Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - DC/DC voltage regulator Boost, Flyback, Forward converter TO 263 5

Simple Step-Up Voltage Regulator

•

Requires Few External Components

•

NPN Output Switches 3.0A, 65V(max)

•

Extended Input Voltage Range: 3.0V to 40V

•

Current Mode Operation for Improved

Transient Response, Line Regulation, and

Current Limiting

•

Soft Start Function Provides Controlled

Startup

•

52kHz Internal Oscillator

•

Output Switch Protected by Current Limit,

Undervoltage Lockout and Thermal

Shutdown

•

Improved Replacement for LM2577-ADJ

Series

The UC2577-ADJ device provides all the active functions neces-

sary to implement step-up (boost), flyback, and forward converter

switching regulators. Requiring only a few components, these sim-

ple regulators efficiently provide up to 60V as a step-up regulator,

and even higher voltages as a flyback or forward converter regula-

tor.

The UC2577-ADJ features a wide input voltage range of 3.0V to

40V and an adjustable output voltage. An on-chip 3.0A NPN switch

is included with undervoltage lockout, thermal protection circuitry,

and current limiting, as well as soft start mode operation to reduce

current during startup. Other features include a 52kHz fixed fre-

quency on-chip oscillator with no external components and current

mode control for better line and load regulation.

A standard series of inductors and capacitors are available from

several manufacturers optimized for use with these regulators and

are listed in this data sheet.

UC2577-ADJ

3/97

FEATURES DESCRIPTION

CONNECTION DIAGRAM

BLOCK DIAGRAM

UDG-94034

•

Simple Boost and Flyback Converters

•

SEPIC Topology Permits Input Voltage to

be Higher or Lower than Output Voltage

•

Transformer Coupled Forward Regulators

•

Multiple Output Designs

TYPICAL APPLICATIONS

5-Pin TO-220 (Top View)

Also available in TO-263 Package.

Summary of content (15 pages)

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UC2577-ADJ Simple Step-Up Voltage Regulator FEATURES DESCRIPTION • Requires Few External Components • NPN Output Switches 3.0A, 65V(max) • Extended Input Voltage Range: 3.0V to 40V • Current Mode Operation for Improved Transient Response, Line Regulation, and Current Limiting The UC2577-ADJ device provides all the active functions necessary to implement step-up (boost), flyback, and forward converter switching regulators.
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UC2577-ADJ ABSOLUTE MAXIMUM RATINGS (Note 1) RECOMMENDED OPERATING RANGE Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45V Output Switch Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65V Output Switch Current (Note 2) . . . . . . . . . . . . . . . . . . . . . 6.0A Power Dissipation . . . . . . . . . . . . . . . . . . . . . . Internally Limited Storage Temperature Range . . . . . . . . . . . . . −65°C to +150°C Lead Temperature (Soldering, 10 sec.
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UC2577-ADJ ELECTRICAL CHARACTERISTICS Unless otherwise stated, these specifications apply for TA = −40°C to +125°C, VIN = 5V, VFB = VREF, ISWITCH = 0, and TA =TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Device Parameters (cont.) Switch Transconductance Switch Leakage Current 12.5 VSWITCH = 65V, VFB = 1.5V (Switch Off) 10 TJ = 25°C Switch Saturation Voltage ISWITCH = 2.0A, VCOMP = 2.0V (Max Duty Cycle) 0.5 TJ = 25°C NPN Switch Current Limit VCOMP = 2.
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UC2577-ADJ APPLICATIONS INFORMATION Step-up (Boost) Regulator The Block Diagram shows a step-up switching regulator utilizing the UC2577. The regulator produces an output voltage higher than the input voltage. The UC2577 turns its switch on and off at a fixed frequency of 52kHz, thus storing energy in the inductor (L). When the NPN switch is on, the inductor current is charged at a rate of VIN/L.
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UC2577-ADJ APPLICATIONS INFORMATION (cont.) 2. Inductor Selection (L) A. Preliminary Calculations To select the inductor, the calculation of the following three parameters is necessary: If Lmin is smaller than the inductor values found in step B1, go on to step C. Otherwise, the inductor value found in step B1 is too low; an appropriate inductor code should be obtained from the graph as follows: Dmax, the maximum switch duty cycle (0 ≤ D ≤ 0.9): 1.
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UC2577-ADJ APPLICATIONS INFORMATION (cont.
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UC2577-ADJ APPLICATIONS INFORMATION (cont.) 4. Input Capacitor Selection (CIN) To reduce noise on the supply voltage caused by the switching action of a step-up regulator (ripple current noise), VIN should be bypassed to ground. A good quality 0.1µF capacitor with low ESR should provide sufficient decoupling. If the UC2577 is located far from the supply source filter capacitors, an additional electrolytic (47µF, for example) is required.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 31-Oct-2013 (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided.
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PACKAGE MATERIALS INFORMATION www.ti.com 12-Aug-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device UC2577TDKTTT-ADJ Package Package Pins Type Drawing DDPAK/ TO-263 KTT 5 SPQ 50 Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 330.0 24.4 Pack Materials-Page 1 10.6 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 15.6 4.9 16.0 24.
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PACKAGE MATERIALS INFORMATION www.ti.com 12-Aug-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) UC2577TDKTTT-ADJ DDPAK/TO-263 KTT 5 50 367.0 367.0 45.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.