HD64F38024HV Datasheet, PDF (454/684 Pages) Renesas Technology Corp – Hardware Manual Renesas 8-Bit Single-Chip Microcomputer H8 Family/H8/300L Super Low Power Series

Section 14 Power-On Reset and Low-Voltage Detection Circuits (H8/38124 Group Only)
Two pairs of detection levels for reset generation voltage are available: when only the LVDR
circuit is used, or when the LVDI and LVDR circuits are both used. In addition, power supply
rise/drop detection voltages and a detection voltage reference voltage may be input from an
external source, allowing the detection level to be set freely by the user.
14.1.2 Block Diagram
A block diagram of the power-on reset circuit and low-voltage detection circuit are shown in
figure 14.1.
RES
External
power
supply
External
ladder
resistor
extD
extU
Vref
External
reference voltage
generator
Noise
canceler
Noise
canceler
φ
CK
PSS
R
OVF
R
Q
S
Power-on reset circuit
Internal reset
signal
Vreset
Vcc
Ladder
resistor
Vint
+
−
LVDRES
+
− _LVDINT
Interrupt
control
circuit
LVDCR
LVDSR
On-chip
reference voltage
generator
Interrupt
request
[Legend]
PSS:
Prescaler S
LVDCR: Low-voltage-detection control register
LVDSR: Low-voltage-detection status register
LVDRES: Low-voltage-detection reset signal
LVDINT: Low-voltage-detection interrupt signal
Vreset: Reset detection voltage
Vint:
Power-supply fall/rise detection voltage
extD: Power supply drop detection voltage input pin
extU: Power supply rise detection voltage input pin
Vref:
Reference voltage input pin
Low-voltage detection circuit
Figure 14.1 Diagram of Power-On Reset Circuit and Low-Voltage Detection Circuit
Rev. 8.00 Mar. 09, 2010 Page 432 of 658
REJ09B0042-0800