Fujitsu FR81S Manual De Usuario
CHAPTER 32: LOW-VOLTAGE DETECTION (EXTERNAL
LOW-VOLTAGE DETECTION)
6. Notes
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : LOW-VOLTAGE DETECTION (EXTERNAL LOW-VOLTAGE DETECTION)
FUJITSU SEMICONDUCTOR CONFIDENTIAL
11
6. Notes
This section provides notes on the low-voltage detection (external low-voltage detection).
Notes on using the low-voltage detection reset circuit
Operation by program
⋅
The low-voltage detection reset circuit operates in accordance with settings, except for the external
low-voltage detection rise detection which is used as power-on reset.
⋅
Because the external low-voltage detection rise detection operates constantly, current is consumed even
in sleep mode, stop mode, and watch mode.
Operation in stop mode
⋅
The low-voltage detection reset can continue to operate even in stop mode by settings. If a low-voltage is
then detected in stop mode, the settings initialization reset is generated and the stop mode is cleared.
Hysteresis of detection/reset release voltage
⋅
Since the detection voltage and reset voltage exhibit hysteresis of 0.1V, the reset release voltage becomes
the set detection voltage + 0.1V. For example, when LVD5F: 4.1V±8% is set, the release voltage
becomes 4.2V±8%.
Be sure to connect an external reset IC if an interrupt is generated when
low-voltage is detected.
In addition, be sure to set voltage of the reset request signal 2.7V or more at which operation of the CPU is
assured.
Reset IC (external)
Low-voltage detection (Internal power supply low-voltage
detection) (fixed at 0.9V)
Low-voltage detection interrupt (2.8V,3.0V,3.2V,3.6V,3.7V,3.8V,3.9V,4.0V,4.1V,4.2V,4.3V)
MB91F52x
Vcc
RSTX
Pxx
Reset IC
Vcc
Reset
xx
Vcc5
MB91520 Series
MN705-00010-1v0-E
1162