # PIN SYMBOL FUNCTION
20L SO 12 13 18 19 20
14L PDIP 9 10 11 12 13 14 SQOUT SQIN VREG VCOS VCC Pwr Gnd Buffered square wave output signal. Speed or RPM input signal. Voltage regulator output. Cosine output signal. Supply voltage. Power Ground connection.
Note 1: Vsine measured Vsine to VZ. VCOS measured VCOS to VZ. All other voltages specified are measured to ground. Note 2: Max PWR dissipation VCC X ICC - (V2 Isine + V12 ICOS).
Typical Performance Characteristics
Output Angle in Polar Form Charge Pump Output Voltage
Relationship of E, and Frequency
+
COSINE OUTPUT
7.1
VP COS
6 F/V Output (V)
VP SIN
5 4 3
VZ
+
SINE OUTPUT
2.1
F/VOUT = 2.0V + FREQ X CT X RT X VREG 0 45° 90° 135° 180° 225° 270°
Frequency/Output Angle (°)
Function Generator Output Voltage
2.1 4.5 3.5 VSINE VSINE, VCOS (V) 2.5 1.5 VZ -1.5 -2.5 -3.5 -4.5 0 45° 90° 135° 180° 225° Tachometer Angular Deflection (°) 270° 4.5V 4.5V VCOS 3.8 5.45 7.1
3
CS289
Circuit Description
Charge Pump Function Generator/Sine and Cosine Amplifiers
The input frequency is buffered through a transistor, then applied to the charge pump for frequency-to-voltage conversion (Figure 1). The charge pump output voltage, E, will range from 2.1V with no input (= 0°) to 7.1V at = 270°. The charge that appears on CT is reflected to COUT through a Norton amplifier. The frequency applied at SQIN charges and discharges CT through R1 and R2. COUT reflects the charge as a voltage across resistor RT.
The output waveforms of the sine and cosine amplifiers are derived by On-Chip Amplifier/Comparator circuitry. The various trip points for the circuit (i.e. 90°, 180°, 270°) are determined by an internal resistor divider connected to the voltage regulator. The voltage E is compared to the divider network by the function generator circuitry. Use of an external zener reference at VZ allows both sine and cosine amplifiers to swing positive and negative with respect to this reference. The output magnitudes and directions have the relationship as shown in Typical Characteristics diagrams. Note: Pin connections referenced are for the 14L DIP.
Function Generator Output (): VCC=13.1V, TA=25°C =ArcTan V sine (Measured angle after calibration at 180°C) V cos For A=45°, 90°, 135°, 180°, 225°, 270°, (Desired angle) (A-M)4.0° Temperature Sensitivity: VCC=13.1V MT=M (T=25°C) -M (-20°CT+85°C)
SQOUT F-VOUT COUT 1µF ±10% VCOS VREG SQIN 15 B+ 18V R2 2k E 1k TACH INPUT 2k
(MT)3.5°C, -20°CT+85°C Voltage Sensitivity: TA=25°C MV=M (VCC=13.1V) -M (11.3VVCC15V) (MV)2°, 11.3VVCC15V
100 B+
Gnd
VCC
CS289
RT 180k *
VSINE
VBIAS
CP
80mH 225 R1 SINE 80mH 225 1k CT 0.01µF
ZENER 5.4V
* ADJUST FOR TRIMMING
Figure 1. Functional Diagram of CS289 Circuit.
4
CP+
Gnd
NC
VZ
CS289
Tachometer Application RPM x # OF CYL. = Frequency 60 2 VF/VOUT = 2.1 + Frequency x CT x RT (VREG -0 .7) The above equations were used in calculating the following values, where VF/VOUT = 7.1V at =270° and CT = 0.01 F. 4 cylinder: Freq = 200Hz, RT = 320k 6 cylinder: Freq = 300Hz, RT = 220k 8 cylinder: Freq = 400Hz, RT = 150k Typical values shown above apply to a nominal value of VREG of 8.5 volts. It must be realized that trimming of RT will be necessary to compensate for variations in regulator voltage from one unit to another. An alternative to this adjustment is to replace R2 with a potentiometer, as shown in Figure 2. Partial schematic shown in Figure 3 represents one method for use with DC applications instead of frequency.
10k
TRIM
IOUT/E
SQOUT
F-VOUT
VCOS
VREG
SQIN
F-VOUT RT RT CP Gnd CP+ CP
CP
VBIAS
Gnd
CP+
CP
NC
2.1V 0.7V CT IIN 1k
Figure 2: Alternate Trimming Method Figure 3: DC Application
5
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