Cherry CS8190EDWF20 Precision air-core tach/speedo driver with return to zero Datasheet

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
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