Power
Supply
Terminals
ESICI0
ESICI
ESICI1
ESICI2
ESICI3
AV
CC
DV
CC
DV
SS
AV
SS
ESIDVSS
ESICOM
ESICH1
ESICH0
ESICH2
ESICH3
/ESIDVCC
ESI Operation
990
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
Extended Scan Interface (ESI)
37.2.8.2 Using the ESI With Resistive Sensors
Systems with GMRs use magnets on an impeller to measure rotation. The damping material and magnets
modify the electrical behavior of the sensor so that rotation and direction can be detected.
Rotation is measured with resistive sensors by connecting the resistor dividers to ground for a short time
allowing current flow through the dividers. The resistors are affected by the rotating disc creating different
divider voltages. The divider voltages are sampled with the sample-and-hold circuits. After the signals
have settled the dividers may be switched off to prevent current flow and reduce power consumption. The
DAC is used to set the reference level for the comparator, and the comparator detects if the sampled
voltage is above or below the reference level. If the sampled voltage is above the reference level the
comparator output is high.
shows the connection for resistive sensors.
Figure 37-19. Resistive Sensor Connections