REGULATOR CONTROLLER. S-8338 Datasheet
© ABLIC Inc., 2003-2010
STEP-UP, 1.2 MHz HIGH-FREQUENCY, PWM CONTROL
SWITCHING REGULATOR CONTROLLER
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 V1.5%, 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.
Low voltage operation: 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)
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.
Phase compensation external setting:
Adjustable by connecting resistor and capacitor in series to GND.
S-8338 Series, shutdown current consumption: 1.0 A max.
Lead-free, Sn 100%, halogen-free*1
*1. Refer to “ Product Name Structure” for details.
Power supplies for LCDs and CCDs
Power supplies for portable equipment
STEP-UP, 1.2 MHz HIGH-FREQUENCY, PWM CONTROL SWITCHING REGULATOR CONTROLLER
RDuty (S-8337) or
Maximum duty circuit
(1.0 V) soft-start
Figure 1 Block Diagram