TL H 11731
LM2567
LAN
DCDC
Converter
November 1992
LM2567
LAN DC DC Converter
General Description
The LM2567 DC DC converter is intended for use in LAN
applications as a power supply for the DP8392 Coaxial
Transceiver The converter may be operated from an input
voltage of 5V (
g
10%) to 15V It provides an isolated output
of
b
9V for loads of up to 180 mA with an efficiency of 78%
(typical) The few external components required for the con-
verter are completely specified within this datasheet
Protection features for the LM2567-based DC DC converter
include thermal and current limit Undervoltage lockout and
soft-start are incorporated to minimize the inrush current
during start-up
Features
Y
Wide input voltage range 5V to 15V
Y
Tight line regulation 0 5% (typ)
Y
Output voltage tolerance
g
5%
Y
Few external components required
Y
Surface-mount packaging
Y
Fixed switching frequency of 52 kHz
Y
Current-mode operation for improved transient re-
sponse
Typical Applications
Y
Power supply for DP8392 (LAN) coaxial transceiver
Isolated
b
9V output for up to 180 mA load
Typical Application
DC-to-DC Converter for DP8392 Coaxial Transceiver
TL H 11731 1
Connection Diagram and Ordering Information
24-Lead Surface Mount (M)
TL H 11731 2
No internal connection
Top View
Order Number LM2567M
See NS Package Number M24B
C1995 National Semiconductor Corporation
RRD-B30M115 Printed in U S A
Absolute Maximum Ratings
(Note 1)
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Supply Voltage
40V
Output Switch Voltage
50V
Output Switch Current
6 0A
Power Dissipation
Internally Limited
Storage Temperature Range
b
65 C to
a
150 C
Lead Temperature (Soldering 10 sec )
260 C
Maximum Junction Temperature
150 C
Minimum ESD Rating (C
e
100 pF R
e
1 5 kX)
2 kV
Operating Ratings
Supply Voltage
3 5V
s
V
IN
s
35V
Output Switch Voltage
0V
s
V
SW
s
45V
Output Switch Current
I
SW
s
3 0A
Junction Temperature Range
0 C
s
T
J
s
a
125 C
Ambient Temperature Range
0 C
s
T
A
s
a
70 C
Electrical Characteristics
Specifications with standard type face are for T
J
e
25 C and those in bold typeface apply over full Operating Temperature
Range
Unless otherwise specified V
IN
e
5V V
FB
e
V
REF
and I
SWITCH
e
0 (Note 2)
Symbol
Parameter
Conditions
Typ
Min
Max
Units
GENERAL DEVICE PARAMETERS
I
S
Input Supply Current
V
FB
e
1 5V (Switch Off)
7 5
10 0
mA
14 0
mA
I
SW
e
2 0A
20
50
mA
V
COMP
e
2 0V (Max Duty Cycle)
85
mA
V
UV
Input Supply
I
SW
e
100 mA
2 90
2 60
3 10
V
Undervoltage Lockout
V
COMP
e
1 2V
2 55
3 15
V
f
O
Oscillator Frequency
Measured at Switch Pin
52
48
56
kHz
I
SW
e
100 mA
42
62
kHz
V
REF
Reference Voltage
Measured at Feedback Pin
1 230
1 214
1 246
V
V
IN
e
3 5V to 35V
1 206
1 254
V
V
COMP
e
1 0V
D
V
REF
Reference Voltage
V
IN
e
3 5V to 35V
0 5
mV
D
V
IN
Line Regulation
i
JA
Thermal Resistance
Junction-to-Ambient (Note 3)
100
C W
ERROR AMPLIFIER PARAMETERS
I
B
Error Amp
V
COMP
e
1 0V
100
300
nA
Input Bias Current
800
nA
G
M
Error Amp
I
COMP
e b
30 mA to
a
30 mA
3700
2400
4800
m
mho
Transconductance
V
COMP
e
1 0V
1600
5800
m
mho
A
V
Error Amp
V
COMP
e
1 1V to 1 6V
800
500
V V
Voltage Gain
R
COMP
e
1 0 MX (Note 4)
250
V V
Error Amp
Upper Limit
2 4
2 2
V
Output Swing
V
FB
e
1 0V
2 0
V
Lower Limit
0 3
0 40
V
V
FB
e
1 5V
0 55
V
Error Amp
V
FB
e
1 0V to 1 5V
g
200
g
130
g
300
m
A
Output Current
V
COMP
e
1 0V
g
90
g
400
m
A
I
SS
Soft Start Current
V
FB
e
1 0V
5 0
2 5
7 5
m
A
V
COMP
e
0V
1 5
9 5
m
A
D
Maximum Duty Cycle
V
COMP
e
1 2V
95
93
%
ISW
e
100 mA
88
%
2
Electrical Characteristics
(Continued)
Specifications with standard type face are for T
J
e
25 C and those in bold typeface apply over full Operating Temperature
Range
Unless otherwise specified V
IN
e
5V V
FB
e
V
REF
and I
SWITCH
e
0 (Note 2)
Symbol
Parameter
Conditions
Typ
Min
Max
Units
SWITCH PARAMETERS
D
I
SWITCH
Switch
12 5
A V
D
V
COMP
Transconductance
I
L
Switch Leakage
Switch Off (V
FB
e
1 5V)
10
300
m
A
Current
V
SW
e
50V
600
m
A
V
SAT
Switch Saturation
I
SW
e
2 0A
0 5
0 75
V
Voltage
V
COMP
e
1 2V
1 0
V
I
CL
NPN Switch
V
COMP
e
2 0V
4 3
3 7
5 3
A
Current Limit
3 0
6 0
A
Note 1
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur Operating ratings indicate conditions the device is intended to
be functional but device parameter specifications may not be guaranteed under these conditions For guaranteed specifications and test conditions see the
Electrical Characteristics
Note 2
All limits guaranteed at room temperature (standard typeface) and at temperature extremes (boldface type) All room temperature limits are 100%
production tested All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods
Note 3
Junction-to-Ambient thermal resistanoe with approximately 1 square inch of p c board copper surrounding the leads Additional copper area will lower
thermal resistance further
Note 4
A 1 0 MX resistor is connected to the compensation pin (which is the error amplifier's output) to ensure accuracy in measuring A
VOL
In actual applications
this pin's load resistance should be
t
10 MX resulting in A
VOL
that is typically twice the guaranteed minimum limit
3
Typical Performance Characteristics
vs Temperature
Supply Current
vs Temperature
Reference Voltage
vs Supply Voltage
D Reference Voltage
vs Switch Current
Supply Current
vs Temperature
Current Limit
Time vs Overdrive
Current Limit Response
vs Switch Current
Switch Saturation Voltage
vs Temperature
Switch Transconductance
vs Temperature
Oscillator Frequency
Current vs Temperature
Feedback Pin Bias
vs Temperature
Error Amp Transconductance
Gain vs Temperature
Error Amp Voltage
TL H 11731 4
4
LM2567 Block Diagram
TL H 11731 5
LM2567 DC-to-DC Converter in DP8392C Typical Application
( See Typical Application on Front Page of this Datasheet )
TL H 11731 6
Note
T1 is a 1 1 pulse transformer L
e
100 mH
Pulse Engineering (San Diego) Part No 64103
Valor Electronics (San Diego) Part No LT6003 or equivalent
5
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