Rev.1.3
_10
BATTERY BACKUP SWITCHING IC
S-8424A Series
The S-8424A Series is a CMOS IC designed for use in the switching
circuits of primary and backup power supplies on a single chip. It
consists of two voltage regulators, three voltage detectors, a power
supply switch and its controller, as well as other functions.
In addition to the switching function between the primary and backup
power supply, the S-8424A Series can provide the micro controllers
with three types of voltage detection output signals corresponding to
the power supply voltage.
Moreover adopting a special sequence for switch control enables
the effective use of the backup power supply, making this IC ideal
for configuring a backup system.
Features
•
Low power consumption
Normal operation: 15
µA
Max. (V
IN
=
6 V)
Backup: 2.1
µA
Max.
•
Voltage regulator
Output voltage tolerance :
±2
%
Output voltage:
Independently selectable in 0.1 V steps in the range of 2.3 V to 5.4 V
•
Three built-in voltage detectors (CS, PREEND , RESET )
Detection voltage precision:
±2
%
Detection voltage:
Selectable in 0.1 V steps in the range of 2.4 V to 5.3 V (CS voltage detector)
Selectable in 0.1 V steps in the range of 1.7 V to 3.4 V ( PREEND , RESET
voltage detector)
•
Switching circuit for primary power supply and backup power supply configurable on one chip
•
Efficient use of backup power supply possible
•
Special sequence
Backup voltage is not output when the primary power supply voltage does not reach the initial voltage at which
the switch unit operates.
Package
•
8-Pin TSSOP (Package drawing No.: FT008-A)
•
8-Pin SON(B) (Package drawing No.: PA008-B)
Applications
•
Video camera recorders
•
Still video cameras
•
Memory cards
•
SRAM backup equipment
Seiko Instruments Inc.
1
BATTERY BACKUP SWITCHING IC
S-8424A Series
Selection Guide
Part No.
Type
S-8424AAAFT-TB
S-8424AAAPA-TF
S-8424AABFT-TB
S-8424AACFT-TB
S-8424AADFT-TB
S-8424AAFFT-TB
S-8424AAGFT-TB
S-8424AAJFT-TB
S-8424AAKFT-TB
8-Pin TSSOP
8-Pin SON(B)
8-Pin TSSOP
8-Pin TSSOP
8-Pin TSSOP
8-Pin TSSOP
8-Pin TSSOP
8-Pin TSSOP
8-Pin TSSOP
3.300
3.200
5.000
3.200
2.800
3.100
3.200
3.300
3.200
5.000
3.200
2.800
3.100
3.200
4.000
3.300
4.600
4.400
4.400
4.400
4.600
4.129
3.401
4.753
4.545
4.545
4.545
4.753
2.300
2.400
2.300
2.400
2.400
2.200
2.400
2.420
2.528
2.420
2.528
2.528
2.312
2.528
2.500
2.600
2.500
2.600
2.600
2.600
2.600
2.640
2.748
2.640
2.748
2.748
2.748
2.748
+V
DET1
×
0.77
+V
DET1
×
0.85
+V
DET1
×
0.77
+V
DET1
×
0.77
+V
DET1
×
0.77
+V
DET1
×
0.77
+V
DET1
×
0.77
Package
Output
Voltage
(V)
V
RO
3.000
V
OUT
3.000
CS Voltage
(V)
−V
DET1
3.300
+V
DET1
3.401
RESET Voltage
(V)
−V
DET2
2.200
+V
DET2
2.312
−V
DET3
2.600
PREEND
Voltage
Rev.1.3
_10
(V)
+V
DET3
2.748
Switch
Voltage
(V)
V
SW1
+V
DET1
×
0.85
Caution Set the CS voltage so that the switch voltage (V
SW1
) is equal to or greater than the
RESET
detection voltage (−V
DET2
).
−
Remark 1.
The selection range is as follows.
V
RO
, V
OUT
: 2.3 to 5.4 V (0.1 V steps)
−V
DET1
:
2.4 to 5.3 V (0.1 V steps)
−V
DET2
:
1.7 to 3.4 V (0.1 V steps )
−V
DET3
:
1.7 to 3.4 V (0.1 V steps)
V
SW1
:
+V
DET1
×
0.85 or
+V
DET1
×
0.77
2.
If a product with a voltage other than above is required, contact our sales representative.
S-8424A xx
xx - xx
IC direction in tape specification
TB: 8-Pin TSSOP
TF: 8-Pin SON(B)
Package code
FT: 8-Pin TSSOP
PA: 8-Pin SON(B)
Serial code
2
Seiko Instruments Inc.
Rev.1.3
_10
Block Diagram
VOUT
BATTERY BACKUP SWITCHING IC
S-8424A Series
VIN
M1
REG2
VBAT
PREEND
V
SW1
Detector
PREEND
Voltage
detector
CS
CS
Voltage
detector
RESET
V
SW2
Detector
RESET
Voltage
detector
Switch
controller
REG1
VRO
VSS
Figure 1 Block Diagram
Seiko Instruments Inc.
3
BATTERY BACKUP SWITCHING IC
S-8424A Series
Pin Assignment
8-Pin TSSOP
Top View
VSS
PREEND
VBAT
CS
Rev.1.3
_10
Table 1 Pin description
Pin No.
1
2
3
4
5
6
7
8
Pin Name
VSS
PREEND
*1
VBAT
CS
RESET
*2
VOUT
*3
VIN
*4
VRO
Functions
Ground
Output pin of PREEND voltage detector
Backup power supply input pin
Output pin of CS voltage detector
Output pin of RESET voltage detector
Output pin of voltage regulator 2
Primary power supply input pin
Output pin of voltage regulator 1
1
2
3
4
8
7
6
5
VRO
VIN
VOUT
RESET
Figure 2
*1 to *4.
Mount capacitors between VSS (GND pin) and the VIN, VBAT,
VOUT, and VRO pins. (Refer to the
“Standard Circuit”)
Table 2 Pin description
Pin No.
1
2
3
4
5
6
7
8
Pin Name
VSS
PREEND
*1
VBAT
CS
RESET
*2
VOUT
*3
VIN
*4
VRO
Functions
Ground
Output pin of PREEND voltage detector
Backup power supply input pin
Output pin of CS voltage detector
Output pin of RESET voltage detector
Output pin of voltage regulator 2
Primary power supply input pin
Output pin of voltage regulator 1
8-Pin SON(B)
Top View
VSS
1
PREEND
2
8
VRO
7
VIN
6
VOUT
5
RESET
VBAT
3
CS
4
Figure 3
*1 to *4.
Mount capacitors between VSS (GND pin) and the VIN, VBAT,
VOUT, and VRO pins. (Refer to the
“Standard Circuit”)
4
Seiko Instruments Inc.
Rev.1.3
_10
Absolute Maximum Ratings
BATTERY BACKUP SWITCHING IC
S-8424A Series
Parameter
Primary power supply input voltage
Backup power supply input voltage
Output voltage of voltage regulator
CS output voltage
RESET output voltage
PREEND output voltage
Power dissipation
Operating ambient temperature
Storage temperature
Table 3 Absolute Maximum Ratings
(Unless otherwise specified: Ta
=
25°C)
Symbol
Ratings
Unit
V
IN
V
V
SS
−0.3
to V
SS
+18
V
BAT
V
RO
, V
OUT
V
SS
−0.3
to V
IN
+0.3
V
CS
V
SS
−0.3
to V
SS
+18
V
RESET
V
PREEND
P
D
T
opr
T
stg
8-Pin TSSOP
300
8-Pin SON(B)
300
−40
to
+85
−40
to
+125
mW
°C
Caution The absolute maximum ratings are rated values exceeding which the product could suffer
physical damage. These values must therefore not be exceeded under any conditions.
Seiko Instruments Inc.
5
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