S-8520A20MC-AVFT2X Datasheet, PDF (1/44 Pages) Seiko Instruments Inc – SWITCHING REGULATOR CONTROLLER

S-8520/8521 Series
www.sii-ic.com
STEP-DOWN, PWM CONTROL or PWM / PFM SWITCHABLE
SWITCHING REGULATOR CONTROLLER
© SII Semiconductor Corporation, 1997-2010
Rev.9.0_01
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.
 Features
• Low current consumption During operation: 60 μA max. (A, B types)
21 μA max. (C, D types)
100 μA max. (E, F types)
During shutdown: 0.5 μA max.
• Input voltage:
2.5 V to 16 V (B, D, F types)
2.5 V to 10 V (A, C, E types)
• Output voltage:
Selectable between 1.5 V and 6.0 V in 0.1 V step
• Duty ratio:
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).
• Oscillation frequency:
180 kHz typ. (A, B types)
60 kHz typ. (C, D types)
300 kHz typ. (E, F types)
• Soft-start function:
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)
2.6 ms. typ. (E type)
• Lead-free, Sn 100%, halogen-free^*1
*1. Refer to “ Product Name Structure” for details.
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