3.0A, 150Khz, Step-Down Switching Regulator
FEATURES
3.3V, 5.0V, 12V, 15V, and Adjustable Output Versions
Adjustable Version Output Voltage Range, 1.23 to 37V
+/- 4%. Maximum Over Line and Load Conditions
Guaranteed 3.0A Output Current
Wide Input Voltage Range
Requires Only 4 External Components
150Khz Fixed Frequency Internal Oscillator
TTL Shutdown Capability, Low Power Standby Mode
High Efficiency
Uses Readily Available Standard Inductors
Thermal Shutdown and Current Limit Protection
Moisture Sensitivity Level(MSL) Equals1
TO-263(D2)
TO-220V
TO-220
LM2596
Applications
Simple High-Efficiency Step-Down(Buck) Regulator
Efficient Pre-Regulator for Linear Regulators
On-Card Switching Regulators
Positive to Negative Converter(Buck-Boost)
Negative Step-Up Converters
Power Supply for Battery Chargers
1.
2.
3.
4.
5.
Vin
Output
Ground
Feedback
On/Off
DESCRIPTION
The LM2596 series of regulators are monolithic integrated
circuits ideally suited for easy and convenient design of a
step-down switching regualtor(buck converter).
All circuits of this series are capable of driving a 3.0A load
with excellent line and load regulation. These devices are
available in fixed output voltages of 3.3V, 5.0V,12V, 15V,
and an adjustable output version.
ORDERING INFORMATION
Device
LM2596T-X.X
LM2596TV-X.X
LM2596R
Marking
LM2596T-X.X
LM2596T-X.X
LM2596R-X.X
Package
TO-220
TO-220V
TO-263
These regulatiors were designed to minimize the number of externalcomponents to simplify the
power supply design. Standard series of inductors optimized for use with the LM2576 are offered
by several different inductor manufacturers.
Since the LM2596 converter is a switch-mode power supply, its efficiency is significantly higher in
comparison with popular three-terminal limear reguators, especially with higher input voltages.
In many cases, the power dissipated is so low that no heatsink is required or its size could
be reduced dramatically. A standard series of inductors optimized for use with the LM2596 are
available from several different manufacturers. This feature greatly simplifies the design of
switch-mode power supplies. The LM2596 features include a guaranteed +/- 4% tolerance
on output voltage within specified input voltages and output load conditions, and +/-15% on the
oscillator frequency (+/- 2% over 0oC to 125 oC).
External shutdown is included, featuring 80 uA(typical) standby current. The output switch includes
cycle-bycycle current limiting, as well as thermal shutdown for full protection under fault conditions.
HTC
1
Oct 2004 - Rev 0
3.0A, 15V, Step-Down Switching Regulator
Typical Application (Fixed Output Voltage Versions)
LM2596
LM2596-5.0
33 uH
680 uF
1N5824
220 uF
Figure 1. Block Diagram and Typical Application
ABSOLUTE MAXIMUM RATINGS
(Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.)
Power Dissipation
TO-220, 5-Lead
Thermal Resistance, Junction-to-Ambient
Thermal Resistance, Junction-to-case
TO-263
Thermal Resistance, Junction-to-Ambient
Thermal Resistance, Junction-to-case
HTC
2
Oct 2004 - Rev 0
3.0A, 15V, Step-Down Switching Regulator
LM2596
OPERATING RATINGS
(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.)
ELECTRICAL CHARACTERISTICS
/ SYSTEM PARAMETERS ([Note 1] Test Circuit Figure 2)
(Unless otherwise specified, Vin = 12 V for the 3.3 V, 5.0 V, and Adjustable version, Vin = 25 V for
the 12 V version, and Vin = 30 V for the 15 V version. ILoad = 500 mA. For typical values TJ = 25°C,
for min/max values TJ is the operating junction temperature range that applies [Note 2], unless
otherwise noted.)
LM2596-3.3
([ Note 1]. Test Circuit Figure 2 )
73
LM2596-5.0
([ Note 1]. Test Circuit Figure 2 )
1
80
LM2596-12
([ Note 1]. Test Circuit Figure 2 )
90
LM2596-15
([ Note 1]. Test Circuit Figure 2 )
98
LM2596-ADJ
([ Note 1]. Test Circuit Figure 2 )
73
HTC
3
Oct 2004 - Rev 0
3.0A, 15V, Step-Down Switching Regulator
ELECTRICAL CHARACTERISTICS / Device Parameters
LM2596
(Unless otherwise specified, Vin = 12 V for the 3.3 V, 5.0 V, and Adjustable version, Vin = 25 V for the 12
V version, and Vin = 30 V for the 15 V version. ILoad = 500 mA. For typical values Tj = 25°C, for min/max
values Tj is the operating junction temperature range that applies [Note 2], unless otherwise noted.)
10
0
127
110
150
50
100
173
173
1.16
0
1.4
1.5
-
3.6
3.4
100
4.5
6.9
7.5
50
30
-
10
0
-
2
5
0
0
2
-
0
2.0
2.0
2
V
LOGIC
= 2.5V (Regulator OFF)
V
LOGIC
= 0.5V (Regulator ON)
5
0.02
1.3
1.3
250
0.6
0.6
-
-
15
5.0
0
1. External components such as the catch diode, inductor, input and output capacitors can affect switching
regulator system performance.
When the LM2596 is used as shown in the Figure 1 test circuit, system performance will be as shown in system
parameters section .
2. Tested junction temperature range for the LM2596 : T
LOW
= –0°C T
HIGH
= +125°C
3. The oscillator frequency reduces to approximately 18 kHz in the event of an output short or an overload which
causes the regulated output voltage to drop approximately 40% from the nominal output voltage. This self
protection feature lowers the average dissipation of the IC by lowering the minimum duty cycle from 5% down to
approximately 2%.
4. Output (Pin 2) sourcing current. No diode, inductor or capacitor connected to output pin.
5. Feedback (Pin 4) removed from output and connected to 0 V.
6. Feedback (Pin 4) removed from output and connected to +12 V for the Adjustable, 3.3 V, and 5.0V ersions, and
+25 V for the 12 V and15 V versions, to force the output transistor “off”.
7. Vin = 40 V.
HTC
4
Oct 2004 - Rev 0
3.0A, 15V, Step-Down Switching Regulator
TYPICAL PERFORMANCE CHARACTERISTICS
(Circuit of Figure 2)
LM2596
HTC
5
Oct 2004 - Rev 0
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