Page 1
1
Features
■
Direct Sensor Input
■
High Output Torque
■
Low Pointer Flutter
■
High Input Impedance
■ Overvoltage Protection
Package Option
20 Lead PDIP
CS4101
Precision Air-Core Tach/Speedo Driver
with Separate Function Generator Input
1
CP+
2
3
4
5
6
7
8
SQ
OUT
FREQ
IN
BIAS
Gnd
Gnd
NC
COS+
16
15
14
13
12
11
10
CP-
F/V
OUT
V
REG
NC
Gnd
Gnd
NC
SIN+
9
COS- SIN-
17
18
V
CC
F
GEN
19
20
CS4101
Description
The CS4101 is specifically designed
for use with air-core meter movements. The IC provides all the functions necessary for an analog
tachometer or speedometer. The
CS4101 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
CS-289 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.
Block Diagram
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
Rev 11/20/98
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
¨
BIAS
SQ
FREQ
CP+
OUT
IN
Charge Pump
Input
Comp.
+
Ð
+
Ð
Voltage
Regulator
F/V
CP-
F
V
OUT
GEN
REG
Gnd
Gnd
+
COS
COS
V
-
CC
Output
COS
V
REG
7.0V
Ð
+
+
Ð
Func.
Gen.
High Voltage
Protection
Ð
+
SINE
Output
+
Ð
Gnd
Gnd
SINE+
SINE-
Page 2
2
Electrical Characteristics:
-40¡C ² TA² 85¡C, 8.5V ² VCC² 15V unless otherwise specified.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
CS4101
■ Supply Voltage Section
I
CC
Supply Current VCC= 16V, -40¡C, No Load 50 125 mA
VCCNormal Operation Range
8.5 13.1 16.0 V
■ Input Comparator Section
Positive Input Threshold 2.4 3.4 4.4 V
Input Hysteresis 200 400 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 V
SAT
ICC= 10mA 0.15 0.40 V
Output Leakage V
CC
= 7V 10 µA
Low V
CC
Disable Threshold 7.0 8.0 8.5 V
Logic 0 Input Voltage 2.4 V
*Note: Input is clamped by an internal 12V Zener.
■ 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 8.5V ² V
CC
² 16V 20 150 mV
Power Supply Rejection V
CC
= 13.1V, 1Vp/p 1kHz 34 46 dB
■ Charge Pump Section
Inverting Input Voltage 1.5 2.0 2.5 V
Input Bias Current 40 150 nA
V
bias
Input Voltage 1.5 2.0 2.5 V
Non Invert. Input Voltage I
IN
= 1mA 0.7 1.1 V
Linearity* @ 0, 87.5, 175, 262.5, + 350Hz -0.10 0.28 +0.70 %
F/V
OUT
Gain @ 350Hz, CT= 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¡).
■ Function Generator Section: -40¡ ² T
A
² 85¡C, VCC= 13.1V unless otherwise noted.
Differential Drive Voltage 8.5V ² V
CC
² 16V 5.5 6.5 7.5 V
(V
COS
+ - V
COS
-) Q = 0¡
Differential Drive Voltage 8.5V ² V
CC
² 16V 5.5 6.5 7.5 V
(V
SIN
+ - V
SIN
-) Q = 90¡
Differential Drive Voltage 8.5V ² V
CC
² 16V -7.5 -6.5 -5.5 V
(V
COS
+ - V
COS
-) Q = 180¡
Differential Drive Voltage 8.5V ² V
CC
² 16V -7.5 -6.5 -5.5 V
(V
SIN
+ - V
SIN
-) Q = 270¡
Differential Drive Current 8.5V ² V
CC
² 16V 33 42 mA
Zero Hertz Output Angle -1.5 0.0 1.5 deg
Function Generator Error * V
CC
= 13.1V -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¡.
Page 3
3
PACKAGE LEAD # LEAD SYMBOL FUNCTION
CS4101
Electrical Characteristics:
continued
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
■ Function Generator Section: continued
Function Generator Error 13.1V ² V
CC
² 16V -2.5 0 +2.5 deg
Function Generator Error 13.1V ² V
CC
² 11V -1 0 +1 deg
Function Generator Error 13.1V ² V
CC
² 9V -3 0 +3 deg
Function Generator Error 25¡C ² T
A
² 80¡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/V
OUT
60 77 95 ¡/V
Package Lead Description
Typical Performance Characteristics
0 45 90 135 180 225 270 315
Output Voltage (V)
Degrees of Deflection (°)
7
6
5
4
3
2
1
0
-1
-2
-3
-4
-5
-6
-7
COS
SIN
045
90
135 180 225 270 315
F/V Output (V)
Frequency/Output Angle (°)
7
6
5
4
3
2
1
0
Figure 2: Charge Pump Output Voltage vs Output Angle
Figure 1: Function Generator Output Voltage
vs Degrees of Deflection
F/V
OUT
= 2.0V + 2 FREQ ´ CT´ RT´ (V
REG
- 0.7)
20L
1 CP+ Positive input to charge pump.
2SQ
OUT
Buffered square wave output signal.
3 FREQ
IN
Speed or rpm input signal.
4 BIAS Test point or Zero adjustment.
5, 6, 15, 16 Gnd Ground Connections.
7, 14, 17 NC No Connection.
8 COS+ Positive cosine output signal.
9 COS- Negative cosine output signal.
10 V
CC
Ignition or battery supply voltage.
11 F
GEN
Function generator input signal.
12 SIN- Negative sine output signal.
13 SIN+ Positive sine output signal.
18 V
REG
Voltage regulator output.
19 F/V
OUT
Output voltage proportional to input signal frequency.
20 CP- Negative input to charge pump.
Page 4
4
Typical Performance Characteristics continued
CS4101
Nominal Angle vs. Ideal Angle (After calibrating at 180¡)
+7V
Ð7V
(V
COS+
) - (V
COS-
)
7V
Angle
-7V
Q
(V
SINE+
) - (V
SINE-
)
]
V
SIN+
Ð V
SIN-
V
COS+
Ð V
COS-
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 Deviation
Figure 3: Output Angle in Polar Form
Ideal Angle (Degrees)
Nominal Angle (Degrees)
0
5
10
15
20
25
30
35
40
45
1 5 9 13 17 21 25 29 33 37 41 45
Ideal Degrees
Nominal Degrees
00
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
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.
Page 5
5
CS4101
The CS4101 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 FREQINlead, this is the
input to a high impedance comparator with a typical positive input threshold of 3.4V and typical hysteresis of
0.4V. The output of the comparator, SQ
OUT
, is applied to
the charge pump input CP+ through an external capacitor CT. When the input signal changes state, CTis
charged or discharged through R3 and R4. The charge
accumulated on CTis mirrored to C4by the Norton
Amplifier circuit comprising Q1, Q2 and Q3. The charge
pump output 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´ (V
REG
Ð 0.7V)
RTis 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
input lead, F
GEN
. An additional filter circuit can be added
between F/V
OUT
and F
GEN
to reduce needle flutter. 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 = A
F/V
´ AFG,
where:
A
FG
= 77¡/V (typ)
The relationship between input frequency and output
angle is:
Q = A
FG
´ 2 ´ FREQ ´ CT´ RT´ (V
REG
Ð 0.7V)
or, Q = 970 ´ FREQ ´ CT´ R
T
The ripple voltage at the F/V converterÕs output is determined by the ratio of CTand C4 in the formula:
ÆV =
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 R
T
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 = 350Hz
1. Select R
T
and C
T
Q = A
GEN
´ Æ
F/V
Æ
F/V
= 2 ´ FREQ ´ CT´ RT´ (V
REG
Ð 0.7V)
Q = 970 ´ FREQ ´ CT´ R
T
Let CT= 0.0033µF, Find R
T
RT=
RT= 243k½
RTshould 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 R3must ensure that the current does not
exceed this limit.
Choose R3 = 3.3k½
The charge current for C
T
is:
= 1.90mA
C1must charge and discharge fully during each cycle of
the input signal. Time for one cycle at maximum frequency is 2.85ms. To ensure that CTis discharged, assume that
the (R3 + R4) CTtime 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)C
T
= 4.3k½ ´ 0.0033µF = 14.2µs
3. Determine C4
C4 is selected to satisfy both the maximum allowable ripple 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 CS4101 and the CS-8441 are used
to produce a speedometer and odometer circuit.
C
T(VREG
Ð 0.7V)
V
RIPPLE(MAX)
V
REG
Ð 0.7V
3.3k½
270¡
970 ´ 350Hz ´ 0.0033µF
C
T(VREG
Ð 0.7V)
C4
Circuit Description and Application Notes
Page 6
6
CS4101
Circuit Description and Application Notes: continued
+
Ð
R
T
C4
CPÐ
+
Ð
F/V
OUT
F to V
2.0V
Q2Q1
Q3
0.25V
CP+
R4C
T
VC(t)
+Ð
R3
V
REG
SQ
OUT
Q
SQUARE
3.4V
FREQ
IN
Figure 5A: Partial Schematic of Input and Charge Pump
Figure 5B: Timing Diagram of FREQINand I
CP
T
PW T-PW
IN
OUT
0
FREQ
SQ
0
I
CP+
V
CP+
0
V
CC
V
REG
Page 7
7
Speedometer/Odometer or Tachometer Application
CS4101
R1 - 3.9, 500mW
R2 - 10k½
R3 - 3k½
R4 - 1k½
R
T
- Trim Resistor +/- 20 PPM/DEG. C
C1 - 0.1µF
C2 - 1. Stand alone Speedo or Tach "0" µF
2. Stand alone Speedo or Tach with return to Zero, 2000µF
3. With CS-8441 application, 10µF
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
T
MAX
= CT(R3+R4)
f
MAX
= maximum speed input frequency
Note 1: The product of CTand RThave a direct effect on
gain and therefore directly effect temperature
compensation
Note 2: C4 Range; 20pF to .2µF
Note 3: R4 Range; 100k½ to 500k½
Note 4: The IC must be protected from transients above
60V and reverse battery conditions
Note 5: Additional filtering on the FREQ
IN
lead may be
required
Figure 6
Figure 7
Speedo
Input
Battery
R1D1
R3
R2
C3
R4
C
T
C1D2
C2
CP+
CP+
1
SQ
2
OUT
3
FREQ
IN
4
BIAS
5
Gnd
6
Gnd
7
NC
COS+
8
COS-
9
V
10
CC
COSINE SINE
CP-
F/V
OUT
V
REG
NC
Gnd
Gnd
CS4101
NC
SIN+
SINE-
F
GEN
20
19
18
17
16
15
14
13
12
11
C4
+
R
T
Speedo
Input
Battery
R1D1
Air Core
Gauge
200W
Speedometer
R3
R2
C3
R4
C
T
C1D2
CP+
CP+
1
SQ
2
OUT
3
FREQ
IN
4
BIAS
5
Gnd
6
Gnd
7
NC
COS+
8
COS-
9
V
10
CC
COSINE SINE
CP-
F/V
OUT
V
REG
NC
Gnd
Gnd
CS4101
NC
SIN+
SINE-
F
GEN
20
19
18
17
16
15
14
13
12
11
C4
+
R
T
Air Core
Gauge
200W
C2
1
Speedometer
CS8441
Air Core
Stepper Motor
200W
Odometer
Page 8
8
Rev. 11/20/98
CS4101
Part Number Description
CS4101EN20 20L PDIP
D
Lead Count Metric English
Max Min Max Min
20 Lead PDIP 26.92 24.89 1.060 .980
Ordering Information
Thermal Data 20L PDIP
R
QJC
typ 25 ûC/W
R
QJA
typ 65 ûC/W
Package Specification
PACKAGE DIMENSIONS IN mm (INCHES)
PACKAGE THERMAL DATA
© 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.
Plastic DIP (N); 300 mil wide
0.39 (.015)
MIN.
2.54 (.100) BSC
1.77 (.070)
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)
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