SR036DB1 Datasheet, PDF (1/2 Pages) Supertex, Inc – Inductorless Switching Power Supply

Introduction
The Supertex SR036 is an inductorless, dual output off-line
regulator intended for 120/240VAC line operation. The
operating principle is to activate a pass element between
line and load only when the input voltage is lower than a
certain value. Thus conduction only occurs with a low
voltage drop across the pass element, resulting in more
efficient operation compared to a standard linear regulator.
The SR036DB1 demo board contains all the circuitry
needed to supply a low-current (<40mA) load. Included are
input protection circuitry, a full wave bridge rectifier, a pass
element, and output capacitors.
SR036DB1
Inductorless Switching Power Supply
Specifications
AC Input
Output Voltages
V_UNREG
V_REG
24VAC to 264VAC
40Hz to 100Hz
18V±20%
3.3V ±10%
Output Current
I_UNREG + I_REG
Efficiency
AC_IN=120VAC 60Hz, I_U=40mA, I_R=0mA
40mA @ 120VAC
30mA @ 240VAC
40% typ
Board Layout and Connections
AC_IN
Z₁
F₁
Q₁
D₁
IC₁
C₁
C₂
WARNING!!!
Do not connect to scope ground or to the ground of other
earth-grounded instruments. Doing so will short the AC line,
resulting in damage to the circuit and/or instrument. Either
use an isolation transformer on the AC line, use a differential
probe, or use a floating, battery-powered instrument to make
measurements.
GND
V_REG
V_UNREG
WARNING!!!
No galvanic isolation. Dangerous voltages are
present when connected to the AC mains.
AC_IN
Connect to the AC line. Neutral to top, hot to bottom.
GND
Circuit common.
Note that since galvanic isolation is not provided, connecting
this point to an earth-grounded instrument (such as an
oscilloscope) will short the AC line, resulting in circuit and/or
instrument damage.
Also note that GND may be at a higher potential with respect
to earth ground, even if the AC is switched off. Use caution!
Do not connect to earth-ground.
V_UNREG
The unregulated output. Nominal output voltage is 18 volts.
This output will have a certain amount of 120Hz ripple,
depending on load.
Do not connect to earth-grounded loads.
V_REG
The regulated output. 5V nominal output voltage.
Do not connect to earth-grounded loads.
Fuse
The AC input is fused to protect against overloads. It should
be replaced with a 125mA, 250V standard 3AG fuse.
16APR02
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