Rev.2.1
_01
STEP-UP, 1.2 MHz HIGH-FREQUENCY, PWM CONTROL
SWITCHING REGULATOR CONTROLLERS
S-8337/8338 Series
The S-8337/8338 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.
With the S-8337 Series, the maximum duty ratio of PWM control can be
controlled by the resistor connected to the RDuty pin. With the S-8338 Series,
the maximum duty ratio is fixed (to 88%). 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. This condition is
cleared by re-application of power or by setting the switching regulator (S-8338
Series) to the shutdown status. 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)
47 to 88.5% (selectable by external resistor) (S-8337 Series)
Fixed to 88% typ. (S-8338 Series)
Reference voltage:
1.0 V±1.5%
UVLO (under-voltage lockout) function:
Detection voltage can be selected from between 1.5 V and 2.3 V in 0.1 V steps.
Hysteresis width can be selected from between 0.1 V and 0.3 V in 0.1 V steps.
Timer latch short-circuit protection circuit:
Delay time can be set using an external capacitor.
Soft-start time can be selected in three steps, 10 ms, 15 ms, and 20 ms.
Soft-start function:
Phase compensation external setting:
Adjustable by connecting resistor and capacitor in series to GND.
Shutdown function:
S-8338 Series, shutdown current consumption: 1.0
µA
max.
8-pin SON(A), 8-pin TSSOP
Small package:
Applications
•
Power supplies for LCDs and CCDs
•
Power supplies for portable equipment
Packages
Package name
8-Pin SON(A)
8-Pin TSSOP
Package
PN008-A
FT008-A
Drawing code
Tape
PN008-A
FT008-E
Reel
PN008-A
FT008-E
1
Seiko Instruments Inc.
STEP-UP, 1.2 MHz HIGH-FREQUENCY, PWM CONTROL SWITCHING REGULATOR CONTROLLERS
Rev.2.1
_01
S-8337/8338 Series
Pin Assignment
Table 1
Pin No.
8-Pin SON(A)
Top view
1
2
3
4
8
7
6
5
Symbol
CC
FB
CSP
VIN
EXT
VSS
ROSC
RDuty
ON/OFF
1
2
3
4
5
6
7
Figure 2
8
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 (S-8337 Series)
Shutdown pin (S-8338 Series)
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
ON/OFF
2
3
4
5
6
7
Figure 3
8
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 (S-8337 Series)
Shutdown pin (S-8338 Series)
4
Seiko Instruments Inc.
PCB设计
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