SwRitecghuinlagtors STR-A6251 AND Data Sheet
STR-A6252 28103.42b
ABSOLUTE MAXIMUM RATINGS
at TA = +25C Universal-Input/15 W 50 kHz
Flyback Switching Regulators
Control Supply Voltage, VCC . . . . 36 V
Drain-Source Voltage, VDSS . . . . . . 650 V The STR-A6251 and STR-A6252 are 50 kHz PWM topology (with
Drain Switching Current, ID 5% frequency jittering for minimum EMI) regulators specifically
designed to satisfy the requirements for increased integration and
STR-A6251 . . . . . . . . . . . . . . 2.5 A* reliability in flyback converters. They incorporate a primary control and
STR-A6252 . . . . . . . . . . . . . . 3.0 A* drive circuit with avalanche-rated power MOSFETs. The STR-A6252
Peak Drain Switching Current, IDM features higher allowable switching current and lower on-resistance.
STR-A6251 . . . . . . . . . . . . . . . 2.5 A The STR-A6251 is also available for 67 kHz operation.
STR-A6252 . . . . . . . . . . . . . . . 3.0 A
Single-Pulse Avalanche Energy, EAS Covering the power range from below 21 watts or 24 watts for a
STR-A6251 . . . . . . . . . . . . . . 72 mJ 230 VAC input, or to 15 or 20 watts for a universal (85 to 264 VAC)
STR-A6252 . . . . . . . . . . . . . 123 mJ input, these devices can be used in a wide range of applications, from
S/OCP Voltage Range, DVD players and VCR player/recorders to ac adapters for cellular
VOCP . . . . . . . . . . . . 0.3 V to +6 V phones and digital cameras. An auto-burst standby function reduces
FB/CC/OLP Voltage Range, power consumption at light load, while multiple protections, including
VFB/OLP . . . . . . . . . . 0.3 V to +12 V the avalanche-energy guaranteed MOSFET, provide high reliability of
FM Voltage Range, system design.
VFM . . . . . . . . . . . . . 0.3 V to +6 V
Package Power Dissipation, PD Cycle-by-cycle current limiting, undervoltage lockout with hyster-
control (VCC ICC(ON)) . . . . . 0.15 W esis, overvoltage protection, and thermal shutdown protect the power
MOSFET (VDSS ID) . . . . . . 1.35 W supply during the normal overload and fault conditions. Overvoltage
total . . . . . . . . . . . . . . . . . . . . 1.5 W protection and thermal shutdown are latched after a short delay. The
MOSFET Channel Temp., TJ . +150C latch may be reset by cycling the input supply. Low start-up current and
Internal Frame Temp., TF . . . . +125C a low-power standby mode selected from the secondary circuit completes
Storage Temperature Range, a comprehensive suite of features. Both devices are provided in an 8-pin
TS . . . . . . . . . . . . -40C to +125C mini-DIP plastic package with pin 6 removed.
* Drain switching current is limited by tem-
perature (page 2) and safe operating area FEATURES AND BENEFITS
(page 4).
50 kHz PWM with 5% Frequency Jittering
Cost Reduction of EMI Noise Filtering
Rugged 650 V Avalanche-Rated MOSFET
Simplified Surge Absorption
No VDSS Derating Required
Choice of rDS(on) (2.8 or 3.95 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 continued
Low Operating Current (4 mA max)
Always order by complete part number, e.g., STR-A6251 .
Sanken Power Devices
from Allegro MicroSystems
STR-A6251 and STR-A6252 SwRitecghuinlagtors
Universal-Input/15 W 50 kHz
Flyback Switching Regulators
FUNCTIONAL BLOCK DIAGRAM
FEATURES AND BENEFITS (cont'd)
Automatic Burst Stand-By (intermittent operation)
Input Power <0.1 W at No Load
Auto-Bias Function
Stable Burst Operation Without Generating Interference
Internal Off-Timer Circuit
Built-In Constant-Voltage/Constant Current
Multiple Protections:
Pulse-by-Pulse Overcurrent Protection (OCP)
Overload Protection (OLP) with Auto Restart
Latching Overvoltage Protection (OVP)
Undervoltage Lockout (UVLO) with Hysteresis
Latching Thermal Shutdown (TSD)
Molded Small-Size 8-Pin Package
For Low-Height SMPS
This data sheet is based on Sanken data sheet SSE-23297 and SSE-23298.
2 115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
Copyright 2005 Allegro MicroSystems, Inc.
SwRitecghuinlagtors STR-A6251 and STR-A6252
Universal-Input/15 W 50 kHz
Flyback Switching Regulators
ELECTRICAL CHARACTERISTICS at TA = 25C, VCC = 18 V (unless otherwise specified).
Pin Ratings
Characteristic No. Symbol Test Conditions Min Typ Max Units
Drain-to-Source Breakdown Volt. 8 - 1 V(BR)DSS ID = 300 A, 650 - -V
V1 V3 = 0 V (short)
Drain Leakage Current 8 IDSS VDS = 650 V, - - 300 A
On-State Resistance
V1 V3 = 0 V (short)
8 - 1 rDS(on) STR-A6251, ID = 0.4 A - - 3.95
STR-A6252, ID = 0.4 A - - 2.8
MOSFET Switching Time 8-3 tf - - - 250 ns
Operation-Start Voltage 5-3 VCC(ON) VCC = 0 t 15.7 V
Operation-Stop Voltage 5-3 VCC(OFF) VCC = 15.7 t 9 V 12.9 14.3 15.7 V
9.0 10 11 V
Maximum Switching Frequency 8 - 3 fosc(max) - 45 50 55 kHz
Frequency-Jitter Deviation 3.0 5.0 7.0 kHz
Maximum ON Duty Cycle 8 - 3 fosc - 70 76 82 %
8 - 3 D max -
Circuit Current in Operation 5 ICC(ON) - - - 4.0 mA
Circuit Current in Non-Operation 5 ICC(OFF) VCC = 12 V - 14 25 A
FM Voltage 2 - 3 VFMH fosc = fosc(max) 4.0 4.5 5.0 V
VFML fosc < fosc(max) 3.2 3.6 4.0 V
FM Current 2 IFMH -7.7 -11.0 -14.3 A
7.7 11.0 14.3 A
OCP Threshold Voltage IFML 0.67 0.74 0.81 V
Leading Edge Blanking Time 220 320 420 ns
1 - 3 VOCP -
8-3 tbw -
Burst Threshold Voltage 4 - 3 Vburst - 1.00 1.12 1.24 V
OLP Threshold Voltage 4 - 3 VOLP - 7.3 8.6 9.9 V
Current at OLP Operation 4 IOLP - -12 -17 -22 A
OLP Delay Time 4-3 tOLP - 0.84 1.20 1.56 s
Maximum FB Current 4 IFB(MAX) - 220 310 400 A
CC Set Voltage VSET(CC) - 4.9 5.8 6.7 V
CC Reset Voltage 4-3 VRES(CC) VCC = 25 V 3.5 3.9 4.3 V
4-3
Start-Up Current 5 Istartup VCC = 13 V 0.77 1.10 1.43 mA
OVP Operation Voltage 5-3 VCC = 18 t 35.2 V 28.8 32.0 35.2 V
OVP/TSD Latch Sustaining Current VCC(OVP) VCC =35.2 t 8.6 V 270 A
OVP/TSD Latch Release Voltage 5 ICC(H) VCC =35.2 t 5.9 V - - 8.6 V
Thermal Shutdown 5-3 VCC 5.9 7.2 C
Thermal Resistance TJ - 125 140 - C/W
- RJF 52
- - - -
Typical values are given for circuit design information only.
Negative current is defined as coming out of (sourcing) the specified terminal.
www.allegromicro.com 3
STR-A6251 and STR-A6252 SwRitecghuinlagtors
Universal-Input/15 W 50 kHz
Flyback Switching Regulators
MOSFET TYPICAL CHARACTERISTICS
STR-A6251 STR-A6252
Avalanche energy is measured at VDD = 99 V, Avalanche energy is measured at VDD = 99 V,
L = 20 mH, IL = 2.5 A. L = 20 mH, IL = 3.0 A.
Recommended Operating Conditions
Operating Ambient Temperature ....... -20C to +100C
Operating Junction Temperature ....... -20C to +125C
Maximum Frame Temperature ........................ +115C
For the availability of parts meeting -40C requirements, contact
Allegro's Sales Representative.
4 115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
SwRitecghuinlagtors STR-A6251 and STR-A6252
Universal-Input/15 W 50 kHz
Flyback Switching Regulators
MOSFET TYPICAL CHARACTERISTICS (cont'd)
STR-A6251
STR-A6252
WARNING -- These devices are designed to be operated at lethal voltages and energy levels. 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.
The use of an isolation transformer is recommended during circuit development and breadboarding.
www.allegromicro.com 5
STR-A6251 and STR-A6252 SwRitecghuinlagtors
Universal-Input/15 W 50 kHz
Flyback Switching Regulators
APPLICATIONS INFORMATION
Typical Application Complete product description and applications information
NOTE: The start-up performance of the IC can only be is provided in Application Note 28103.40, Series STR-
guaranteed for values of C2 greater than 22 F. This value A6200 Flyback Switching Regulators.
is required to keep the internal supply voltage within
regulation during IC initialization.
The products described herein are manufactured in Japan by Sanken Sanken products listed in this publication are designed and intended
Electric Co., Ltd. for sale by Allegro MicroSystems, Inc. for use as components in general-purpose electronic equipment or
apparatus (home appliances, office equipment, telecommunication
Sanken and Allegro reserve the right to make, from time to time, such equipment, measuring equipment, etc.). Their use in any application
departures from the detail specifications as may be required to permit requiring radiation hardness assurance (e.g., aerospace equipment) is
improvements in the performance, reliability, or manufacturability of its not supported.
products. Therefore, the user is cautioned to verify that the information
in this publication is current before placing any order. When considering the use of Sanken products in applications where
higher reliability is required (transportation equipment and its control
When using the products described herein, the applicability and systems or equipment, fire- or burglar-alarm systems, various safety
suitability of such products for the intended purpose shall be reviewed at devices, etc.), contact a company sales representative to discuss and
the users responsibility. obtain written confirmation of your specifications.
Although Sanken undertakes to enhance the quality and reliability of The use of Sanken products without the written consent of Sanken in
its products, the occurrence of failure and defect of semiconductor applications where extremely high reliability is required (aerospace
products at a certain rate is inevitable. equipment, nuclear power-control stations, life-support systems, etc.) is
strictly prohibited.
Users of Sanken products are requested to take, at their own risk,
preventative measures including safety design of the equipment or The information included herein is believed to be accurate and
systems against any possible injury, death, fires or damages to society reliable. Application and operation examples described in this publica-
due to device failure or malfunction. tion are given for reference only and Sanken and Allegro assume no
responsibility for any infringement of industrial property rights,
intellectual property rights, or any other rights of Sanken or Allegro or
any third party that may result from its use.
6 115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036
SwRitecghuinlagtors STR-A6251 and STR-A6252
Universal-Input/15 W 50 kHz
Flyback Switching Regulators
PACKAGE DIMENSIONS
Dimensions in Inches
(for reference only)
www.allegromicro.com Dimensions in Millimeters
(controlling dimensions)
Terminal Finish: Pure Sn, 2nd level interconnect category (e3).
Product Weight: Approx. 0.51 g.
Frame temperature, TF, is measured at the root of pin 3.
For more efficient heat radiation, connect a broad PCB pattern
at pins 7 and 8.
EI 26EI
7
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