POWER SUPPLY ICs
BATTERY BACKUP 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. It
consists of two voltage regulators, three voltage detectors, a
power supply switch and its controller, as well as other
functions on a single chip.
In addition to the switching function between the primary and
backup power supply, the S-8424A series can provide the
microcontrollers 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 current consumption
15 µA max. (VIN = 6 V, during normal operation)
2.1 µA max. (during backup)
• Voltage regulator
• Output voltage accuracy: ±2%
• Output voltage: 2.3 V to 5.4 V (selectable in 0.1 V steps)
• Three built-in voltage detectors (CS, PREEND, RESET)
• Detection voltage accuracy: ±2%
• Detection voltage: 2.4 V to 5.3 V (selectable in 0.1 V steps)
(CS voltage detector)
1.7 V to 3.4 V (selectable in 0.1 V steps)
(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
8-pin SON(B)
PIN CONFIGURATION
8-pin TSSOP
Top view
1
8
2
7
3
6
4
5
8-pin SON(B)
Top view
1. VSS
2. PREEND
3. VBAT
4. CS
5. RESET
6. VOUT
7. VIN
8. VRO
1
1. VSS
2. PREEND
3. VBAT
7 4. CS
5. RESET
6 6. VOUT
5 7. VIN
8. VRO
8
2
3
4
APPLICATIONS
•
•
•
•
Camcorders
Digital still cameras
Memory cards
SRAM backup equipment
SELECTION GUIDE
Item
Product name
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
Package
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
Output voltage (V)
VRO
VOUT
CS voltage (V)
–VDET1
+VDET1
RESET voltage (V) PREEND voltage (V) Switch voltage (V)
–VDET2
+VDET2
–VDET3
+VDET3
VSW1
3.000
3.000
3.300
3.401
2.200
2.312
2.600
2.748
+VDET1 × 0.85
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
+VDET1 × 0.77
+VDET1 × 0.85
+VDET1 × 0.77
+VDET1 × 0.77
+VDET1 × 0.77
+VDET1 × 0.77
+VDET1 × 0.77
BLOCK DIAGRAM
VOUT
VIN
M1
REG2
VBAT
PREEND
PREEND
Voltage detector
VSW1
Detector
RESET
CS
VSW2
Detector
CS
Voltage detector
RESET
Voltage detector
Switch
controller
REG1
VSS
46
VRO
