Rev.2.3
_00
STEP-DOWN, SYNCHRONOUS PWM CONTROL
SWITCHING REGULATOR CONTROLLER
S-8533 Series
The S-8533 Series is a synchronous PWM control CMOS step-down
switching regulator controller that includes a reference voltage source,
synchronous circuit, oscillation circuit, error amplifier, phase
compensation circuit, and PWM controller.
An efficient step-down switching regulator can be realized simply by
adding external P-channel and N-channel power MOS FETs, one coil,
and three capacitors.
Since the oscillation frequency is a high 300 kHz, the S-8533 can be
used to configure a high efficiency step-down switching regulator
capable of driving high output current using small external parts and a
3 to 10% increase in efficiency is obtained compared to conventional
step-down switching regulators.
The 8-Pin TSSOP package and high oscillation frequency make the S-
8533 ideal as the main power supply for portable devices.
Features
•
Synchronous rectification system realizing high efficiency (typ. 94%)
•
Use at maximum duty ratio = 100% and use of a battery up to maximum life is possible by using P-channel and N-
channel power MOS FETs externally.
•
Oscillation frequency :
300 kHz typ.
•
Input voltage :
2.7 to 16.0 V
•
Output voltage :
1.25 V
1.3 to 6.0 V, selectable in 0.1 V steps
•
Output voltage accuracy :
±2.0%
•
Soft-start function set by an external capacitor (C
SS
)
•
Shutdown function
•
Small package :
8-Pin TSSOP
•
Lead-free products
Applications
•
•
•
•
Constant voltage power supply for hard disks and DVD drivers
Power supplies for portable devices, such as digital cameras, PDAs, electronic organizers, and cellular phones
Main or sub power supply for notebook PCs and peripherals
Constant voltage power supply for cameras, video equipment, and communication equipment
Package
Package Name
8-Pin TSSOP
Package
FT008-A
Drawing Code
Tape
FT008-E
Reel
FT008-E
Seiko Instruments Inc.
1
STEP-DOWN, SYNCHRONOUS PWM CONTROL SWITCHING REGULATOR CONTROLLER
Rev.2.3
_00
S-8533 Series
Block Diagram
L
VIN
Oscillation
circuit
Tr
VOUT
PDRV
+
PWM control circuit
P.N feed-through
prevention circuit
−
+
C
OUT
+
V
IN
C
IN
C
SS
Tr
NDRV
CSS
Reference voltage
source with soft start
VSS
ON / OFF
Remark
All the diodes in the figure are parasitic diodes.
Figure 1
2
Seiko Instruments Inc.
STEP-DOWN, SYNCHRONOUS PWM CONTROL SWITCHING REGULATOR CONTROLLER
Rev.2.3
_00
S-8533 Series
Product Name Structure
The output voltage for the S-8533 Series can be selected depending on usage. Refer to “1.
Product name”
for the
definition of the product name and “2.
Product name list”
for the full product names.
1. Product Name
S-8533A
xx
x
FT
−
TB
−
G
IC direction in tape specifications
*1
Package code
FT : 8-Pin TSSOP
Output voltage
A : 1.3 to 6.0 V
5 : 1.25 V
Output voltage
13 to 60
(E.g., when the output voltage is 1.5 V, it is expressed as 15.)
The product whose output voltage is 1.25 V expresses 12.
*1.
Refer to the taping specifications.
2. Product Name List
Output Voltage
Product Name
1.25 V
S-8533A125FT-TB-G
1.3 V
S-8533A13AFT-TB-G
1.4 V
S-8533A14AFT-TB-G
1.5 V
S-8533A15AFT-TB-G
1.8 V
S-8533A18AFT-TB-G
2.5 V
S-8533A25AFT-TB-G
2.7 V
S-8533A27AFT-TB-G
2.8 V
S-8533A28AFT-TB-G
3.0 V
S-8533A30AFT-TB-G
3.3 V
S-8533A33AFT-TB-G
3.9 V
S-8533A39AFT-TB-G
4.1 V
S-8533A41AFT-TB-G
4.5 V
S-8533A45AFT-TB-G
4.8 V
S-8533A48AFT-TB-G
4.9 V
S-8533A49AFT-TB-G
5.0 V
S-8533A50AFT-TB-G
5.5 V
S-8533A55AFT-TB-G
6.0 V
S-8533A60AFT-TB-G
Remark
Contact the SII marketing department for the availability of product samples other than those specified
above.
Seiko Instruments Inc.
3
STEP-DOWN, SYNCHRONOUS PWM CONTROL SWITCHING REGULATOR CONTROLLER
Rev.2.3
_00
S-8533 Series
Pin Configurations
Table 1
8-Pin TSSOP
Top view
1
2
3
4
8
7
6
5
Figure 2
No connection
Output voltage pin
Shutdown pin
H : Normal operation (step-down operation)
3
ON/
OFF
L : Step-down operation stopped (all circuits
deactivated)
4
CSS
Soft start capacitor connection pin
5
VSS
GND pin
6
NDRV
External N-channel connection pin
7
PDRV
External P-channel connection pin
8
VIN
IC power supply pin
*1.
The NC pin is electrically open. Connection of this pin to VIN or VSS is
allowed.
Pin No.
1
2
Symbol
NC
*1
VOUT
Pin Description
4
Seiko Instruments Inc.
STEP-DOWN, SYNCHRONOUS PWM CONTROL SWITCHING REGULATOR CONTROLLER
Rev.2.3
_00
S-8533 Series
Absolute Maximum Ratings
Table 2
Parameter
VIN pin voltage
VOUT pin voltage
ON/OFF pin voltage
CSS pin voltage
NDRV pin voltage
PDRV pin voltage
NDRV pin current
PDRV pin current
Power dissipation
Symbol
V
IN
V
OUT
V
ON/OFF
V
CSS
V
NDRV
V
PDRV
I
NDRV
I
PDRV
P
D
(Ta = 25°C unless otherwise specified)
Absolute Maximum Rating
Unit
V
SS
−
0.3 to V
SS
+
18
V
V
SS
−
0.3 to V
SS
+
18
V
V
SS
−
0.3 to V
SS
+
18
V
V
SS
−
0.3 to V
IN
+
0.3
V
V
SS
−
0.3 to V
IN
+
0.3
V
V
SS
−
0.3 to V
IN
+
0.3
V
±100
mA
±100
mA
300 (When not mounted on board)
mW
*1
700
mW
−40
to
+85
°C
−40
to
+125
°C
Operating ambient temperature
T
opr
Storage temperature
T
stg
*1.
When mounted on board
[Mounted board]
(1) Board size : 114.3 mm
×
76.2 mm
×
t1.6 mm
(2) Board name : JEDEC STANDARD51-7
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.
(1) When mounted on board
(2) When not mounted on board
800
Power dissipation P
D
(mW)
700
600
500
400
300
200
100
0
0
50
100
150
Power dissipation P
D
(mW)
400
300
200
100
0
0
50
100
150
Ambient temperature Ta (°C)
Ambient temperature Ta (°C)
Figure 3 Power Dissipation of Package
Seiko Instruments Inc.
5
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