Micrel LM2576-12WT 52khz simple 3a buck regulator Datasheet

LM2576
Micrel, Inc.
LM2576
52kHz Simple 3A Buck Regulator
General Description
Features
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
±3% for fixed versions, within specified input voltages and
output load conditions. The oscillator frequency is guaranteed
to ±10%. External shutdown is included, featuring less than
200µA standby current. The output switch includes cycle-bycycle current limiting and thermal shutdown for full protection
under fault conditions.
• 3.3V, 5V, 12V, and adjustable output versions
• Voltage over specified line and load conditions:
Fixed version: ±3% max. output voltage
Adjustable version: ±2% max. feedback voltage
• Guaranteed 3A output current
• Wide input voltage range:
4V to 40V
• Wide output voltage range
1.23V to 37V
• Requires only 4 external components
• 52kHz fixed frequency internal oscillator
• Low power standby mode IQ typically < 200µA
• 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
external components
• Negative Boost Converter
Typical Applications
7V–40V
Unregulated
DC Input
1
4
LM2575-5.0 Output L1
2
330µH
3
5
Gnd On/Off
D1
1N5822
+VIN
+
CIN
100µF
7V–40V
Unregulated
DC Input
+5V, 1A
Regulated
Output
Feedback
1
+VIN
+
+
CIN
100µF
COUT
330µF
Note: Pin numbers are for TO-220 Package
4
LM2575
3
5
Gnd On/Off
+5V, 1A
Regulated
Output
Feedback
Output L1
2
330µH
D1
1N5822
+
R2 3.09k
COUT
330µF
R1 1k
Note: Pin numbers are for TO-220 Package
VOUT = 1.23 1 + R2
R1
(
Fixed Regulator in Typical Application
)
Adjustable Regulator in Fixed Output Application
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
August 2005
1
M9999-082605-B
LM2576
Micrel, Inc.
Ordering Information
Part Number‡
Standard
RoHS Compliant**
LM2576BT*†
LM2576WT*†
†
LM2576-3.3BT
†
Range
Temperature
Package
–40°C to +85°C
TO-220-5
†
–40°C to +85°C
TO-220-5
†
LM2576-3.3WT
LM2576-5.0BT
LM2576-5.0WT
–40°C to +85°C
TO-220-5
†
†
LM2576-12BT
LM2576-12WT
–40°C to +85°C
TO-220-5
LM2576BU*
LM2576WU*
–40°C to +85°C
TO-263-5
LM2576-3.3BU
LM2576-3.3WU
–40°C to +85°C
TO-263-5
LM2576-5.0BU
LM2576-5.0WU
–40°C to +85°C
TO-263-5
LM2576-12BU
LM2576-12WU
–40°C to +85°C
TO-263-5
* 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
5-LEAD TO-263 (U)
GND
5- ON/OFF
4- FEEDBACK
3- GROUND
2- OUTPUT
1- VIN
2
5- ON/OFF
4- FEEDBACK
3- GROUND
2- OUTPUT
1- VIN
August 2005
LM2576
Micrel, Inc.
Absolute Maximum Ratings (Note 1)
Maximum Supply Voltage
ON/OFF Pin Input Voltage
Output Voltage to Ground (Steady State)
Power Dissipation
Storage Temperature Range
Minimum ESD Rating
C = 100pF, R = 1.5kΩ
FB Pin
Lead Temperature (soldering, 10 sec.)
Maximum Junction Temperature
Operating Ratings
45V
–0.3V ≤ V ≤ +40V
–1V
Internally Limited
–65°C to +150°C
–40°C ≤ TJ ≤ +125°C
40V
Temperature Range
Supply Voltage
2 kV
1 kV
260°C
150°C
Electrical Characteristics
Specifications with standard typeface are for TJ = 25°C, and those with boldface type apply
over full Operating Temperature Range. Unless otherwise specified, VIN = 12V, and ILOAD = 500mA.
LM2576
Symbol
Parameter
Conditions
Typ
Limit
(Note 2)
Units
(Limits)
1.217
1.243
V
V(min)
V(max)
1.193/1.180
1.267/1.280
V
V(min)
V(max)
SYSTEM PARAMETERS, ADJUSTABLE REGULATORS (Note 3) Test Circuit Figure 1
VOUT
Feedback Voltage
VIN = 12V , ILOAD = 0.5A
VOUT = 5V
1.230
VOUT
Feedback Voltage
LM2576
0.5A ≤ ILOAD ≤ 3A, 8V ≤ VIN ≤ 40V
VOUT = 5V
1.230
η
Efficiency
VIN = 12V, ILOAD = 3A, VOUT = 5V
82
%
SYSTEM PARAMETERS, 3.3V REGULATORS (Note 3) Test Circuit Figure 1
VOUT
Output Voltage
VIN = 12V , ILOAD = 0.5A
VOUT = 3.3V
3.3
VOUT
Output Voltage
LM2576-3.3
0.5A ≤ ILOAD ≤ 3A, 6V ≤ VIN ≤ 40V
VOUT = 3.3V
3.3
η
Efficiency
VIN = 12V, ILOAD = 3A
75
3.234
3.366
V
V(min)
V(max)
3.168/3.135
3.432/3.465
V
V(min)
V(max)
%
SYSTEM PARAMETERS, 5V REGULATORS (Note 3) Test Circuit Figure 1
VOUT
Output Voltage
VIN = 12V , ILOAD = 0.5A
VOUT = 5V
5.0
VOUT
Output Voltage
LM2576-5.0
0.5A ≤ ILOAD ≤ 3A, 8V ≤ VIN ≤ 40V
VOUT = 5V
5.0
η
Efficiency
VIN = 12V, ILOAD = 3A
82
4.900
5.100
V
V(min)
V(max)
4.800/4.750
5.200/5.250
V
V(min)
V(max)
%
SYSTEM PARAMETERS, 12V REGULATORS (Note 3) Test Circuit Figure 1
VOUT
Output Voltage
VIN = 25V , ILOAD = 0.5A
VOUT = 12V
12
VOUT
Output Voltage
LMLM2576-12
0.5A ≤ ILOAD ≤ 3A, 15V ≤ VIN ≤ 40V
VOUT = 12V
12
η
Efficiency
VIN = 25V, ILOAD = 3A
88
August 2005
3
11.760
12.240
V
V(min)
V(max)
11.520/11.400
12.480/12.600
V
V(min)
V(max)
%
M9999-082605-B
LM2576
Micrel, Inc.
Electrical Characteristics (continued)
Symbol
Parameter
Conditions
LM2576
Units
Typ
Limit
(Note 2)
(Limits)
50
100/500
nA
47/42
58/63
kHz
kHz (min)
kHz (max)
1.8/2.0
V
V(max)
93
%
%(min)
4.2/3.5
6.9/7.5
A
A(min)
A(max)
DEVICE PARAMETERS, ADJUSTABLE REGULATOR
IB
Feedback Bias Current
VOUT = 5V
DEVICE PARAMETERS, FIXED and ADJUSTABLE REGULATORS
fO
Oscillator Frequency
VSAT
Saturation Voltage
DC
Max Duty Cycle (ON)
ICL
Current Limit
IL
Output Leakage Current
52
IOUT = 3A (Note 4)
1.4
(Note 5)
98
Peak Current, tON ≤ 3µs (Note 4)
VIN = 40V, (Note 6),
(Note 6)
Output = 0V
Output = –1V
Output = –1V
IQ
Quiescent Current
ISTBY
Standby Quiescent
Current
ON/OFF Pin = 5V (OFF)
θJA
θJA
θJC
Thermal Resistance
T,U Package, Junction to Ambient (Note 7)
T,U Package, Junction to Ambient (Note 8)
T,U Package, Junction to Case
M9999-082605-B
(Note 6)
5.8
2
30
mA(max)
mA
mA(max)
10
mA
mA(max)
200
µA
µA(max)
7.5
5
50
4
65
45
2
°C/W
August 2005
LM2576
Micrel, Inc.
Electrical Characteristics (continued)
Symbol
Parameter
Conditions
Typ
LM2576
Units
Limit
(Note 2)
(Limits)
2.2/2.4
1.0/0.8
V(min)
V(max)
30
µA
µA(max)
10
µA
µA(max)
ON/OFF CONTROL, FIXED and ADJUSTABLE REGULATORS Test Circuit Figure 1
VIH
VIL
ON/OFF Pin Logic
Input Level
VOUT = 0V
VOUT = 5V
IIH
ON /OFF Pin Logic
Current
ON /OFF Pin = 5V (OFF)
IIL
1.4
1.2
4
ON/OFF Pin = 0V (ON)
0.01
Note 1:
Absolute Maximum Rating indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device
is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical
Characteristics.
Note 2:
All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face) . All room temperature limits are
100% production tested. 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. No diode, inductor or capacitor connected to output.
Note 5:
Feedback (pin 4) removed from output and connected to 0V.
Note 6:
Feedback (pin 4) removed from output and connected to 12V to force the output transistor OFF.
Note 7:
Junction to ambient thermal resistance (no external heat sink) for the 5-lead TO-220 package mounted vertically, with 1/2" leads in a socket, or
on PC board with minimum copper area.
Note 8:
Junction to ambient thermal resistance (no external heat sink) for the 5-lead TO-220 package mounted vertically, with 1/4" leads soldered to PC
board containing approximately 4 square inches of copper area surrounding the leads.
Note 9:
Junction to ambient thermal resistance with approximately 1 square inch of pc board copper surrounding the leads. Additional copper will lower
thermal resistance further.
Typical Performance Characteristics
Feedback Voltage
vs Duty Cycle*
20
25
20
15
10
5
ILOAD = 200 mA
VIN = 12V
ILOAD = 200mA
Normalized to TJ = 25˚C
FEEDBACK VOLTAGE CHANGE (mV)
NORMALIZED FEEDBACK VOLTAGE (mV)
Normalized
Feedback Voltage*
0
-5
-10
-15
-20
-25
-75 -50 -25 0
25 50 75 100 125 150
15
10
5
VIN = 40V
0
-5
VIN = 7V
-10
-15
-20
0
JUNCTION TEMPERATURE (˚C)
20
40
60
80
100
DUTY CYCLE (%)
* Adjustable version only
August 2005
5
M9999-082605-B
LM2576
Micrel, Inc.
Typical Performance Characteristics (continued)
Supply Current
vs. Duty Cycle
Supply Current
17.5
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
20.0
Measured at
Ground Pin
TJ = 25˚C
VOUT = 5V
16
14
12
10
ILOAD to 1A
8
15.0
12.5
10.0
ILOAD = 200 mA
7.5
5.0
6
4
VIN from 7V to 40V
2.5
0
10
20
30
40
50
Standby
Quiescent Current
STANDBY QUIESCENT CURRENT (µA)
20
18
(Circuit of Figure 1)
0
60
0
20
INPUT VOLTAGE (V)
40
60
80
3
Efficiency
100
1.0
-55˚C
-40˚C
0.8
25˚C
0.6 125˚C
150˚C
0.2
2.5
2.0
VOUT = 1.23V
ILOAD = 200 mA
8
6
25
0
-25
-50
-75
-100
-75 -50 -25 0
25 50 75 100 125 150
JUNCTION TEMPERATURE (˚C)
M9999-082605-B
VOUT = 3V
0
0
10
15
20
10 15 20 25 30
75
50
25
0
-25
-50
-75
25
-100
-75 -50 -25 0
30
INPUT VOLTAGE (V)
25 50 75 100 125 150
JUNCTION TEMPERATURE (˚C)
Oscillator Frequency
Dropout Voltage
2.0
Normalized at 25˚C
+6
+4
+2
0
-2
VIN = 40V
-4
--6
VIN = 12V
-8
-75 -50 -25 0 25 50 75 100 125 150
JUNCTION TEMPERATURE (˚C)
6
35 40
100
-6
5
5
Feedback Pin Current
-2
-4
+8
1A
INPUT VOLTAGE (V)
2
0
NORMALIZED FREQUENCY (%)
OUTPUT VOLTAGE CHANGE (mV)
50
1.0
4
25 50 75 100 125 150
VIN = 12V
ILOAD = 200mA
Normalized to TJ = 25˚C
0.8
Normalized to V IN = 10V
VOUT = 5V
ILOAD = 500mA
TJ = 25
10
Normalized
Output Voltage
75
0.6
Line Regulation
14
12
JUNCTION TEMPERATURE (˚C)
100
0.4
STANDBY QUIESCENT CURRENT (µA)
3.0
75
65
INPUT-OUTPUT DIFFERENTIAL (V)
3.5
200 mA
200 mA
80
SWITCH CURRENT (A)
NORMALIZED FEEDBACK VOLTAGE (mV)
INPUT VOLTAGE (V)
4.0
1A
60
0
JUNCTION TEMPERATURE (˚C)
5.0
4.5
85
70
0.4
Minimum Operating
Voltage
VOUT = 12V
90
EFFICIENCY (%)
SATURATION VOLTAGE (V)
OUTPUT CURRENT (A)
95
0
-75 -50 -25 0 25 50 75 100 125 150
0.5
0
-75 -50 -25 0
VIN = 12V
50
JUNCTION TEMPERATURE (˚C)
VI N = 25V
1
VON/OFF = 5V
100
0
-75 -50 -25 0 25 50 75 100 125 150
100
1.2
1.0
150
Switch
Saturation Voltage
2
VIN = 40V
DUTY CYCLE (%)
Current Limit
1.5
200
1.5
ILOAD = 1A
∆VOUT = 5%
R IND = 0.2Ω
1.0
0.5
ILOAD = 200 mA
0
-75 -50 -25 0 25 50 75 100 125 150
JUNCTION TEMPERATURE (˚C)
August 2005
LM2576
Micrel, Inc.
Typical Performance Characteristics (Circuit of Figure 1)
Load Transient Response
+100mV
Output
Voltage
Change
0
-100mV
3A
Output
Current
2A
1A
0
100 µS/div.
Switching Waveforms
50V
A
0
4A
B
2A
0
4A
C
2A
0
D
5 µS/div.
V OUT = 5V VIN = 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: 5µS/div
August 2005
7
M9999-082605-B
LM2576
Micrel, Inc.
Test Circuits and Layout Guidelines
FEEDBACK
+VIN
4
LM2575
7V - 40V
UNREGULATED
DC INPUT
+
100 µF
GND 3
330 µH
2
ON/OFF 5
VOUT
5.00V
L1
OUTPUT
1
+
D1
MBR360
CIN
R2
COUT
470µF
R1
CIN — 100µF, 75V Aluminum Electrolytic
COUT — 470µF, 15V Aluminum Electrolytic
D1 — Schottky, MBR360
L1 — 330µH, 415-0926 (AIE)
R1 — 1k, 0.01%
R2 — 3.065k, 0.01%
5-pin TO-220 socket—2936 (Loranger Mfg. Co.)
4-pin TO-3 socket—8112-AG7 (Augat Inc.)
L
O
A
D
FEEDBACK
+VIN
4
LM2575-5.0
7V - 40V
UNREGULATED
DC INPUT
+
100 µF
GND 3
330 µH
2
ON/OFF 5
VOUT
5.00V
L1
OUTPUT
1
+
D1
11DQ06
CIN
COUT
220µF
CIN — 100µF, 75V Aluminum Electrolytic
COUT — 330µF, 15V Aluminum Electrolytic
D1 — Schottky, 11DQ06
L1 — 100µH, 415-0926 (AIE)
5-pin TO-220 socket—2936 (Loranger Mfg. Co.)
4-pin TO-3 socket—8112-AG7 (Augat Inc.)
L
O
A
D
Note: Pin numbers are for TO-220 Package
Figure 1.
As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring inductance generate voltage transients
which can cause problems. For minimal stray inductance and ground loops, the length of the leads indicated by heavy lines should be kept as
short as possible. Single-point grounding (as indicated) or ground plane construction should be used for best results.
Block Diagrams
V IN
1
FEEDBACK
4
INTERNAL
REGULATOR
V IN
INTERNAL
REGULATOR
1
+
-
FEEDBACK
3 AMP
SWITCH
COMPARATOR
-
4
5
ON/OFF
-
2
OUTPUT
RESET
THERMAL
SHUTDOWN
CURRENT
LIMIT
3
3
GND
3 AMP
SWITCH
COMPARATOR
+
DRIVER
2
52 kHz
OSCILLATOR
ON/OFF
FIXED GAIN
ERROR AMP
+
1.23V
BAND-GAP
REFERENCE
ON/OFF
FIXED GAIN
ERROR AMP
3.1k
1.0k
5
ON/OFF
+
-
DRIVER
OUTPUT
1.23V
BAND-GAP
REFERENCE
GND
52 kHz
OSCILLATOR
RESET
THERMAL
SHUTDOWN
CURRENT
LIMIT
Note: Pin numbers are for the TO-220 package
Fixed Regulator
M9999-082605-B
Adjustable Regulator
8
August 2005
LM2576
Micrel, Inc.
Package Information
0.150 D ±0.005
(3.81 D ±0.13)
0.177 ±0.008
(4.50 ±0.20)
0.400 ±0.015
(10.16 ±0.38)
0.050 ±0.005
(1.27 ±0.13)
0.108 ±0.005
(2.74 ±0.13)
0.241 ±0.017
(6.12 ±0.43)
0.578 ±0.018
(14.68 ±0.46)
SEATING
PLANE
7°
Typ.
0.550 ±0.010
(13.97 ±0.25)
0.067 ±0.005
(1.70 ±0.127)
0.032 ±0.005
(0.81 ±0.13)
0.268 REF
(6.81 REF)
0.018 ±0.008
(0.46 ±0.20)
0.103 ±0.013
(2.62±0.33)
Dimensions: inch
(mm)
5-Lead TO-220 (T)
0.176 ±0.005
0.405±0.005
0.065 ±0.010
20°±2°
0.060 ±0.005
0.050±0.005
0.360±0.005
0.600±0.025
SEATING PLANE
0.004 +0.004
–0.008
8° MAX
0.032 ±0.003
0.067±0.005
0.100 ±0.01
0.015 ±0.002
DIM. = INCH
5-Lead TO-263 (U)
MICREL INC. 2180 FORTUNE DRIVE
TEL
+ 1 (408) 944-0800
FAX
SAN JOSE, CA 95131
+ 1 (408) 474-1000
WEB
USA
http://www.micrel.com
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.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can
reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into
the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s
use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify
Micrel for any damages resulting from such use or sale.
© 2005 Micrel, Incorporated.
August 2005
9
M9999-082605-B
Similar pages