S-8333 Series
www.sii-ic.com
© Seiko Instruments Inc., 2004-2015
STEP-UP, FOR LCD BIAS SUPPLY, 1-CHANNEL,
PWM CONTROL SWITCHING REGULATOR CONTROLLER
Rev.4.2
_00
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 1.08 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
280 kHz to 1.08 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
*1
Lead-free, Sn 100%, halogen-free
•
•
•
•
•
•
•
*1.
Refer to “
Product Name Structure”
for details.
Applications
•
Power supplies for LCDs and CCDs
•
Power supplies for portable equipment
Packages
•
SNT-8A
•
8-Pin TSSOP
Seiko Instruments Inc.
1
STEP-UP, FOR LCD BIAS SUPPLY, 1-CHANNEL, PWM CONTROL SWITCHING REGULATOR CONTROLLER
Rev.4.2
_00
S-8333 Series
Pin Configurations
1. SNT-8A
Table 1
Top view
1
2
3
4
8
7
6
5
Pin No.
1
2
3
4
5
6
7
8
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
Figure 2
2. 8-Pin TSSOP
Table 2
Top view
1
2
3
4
8
7
6
5
Pin No.
1
2
3
4
5
6
7
8
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
Figure 3
Seiko Instruments Inc.
5
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