LM2576-3.3WU Micrel Inc, LM2576-3.3WU Datasheet

IC REG BUCK 3A 3.3V TO-263-5

LM2576-3.3WU

Manufacturer Part Number
LM2576-3.3WU
Description
IC REG BUCK 3A 3.3V TO-263-5
Manufacturer
Micrel Inc
Type
Step-Down (Buck)r
Datasheet

Specifications of LM2576-3.3WU

Internal Switch(s)
Yes
Synchronous Rectifier
No
Number Of Outputs
1
Voltage - Output
3.3V
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
Lead free / RoHS 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 LM2576-3.3WU

LM2576-3.3WU Summary of contents

Page 1

... 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 ...

Page 2

... LM2576WT* † – +85 C † LM2576-3.3WT † – +85 C † † LM2576-5.0WT – +85 C † † LM2576-12WT – +85 C LM2576WU* – +85 C LM2576-3.3WU – +85 C LM2576-5.0WU – +85 C LM2576-12WU – +85 C GND 5- ON/OFF 4- FEEDBACK 3- GROUND 2- OUTPUT Temperature Package TO-220-5 TO-220-5 TO-220-5 ...

Page 3

... Output Voltage 0.5A OUT LM2576-5.0 V Efficiency V SYSTEM PARAMETERS, 12V REGULATORS (Note 3) Test Circuit Figure 1 V Output Voltage V OUT V V Output Voltage 0.5A OUT LMLM2576-12 V Efficiency V August 2005 Operating Ratings (Note 1) 45V Temperature Range –0.3V V +40V Supply Voltage –1V Internally Limited – +150 ...

Page 4

... T,U Package, Junction to Ambient (Note 7) JA T,U Package, Junction to Ambient (Note 8) JA T,U Package, Junction to Case JC M9999-082605 OUT = 3A (Note 4) OUT 3 s (Note 40V, (Note 6), Output = 0V IN Output = –1V Output = –1V 4 LM2576 Typ Limit (Note 2) 50 100/500 52 47/42 58/63 1.4 1.8/2 5.8 4.2/3.5 6.9/7.5 2 7.5 30 ...

Page 5

... All limits at temperature extreme are guaranteed via testing. Note 3: External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2576/LM1576 is used as shown in Figure 1 test circuit, system performance will be shown in system parameters section of Electrical Characteristics. Note 4: Output (pin 2) sourcing current ...

Page 6

... LM2576 Typical Performance Characteristics (continued) Supply Current 20 Measured at Ground Pin 25˚ OUT = LOAD INPUT VOLTAGE (V) Current Limit 25V -75 -50 - 100 125 150 JUNCTION TEMPERATURE (˚C) Minimum Operating Voltage 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 V OUT = 1.23V 1.0 I LOAD = 200 mA ...

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 µS/div OUT = 45V A: Output pin voltage 50V/div B: Output pin current 2A/div C: Inductor current 2A/div D: Output ripple voltage 50 mV/div., AC coupled Horizontal Time Base: 5µ ...

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 Note: Pin numbers are for TO-220 Package As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring inductance generate voltage transients which can cause problems ...

Page 9

... LM2576 Package Information 0.108 0.005 (2.74 0.13) 0.067 0.005 (1.70 0.127) 0.268 REF (6.81 REF) 0.065 0.010 20 2 0.067 0.005 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. ...

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