S-8425 Series
www.sii-ic.com
© Seiko Instruments Inc., 2002-2012
BATTERY BACKUP SWITCHING IC
Rev.3.0
_01
The S-8425 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 three voltage regulators, two voltage detectors, a power supply switch
and its controller, as well as other functions.
In addition to the function for switching between the primary and backup power supply, the S-8425 Series can
provide microcontrollers with two 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
•
Two built-in voltage detectors (CS, RESET)
Detection voltage tolerance:
±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 (RESET voltage
detector)
•
RESET release delay: 300
μs
min.
•
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.
•
Lead-free, Sn 100%, halogen-free
*1
*1.
Refer to “
Product Name Structure”
for details.
Packages
•
8-Pin TSSOP
•
8-Pin SON(B)
Applications
•
Camcorders
•
Digital cameras
•
Memory cards
•
SRAM backup equipment
Seiko Instruments Inc.
1
BATTERY BACKUP SWITCHING IC
S-8425 Series
Product Name Structure
1. Product Name
(1) 8-Pin TSSOP
S-8425A xx
FT - TB - x
Rev.3.0
_01
Environmental code
U: Lead-free (Sn 100%), halogen-free
G: Lead-free (for details, please contact our sales office)
IC direction in tape specification
Package code
FT: 8-Pin TSSOP
Serial code
(2) 8-Pin SON(B)
S-8425A xx
PA - TF - G
Environmental code
G: Lead-free (for details, please contact our sales office)
IC direction in tape specification
Package code
PA: 8-Pin SON(B)
Serial code
2. Packages
Package Name
8-Pin TSSOP
8-Pin SON(B)
Environmental code = G
Environmental code = U
Package
FT008-A-P-SD
FT008-A-P-SD
PA008-B-P-SD
Drawing Code
Tape
FT008-E-C-SD
FT008-E-C-SD
PA008-B-C-SD
Reel
FT008-E-R-SD
FT008-E-R-S1
PA008-B-R-SD
2
Seiko Instruments Inc.
Rev.3.0
_01
BATTERY BACKUP SWITCHING IC
S-8425 Series
3. Product Name List
Item
Product name
S-8425AAAFT-TB-x
S-8425AAAPA-TF-G
8-Pin
TSSOP
8-Pin
SON(B)
Package
Output Voltage (V)
V
RO
3.000
3.000
V
OUT
3.000
3.000
V
CH
3.300
3.300
CS Voltage
(V)
−V
DET1
3.300
3.300
+V
DET1
3.401
3.401
RESET Voltage
(V)
−V
DET2
2.200
2.200
+V
DET2
2.312
2.312
Switch Voltage
(V)
V
SW1
+V
DET1
×
0.85
+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
).
V
RO
, V
OUT
, V
CH
:
2.3 to 5.4 V (0.1 V steps)
Remark 1
The selection range is as follows.
−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
SW1
:
+V
DET1
×
0.85 or
+V
DET1
×
0.77
2.
Please contact our sales office for the products with a voltage other than those specified above.
3.
x: G or U
4.
Please select products of environmental code = U for Sn 100%, halogen-free products.
Seiko Instruments Inc.
3
BATTERY BACKUP SWITCHING IC
S-8425 Series
Block Diagram
VOUT
Rev.3.0
_01
M1
VIN
REG2
VBAT
V
SW1
detector
RESET
Voltage
detector
RESET
CS
CS
Voltage
detector
Switch
controller
V
SW2
detector
Delay
circuit
REG1
VRO
REG3
VCH
VSS
Figure 1
Block Diagram
4
Seiko Instruments Inc.
Rev.3.0
_01
BATTERY BACKUP SWITCHING IC
S-8425 Series
Pin Configurations
8-Pin TSSOP
Top View
VSS
VCH
VBAT
CS
Pin
No.
VRO
VIN
VOUT
RESET
Symbol
VSS
VCH
*1
VBAT
*1
CS
RESET
VOUT
*1
VIN
*1
VRO
*1
Description
Ground
Output pin of voltage regulator 3
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
8-Pin SON(B)
Top View
VSS
VCH
VBAT
CS
1
2
3
4
8
7
6
5
VRO
VI N
VOUT
RESET
1
2
3
4
5
6
7
8
Figure 2
*1.
Pin Configurations
Mount capacitors between VSS (GND) and the VIN, VBAT, VOUT, VRO, and VCH pins (see the
Standard Circuit
section).
Seiko Instruments Inc.
5
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