CS1124-D Datasheet, PDF (3/8 Pages) ON Semiconductor – Dual Variable-Reluctance Sensor Interface IC

PACKAGE PIN DESCRIPTION*
PACKAGE PIN #
SO–8
1
PIN SYMBOL
IN_Adj
2
IN1
3
IN2
4
GND
5
DIAG
6
OUT2
7
OUT1
8
V_CC
CS1124
FUNCTION
External resistor to ground that sets the trip levels of both channels.
Functions for both diagnostic and normal mode.
Input to channel 1.
Input to channel 2.
Ground.
Diagnostic mode switch. Normal mode is low.
Output of channel 2.
Output of channel 1.
Positive 5.0 volt supply input.
V_CC
R1
R_RS
DIAG
IN1
C1
V_{RS Variable}
Reluctance
Sensor
V_CC
INP1
V_CC
V_CC
V_CC
IN_Adj
Active
Clamp
+
–
COMP1
R_Adj
GND
OUT1
To µP
Figure 2. Application Diagram
THEORY OF OPERATION
NORMAL OPERATION
Figure 2 shows one channel of the CS1124 along with the
necessary external components. Both channels share the
IN_Adj pin as the negative input to a comparator. A brief
description of the components is as follows:
V_RS – Ideal sinusoidal, ground referenced, sensor output
– amplitude usually increases with frequency, depending on
loading.
R_RS – Source impedance of sensor.
R1/R_Adj – External resistors for current limiting and
biasing.
INP1/IN_Adj – Internal current sources that determine trip
points via R1/R_Adj.
COMP1 – Internal comparator with built–in hysteresis
set at 160 mV.
OUT1 – Output 0 V – 5.0 V square wave with the same
frequency as V_RS.
By inspection, the voltage at the (+) and (–) terminals of
COMP1 with V_RS = 0V are:
V+ + INP1(R1 ) RRS)
(1)
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