SR08X Datasheet, PDF (1/7 Pages) Supertex, Inc – Adjustable Off-Line Inductorless Switching Regulator

Supertex inc.
SR086/SR087
Adjustable Off-Line
Inductorless Switching Regulator
Initial Release
Features
► Efficient operation without magnetics
► No high voltage capacitors
► Adjustable main output voltage (9V to 50V)
► Additional 3.3V or 5V internal regulator
► Up to 100mA combined output current
► Single BOM for 120VAC/230VAC
► Built-in soft start
► Less than 200mW standby power
Applications
► White goods
► Household appliances
► Lighting controls
► Circuit breakers
► Keep-alive supplies
General Description
The Supertex SR08x is an inductorless switching regulator
designed to operate directly from a rectified AC line. The
operating principle is to turn on a pass transistor when the
rectified AC is below the output voltage, and to turn it off when
the output voltage reaches a specific level. A linear regulator
supplied by V_OUT provides an additional fixed 3.3V output
(SR086) or 5V output (SR087). Efficiencies of around 55%
may be realized for loads up to 1W in 120VAC applications,
with around 50% efficiencies for loads up to 800mW in 230VAC
applications.
A logic-level enable input allows the SR08x to be disabled
– useful when the SR08x is employed as a keep-alive power
supply.
WARNING! Galvanic isolation is not provided. Dangerous
voltages are present when connected to the AC line. It is
the responsibility of the designer employing the SR08x
to ensure adequate safeguards are in place to protect the
end user from electrical shock.
Typical Application Circuit
1.25A
90VAC
to
270VAC
50/60HZ
275V
50A
1.0kV
1A
390kΩ
STGD5NB120SZ
1.1MΩ
100nF
Enable
GATE V_GD
V_IN
V_OUT
FB
SR08x
EN
V_REG
GND
V_OUT
9-50VDC
@ 100mA - I_REG
1μF
470μF
- ^R1
= R₂
⎜⎛
⎝
V_OUT
1.25V
1
3.3V or 5V
@ 60mA
100nF
R₂
12.4kΩ
NR040306
· · · · ^{Supertex inc. 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: [phone] FAX: [phone] www.supertex.com}
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