Rev.2.3
_00
STEP-UP, FOR LCD BIAS SUPPLY, 1-CHANNEL, PWM
CONTROL SWITCHING REGULATOR CONTROLLER
S-8333 Series
The S-8333 Series is a CMOS step-up switching regulator which mainly consists of a reference voltage
circuit, an oscillator, an error amplifier, a PWM controller, an under voltage lockout circuit (UVLO), and a
timer latch short-circuit protection circuit. Because its minimum operating voltage is as low as 1.8 V, this
switching regulator is ideal for the power supply of an LCD or for portable systems that operate on a low
voltage. The internal oscillation frequency can be set up to 1.133 MHz, via the resistor connected to the
ROSC pin.
The maximum duty ratio of PWM control can be controlled by the resistor connected to the RDuty pin. The
soft-start function at power application is accomplished by combining the reference voltage control and
maximum duty control methods. Even if the voltage of the FB pin is retained lower than the reference
voltage due to the factor outside the IC, the output voltage is raised by controlling the maximum duty. The
phase compensation and gain value can be adjusted according to the values of the resistor and capacitor
connected to the CC pin. Therefore, the operation stability and transient response can be correctly set for
each application. The reference voltage accuracy is as high as 1.0 V
±1.5%,
and any voltage can be
output by using an external output voltage setting resistor.
In addition, the delay time of the short-circuit protection circuit can be set by using the capacitor
connected to the CSP pin. If the maximum duty condition continues because of short-circuiting, the
capacitor externally connected to the CSP pin is charged, and oscillation stops after a specific time. The
short-circuit protection function is cancelled when the power supply is raised to the UVLO release voltage
after it has been lowered to the UVLO detection voltage. A ceramic capacitor or a tantalum capacitor is
used as the output capacitor, depending on the setting. This controller IC allows various settings and
selections and employs a small package, making it very easy to use.
Features
•
Low voltage operation:
•
Oscillation frequency:
•
Maximum duty:
1.8 V to 6.0 V
286 kHz to 1.133 MHz (selectable by external resistor)
Settable up to 88.5% by external resistor
47 to 88.5% (oscillation frequency; 500 kHz or more)
47 to 80% (oscillation frequency; less than 500 kHz)
Reference voltage:
1.0 V
±1.5%
Range of operation temperature:
−40
to
+85°C
UVLO (under-voltage lockout) function:
Detection voltage can be selected from between 1.5 V and 2.3 V in 0.1 V step.
Hysteresis width can be selected from between 0.1 V and 0.3 V in 0.1 V step.
Timer latch short-circuit protection circuit:
Delay time can be set using an external capacitor.
Soft-start function:
Soft-start time can be selected in three steps, 10 ms, 15 ms, and 20 ms.
Both reference voltage control and maximum duty control methods are applied
Phase compensation external setting:
Control is possible via the resistor connected between the CC and GND pins
and capacitor
Small package:
SNT-8A, 8-Pin TSSOP
Lead-free products
•
•
•
•
•
•
•
•
Applications
•
Power supplies for LCDs and CCDs
•
Power supplies for portable equipment
Packages
Package Name
SNT-8A
8-Pin TSSOP
Drawing Code
Package
PH008-A
FT008-A
Tape
PH008-A
FT008-E
Reel
PH008-A
FT008-E
Land
PH008-A
Seiko Instruments Inc.
1
STEP-UP, FOR LCD BIAS SUPPLY, 1-CHANNEL, PWM CONTROL SWITCHING REGULATOR CONTROLLER
Rev.2.3
_00
S-8333 Series
Pin Configurations
Table 1
Pin No.
1
8
7
6
5
SNT-8A
Top view
1
2
3
4
Symbol
CC
FB
CSP
VIN
EXT
VSS
ROSC
RDuty
Description
Error amplifier circuit output phase
compensation pin
Output voltage feedback pin
Short-circuit protection delay time setting pin
Power supply input pin
External transistor connection pin
GND pin
Oscillation frequency setting resistor
connection pin
Maximum duty setting resistor connection pin
2
3
4
5
6
7
Figure 2
8
Table 2
Pin No.
1
8
7
6
5
8-Pin TSSOP
Top view
1
2
3
4
Symbol
CC
FB
CSP
VIN
EXT
VSS
ROSC
RDuty
Description
Error amplifier circuit output phase
compensation pin
Output voltage feedback pin
Short-circuit protection delay time setting pin
Power supply input pin
External transistor connection pin
GND pin
Oscillation frequency setting resistor
connection pin
Maximum duty setting resistor connection pin
2
3
4
5
6
7
Figure 3
8
4
Seiko Instruments Inc.
STEP-UP, FOR LCD BIAS SUPPLY, 1-CHANNEL, PWM CONTROL SWITCHING REGULATOR CONTROLLER
Rev.2.3
_00
S-8333 Series
Absolute Maximum Ratings
Table 3 Absolute Maximum Ratings
(Unless otherwise specified: Ta
=
25°C, V
SS
=
0 V)
Parameter
VIN pin voltage
FB pin voltage
EXT pin voltage
CSP pin voltage
CC pin voltage
CC pin current
ROSC pin voltage
ROSC pin current
RDuty pin voltage
RDuty pin current
SNT-8A
Power dissipation
8-Pin TSSOP
Operating ambient temperature
Storage temperature
*1.
When mounted on board
[Mounted board]
(1) Board size:
(2) Name:
Caution
114.3 mm
×
76.2 mm
×
t1.6 mm
JEDEC STANDARD51-7
Symbol
V
IN
V
FB
V
EXT
V
CSP
V
CC
I
CC
V
ROSC
I
ROSC
V
RDuty
I
RDuty
P
D
T
opr
T
stg
Ratings
V
SS
−
0.3 to V
SS
+
6.5
V
SS
−
0.3 to V
SS
+
6.5
V
SS
−
0.3 to V
IN
+
0.3
V
SS
−
0.3 to V
IN
+
0.3
V
SS
−
0.3 to V
IN
+
0.3
±10
V
SS
−
0.3 to V
IN
+
0.3
±10
V
SS
−
0.3 to V
IN
+
0.3
±10
450
*1
300 (When not mounted on board)
700
*1
−40
to
+85
−40
to
+125
Unit
V
V
V
V
V
mA
V
mA
V
mA
mW
mW
mW
°C
°C
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.
800
Power dissipation (P
D
) [mW]
600
8-Pin TSSOP
SNT-8A
400
200
0
0
50
100
150
Ambient temperature (Ta) [°C]
Figure 4 Power Dissipation of Package (When mounted on board)
Seiko Instruments Inc.
5
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