25 RF Converters (RFC)
S1C17602 TECHNICAL MANUAL
EPSON
25-3
RFC
25.3 Operation Mode
R/F converter has 3 measurement modes according to self oscillations and mode measuring external clock entry.
Moreover, as a function to confirm self oscillation frequency, continuous oscillation function which do not make
to strop CR oscillation automatically irrespective of change condition and monitor function of the CR oscillation
clock (RFCLK) are provided. These modes can be set per channel.
DC oscillation mode for measuring resistive sensor
It is a mode that can observe the difference between reference resistance and oscillation cycles of resistive
sensor, Resistive sensor and reference register are DC driven. 1 reference register and maximum 2 resistive
sensors can be connected to 1 channel. When only 1 resistive sensor is in use, unused terminal is set to “Open”.
Set SMODE register to “0” to enable this function. Set the function of the required terminals to R/F converter
for each channel (Refer to the “10.2 Input/Output Pin Function Selection (Port MUX)”). Reference oscillation
startup, sensor A oscillation startup and sensor B oscillation startup are set by using SREF register, SSENA
register and SSENB register respectively.
RREF: Reference Resistance
RSEN1: Resistive Sensor
RSEN2: Resistive Sensor
CREF: Reference Capacity
Direction of current flow
(DC driven)
REF
SENA
SENB
RFIN
RREF
RSEN1
RSEN2
CREF
Figure 25.3.1: Example of DC Oscillation Mode Connection for Measuring Resistive Sensor
AC oscillation mode for measuring resistive sensor
This mode can observe the difference between reference resistance and oscillation cycles of resistive sensor.
Resistive sensor and reference resistance are AC driven. One each of reference register and resistive sensor can
be connected.
Set SMODE register to “1” to enable this function. Set the function of the required terminals to R/F converter
for each channel (Refer to the “10.2 Input/Output Pin Function Selection (Port MUX)”). Reference oscillation
startup is set by using SREF register and sensor oscillation startup is set by using SSENA register.
RREF : Reference Resistance
RSEN : Resistive Sensor
CREF : Reference Capacity
RREF
REF
SENA
SENB
RFIN
CREF
RSEN
Direction of current
flow (AC driven)
Figure 25.3.2: Example of AC Oscillation Mode Connection for Measuring Resistive Sensor