sp690acp Exar Corporation, sp690acp Datasheet - Page 11

• Manufacturer Part Number: sp690acp
• Description: Low Power Microprocessor Supervisory With Battery Switch-over
• Manufacturer: Exar Corporation

Figure 14. Input and Output Status in Battery-Backup Mode.
To enter the Battery-Backup mode, V
Reset threshold and less than V
Using a High Capacity Capacitor
as a Backup Power Source
V
V
ages are typically +20mV centered at V
allowing use of a capacitor and a simple charging
circuit as a backup source (see Figure 16).
Figure 15. Allowable BACKUP-BATTERY Voltages
Date: 11/29/04
BATT
CC
I S
R
R
N
N
N
N
N
, and the battery-switchover threshold volt-
S
S
V
S
S
P
S
S
V
W
G
E
E
V
P
U
U
U
U
U
P
B
P
P
P
P
O
F
P
P
S
S
N
C
A
I F
I D
has the same operating voltage range as
M
M
M
M
M
U
A
O
8
8
C
T
6
6
E
E
8
8
A
T
T
0
0
R
9
9
B
B
B
0
0
B
B
T
T
L
2
5
0
2
2
5
T
E
E
E
E
E
M
M
A
A
L
L
R
R
R
R
R
SP690A/692A Low Power Microprocessor Supervisory with Battery Switch-Over
i D
e l
P
L
L
L
C
a
C
d
V
d
W
o
o
o
n
a r
s i
o
C
o
o
s s
c s
a
g
g
g
C
w
n
n
a
n i
w
c t
c i
c i
c i
n
n
<
b
o
e
h t
e t
n
B
B
B
B
B
h
e
e
e l
n
f - r
o l
o l
h
V
d
a
c
c
A
A
A
n
n r
A
A
f
BATT
. d
g i
o r
B
e t
e t
n
i a
w
w
o
e
C
C
C
V
V
V
V
V
A
C
C
l a
h
g
c
T
m
c l
.
d
d
0
S
O
O
O
O
O
T
K
K
K
K
K
M
e t
i t
6 .
S (
CC
8
T
o t
o t
-
o
U
U
U
L
L
L
L
L
m
U
U
h t
d
A
must be less than the
A
m
1
P
T
T
T
T
T
P
P
P
P
P
4
4
e
r e
I X
V
V
, A
f
. V
T
8
A
A
A
o r
p
A
A
P
B -
B -
B -
8 .
5 .
B -
B -
B
O
U
b
0
r a
M
M
G
G
G
A
s i
G
G
U
m
a
t a
5
0
5
T
S
T
A
A
A
A
A
t a
T
s
O
U
.
E
E
E
E
E
d
e t
o
V
T
T
T
T
T
h t
S
o l
r o
M
s i
C
l n
[
[
[
[
[
y r
O
T
T
T
T
T
o r
] V
] V
] V
] V
] V
n
a
U
r u
) y
s
E
E
E
E
E
s i
T
g
b
w
s i
u
R
R
R
e r
R
R
BATT
e l
g
c t i
a
Y
Y
Y
Y
Y
t n
d
h
s
h
,
11
Figure 16. Backup Power Source Using High Capacity
Capacitor with SP690A/802L/805L and a +5V ±5% Supply
If V
is 0.5V above V
V
less than 0.5V above V
Leakage current through the capacitor charging
diode and the SP690A/SP802L/SP805L internal
power diode eventually discharges the capacitor
to V
above the reset threshold and power is lost at
V
V
SP690A/SP802L/SP805L then switches to
battery-backup mode.
Figure 17. Backup Power Source Using High Capacity
Capacitor with SP692A/802M/805M and a +5V ±10% Supply
CC
CC
CC
100KΩ
CC
CC
0.1F
, the capacitor on V
until V
V
from V
0.1F
BATT
. Also, if V
is above the reset threshold and V
V
BATT
BATT
BATT
+5V
GND
V
CC
CC
reaches the reset threshold; the
+5V
CC
until the voltage at V
, current flows to VOUT and
GND
V
CC
and V
(RESET)*
V
RESET
OUT
BATT
© Copyright 2004 Sipex Corporation
CC
(RESET)*
V
*( ) SP805L only
RESET
OUT
.
BATT
*( ) SP805M only
discharges through
CONNECT TO
STATIC RAM
start from 0.5V
CONNECT TO
STATIC RAM
CONNECT
CONNECT
TO µP
TO µP
BATT
BATT
is