3.0A, 150kHz, Step-Down Switching Regulator
LM2596
FEATURES
TO-220 PKG
3.3V, 5.0V, 12V, and Adjustable Output Versions
Adjustable Version Output Voltage Range, 1.2 to 37V
+/- 4%. Maximum Over Line and Load Conditions
Guaranteed 3.0A Output Current
Wide Input Voltage Range
1
Requires Only 4 External Components
5
150kHz Fixed Frequency Internal Oscillator
TO-220V PKG
TTL Shutdown Capability, Low Power Standby Mode
High Efficiency
1
Uses Readily Available Standard Inductors
Thermal Shutdown and Current Limit Protection
Moisture Sensitivity Level 3
5
Applications
TO-263 PKG
Simple High-Efficiency Step-Down(Buck) Regulator
Efficient Pre-Regulator for Linear Regulators
On-Card Switching Regulators
1
Positive to Negative Converter(Buck-Boost)
5
Negative Step-Up Converters
1. Vin 2. Output 3. Ground
4. Feedback 5. On/Off
Power Supply for Battery Chargers
DESCRIPTION
ORDERING INFORMATION
The LM2596 series of regulators are monolithic integrated
Device
Marking
Package
circuits ideally suited for easy and convenient design of a
LM2596T-X.X
LM2596-X.X
TO-220
step-down switching regulator(buck converter).
LM2596TV-X.X
LM2596-X.X
TO-220V
LM2596R
LM2596-X.X
TO-263
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,
and an adjustable output version.
These regulators were designed to minimize the number of external components to simplify the
power supply design. Standard series of inductors optimized for use with the LM2596 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 regulators, 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 TJ2596 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 0℃ to 125℃).
External shutdown is included, featuring 80㎂ (typical) standby current. Self protection features include
a two stage frequency reducing current limit for output switch and an over temperature shutdown for complete
protection under fault conditions.
HTC
Dec. 2009 - Rev.1.3.1
−1−
3.0A, 150kHz, Step-Down Switching Regulator
LM2596
Typical Application (Fixed Output Voltage Versions)
LM2596-5.0
680 uF
33 uH
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.)
Rating
Symbol
Value
Unit
Maximum Supply Voltage
V
Vin
45
-0.3V ≤ V ≤ +Vin
On/Off Pin Input Voltage
V
- 1.0
Output Voltage to Ground (Steady-State)
V
Power Dissipation
PD
Internally Limited
TO-220 5Lead
W
PθJA
Thermal Resistance, Juntion to Ambient
65
℃/W
PθJC
Thermal Resistance, Juntion to Case
5.0
℃/W
PD
TO-263 5Lead
Internally Limited
W
PθJA
70
Thermal Resistance, Juntion to Ambient
℃/W
PθJC
5.0
Thermal Resistance, Juntion to Case
℃/W
Tstg
-60 to +150
Storage Temperature Range
℃
Minimum ESD Rating(Human Body Model :
2.0
kV
C=100 pF, R=1.5㏀)
260
Lead Temperature (Soldering,10seconds)
℃
T
J
℃
Maximum Junction Temperature
150
HTC
−2−
3.0A, 150kHz, 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.)
Symbol
TJ
Rating
Operating Junction Temperature Range
Supply Voltage
Value
-40 to +125
40
Vin
Unit
℃
V
ELECTRICAL CHARACTERISTICS / SYSTEM PARAMETERS ([Note 1] Test Circuit Figure 2)
(Unless otherwise specified, Vin = 12V for the 3.3V, 5.0V, and Adjustable version, Vin = 25V for the 12V versio
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.)
Characteristics
Symbol
Min
TYP
Max
Unit
Vout
Vout
3.234
3.3
3.366
V
3.168
3.135
-
3.3
73
3.432
3.465
-
V
%
4.9
5.0
5.1
V
4.8
4.75
-
5.0
80
5.2
5.25
-
V
%
11.76
12
12.24
V
11.52
11.4
-
12
90
12.48
12.6
-
V
%
1.217
1.23
1.243
V
1.193
1.18
-
1.23
73
1.267
1.28
-
V
LM2596-3.3V ([Note 1] Test Circuit Figure 2)
Output Voltage (Vin = 12V, ILOAD=0.5A, TJ=25℃)
Output Voltage (6.0V≤Vin≤40V, 0.5A≤ILOAD≤3.0A
TJ=25℃
TJ= -40℃ ~ +125℃
η
Efficiency (Vin=12V, ILOAD=3.0A)
LM2596-5.0V ([Note 1] Test Circuit Figure 2)
Output Voltage (Vin = 12V, ILOAD=0.5A, TJ=25℃)
Output Voltage (8.0V≤Vin≤40V, 0.5A≤ILOAD≤3.0A
Vout
Vout
TJ=25℃
TJ= -40℃ ~ +125℃
η
Efficiency (Vin=12V, ILOAD=3.0A)
LM2596-12V ([Note 1] Test Circuit Figure 2)
Output Voltage (Vin = 25V, ILOAD=0.5A, TJ=25℃)
Output Voltage (15V≤Vin≤40V, 0.5A≤ILOAD≤3.0A
Vout
Vout
TJ=25℃
TJ= -40℃ ~ +125℃
η
Efficiency (Vin=12V, ILOAD=3.0A)
LM2596-ADJ ([Note 1] Test Circuit Figure 2)
Feedback Voltage (Vin=12V, ILOAD=0.5A, TJ=25℃)
Feedback Voltage(8.0V≤Vin≤40V, 0.5A≤ILOAD≤3.0A, Vout=5.0V)
Vout
Vout
TJ=25℃
TJ= -40℃ ~ +125℃
η
Efficiency (Vin=12V, ILOAD=3.0A, Vout=5.0V)
%
HTC
−3−
3.0A, 150kHz, Step-Down Switching Regulator
LM2596
ELECTRICAL CHARACTERISTICS / Device Parameters
(Unless otherwise specified, Vin = 12V for the 3.3V, 5.0V, and Adjustable version, Vin = 25V for the 12V versio
ILoad = 500 mA. For typical values Tj = 25°C, for min/max values TJ is the operating junction temperature ran
that applies [Note 2], unless otherwise noted.)
Characteristics
All Output Voltage Versions
Symbol
Feedback Bias Current (Vout=5.0V [Adjustable Version Only])
Min
TYP
Max
Unit
Ib
TJ=25℃
11.52
12
12.48 nA
TJ= 0 ~ +125℃
11.4
12.6
Oscillator Frequency [Note 3]
Fosc
TJ=25℃
kHz
127
150
173
TJ= 0 ~ +125℃
173
110
Saturation Voltage (Iout=3.0A [note 4])
Vsat
TJ=25℃
V
1.4
1.16
TJ= 0 ~ +125℃
1.5
%
Max Duty Cycle ("0") [Note 5]
DC
100
I
CL
Current Limit (Peak Current [Note 3 and 4])
TJ=25℃
A
3.6
4.5
6.9
TJ= 0 ~ +125℃
3.4
7.5
IL
Output Leakage Current [Note 6 and 7], TJ=25℃
mA
50
Output = 0V
Output = -1.0V
2
30
IQ
Quiescent Current [Note 6]
TJ=25℃
mA
5
TJ= 0 ~ +125℃
10
ISTBY
Standby Quiescent Current (ON/OFF Pin = 5.0V ("off"))
TJ=25℃
㎂
200
80
TJ= 0 ~ +125℃
250
ON/OFF Pin Logic Input Level (Test circuit Figure 2)
VIH
Vout=0V
TJ=25℃
2.0
1.3
TJ= 0 ~ +125℃
V
2.0
VIL
Vout=Nominal Ouput Voltage
TJ=25℃
1.3
0.6
TJ= 0 ~ +125℃
0.6
ON/OFF Pin Input Current (Test Circuit Figure 2)
IIH
VLOGIC = 2.5V (Regulator OFF)
㎂
5
15
IIL
VLOGIC = 0.5V (Regulator ON)
0.02
5.0
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 TJ2596 : TLOW = –40°C THIGH = +125°C
3. The oscillator frequency reduces to approximately 18kHz 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 +12V for the Adjustable, 3.3V, and 5.0V
versions, and '+25 V for the 12V versions, to force the output transistor “off”.C195
7. Vin = 40 V.
HTC
−4−
3.0A, 150kHz, Step-Down Switching Regulator
LM2596
TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 2)
HTC
−5−
3.0A, 150kHz, Step-Down Switching Regulator
LM2596
TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 2)
Feedback Pin Bias Current
HTC
−6−
3.0A, 150kHz, Step-Down Switching Regulator
LM2596
Test Circuit and Layout Guidelines
Cin = 470㎌, 50V, Cout = 220㎌, 25V (Aluminum Electrilytic Nichicon "PL Series"
D1 = 5A, 40V Schottky Rectifier, IN5825
L1 = 68uH, L38
Cin = 470㎌, 50V, Cout = 220㎌, 35V (Aluminum Electrilytic Nichicon "PL Series"
D1 = 5A, 40V Schottky Rectifier, IN5825
L1 = 68uH,
R1 = 1㏀, 1%
R2 = R1 x (Vout / Vref - 1)
Figure 2. Typical Test Circuits and Layout Guide
As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring
inductance can generate voltage transients which can cause problems. For minimal inductance and
ground loops, the wires indicated by heavy lines should be wide printed circuit traces and should be
kept as short as possible. For best results, external components should be located as close to the
switching lC as possible using ground plane construction or single point grounding. If open core
inductors are used, special care must be taken as to the location and positioning of this type of
inductor. Allowing the inductor flux to intersect sensitive feedback, lC groundpath and COUT wiring
can cause problems. When using the adjustable version, special care must be taken as to the location
of the feedback resistors and the associated wiring. Physically locate both resistors near the IC, and
route the wiring away from the inductor, especially an open core type of inductor.
HTC
−7−
3.0A, 150kHz, Step-Down Switching Regulator
LM2596
PIN FUNCTION DESCRIPTION
Symbol
1
Vin
Description
This pin is the positive input supply for the LM2596 step–down switching
regulator.In order to minimize voltage transients and to supply the switching
currents needed by the regulator, a suitable input bypass capacitor must be
present .(Cin in Figure 1).
2
Output
This is the emitter of the internal switch. The saturation voltage Vsat of this
output switch is typically 1.5 V. It should be kept in mind that the PCB area
connected to this pin should be kept to a minimum in order to minimize
coupling to sensitive circuitry.
3
4
Gnd
Circuit ground pin. See the information about the printed circuit board layout.
Feedback This pin senses regulated output voltage to complete the feedback loop.
The signal is divided by the internal resistor divider network R2, R1 and
applied to the non–inverting input of the internal error amplifier. In the
Adjustable version of the LM2596 switching regulator this pin is the direct
input of the error amplifier and the resistor network R2, R1 is connected
externally to allow programming of the output voltage.
5
ON/OFF It allows the switching regulator circuit to be shut down using logic level
signals, thus dropping the total input supply current to approximately 80mA.
The threshold voltage is typically 1.4V. Applying a voltage above this value
(up to +Vin) shuts the regulator off. If the voltage applied to this pin is lower
than 1.4V or if this pin is left open, the regulator will be in the "on" condition
HTC
−8−