converters with indirect feedback. The device incorporates the primary
control and proportional drive circuit with a third-generation high-voltage
bipolar switching transistor.
Crucial system parameters such as maximum ON time and OFF
time are fixed during manufacture. Local control circuit decoupling and
layout are optimized within each device.
Cycle-by-cycle current limiting, under-voltage lock-out with hysteresis, over-voltage protection, and thermal shutdown protect these
devices during all normal and overload conditions. Over-voltage
protection and thermal shutdown are latched after a short delay. A
primary-side error amplifier with reference is included to facilitate
regulation from an auxiliary or bias winding of the power transformer. A
versatile triple-level inhibit circuit includes the OFF time synchronization
required to establish quasi-resonant operation. The inhibit function has
also been expanded to initiate operation in stand-by mode in which the
power supply delivers a small fraction of the steady-state output power.
The dual requirements of dielectric isolation and low transient thermal
impedance and steady-state thermal resistance are satisfied in an overmolded single-in-line power package.
Proven in substantial volumes, this device and its fixed-frequency
counterparts represents a significant advance in off-line SMPS reliability
growth and integration. Similar devices with increased ratings are the
STR-S5707 and STR-S5708.
FEATURES
■ Quasi-Resonant Operation for Low EMI and High Efficiency
■ Output Power to 140 W
■ Low-Power Output Standby Mode
■ Indirect Feedback from Auxiliary Winding
Reduces External Component Count
■ Pulse-by-Pulse Over-Current Protection
■ Latched Over-Voltage and Thermal Protection
■ Third-Generation Switching Transistor with Proportional Drive
■ Maximum ON Time and Off Time Set During Manufacture
■ Internal Under-Voltage Lockout with Hysteresis
■ Over-Molded SIP with Integral Isolated Heat Spreader
WARNING: lethal potentials are present. See below.
+ OUTPUT
AC INPUT
RECTIFIER
FULL-BRIDGE
7
+
WARNING —
Circuit designs that embody these components must conform with applicable safety requirements.
Precautions must be taken to prevent accidental contact with power-line potentials.
Do not connect grounded test equipment.
9
R
SQ
+
+
+
+
6
8
4
3
1
2
5
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★
APPLICATIONS INFORMATION
These devices are designed to be operated at lethal voltages and energy levels.
+
– OUTPUT
Dwg. EK-005A
The use of an isolation transformer is recommended during circuit development and breadboarding.
* Complete part number includes additional characters to indicate operating temperature range and package style.
Also — 83145 and 84145 Latched, Universal Input-Voltage Switches.
O
Max DC InMax DropoutMax I
O
Package
Allegro MicroSystems, Inc. reserves the right to make, from time to time, such
departures from the detail specifications as may be required to permit improvements in
the design of its products. Components made under military approvals will be in
accordance with the approval requirements.
The information included herein is believed to be accurate and reliable. However,
Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringements
of patents or other rights of third parties which may result from its use.