LM2576BU Micrel Inc, LM2576BU Datasheet

IC REG BUCK 3A ADJ TO-263-5

LM2576BU

Manufacturer Part Number
LM2576BU
Description
IC REG BUCK 3A ADJ TO-263-5
Manufacturer
Micrel Inc
Type
Step-Down (Buck)r
Datasheet

Specifications of LM2576BU

Internal Switch(s)
Yes
Synchronous Rectifier
No
Number Of Outputs
1
Voltage - Output
1.23 ~ 37 V
Current - Output
3A
Frequency - Switching
42kHz ~ 63kHz
Voltage - Input
4 ~ 40 V
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
D²Pak, TO-263 (5 leads + tab)
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Power - Output
-
LM2576
General Description
The LM2576 series of monolithic integrated circuits provide
all the active functions for a step-down (buck) switching
regulator. Fixed versions are available with a 3.3V, 5V, or 12V
fixed output. Adjustable versions have an output voltage
range from 1.23V to 37V. Both versions are capable of driving
a 3A load with excellent line and load regulation.
These regulators are simple to use because they require a
minimum number of external components and include internal
frequency compensation and a fixed-frequency oscillator.
The LM2576 series offers a high efficiency replacement for
popular three-terminal adjustable linear regulators. It
substantially reduces the size of the heat sink, and in many
cases no heat sink is required.
A standard series of inductors available from several different
manufacturers are ideal for use with the LM2576 series. This
feature greatly simplifies the design of switch-mode power
supplies.
The feedback voltage is guaranteed to 2% tolerance for
adjustable versions, and the output voltage is guaranteed to
output load conditions. The oscillator frequency is guaranteed
to 10%. External shutdown is included, featuring less than
200 A standby current. The output switch includes cycle-by-
cycle current limiting and thermal shutdown for full protection
under fault conditions.
Typical Applications
August 2005
3% for fixed versions, within specified input voltages and
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
Unregulated
Note: Pin numbers are for TO-220 Package
DC Input
7V–40V
100µF
Fixed Regulator in Typical Application
C
IN
+
+V
IN
Gnd
1
LM2575-5.0
3
On/Off
5
4
Output
2
1N5822
Feedback
D1
330µH
L1
+
330µF
C
OUT
Regulated
+5V, 1A
Output
1
Unregulated
Note: Pin numbers are for TO-220 Package
Features
• 3.3V, 5V, 12V, and adjustable output versions
• Voltage over specified line and load conditions:
• Guaranteed 3A output current
• Wide input voltage range:
• Wide output voltage range
• Requires only 4 external components
• 52kHz fixed frequency internal oscillator
• Low power standby mode I
• 80% efficiency (adjustable version typically > 80%)
• Uses readily available standard inductors
• Thermal shutdown and current limit protection
• 100% electrical thermal limit burn-in
Applications
• Simple high-efficiency step-down (buck) regulator
• Efficient pre-regulator for linear regulators
• On-card switching regulators
• Positive to negative converter (inverting Buck-Boost)
• Isolated Flyback Converter using minimum number of
• Negative Boost Converter
DC Input
7V–40V
100µF
V
external components
Adjustable Regulator in Fixed Output Application
C
OUT
IN
Fixed version: 3% max. output voltage
Adjustable version: 2% max. feedback voltage
4V to 40V
1.23V to 37V
+
= 1.23 1 +
52kHz Simple 3A Buck Regulator
+V
IN
Gnd
1
(
3
LM2575
On/Off
R2
R1
)
5
LM2576
4
Output
2
1N5822
Feedback
Q
330µH
D1
L1
typically < 200 A
+
330µF
C
OUT
M9999-082605-B
Regulated
+5V, 1A
Output
R2 3.09k
R1 1k
Micrel, Inc.

Related parts for LM2576BU

LM2576BU Summary of contents

Page 1

LM2576 General Description The LM2576 series of monolithic integrated circuits provide all the active functions for a step-down (buck) switching regulator. Fixed versions are available with a 3.3V, 5V, or 12V fixed output. Adjustable versions have an output voltage range ...

Page 2

... LM2576 Ordering Information Standard LM2576BT* LM2576-3.3BT LM2576-5.0BT LM2576-12BT LM2576BU* LM2576-3.3BU LM2576-5.0BU LM2576-12BU * Adjustable output regulators. **RoHS compliant with "hot-melting solder" exemption. † Contact factory for bent or staggered leads option. Pin Configurations 5-LEAD TO-220 (T) GND M9999-082605-B Part Number ‡ RoHS Compliant** Range † ...

Page 3

LM2576 Absolute Maximum Ratings Maximum Supply Voltage ON/OFF Pin Input Voltage Output Voltage to Ground (Steady State) Power Dissipation Storage Temperature Range Minimum ESD Rating C = 100pF 1.5k FB Pin Lead Temperature (soldering, 10 sec.) Maximum Junction ...

Page 4

LM2576 Electrical Characteristics (continued) Symbol Parameter Conditions DEVICE PARAMETERS, ADJUSTABLE REGULATOR I Feedback Bias Current V B DEVICE PARAMETERS, FIXED and ADJUSTABLE REGULATORS f Oscillator Frequency O V Saturation Voltage I SAT DC Max Duty Cycle (ON) (Note 5) I ...

Page 5

LM2576 Electrical Characteristics (continued) Symbol Parameter Conditions ON/OFF CONTROL, FIXED and ADJUSTABLE REGULATORS Test Circuit Figure 1 V ON/OFF Pin Logic Input Level /OFF Pin Logic ON /OFF Pin = 5V (OFF) IH ...

Page 6

LM2576 Typical Performance Characteristics (continued) Supply Current 20 Measured at Ground Pin 25˚ OUT = LOAD INPUT VOLTAGE ...

Page 7

LM2576 Typical Performance Characteristics Output Voltage Change Output Current August 2005 (Circuit of Figure 1 ) Load Transient Response +100mV 0 -100mV 100 µS/div. Switching Waveforms 50V ...

Page 8

LM2576 Test Circuits and Layout Guidelines +V IN LM2575 40V 100 µF + UNREGULATED GND 3 DC INPUT LM2575-5 40V 100 µF + UNREGULATED GND 3 DC INPUT C IN ...

Page 9

... DIM. = INCH MICREL INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA + 1 (408) 944-0800 TEL This information furnished by Micrel in this data sheet is believed to be accurate and reliable. However no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. ...

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