FUJITSU MB3773 - Manual (Page 21)

MB3773
21
EXAMPLE 9: Reducing Reset Hold Time
V
CC
(
=
5 V)
1
2
3
4
8
7
6
5
C
T
MB3773
RESET
RESET
CK
GND
Logic circuit
(a) T
PR
reduction method
V
CC
(
=
5 V)
1
2
3
4
8
7
6
5
C
T
MB3773
RESET
RESET
CK
GND
Logic circuit
Notes :
•
RESET is the only output that can be used.
•
Standard T
PR
, T
WD
and T
WR
value can be found using the following formulas.
Formulas: T
PR
(ms) := 100
×
C T (
µ
F)
T
WD
(ms) := 100
×
C T (
µ
F)
T
WR
(ms) := 16
×
C T (
µ
F)
•
The above formulas become standard values in determining T
PR
, T
WD
and T
WR
.
Reset hold time is compared below between the reduction circuit and the standard circuit.
(b) Standard usage
C
T
=
0.1
µ
F
T
PR
reduction circuit Standard circuit
T
PR
:= 10 ms 100 ms
T
WD
:= 10 ms 10 ms
T
WR
:= 1.6 ms 2.0 ms