CS4192 ON Semiconductor, CS4192 Datasheet - Page 5

• Manufacturer Part Number: CS4192
• Description: Single Air-Core Gauge Driver
• Manufacturer: ON Semiconductor

microprocessor and air−core meter movements commonly
used in automotive vehicles for speedometers and
tachometers. These movements are built using two coils
placed at a 90 orientation to each other. A magnetized disc
floats in the middle of the coils and responds to the magnetic
field generated by each coil. The disc has a shaft attached to
it that protrudes out of the assembly. A pointer indicator is
attached to this shaft and in conjunction with a separate
printed scale displays the vehicle’s speed or the engine’s
speed.
voltages applied to the coils. Ideally, this relationship
follows a sine/cosine equation. Since this is a transcendental
and non−linear function, devices of this type use an
approximation for this relationship. The SACD uses a
tangential algorithm as shown in Figure 2. Only one output
varies in any 45 degree range.
Quadrant I
SIN+
Output
SIN−
Output
COS+
Output
COS−
Output
The SACD is for interfacing between a microcontroller or
The disc (and pointer) respond to the vector sum of the
Max(128)
Max(128)
Max(128)
Max(128)
Min(0)
Min(0)
Min(0)
Min(0)
q + Tan −1
For q + 0.176°to 44.824° :
For q + 45.176°to 89.824° :
000
0
V SIN + Tanq
V COS + 0.748
V SIN + 0.748
V COS + Tan(90° * q)
Figure 2. SIN, COS Outputs
THEORY OF OPERATION
001
45
V COS) * V COS*
010
90
V SIN) * V SIN*
Degrees of Rotation
MUX bits (D9−D7)
135
011
0.748
V BB
V BB
180
100
V BB
0.748
101
225
APPLICATIONS INFORMATION
270
110
V BB
315
111
http://onsemi.com
360
000
CS4192
5
Quadrant II
Quadrant III
Quadrant IV
q + 180°−Tan −1
For q + 90.176°to 134.824° :
For q + 135.176°to 179.824° :
q + 180° ) Tan −1
For q + 180.176°to 224.824° :
For q + 225.176°to 269.824° :
q + 360° * Tan −1
For q + 270.176°to 314.824° :
For q + 315.176° * 359.824° :
V SIN + 0.748
V COS + *Tan (q * 90°)
V SIN + Tan(180° * q)
V COS + *0.748
V SIN + *Tan (q * 180°)
V COS + *0.748
V SIN + *0.748
V COS + *Tan (270° * q)
V SIN + *0.748
V COS + Tan(q * 270°)
V SIN + *Tan (360° * q)
V COS + 0.748
V COS) * V COS*
V SIN) * V SIN*
V BB
V COS) * V COS*
V COS) * V COS*
V BB
V SIN) * V SIN*
V SIN) * V SIN*
V BB
V BB
V BB
V BB
0.748
0.748
0.748
0.748
0.748
0.748
V BB
V BB
V BB
V BB
V BB
V BB