The LM2595 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving a 1A load with
excellent line and load regulation. These devices are avail-
able in fixed output voltages of 3.3V, 5V, 12V, and an adjust-
able output version.
Requiring a minimum number of external components, these
regulators are simple to use and include internal frequency
compensation
†
, and a fixed-frequency oscillator.
The LM2595 series operates at a switching frequency of
150 kHz thus allowing smaller sized filter components than
what would be needed with lower frequency switching regu-
lators. Available in a standard 5-lead TO-220 package with
several different lead bend options, and a 5-lead TO-263
surface mount package. Typically, for output voltages less
than 12V, and ambient temperatures less than 50˚C, no heat
sink is required.
A standard series of inductors are available from several dif-
ferent manufacturers optimized for use with the LM2595 se-
ries. This feature greatly simplifies the design of
switch-mode power supplies.
Other features include a guaranteed
±
4% tolerance on out-
put voltage under specified input voltage and output load
conditions, and
±
15% on the oscillator frequency. External
shutdown is included, featuring typically 85 µA stand-by cur-
rent. Self protection features include a two stage frequency
reducing current limit for the output switch and an over tem-
perature shutdown for complete protection under fault condi-
tions.
Features
n
3.3V, 5V, 12V, and adjustable output versions
n
Adjustable version output voltage range, 1.2V to 37V
±
4% max over line and load conditions
n
Available in TO-220 and TO-263 (surface mount)
packages
n
Guaranteed 1A output load current
n
Input voltage range up to 40V
n
Requires only 4 external components
n
Excellent line and load regulation specifications
n
150 kHz fixed frequency internal oscillator
n
TTL shutdown capability
n
Low power standby mode, I
Q
typically 85 µA
n
High efficiency
n
Uses readily available standard inductors
n
Thermal shutdown and current limit protection
Applications
n
n
n
n
Simple high-efficiency step-down (buck) regulator
Efficient pre-regulator for linear regulators
On-card switching regulators
Positive to negative converter
Note:
†
Patent Number 5,382,918.
Typical Application
(Fixed Output Voltage Versions)
DS012565-1
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1
2018 JUN
LM2595-XX
Connection Diagrams and Ordering Information
Bent and Staggered Leads, Through Hole Package
5–Lead TO-220 (T)
Surface Mount Package
5-Lead TO-263 (S)
DS012565-2
Order Number LM2595T-3.3, LM2595T-5.0,
LM2595T-12 or LM2595T-ADJ
See NS Package Number T05D
DS012565-3
Order Number LM2595S-3.3, LM2595S-5.0,
LM2595S-12 or LM2595S-ADJ
See NS Package Number TS5B
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2018 JUN
LM2595-XX
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Maximum Supply Voltage
ON /OFF Pin Input Voltage
Feedback Pin Voltage
Output Voltage to Ground
(Steady State)
Power Dissipation
Storage Temperature Range
ESD Susceptibility
45V
−0.3
≤
V
≤
+25V
−0.3
≤
V
≤
+25V
−1V
Internally limited
−65˚C to +150˚C
Human Body Model (Note 2)
Lead Temperature
S Package
Vapor Phase (60 sec.)
Infrared (10 sec.)
T Package (Soldering, 10 sec.)
Maximum Junction Temperature
2 kV
+215˚C
+245˚C
+260˚C
+150˚C
Operating Conditions
Temperature Range
Supply Voltage
−40˚C
≤
T
J
≤
+125˚C
4.5V to 40V
LM2595-3.3
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over
full Operating Tempera-
ture Range.
Symbol
Parameter
Conditions
Typ
(Note 3)
SYSTEM PARAMETERS
(Note 5) Test Circuit
Figure 1
V
OUT
Output Voltage
4.75V
≤
V
IN
≤
40V, 0.1A
≤
I
LOAD
≤
1A
3.3
3.168/3.135
3.432/3.465
η
Efficiency
V
IN
= 12V, I
LOAD
= 1A
78
V
V(min)
V(max)
%
LM2595-3.3
Limit
(Note 4)
Units
(Limits)
LM2595-5.0
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over
full Operating Tempera-
ture Range.
Symbol
Parameter
Conditions
Typ
(Note 3)
SYSTEM PARAMETERS
(Note 5) Test Circuit
Figure 1
V
OUT
Output Voltage
7V
≤
V
IN
≤
40V, 0.1A
≤
I
LOAD
≤
1A
5.0
4.800/4.750
5.200/5.250
η
Efficiency
V
IN
= 12V, I
LOAD
= 1A
82
V
V(min)
V(max)
%
LM2595-5.0
Limit
(Note 4)
Units
(Limits)
LM2595-12
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over
full Operating Tempera-
ture Range.
Symbol
Parameter
Conditions
Typ
(Note 3)
SYSTEM PARAMETERS
(Note 5) Test Circuit
Figure 1
V
OUT
Output Voltage
15V
≤
V
IN
≤
40V, 0.1A
≤
I
LOAD
≤
1A
12.0
11.52/11.40
12.48/12.60
η
Efficiency
V
IN
= 25V, I
LOAD
= 1A
90
V
V(min)
V(max)
%
LM2595-12
Limit
(Note 4)
Units
(Limits)
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2018 JUN
LM2595-XX
LM2595-ADJ
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over
full Operating Tempera-
ture Range.
Symbol
Parameter
Conditions
Typ
(Note 3)
SYSTEM PARAMETERS
(Note 5) Test Circuit
Figure 1
V
FB
Feedback Voltage
4.5V
≤
V
IN
≤
40V, 0.1A
≤
I
LOAD
≤
1A
V
OUT
programmed for 3V. Circuit of
Figure 1
η
Efficiency
V
IN
= 12V, V
OUT
= 3V, I
LOAD
= 1A
78
1.230
1.193/1.180
1.267/1.280
V
V(min)
V(max)
%
LM2595-ADJ
Limit
(Note 4)
Units
(Limits)
All Output Voltage Versions
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over
full Operating Tempera-
ture Range.
Unless otherwise specified, V
IN
= 12V for the 3.3V, 5V, and Adjustable version and V
IN
= 24V for the 12V ver-
sion. I
LOAD
= 200 mA.
Symbol
Parameter
Conditions
LM2595-XX
Typ
(Note 3)
DEVICE PARAMETERS
I
b
f
O
Feedback Bias Current
Oscillator Frequency
Adjustable Version Only,V
FB
= 1.3V
(Note 6)
10
50/100
150
127/110
173/173
V
SAT
DC
I
CL
Saturation Voltage
Max Duty Cycle (ON)
Min Duty Cycle (OFF)
Current Limit
I
OUT
= 1A (Notes 7, 8)
1
1.2/1.3
(Note 8)
(Note 9)
Peak Current (Notes 7, 8)
100
0
1.5
1.2/1.15
2.4/2.6
I
L
Output Leakage Current
Output = 0V
(Notes 7, 9) and (Note 10)
Output = −1V
(Note 9)
ON/OFF pin = 5V (OFF)
(Note 10)
50
2
15
I
Q
I
STBY
θ
JC
θ
JA
θ
JA
θ
JA
θ
JA
ON /OFF Pin Logic Input
V
IH
V
IL
Threshold Voltage
Low (Regulator ON)
High (Regulator OFF)
Quiescent Current
Standby Quiescent
Current
Thermal Resistance
TO-220 or TO-263 Package, Junction to Case
TO-220 Package, Junction to Ambient (Note 11)
TO-263 Package, Junction to Ambient (Note 12)
TO-263 Package, Junction to Ambient (Note 13)
TO-263 Package, Junction to Ambient (Note 14)
2
50
50
30
20
1.3
0.6
2.0
5
10
85
200/250
A
A(min)
A(max)
µA(max)
mA
mA(max)
mA
mA(max)
µA
µA(max)
˚C/W
˚C/W
˚C/W
˚C/W
˚C/W
V
V(max)
V(min)
nA
nA (max)
kHz
kHz(min)
kHz(max)
V
V(max)
%
Limit
(Note 4)
Units
(Limits)
ON/OFF CONTROL
Test Circuit
Figure 1
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2018 JUN
LM2595-XX
All Output Voltage Versions
Electrical Characteristics
(Continued)
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over
full Operating Tempera-
ture Range.
Unless otherwise specified, V
IN
= 12V for the 3.3V, 5V, and Adjustable version and V
IN
= 24V for the 12V ver-
sion. I
LOAD
= 200 mA.
Symbol
Parameter
Conditions
LM2595-XX
Typ
(Note 3)
ON/OFF CONTROL
Test Circuit
Figure 1
I
H
I
L
ON/OFF Pin
Input Current
V
LOGIC
= 2.5V (Regulator OFF)
V
LOGIC
= 0.5V (Regulator ON)
5
15
0.02
5
µA
µA(max)
µA
µA(max)
Limit
(Note 4)
Units
(Limits)
Note 1:
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is in-
tended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2:
The human body model is a 100 pF capacitor discharged through a 1.5k resistor into each pin.
Note 3:
Typical numbers are at 25˚C and represent the most likely norm.
Note 4:
All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% produc-
tion tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate
Average Outgoing Quality Level (AOQL).
Note 5:
External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator sys-
tem performance. When the LM2595 is used as shown in the
Figure 1
test circuit, system performance will be as shown in system parameters section of Electrical
Characteristics.
Note 6:
The switching frequency is reduced when the second stage current limit is activated. The amount of reduction is determined by the severity of current over-
load.
Note 7:
No diode, inductor or capacitor connected to output pin.
Note 8:
Feedback pin removed from output and connected to 0V to force the output transistor switch ON.
Note 9:
Feedback pin removed from output and connected to 12V for the 3.3V, 5V, and the ADJ. version, and 15V for the 12V version, to force the output transistor
switch OFF.
Note 10:
V
IN
= 40V.
Note 11:
Junction to ambient thermal resistance (no external heat sink) for the TO-220 package mounted vertically, with the leads soldered to a printed circuit board
with (1 oz.) copper area of approximately 1 in
2
.
Note 12:
Junction to ambient thermal resistance with the TO-263 package tab soldered to a single printed circuit board with 0.5 in
2
of (1 oz.) copper area.
Note 13:
Junction to ambient thermal resistance with the TO-263 package tab soldered to a single sided printed circuit board with 2.5 in
2
of (1 oz.) copper area.
Note 14:
Junction to ambient thermal resistance with the TO-263 package tab soldered to a double sided printed circuit board with 3 in
2
of (1 oz.) copper area on
the LM2595S side of the board, and approximately 16 in
2
of copper on the other side of the p-c board. See Application Information in this data sheet and the thermal
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