LM6125/LM6225/LM6325
High Speed Buffer
General Description
The LM6125 family of high speed unity gain buffers slew at
800 V/µs and have a small signal bandwidth of 50 MHz while
driving a 50
load. These buffers drive
±
300 mA peak and
do not oscillate while driving large capacitive loads. The
LM6125 contains unique features not found in power buffers;
these include current limit, thermal shutdown, electronic
shutdown, and an error flag that warns of fault conditions.
These buffers are built with National's VIP
TM
(Vertically Inte-
grated PNP) process which provides fast PNP transistors
that are true complements to the already fast NPN devices.
This advanced junction-isolated process delivers high speed
performance without the need for complex and expensive di-
electric isolation.
Features
n
High slew rate:
800 V/µs
n
High output current:
±
300 mA
n
Stable with large capacitive loads
n
Current and thermal limiting
n
Electronic shutdown
n
5V to
±
15V operation guaranteed
n
Fully specified to drive 50
lines
Applications
n
Line Driving
n
Radar
n
Sonar
Simplified Schematic and Block Diagram
VIP
TM
is a trademark of National Semiconductor Corporation.
DS009222-1
DS009222-2
Numbers in () are for 14pin N DIP.
December 1994
LM6125/LM6225/LM6325
High
Speed
Buffer
© 1999 National Semiconductor Corporation
DS009222
www.national.com
Pin Configurations
Note 1: Available per 5962-9081501
DS009222-3
*Heat sinking pins.
Internally connected to V-.
Order Number LM6225N
or LM6325N
See NS Package Number N14A
DS009222-4
Note: Pin 4 connected to case
Top View
Order Number LM6125H/883 (Note 1)
or LM6125H
See NS Package Number H08C
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2
Absolute Maximum Ratings
(Note 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
36V (
±
18V)
Input to Output Voltage (Note 2)
±
7V
Input Voltage
±
Vsupply
Output Short-Circuit to GND
(Note 3)
Continuous
Flag Output Voltage
GND
Vflag
+Vsupply
Storage Temperature Range
-65°C to +150°C
Lead Temperature
(Soldering, 10 seconds)
260°C
ESD Tolerance (Note 9)
±
1500V
JA
(Note 4)
H Package
150°C/W
N Package
40°C/W
Maximum Junction
Temperature (T
J
)
150°C
Operating Temperature Range
LM6125
-55°C to +125°C
LM6225
-40°C to +85°C
LM6325
0°C to +70°C
Operating Supply Voltage Range
4.75V to
±
16V
DC Electrical Characteristics
The following specifications apply for Supply Voltage =
±
15V, V
CM
= 0, R
L
100 k
and R
S
= 50
unless otherwise noted.
Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= 25°C.
Symbol
Parameter
Conditions
Typ
LM6125
LM6225
LM6325
Units
Limit
Limit
Limit
(Notes 5, 10)
(Note 5)
(Note 5)
A
V1
Voltage Gain 1
R
L
= 1k
, V
IN
=
±
10V
0.990
0.980
0.980
0.970
0.970
0.950
0.950
A
V2
Voltage Gain 2
R
L
= 50
, V
IN
=
±
10V
0.900
0.860
0.860
0.850
V/V
0.800
0.820
0.820
Min
A
V3
Voltage Gain 3
R
L
= 50
, V+ = 5V
0.840
0.780
0.780
0.750
(Note 6)
V
IN
= 2 V
PP
(1.5 V
PP
)
0.750
0.700
0.700
V
OS
Offset Voltage
R
L
= 1 k
15
30
30
50
mV
50
60
100
Max
I
B
Input Bias Current
R
L
= 1 k
, R
S
= 10 k
1
4
4
5
µA
7
7
7
Max
R
IN
Input Resistance
R
L
= 50
5
M
C
IN
Input Capacitance
3.5
pF
R
O
Output Resistance
I
OUT
=
±
10 mA
3
5
5
5
10
10
6
Max
I
S1
Supply Current 1
R
L
=
15
18
18
20
20
20
22
I
S2
Supply Current 2
R
L
=
, V+ = 5V
14
16
16
18
mA
18
18
20
Max
I
S/D
Supply Current
R
L
=
, V
±
=
±
15V
1.1
1.5
1.5
1.5
in Shutdown
2.0
2.0
2.0
V
O1
Output Swing 1
R
L
= 1 k
13.5
13.3
13.3
13.2
13
13
13
V
O2
Output Swing 2
R
L
= 100
12.7
11.5
11.5
11
±
V
10
10
10
Min
V
O3
Output Swing 3
R
L
= 50
12
11
11
10
9
9
9
V
O4
Output Swing 4
R
L
= 50
1.8
1.6
1.6
1.6
V
PP
1.3
1.4
1.5
Min
PSRR
Power Supply
V+ = 5V (Note 6)
70
60
60
60
dB
Rejection Ratio
55
50
50
Min
V
OL
Flag Pin Output
V
±
=
±
5V to
±
15V
300
300
340
mV
Low Voltage
V
S/D
= 0V
400
400
400
Max
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3
DC Electrical Characteristics
(Continued)
The following specifications apply for Supply Voltage =
±
15V, V
CM
= 0, R
L
100 k
and R
S
= 50
unless otherwise noted.
Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= 25°C.
Symbol
Parameter
Conditions
Typ
LM6125
LM6225
LM6325
Units
Limit
Limit
Limit
(Notes 5, 10)
(Note 5)
(Note 5)
I
OH
Flag Pin Output
V
OH
Flag Pin = 15V
0.01
10
10
10
µA
High Current
(Note 6)
20
20
20
Max
V
TH
Shutdown Threshold
1.4
V
V
IH
Shutdown Pin
2.0
2.0
2.0
V
Trip Point High
2.0
2.0
2.0
Min
V
IL
Shutdown Pin
0.8
0.8
0.8
V
Trip Point Low
0.8
0.8
0.8
Max
I
IL
Shutdown Pin
V
S/D
= 0V
-0.07
-10
-10
-10
µA
Input Low Current
-20
-20
-20
Max
I
IH
Shutdown Pin
V
S/D
= 5V
-0.05
-10
-10
-10
µA
Input High Current
-20
-20
-20
Max
I
O
Bi-State Output
Current
Shutdown Pin = 0V
1
50
50
100
µA
V
OUT
= +5V or -5V
2000
100
200
AC Electrical Characteristics
The following specifications apply for Supply Voltage =
±
15V, V
CM
= 0, R
L
100 k
and R
S
= 50
unless otherwise noted.
Boldface limits apply for T
A
= T
J
= T
MIN
to T
MAX
; all other limits T
A
= T
J
= 25°C.
Symbol
Parameter
Conditions
Typ
LM6125
LM6225
LM6325
Units
Limit
Limit
Limit
(Note 5)
(Note 5)
(Note 5)
SR
1
Slew Rate 1
V
IN
=
±
11V, R
L
= 1 k
1200
V/µs
Min
SR
2
Slew Rate 2
V
IN
=
±
11V, R
L
= 50
800
550
550
550
(Note 8)
SR
3
Slew Rate 3
V
IN
= 2 V
PP
, R
L
= 50
50
V+ = 5V (Note 6)
BW
-3 dB Bandwidth
V
IN
= 100 mV
PP
50
30
30
30
MHz
R
L
= 50
, C
L
10 pF
Min
t
r
, t
f
Rise Time
R
L
= 50
, C
L
10 pF
8.0
ns
Fall Time
V
O
= 100 mV
PP
t
PD
Propagation
R
L
= 50
, C
L
10 pF
4.0
ns
Delay Time
V
O
= 100 mV
PP
O
S
Overshoot
R
L
= 50
, C
L
10 pF
10
%
V
O
= 100 mV
PP
V
FT
V
IN
, V
OUT
Feedthrough
Shutdown Pin = 0V
in Shutdown
V
IN
= 4 V
PP
, 1 MHz
-50
dB
R
L
= 50
C
OUT
Output Capacitance
Shutdown Pin = 0V
30
pF
in Shutdown
t
SD
Shutdown
700
ns
Response Time
Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating
the device beyond its rated operating conditions.
Note 3: During current limit, thermal limit, or electronic shutdown the input current will increase if the input to output differential voltage exceeds 8V. See Overvoltage
Protection in Application Hints.
Note 4: The LM6125 series buffers contain current limit and thermal shutdown to protect against fault conditions.
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4
AC Electrical Characteristics
(Continued)
Note 5: For operation at elevated temperature, these devices must be derated based on a thermal resistance of
JA
and T
J
max, T
J
= T
A
+
JA
P
D
.
JC
for the
LM6125H and LM6225H is 17°C/W. The thermal impedance
JA
of the device in the N package is 40°C/W when soldered directly to a printed circuit board, and the
heat-sinking pins (pins 3, 4, 5, 10, 11, and 12) are connected to 2 square inches of 2 oz. copper. When installed in a socket, the thermal impedance
JA
of the N pack-
age is 60°C/W.
Note 6: Limits are guaranteed by testing or correlation.
Note 7: The input is biased to +2.5V, and V
IN
swings V
PP
about this value. The input swing is 2 V
PP
at all temperatures except for the A
V
3 test at -55°C where it
is reduced to 1.5 V
PP
.
Note 8: The Error Flag is set (low) during current limit or thermal fault detection in addition to being set by the Shutdown pin. It is an open-collector output which re-
quires an external pullup resistor.
Note 9: Slew rate is measured with a
±
11V input pulse and 50
source impedance at 25°C. Since voltage gain is typically 0.9 driving a 50
load, the output swing
will be approximately
±
10V. Slew rate is calculated for transitions between
±
5V levels on both rising and falling edges. A high speed measurement is done to minimize
device heating. For slew rate versus junction temperature see typical performance curves. The input pulse amplitude should be reduced to
±
10V for measurements
at temperature extremes. For accurate measurements, the input slew rate should be at least 1700 V/µs.
Note 10: The test circuit consists of the human body model of 120 pF in series with 1500
.
Note 11: A military RETS specification is available on request. At the time of printing, the LM6125H/883 RETS spec complied with the Boldface limits in this column.
The LM6125H/883 may also be procured as Standard Military Drawing specification #5962-9081501MXX.
Typical Performance Characteristics
T
A
= 25°C, V
S
=
±
15V unless otherwise specified
Frequency Response
DS009222-9
Frequency Response
DS009222-10
Slew Rate vs Temperature
DS009222-11
Overshoot vs Capacitive Load
DS009222-12
Large Signal Response
(R
L
= 1 k
)
DS009222-13
Large Signal Response
(R
L
= 50
)
DS009222-14
Supply Current
DS009222-15
-3 dB Bandwidth
DS009222-16
Slew Rate
DS009222-17
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5
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