26 SuPPlY VOlTaGe DeTeCTOR (SVD)
S1C17624/604/622/602/621 TeChniCal Manual
Seiko epson Corporation
26-1
Supply Voltage Detector (SVD)
26
SVD Module Overview
26.1
The S1C17624/604/622/602/621 includes an SVD (supply voltage detector) circuit to monitor the power voltage
supplied to the V
DD
pin. It generates an interrupt when the power supply voltage drops below the detection level set
with software. The detection results can also be read via software.
The following shows the features of the SVD module:
• Power supply voltage to be detected: V
DD
• Detection voltage levels:
15 levels (1.8 V to 3.2 V)
• Interrupt supported:
1 system (power supply voltage drop detection interrupt)
Figure 26.1.1 shows the SVD configuration.
V
DD
Internal data bus
SVD interrupt request
To ITC
Voltage
comparator
Interrupt
control circuit
Comparison
voltage
setting circuit
Detection
result
SVDDT
SVD
Interrupt enable
SVDIE
SVD enable
SVDEN
Comparison voltage
SVDC[3:0]
Clock enable
Divider
SVDCKEN
Clock source
selection
SVDSRC
SVDCLK
HSCLK
OSC1
1/512
Gate
1.1 SVD Configuration
Figure 26.
Operating Clock
26.2
The SVD module includes a clock source selector, dividers, and a gate circuit for controlling the operation clock.
Clock selection
Use SVDSRC[1:0]/OSC_SVD register to select the clock source from HSCLK (IOSC or OSC3) and OSC1.
Setting SVDSRC to 1 (default) selects OSC1 and setting it to 0 selects HSCLK.
When OSC1 is selected as the clock source, the OSC1 clock (typ. 32.768 kHz) is directly used as SVDCLK.
When HSCLK is selected as the clock source, SVDCLK is generated by dividing HSCLK (IOSC or OSC3
clock) by 512.
Clock enable
The clock supply is enabled with SVDCKEN/OSC_SVD register. The SVDCKEN default setting is 0, which
stops the clock. Setting SVDCKEN to 1 feeds the clock selected to the SVD circuit. If no SVD operation is re-
quired, stop the clock to reduce current consumption.
If SVDCLK is not supplied, the SVD circuit cannot detect voltage levels. However, the SVD control registers
can be accessed even if SVDCLK is stopped.
note: Be sure to set SVDCKEN to 0 before selecting the clock source.