M62055FP Datasheet, PDF (5/6 Pages) Mitsubishi Electric Semiconductor – 3V POWER SUPPLY with WATCHDOG TIMER

MITSUBISHI<Dig./Ana.INTERFACE>
M62055FP
3V POWER SUPPLY with WATCHDOG TIMER
DESCRIPTION of TERMS
tRST(1) _{Time from when TC begins to charge}
until it reaches to VTH2(L).
tWD
Time from when TC is VTH2(L) until it
reaches to VTH2(H).
tRST(2) Time from when TC is VTH2(H) until TC
starts charging.
1. Pin 3 (TC pin) Charging and discharging
time .
When an error is occurred in WD input,
TC waveform is as shown below.
VTH1(H)
Vo
0
output cutoff
VTH1(L)
=^..0.9V
VTH2(H)
2. Pin 2 (WD pin) Input frequency,
input pulse width, charge/discharge
time .
When input of 2 WD is normal, TC waveform 3
is as shown below.
XV
Pin 3
t1 t2
VTH2(H) = 2.4v
VTH2(L) = 1.0v
Pin 2
tWDIN
t1 = C • R1 • ln ²
3-X
TC
VTH2(L)
0
Inside delay time
tRST(1)
tWD
tRST(2)
X ( ^R1 + 1) - 3
t2 = 1000 • C • R1 • ln
1000
R1 _{- 2}
1000
*1
tRST(1) = 0.406 • C • R1 + 300µs
tWD = 1.2 • C • R1
(Charging time)
VO = 3.0V
R1
3
C
Conditions of an input to pin 2 (WD pin)
(1) Input period should be tWD or less.
( Pin discharge is completed before the arrival
of VTH2(H) = 2.4 V )
1
<f
1.2 • C • R1
*1 : Inside delay time (Typical values)
(2) Input pulse width tWDIN should be t2 or less.
The following formula can be obtained because
tRST(2) is equal to the duration of Vo cutoff.
tRST(2)
=
C
•
*3
R•
ln
(
3
0.9
)
*2
+ 300µs
Al
C
*2
= 40 • C + 300µs
*2 : Inside delay time
(Typical values)
*3 : R = Internal resistance
cutoff Tr
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