CS4121
CS4121
Low Voltage Precision Air-Core
Tach/Speedo Driver
Description
The CS4121 is specifically designed
for use with air-core meter move-
ments. The IC provides all the func-
tions necessary for an analog
tachometer or speedometer. The
CS4121 takes a speed sensor input
and generates sine and cosine relat-
ed 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 uti-
lizes differential drivers which elim-
inates 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 allow-
ing for fewer trims and for use in a
speedometer.
The CS4121 is compatible with the
CS8190, and provides higher accu-
racy at a lower supply voltage (8.0V
min. as opposed to 8.5V). It is func-
tionally operational to 6.5V.
Features
s
s
s
s
s
s
Direct Sensor Input
High Torque Output
Low Pointer Flutter
High Input Impedance
Overvoltage Protection
Accurate to 8V
Functional to 6.5V (typ)
Package Options
16 Lead PDIP
(internally fused leads)
CP+
SQ
OUT
FREQ
IN
Gnd
Gnd
COS+
COS-
V
CC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
Absolute Maximum Ratings
Supply Voltage (<100ms pulse transient)..........................................V
CC
= 60V
(continuous) ..............................................................V
CC
= 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
CP+
SQ
OUT
Charge Pump
F/V
OUT
CP-
F/V
OUT
V
REG
Gnd
Gnd
SINE+
SINE-
BIAS
20 Lead SOIC
(internally fused leads)
CP+
1
SQ
OUT
2
3
20
19
18
17
16
15
14
13
12
11
Input
Comp.
+
Voltage
Regulator
V
REG
FREQ
IN
Gnd
V
REG
7.0V
Gnd
COS+
+
Ð
+
Ð
COS
Output
Func.
Gen.
+
Ð
COS-
High Voltage
Protection
V
CC
Rev 12/4/96
Ð
SINE
Output
+
Ð
CP-
CP-
F/V
OUT
V
REG
Gnd
Gnd
Gnd
Gnd
SIN+
SIN-
BIAS
FREQ
IN
Ð
Gnd
4
Gnd
Gnd
Gnd
5
Gnd
6
Gnd
7
SINE+
COS+
8
COS-
9
V
CC
10
SINE-
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
1
A
¨
Company
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
