HA16117F Ver la hoja de datos (PDF) - Renesas Electronics
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HA16117F Datasheet PDF : 31 Pages
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HA16117F Series
Block Diagram
1
5V
VCC
2.52 (117FA)
6 GND
2.36 (117FB) Low voltage detector
2.20 (117FC)
−
1
+
≈1.25 V
COMP.
GND
0.1 µ
4 CR
Power-on and auto-reset circuit
(*I1 < I2)
SW2
I2 adjustment
I2
I1
SW1
−
+
COMP.
RES
5
to Micro-
computer
R1
510 k
R2
750 k
Tadj
8
(SW1 and SW2 are active high)
Watchdog timer
Watchdog filter (f-duty converter)
P-RUN
2
1/2 frequency W.D in
divider
W.D out
duty (%)
n
Normal range
duty 50%
fL/2
fH/2
W.D in frequency (Hz)
W.D out
duty n%
PULSE from I/O port
3 CF
0.01 µ
Mode
Operating
Standby
ACC Voltage
Low
High
Function
Low voltage detection and WDT
Low voltage detection
Note: The power-on reset circuit operates in both operating and standby modes.
ACC
7
Operating: "Low"
Standby: "High"
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.
Watchdog Timer
Reshapes the P-RUN signal (programming-running pulse) from the MPU to obtain a 50% duty cycle, then converts
frequency to duty cycle in the watchdog filter (WD filter).
The watchdog filter is a bandpass filter. The duty cycle of the filter output is highest in the normal frequency range of P-
RUN.
The watchdog filter output controls I2 in the multivibrator, the higher the duty cycle of the watchdog filter output, the
shorter the time during which I2 discharges CR. If the duty cycle is high enough then CR is held at a high potential,
preventing the multivibrator from firing, and the RES output remains high.
Rev.3.00 Jun 15, 2005 page 3 of 30
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