STR-A6251 Datasheet, PDF (1/7 Pages) Allegro MicroSystems – Universal-Input/15 W 50 kHz Flyback Switching Regulators

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ABSOLUTE MAXIMUM RATINGS
at T_A = +25°C
Control Supply Voltage, V_CC . . . . 36 V
Drain-Source Voltage, V_DSS . . . . . . 650 V
Drain Switching Current, I_D
STR-A6251 . . . . . . . . . . . . . . 2.5 A*
STR-A6252 . . . . . . . . . . . . . . 3.0 A*
Peak Drain Switching Current, I_DM
STR-A6251 . . . . . . . . . . . . . . . 2.5 A
STR-A6252 . . . . . . . . . . . . . . . 3.0 A
Single-Pulse Avalanche Energy, E_AS
STR-A6251 . . . . . . . . . . . . . . 72 mJ
STR-A6252 . . . . . . . . . . . . . 123 mJ
S/OCP Voltage Range,
V_OCP . . . . . . . . . . . . –0.3 V to +6 V
FB/CC/OLP Voltage Range,
V_FB/OLP . . . . . . . . . . –0.3 V to +12 V
FM Voltage Range,
V_FM . . . . . . . . . . . . . –0.3 V to +6 V
Package Power Dissipation, P_D
control (V_CC × I_CC(ON)) . . . . . 0.15 W
MOSFET (V_DSS × I_D) . . . . . . 1.35 W
total . . . . . . . . . . . . . . . . . . . . 1.5 W
MOSFET Channel Temp., T_J . +150°C
Internal Frame Temp., T_F . . . . +125°C
Storage Temperature Range,
T_S . . . . . . . . . . . . -40°C to +125°C
* Drain switching current is limited by tem-
perature (page 2) and safe operating area
(page 4).
STR-A6251 AND
STR-A6252
Universal-Input/15 W 50 kHz
Flyback Switching Regulators
The STR-A6251 and STR-A6252 are 50 kHz PWM topology (with
±5% frequency jittering for minimum EMI) regulators specifically
designed to satisfy the requirements for increased integration and
reliability in flyback converters. They incorporate a primary control and
drive circuit with avalanche-rated power MOSFETs. The STR-A6252
features higher allowable switching current and lower on-resistance.
The STR-A6251 is also available for 67 kHz operation.
Covering the power range from below 21 watts or 24 watts for a
230 VAC input, or to 15 or 20 watts for a universal (85 to 264 VAC)
input, these devices can be used in a wide range of applications, from
DVD players and VCR player/recorders to ac adapters for cellular
phones and digital cameras. An auto-burst standby function reduces
power consumption at light load, while multiple protections, including
the avalanche-energy guaranteed MOSFET, provide high reliability of
system design.
Cycle-by-cycle current limiting, undervoltage lockout with hyster-
esis, overvoltage protection, and thermal shutdown protect the power
supply during the normal overload and fault conditions. Overvoltage
protection and thermal shutdown are latched after a short delay. The
latch may be reset by cycling the input supply. Low start-up current and
a low-power standby mode selected from the secondary circuit completes
a comprehensive suite of features. Both devices are provided in an 8-pin
mini-DIP plastic package with pin 6 removed.
FEATURES AND BENEFITS
■ 50 kHz PWM with ±5% Frequency Jittering
Cost Reduction of EMI Noise Filtering
■ Rugged 650 V Avalanche-Rated MOSFET
Simplified Surge Absorption
No V_DSS Derating Required
■ Choice of r_DS(on) (2.8 Ω or 3.95 Ω maximum)
■ Auto-Burst Mode for Stand-By Operation or Light Loads
Less Transformer Audible Noise
■ Built-In Leading Edge Blanking
■ Soft Start and Low Start-Up Current
Start-Up Circuit Disabled in Operation
■ Low Operating Current (4 mA max)
continued
Always order by complete part number, e.g., STR-A6251 .
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