Datasheet

Section 18 Power-On Reset and Low-Voltage Detection Circuits (Optional)
Rev.5.00 Nov. 02, 2005 Page 290 of 418
REJ09B0028-0500
PSS:
LVDCR:
LVDSR:
LVDRES:
LVDINT:
Vreset:
Vint:
Prescaler S
Low-voltage-detection control register
Low-voltage-detection status register
Low-voltage-detection reset signal
Low-voltage-detection interrupt signal
Reset detection voltage
Power-supply fall/rise detection voltage
[Legend]
RES
C
RES
CK
R
PSS
R
S
Q
OVF
Vreset
Vcc
Vint
LVDRES
LVDCR
LVDSR
LVDINT
Reference
voltage
generator
Noise canceler
Noise canceler
Interrupt
control
circuit
Internal reset
signal
Power-on reset circuit
Low-voltage detection circuit
Internal data bus
Ladder
resistor
+
−
+
−
φ
Interrupt
request
Figure 18.1 Block Diagram of Power-On Reset Circuit and Low-Voltage Detection Circuit
18.2 Register Descriptions
The low-voltage detection circuit has the following registers.
• Low-voltage-detection control register (LVDCR)
• Low-voltage-detection status register (LVDSR)
18.2.1 Low-Voltage-Detection Control Register (LVDCR)
LVDCR is used to enable or disable the low-voltage detection circuit, set the detection levels for
the LVDR function, enable or disable the LVDR function, and enable or disable generation of an
interrupt when the power-supply voltage rises above or falls below the respective levels.