HA16117F Series
Block Diagram
1
VCC
5 V
2.52 (117FA)
2.36 (117FB)
2.20 (117FC)
Low voltage detector
GND
−
6
4
+
1
COMP.
≈1.25 V
GND
CR
RES
5
I1
Power-on and auto-reset circuit
(*I1 < I2)
−
0.1 µ
to Micro-
computer
+
SW2
COMP.
I2 adjustment
SW1
I2
(SW1 and SW2 are active high)
Watchdog timer
Watchdog filter (f-duty converter)
R1
510 k
Tadj
8
2
R2
750 k
Normal range
W.D out
duty (%)
P-RUN
n
W.D in
W.D out
duty n%
1/2 frequency
divider
fL/2
fH/2
duty 50%
W.D in frequency (Hz)
CF
3
ACC
7
PULSE from I/O port
0.01 µ
Operating: "Low"
Standby: "High"
Mode
ACC Voltage
Function
Operating
Standby
Low
Low voltage detection and WDT
Low voltage detection
High
Note: The power-on reset circuit operates in both operating and standby modes.
The HA16117F consists of a low voltage detector, power-on and auto-reset circuit, and watchdog timer.
Low Voltage Detector
Uses a reference voltage source (≈ 1.25 V) and high-precision comparator to detect drops in the supply
voltage.
Power-On and Auto-Reset Circuit
Generates the RES waveform, using a multivibrator consisting of a current source I1 that charges the
external capacitor CR, a current source I2 that discharges CR, and a comparator.
3
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