LM2586
SIMPLE SWITCHER
3A Flyback Regulator with
Shutdown
General Description
The LM2586 series of regulators are monolithic integrated
circuits specifically designed for flyback, step-up (boost), and
forward converter applications. The device is available in 4
different output voltage versions: 3.3V, 5.0V, 12V, and adjust-
able.
Requiring a minimum number of external components, these
regulators are cost effective, and simple to use. Included in
the datasheet are typical circuits of boost and flyback regula-
tors. Also listed are selector guides for diodes and capacitors
and a family of standard inductors and flyback transformers
designed to work with these switching regulators.
The power switch is a 3.0A NPN device that can stand-off
65V. Protecting the power switch are current and thermal
limiting circuits, and an undervoltage lockout circuit. This IC
contains an adjustable frequency oscillator that can be pro-
grammed up to 200 kHz. The oscillator can also be synchro-
nized with other devices, so that multiple devices can oper-
ate at the same switching frequency.
Other features include soft start mode to reduce in-rush cur-
rent during start up, and current mode control for improved
rejection of input voltage and output load transients and
cycle-by-cycle current limiting. The device also has a shut-
down pin, so that it can be turned off externally. An output
voltage tolerance of
4%, within specified input voltages and
output load conditions, is guaranteed for the power supply
system.
Features
n
Requires few external components
n
Family of standard inductors and transformers
n
NPN output switches 3.0A, can stand off 65V
n
Wide input voltage range: 4V to 40V
n
Adjustable switching frequency: 100 kHz to 200 kHz
n
External shutdown capability
n
Draws less than 60 A when shut down
n
Frequency synchronization
n
Current-mode operation for improved transient
response, line regulation, and current limit
n
Internal soft-start function reduces in-rush current during
start-up
n
Output transistor protected by current limit, under
voltage lockout, and thermal shutdown
n
System output voltage tolerance of
4% max over line
and load conditions
Typical Applications
n
Flyback regulator
n
Forward converter
n
Multiple-output regulator
n
Simple boost regulator
Flyback Regulator
SIMPLE SWITCHER
and
Switchers Made Simple
are registered trademarks of National Semiconductor Corporation.
DS012516-1
May 1996
LM2586
SIMPLE
SWITCHER
3A
Flyback
Regulator
with
Shutdown
1999 National Semiconductor Corporation
DS012516
www.national.com
Ordering Information
Package Type
NSC Package
Order Number
Drawing
7-Lead TO-220 Bent, Staggered Leads
TA07B
LM2586T-3.3, LM2586T-5.0, LM2586T-12, LM2586T-ADJ
7-Lead TO-263
TS7B
LM2586S-3.3, LM2586S-5.0, LM2586S-12, LM2586S-ADJ
7-Lead TO-263 Tape and Reel
TS7B
LM2586SX-3.3, LM2586SX-5.0, LM2586SX-12,
LM2586SX-ADJ
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2
Absolute Maximum Ratings
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Input Voltage
-0.4V
V
IN
45V
Switch Voltage
-0.4V
V
SW
65V
Switch Current (Note 2)
Internally Limited
Compensation Pin Voltage
-0.4V
V
COMP
2.4V
Feedback Pin Voltage
-0.4V
V
FB
2 V
OUT
ON /OFF Pin Voltage
-0.4V
V
SH
6V
Sync Pin Voltage
-0.4V
V
SYNC
2V
Power Dissipation (Note 3)
Internally Limited
Storage Temperature Range
-65C to +150C
Lead Temperature (Soldering, 10
sec.)
260C
Maximum Junction Temperature
(Note 3)
150C
Minimum ESD Rating
(C = 100 pF, R = 1.5 k
)
2 kV
Operating Ratings
Supply Voltage
4V
V
IN
40V
Output Switch Voltage
0V
V
SW
60V
Output Switch Current
I
SW
3.0A
Junction Temp. Range
-40C
T
J
+125C
Electrical Characteristics
Specifications with standard type face are for T
J
= 25C, and those in bold type face apply over full Operating Temperature
Range. Unless otherwise specified, V
IN
= 5V.
LM2586-3.3
Symbol
Parameters
Conditions
Typical
Min
Max
Units
SYSTEM PARAMETERS Test Circuit of
Figure 1 (Note 4)
V
OUT
Output Voltage
V
IN
= 4V to 12V
3.3
3.17/3.14
3.43/3.46
V
I
LOAD
= 0.3 to 1.2A
V
OUT
/
Line Regulation
V
IN
= 4V to 12V
20
50/100
mV
V
IN
I
LOAD
= 0.3A
V
OUT
/
Load Regulation
V
IN
= 12V
20
50/100
mV
I
LOAD
I
LOAD
= 0.3A to 1.2A
Efficiency
V
IN
= 5V, I
LOAD
= 0.3A
76
%
UNIQUE DEVICE PARAMETERS (Note 5)
V
REF
Output Reference
Measured at Feedback Pin
3.3
3.242/3.234
3.358/3.366
V
Voltage
V
COMP
= 1.0V
V
REF
Reference Voltage
V
IN
= 4V to 40V
2.0
mV
Line Regulation
G
M
Error Amp
I
COMP
= -30 A to +30 A
1.193
0.678
2.259
mmho
Transconductance
V
COMP
= 1.0V
A
VOL
Error Amp
V
COMP
= 0.5V to 1.6V
260
151/75
V/V
Voltage Gain
R
COMP
= 1.0 M
(Note 6)
LM2586-5.0
Symbol
Parameters
Conditions
Typical
Min
Max
Units
SYSTEM PARAMETERS Test Circuit of
Figure 1 (Note 4)
V
OUT
Output Voltage
V
IN
= 4V to 12V
5.0
4.80/4.75
5.20/5.25
V
I
LOAD
= 0.3A to 1.1A
V
OUT
/
Line Regulation
V
IN
= 4V to 12V
20
50/100
mV
V
IN
I
LOAD
= 0.3A
V
OUT
/
Load Regulation
V
IN
= 12V
20
50/100
mV
I
LOAD
I
LOAD
= 0.3A to 1.1A
Efficiency
V
IN
= 12V, I
LOAD
= 0.6A
80
%
UNIQUE DEVICE PARAMETERS (Note 5)
V
REF
Output Reference
Voltage
Measured at Feedback Pin
V
COMP
= 1.0V
5.0
4.913/4.900
5.088/5.100
V
V
REF
Reference Voltage
V
IN
= 4V to 40V
3.3
mV
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3
LM2586-5.0
(Continued)
Symbol
Parameters
Conditions
Typical
Min
Max
Units
UNIQUE DEVICE PARAMETERS (Note 5)
Line Regulation
G
M
Error Amp
I
COMP
= -30 A to +30 A
0.750
0.447
1.491
mmho
Transconductance
V
COMP
= 1.0V
A
VOL
Error Amp
V
COMP
= 0.5V to 1.6V
165
99/49
V/V
Voltage Gain
R
COMP
= 1.0 M
(Note 6)
LM2586-12
Symbol
Parameters
Conditions
Typical
Min
Max
Units
SYSTEM PARAMETERS Test Circuit of
Figure 2 (Note 4)
V
OUT
Output Voltage
V
IN
= 4V to 10V
12.0
11.52/11.40
12.48/12.60
V
I
LOAD
= 0.2A to 0.8A
V
OUT
/
Line Regulation
V
IN
= 4V to 10V
20
100/200
mV
V
IN
I
LOAD
= 0.2A
V
OUT
/
Load Regulation
V
IN
= 10V
20
100/200
mV
I
LOAD
I
LOAD
= 0.2A to 0.8A
Efficiency
V
IN
= 10V, I
LOAD
= 0.6A
93
%
UNIQUE DEVICE PARAMETERS (Note 5)
V
REF
Output Reference
Measured at Feedback Pin
12.0
11.79/11.76
12.21/12.24
V
Voltage
V
COMP
= 1.0V
V
REF
Reference Voltage
V
IN
= 4V to 40V
7.8
mV
Line Regulation
G
M
Error Amp
I
COMP
= -30 A to +30 A
0.328
0.186
0.621
mmho
Transconductance
V
COMP
= 1.0V
A
VOL
Error Amp
V
COMP
= 0.5V to 1.6V
70
41/21
V/V
Voltage Gain
R
COMP
= 1.0 M
(Note 6)
LM2586-ADJ
Symbol
Parameters
Conditions
Typical
Min
Max
Units
SYSTEM PARAMETERS Test Circuit of
Figure 2 (Note 4)
V
OUT
Output Voltage
V
IN
= 4V to 10V
12.0
11.52/11.40
12.48/12.60
V
I
LOAD
= 0.2A to 0.8A
V
OUT
/
Line Regulation
V
IN
= 4V to 10V
20
100/200
mV
V
IN
I
LOAD
= 0.2A
V
OUT
/
Load Regulation
V
IN
= 10V
20
100/200
mV
I
LOAD
I
LOAD
= 0.2A to 0.8A
Efficiency
V
IN
= 10V, I
LOAD
= 0.6A
93
%
UNIQUE DEVICE PARAMETERS (Note 5)
V
REF
Output Reference
Measured at Feedback Pin
1.230
1.208/1.205
1.252/1.255
V
Voltage
V
COMP
= 1.0V
V
REF
Reference Voltage
V
IN
= 4V to 40V
1.5
mV
Line Regulation
G
M
Error Amp
I
COMP
= -30 A to +30 A
3.200
1.800
6.000
mmho
Transconductance
V
COMP
= 1.0V
A
VOL
Error Amp Voltage Gain
V
COMP
= 0.5V to 1.6V,
R
COMP
= 1.0 M
(Note 6)
670
400/200
V/V
I
B
Error Amp
V
COMP
= 1.0V
125
425/600
nA
Input Bias Current
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4
LM2586-ADJ
(Continued)
Symbol
Parameters
Conditions
Typical
Min
Max
Units
COMMON DEVICE PARAMETERS for all versions (Note 5)
I
S
Input Supply Current
Switch Off (Note 8)
11
15.5/16.5
mA
I
SWITCH
= 1.8A
50
100/115
mA
I
S/D
Shutdown Input
V
SH
= 3V
16
100/300
A
Supply Current
V
UV
Input Supply
R
LOAD
= 100
3.30
3.05
3.75
V
Undervoltage Lockout
f
O
Oscillator Frequency
Measured at Switch Pin
R
LOAD
= 100
, V
COMP
= 1.0V
100
85/75
115/125
kHz
Freq. Adj. Pin Open (Pin 1)
R
SET
= 22 k
200
kHz
f
SC
Short-Circuit
Measured at Switch Pin
Frequency
R
LOAD
= 100
25
kHz
V
FEEDBACK
= 1.15V
V
EAO
Error Amplifier
Upper Limit
2.8
2.6/2.4
V
Output Swing
(Note 7)
Lower Limit
0.25
0.40/0.55
V
(Note 8)
I
EAO
Error Amp
(Note 9)
Output Current
165
110/70
260/320
A
(Source or Sink)
I
SS
Soft Start Current
V
FEEDBACK
= 0.92V
11.0
8.0/7.0
17.0/19.0
A
V
COMP
= 1.0V
D
MAX
Maximum Duty Cycle
R
LOAD
= 100
98
93/90
%
(Note 7)
I
L
Switch Leakage
Switch Off
15
300/600
A
Current
V
SWITCH
= 60V
V
SUS
Switch Sustaining Voltage
dV/dT = 1.5V/ns
65
V
V
SAT
Switch Saturation Voltage
I
SWITCH
= 3.0A
0.45
0.65/0.9
V
I
CL
NPN Switch Current Limit
4.0
3.0
7.0
A
V
STH
Synchronization
F
SYNC
= 200 kHz
0.75
0.625/0.40
0.875/1.00
V
Threshold Voltage
V
COMP
= 1V, V
IN
= 5V
I
SYNC
Synchronization
V
IN
= 5V
100
200
A
Pin Current
V
COMP
= 1V, V
SYNC
= V
STH
V
SHTH
ON/OFF Pin (Pin 1)
V
COMP
= 1V
1.6
1.0/0.8
2.2/2.4
V
Threshold Voltage
(Note 10)
I
SH
ON/OFF Pin (Pin 1)
V
COMP
= 1V
40
15/10
65/75
A
Current
V
SH
= V
SHTH
JA
Thermal Resistance
T Package, Junction to
Ambient (Note 11)
65
C/W
JA
T Package, Junction to
Ambient (Note 12)
45
JC
T Package, Junction to Case
2
JA
S Package, Junction to
Ambient (Note 13)
56
JA
S Package, Junction to
Ambient (Note 14)
35
JA
S Package, Junction to
Ambient (Note 15)
26
JC
S Package, Junction to Case
2
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