4571 Datasheet, PDF (42/126 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4571 Group
VOLTAGE DROP DETECTION CIRCUIT
The built-in voltage drop detection circuit is used to set the
voltage drop detection circuit interrupt request flag (VDF) or to
perform system reset.
The voltage drop detection circuit stops at RAM back-up mode.
EPOF instruction
+
POF instruction
Key-on
wakeup signal
SQ
RQ
Oscillation stop
signal
(Note 1)
RESET pin
(Note 2)
(Note 1)
-
VINT
+
Interrupt occurrence
-
VRST^-/VRST⁺
+
Pull-up transistor
Reset occurrence
Voltage drop
detection circuit
VDF
Voltage drop
detection circuit
interrupt
Internal reset signal
Power-on reset circuit
SRST instruction
Watchdog reset signal
WEF
Notes 1:
This symbol represents a parasitic diode.
2: Applied potential to RESET pin must be VDD or less.
Fig 44. Voltage drop detection reset circuit
Rev.1.02 May 25, 2007 Page 42 of 124
REJ03B0179-0102