REGULATOR CONTROLLER. S-8521 Datasheet
© ABLIC Inc., 1997-2010
STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE
SWITCHING REGULATOR CONTROLLER
The S-8520/8521 Series is a CMOS step-down switching regulator-controller with PWM control (S-8520 Series) and PWM
/ PFM switching control (S-8521 Series). The S-8520/8521 Series has a reference voltage source, an oscillation circuit, an
error amplifier, and other components.
The S-8520 Series provides low-ripple power, high efficiency, and excellent transient characteristics due to a PWM control
circuit capable of varying the duty ratio linearly from 0% up to 100%. The S-8520/8521 Series also has a soft-start circuit
that prevents overshoot at startup.
The S-8521 Series works with either PWM control or PFM control. It normally operates using PWM control with a duty ratio
of 25% to 100%, but under a light load, it automatically switches to PFM control with a duty ratio of 25%. The S-8520/8521
Series ensures high efficiency over a wide range of conditions for devices, from the standby mode to the operation.
By adding external Pch power MOS FET or PNP transistor, coil, capacitor, and externally connected diode, the
S-8520/8521 Series can function as a step-down switching regulator, and is ideal for power supply units of portable
devices due to small SOT-23-5 and the feature of low current consumption. It is also ideal for AC adapters due to the input
voltage up to 16 V.
Low current consumption During operation: 60 A max. (A, B types)
21 A max. (C, D types)
100 A max. (E, F types)
During shutdown: 0.5 A max.
2.5 V to 16 V (B, D, F types)
2.5 V to 10 V (A, C, E types)
Selectable between 1.5 V and 6.0 V in 0.1 V step
0% to 100% PWM control (S-8520 Series)
25% to100% PWM / PFM switching control (S-8521 Series)
External parts are Pch power MOS FET or PNP transistor, coil, diode, and capacitor only
(When using PNP transistor, add base resistor and capacitor).
180 kHz typ. (A, B types)
60 kHz typ. (C, D types)
300 kHz typ. (E, F types)
8 ms. typ. (A, B types)
12 ms. typ. (C, D types)
4.5 ms. typ. (E, F types)
With a shutdown function
With a built-in overload protection circuit Overload detection time:
4 ms. typ. (A type)
14 ms. typ. (C type)
Lead-free, Sn 100%, halogen-free*1
2.6 ms. typ. (E type)
*1. Refer to “ Product Name Structure” for details.
STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
On-board power supplies of battery devices for mobile phone, electronic notebooks, PDAs.
Power supplies for audio equipment, including portable CD players and headphone stereo equipment.
Fixed voltage power supply for cameras, video and communication devices.
Power supplies for microcomputers
Conversion from NiH or four NiCd cells or two lithium-ion cells to 3.3 V / 3 V.
Conversion of AC adapter input to 5 V / 3 V.