FEATURES
s
s
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LT1795
Dual 500mA/50MHz
Current Feedback Line Driver
Amplifier
DESCRIPTIO
The LT
®
1795 is a dual current feedback amplifier with high
output current and excellent large signal characteristics.
The combination of high slew rate, 500mA output drive
and up to
±15V
operation enables the device to deliver
significant power at frequencies in the 1MHz to 2MHz
range. Short-circuit protection and thermal shutdown
insure the device’s ruggedness. The LT1795 is stable with
large capacitive loads and can easily supply the large
currents required by the capacitive loading. A shutdown
feature switches the device into a high impedance, low
current mode, reducing power dissipation when the de-
vice is not in use. For lower bandwidth applications, the
supply current can be reduced with a single external
resistor.
The LT1795 comes in the very small, thermally enhanced,
20-lead TSSOP package for maximum port density in line
driver applications.
, LTC and LT are registered trademarks of Linear Technology Corporation.
s
500mA Output Drive Current
50MHz Bandwidth, A
V
= 2, R
L
= 25
Ω
900V/
µ
s Slew Rate, A
V
= 2, R
L
= 25
Ω
Low Distortion: –75dBc at 1MHz
High Input Impedance, 10MΩ
Wide Supply Range,
±5V
to
±15V
Full Rate, Downstream ADSL Supported
Low Power Shutdown Mode
Power Saving Adjustable Supply Current
Stable with C
L
= 10,000pF
Power Enhanced Small Footprint Packages
TSSOP-20, S0-20 Wide
Available in a 20-Lead TSSOP Package
APPLICATIO S
s
s
s
s
s
ADSL HDSL2, G.lite Drivers
Buffers
Test Equipment Amplifiers
Video Amplifiers
Cable Drivers
TYPICAL APPLICATION
Low Loss, High Power Central Office ADSL Line Driver
V
+
+IN
+
1/2
LT1795
12.5Ω
–
1k
1:2*
165Ω
1k
100Ω
–
1/2
LT1795
–IN
12.5Ω
+
V
–
1795 TA01
* MIDCOM 50215 OR EQUIVALENT
U
U
U
1795fa
1
LT1795
ABSOLUTE
AXI U RATI GS
Supply Voltage ......................................................
±18V
Input Current ......................................................
±15mA
Output Short-Circuit Duration (Note 2) ............ Indefinite
Operating Temperature Range ................ – 40°C to 85°C
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
–
1
20 V
–
ORDER PART
NUMBER
LT1795CFE
LT1795IFE
NC 2
–IN 3
+IN 4
SHDN 5
SHDNREF 6
+IN 7
–IN 8
NC 9
V
–
10
19 NC
18 OUT
17 V
+
16 COMP
15 COMP
14 V
+
13 OUT
12 NC
11
V
–
FE PACKAGE
20-LEAD PLASTIC TSSOP
T
JMAX
= 150° C,
θ
JA
= 40°C/W (Note 4)
UNDERSIDE METAL INTERNALLY CONNECTED TO V
–
(PCB CONNECTION OPTIONAL)
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
The
q
denotes the specifications which apply over the full specified temperature range, otherwise specifications are at T
A
= 25°C.
V
CM
= 0V,
±5V ≤
V
S
≤ ±15V,
pulse tested, V
SHDN
= 2.5V, V
SHDNREF
= 0V unless otherwise noted. (Note 3)
SYMBOL
V
OS
PARAMETER
Input Offset Voltage
q
CONDITIONS
Input Offset Voltage Matching
q
Input Offset Voltage Drift
I
IN+
Noninverting Input Current
Noninverting Input Current Matching
q
I
IN–
Inverting Input Current
q
Inverting Input Current Matching
q
e
n
+ i
n
– i
n
Input Noise Voltage Density
Input Noise Current Density
Input Noise Current Density
f = 10kHz, R
F
=1k, R
G
= 10Ω, R
S
= 0Ω
f = 10kHz, R
F
=1k, R
G
= 10Ω, R
S
= 10kΩ
f = 10kHz, R
F
=1k, R
G
= 10Ω, R
S
= 10kΩ
2
U
U
W
W W
U
W
(Note 1)
Specified Temperature Range (Note 3) ... – 40°C to 85°C
Junction Temperature ........................................... 150°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
TOP VIEW
COMP 1
V
+
2
OUT 3
V
–
4
V
–
5
V
–
6
V
–
7
–IN 8
+IN 9
SHDN 10
20 COMP
19 V
+
18 OUT
17 V
–
16 V
–
15 V
–
14 V
–
13 –IN
12 +IN
11 SHDNREF
ORDER PART
NUMBER
LT1795CSW
LT1795ISW
S PACKAGE
20-LEAD PLASTIC SW
T
JMAX
= 150° C,
θ
JA
≈
40°C/W (Note 4)
MIN
TYP
±3
±4.5
±1
±1.5
10
±2
±8
±0.5
±1.5
±10
±20
±10
±20
3.6
2
30
MAX
±13
±17
±3.5
±5.0
±5
±20
±2
±7
±70
±100
±30
±50
UNITS
mV
mV
mV
mV
µV/°C
µA
µA
µA
µA
µA
µA
µA
µA
nV/√Hz
pA/√Hz
pA/√Hz
1795fa
q
q
LT1795
ELECTRICAL CHARACTERISTICS
The
q
denotes the specifications which apply over the full specified temperature range, otherwise specifications are at T
A
= 25°C.
V
CM
= 0V,
±5V ≤
V
S
≤ ±15V,
pulse tested, V
SHDN
= 2.5V, V
SHDNREF
= 0V unless otherwise noted. (Note 3)
SYMBOL
R
IN+
C
IN+
PARAMETER
Input Resistance
Input Capacitance
Input Voltage Range (Note 5)
CMRR
Common Mode Rejection Ratio
Inverting Input Current
Common Mode Rejection
PSRR
Power Supply Rejection Ratio
Noninverting Input Current
Power Supply Rejection
Inverting Input Current
Power Supply Rejection
A
V
R
OL
V
OUT
Large-Signal Voltage Gain
Transresistance,
∆V
OUT
/∆I
IN –
Maximum Output Voltage Swing
CONDITIONS
V
IN
=
±12V,
V
S
=
±15V
V =
±2V,
V
S
=
±5V
V
IN
=
±15V
V
S
=
±15V
V
S
=
±5V
V
S
=
±15V,
V
CM
=
±12V
V
S
=
±5V,
V
CM
=
±2V
V
S
=
±15V,
V
CM
=
±12V
V
S
=
±5V,
V
CM
=
±2V
V
S
=
±5V
to
±15V
V
S
=
±5V
to
±15V
V
S
=
±5V
to
±15V
V
S
=
±15V,
V
OUT
=
±10V,
R
L
= 25Ω
V
S
=
±5V,
V
OUT
=
±2V,
R
L
= 12Ω
V
S
=
±15V,
V
OUT
=
±10V,
R
L
= 25Ω
V
S
=
±5V,
V
OUT
=
±2V,
R
L
= 12Ω
V
S
=
±15V,
R
L
= 25Ω
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
MIN
1.5
0.5
±12
±2
55
50
TYP
10
5
2
±13.5
±3.5
62
60
1
1
MAX
UNITS
MΩ
MΩ
pF
V
V
dB
dB
10
10
500
5
µA/V
µA/V
dB
nA/V
µA/V
dB
dB
kΩ
kΩ
V
V
V
V
A
60
77
30
1
55
55
75
75
±11.5
±10.0
±2.5
±2.0
0.5
68
68
200
200
±12.5
±11.5
±3
±3
1
29
34
42
20
25
200
200
V
S
=
±5V,
R
L
= 12Ω
q
I
OUT
I
S
Maximum Output Current
Supply Current Per Amplifier
Supply Current Per Amplifier,
R
SHDN
= 51k, (Note 6)
Positive Supply Current, Shutdown
Output Leakage Current, Shutdown
Channel Separation
V
S
=
±15V,
R
L
= 1Ω
V
S
=
±15V,
V
SHDN
= 2.5V
q
q
mA
mA
mA
mA
µA
µA
dB
dBc
V/µs
V/µs
MHz
MHz
V
S
=
±15V
q
15
q
V
S
=
±15V,
V
SHDN
= 0.4V
V
S
=
±15V,
V
SHDN
= 0.4V
V
S
=
±15V,
V
OUT
=
±10V,
R
L
= 25Ω
f = 1MHz, V
O
= 20V
P-P
, R
L
= 50, A
V
= 2
A
V
= 4, R
L
= 400Ω
A
V
= 4, R
L
= 25Ω
A
V
= 2, V
S
=
±15V,
Peaking
≤
1.5dB
R
F
= R
G
= 910Ω, R
L
= 100Ω
A
V
= 2, V
S
=
±15V,
Peaking
≤
1.5dB
R
F
= R
G
= 820Ω, R
L
= 25Ω
1
1
80
110
–75
400
900
900
65
50
HD
2
, HD
3
SR
BW
2nd and 3rd Harmonic Distortion
Differential Mode
Slew Rate (Note 7)
Slew Rate
Small-Signal BW
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Applies to short-circuits to ground only. A short-circuit between
the output and either supply may permanently damage the part when
operated on supplies greater than
±10V.
Note 3:
The LT1795C is guaranteed to meet specified performance from
0°C to 70°C and is designed, characterized and expected to meet these
extended temperature limits, but is not tested at – 40°C and 85°C. The
LT1795I is guaranteed to meet the extended temperature limits.
Note 4:
Thermal resistance varies depending upon the amount of PC board
metal attached to the device. If the maximum dissipation of the package is
exceeded, the device will go into thermal shutdown and be protected.
Note 5:
Guaranteed by the CMRR tests.
Note 6:
R
SHDN
is connected between the SHDN pin and V
+
.
Note 7:
Slew rate is measured at
±5V
on a
±10V
output signal while
operating on
±15V
supplies with R
F
= 1k, R
G
= 333Ω (A
V
= +4) and
R
L
= 400Ω.
1795fa
3
LT1795
SMALL-SIGNAL BANDWIDTH
R
SD
= 0Ω, I
S
= 30mA per Amplifer, V
S
=
±15V,
Peaking
≤
1dB, R
L
= 25Ω
A
V
–1
1
2
10
R
F
976
1.15k
976
649
R
G
976
—
976
72
–3dB BW
(MHz)
44
53
48
46
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Ambient
Temperature
40
V
+
OUTPUT SATURATION VOLTAGE (V)
SUPPLY CURRENT PER AMPLIFIER (mA)
35
30
25
20
15
10
5
–1
–2
–3
–4
OUTPUT SHORT-CIRCUIT CURRENT (A)
V
S
=
±15V
A
V
= 1
R
L
=
∞
R
SD
= 0Ω
R
SD
= 51kΩ
0
–50 –25
50
25
75
0
TEMPERATURE (°C)
SHDN Pin Current vs Voltage
0.6
V
S
=
±15V
V
SHDNREF
= 0V
–40
–50
DISTORTION (dBc)
–60
–70
CURRENT INTO SHDN PIN (mA)
0.5
0.4
0.3
0.2
0.1
0
DISTORTION (dBc)
0
1
2
3
4
VOLTAGE APPLIED AT SHDN PIN (V)
4
U W
U
U
W
R
SD
= 51kΩ, I
S
= 15mA per Amplifer, V
S
=
±15V,
Peaking
≤
1dB, R
L
= 25Ω
A
V
–1
1
2
10
R
F
976
1.15k
976
649
R
G
976
—
976
72
–3dB BW
(MHz)
30
32
32
27
Output Saturation Voltage vs
Junction Temperature
V
S
=
±15V
Output Short-Circuit Current vs
Junction Temperature
2.0
V
S
=
±15V
1.8
1.6
1.4
SOURCING
1.2
SINKING
1.0
0.8
0.6
–50 –25
R
L
= 2k
R
L
= 25Ω
4
3
2
1
R
L
= 2k
25 50
0
75
TEMPERATURE (°C)
100
125
R
L
= 25Ω
100
125
V
–
–50 –25
50
25
75
0
TEMPERATURE (°C)
100
125
LT1795
G01
LT1795 G02
LT1795
G03
Second Harmonic Distortion vs
Frequency
–40
A
V
= 2 DIFFERENTIAL
V
OUT
= 20V
P-P
V
S
=
±15V
R
LOAD
= 50Ω
I
Q
PER AMPLIFIER
I
Q
= 5mA
I
Q
= 10mA
–80
–90
–100
10k
I
Q
= 15mA
I
Q
= 20mA
100k
FREQUENCY (Hz)
1M
LT1795 G05
Third Harmonic Distortion vs
Frequency
A
V
= 2 DIFFERENTIAL
V
OUT
= 20V
P-P
V
S
=
±15V
R
LOAD
= 50Ω
I
Q
PER AMPLIFIER
–50
–60
–70
–80
–90
I
Q
= 5mA
I
Q
= 10mA
I
Q
= 20mA
I
Q
= 15mA
–100
10k
100k
FREQUENCY (Hz)
1M
LT1795 G06
5
1795 G04
1795fa
LT1795
TYPICAL PERFOR A CE CHARACTERISTICS
Second Harmonic Distortion vs
Frequency
–40
–50
A
V
= 10 DIFFERENTIAL
V
OUT
= 20V
P-P
V
S
=
±15V
R
LOAD
= 50Ω
I
Q
PER AMPLIFIER
I
Q
= 20mA
–40
–50
DISTORTION (dBc)
–60
–70
–80
–90
–100
10k
A
V
= 10 DIFFERENTIAL
V
OUT
= 20V
P-P
V
S
=
±15V
R
LOAD
= 50Ω
I
Q
PER AMPLIFIER
I
Q
= 5mA
I
Q
= 10mA
I
Q
= 20mA
I
Q
= 15mA
–100
10k
100k
FREQUENCY (Hz)
1M
LT1795 G07
DISTORTION (dBc)
DISTORTION (dBc)
–60
–70
–80
I
Q
= 15mA
–90
I
Q
= 5mA
Third Harmonic Distortion vs
Frequency
–40
–50
DISTORTION (dBc)
–40
–60
–70
DISTORTION (dBc)
DISTORTION (dBc)
A
V
= 2 DIFFERENTIAL
V
OUT
= 20V
P-P
V
S
=
±12V
R
LOAD
= 50Ω
I
Q
PER AMPLIFIER
I
Q
= 5mA
I
Q
= 20mA
–80
I
Q
= 15mA
–90
I
Q
= 10mA
–100
10k
100k
FREQUENCY (Hz)
1M
LT1795 G10
Second Harmonic Distortion vs
Frequency
–40
–50
DISTORTION (dBc)
–60
–70
I
Q
= 5mA
–80
–90
–100
10k
I
Q
= 20mA
I
Q
= 10mA
I
Q
= 15mA
A
V
= 2 DIFFERENTIAL
V
OUT
= 4V
P-P
V
S
=
±12V
R
LOAD
= 50Ω
I
Q
PER AMPLIFIER
–40
–50
DISTORTION (dBc)
–60
–70
–80
–90
DISTORTION (dBc)
100k
FREQUENCY (Hz)
U W
I
Q
= 10mA
LT1795 G13
Third Harmonic Distortion vs
Frequency
–40
–50
–60
–70
Second Harmonic Distortion vs
Frequency
A
V
= 2 DIFFERENTIAL
V
OUT
= 20V
P-P
V
S
=
±12V
R
LOAD
= 50Ω
I
Q
PER AMPLIFIER
I
Q
= 5mA
I
Q
= 10mA
–80
–90
–100
10k
I
Q
= 15mA
I
Q
= 20mA
100k
FREQUENCY (Hz)
1M
LT1795 G09
100k
FREQUENCY (Hz)
1M
LT1795 G08
Second Harmonic Distortion vs
Frequency
–40
A
V
= 10 DIFFERENTIAL
V
OUT
= 20V
P-P
V
S
=
±12V
R
LOAD
= 50Ω
I
Q
PER AMPLIFIER
Third Harmonic Distortion vs
Frequency
A
V
= 10 DIFFERENTIAL
V
OUT
= 20V
P-P
V
S
=
±12V
R
LOAD
= 50Ω
I
Q
PER AMPLIFIER
I
Q
= 5mA
–70
–80
–90
–100
10k
I
Q
= 10mA
I
Q
= 15mA
100k
FREQUENCY (Hz)
1M
LT1795 G12
–50
–60
–70
–80
–90
–50
–60
I
Q
= 20mA
I
Q
= 10mA
I
Q
= 15mA
I
Q
= 5mA
I
Q
= 20mA
–100
10k
100k
FREQUENCY (Hz)
1M
LT1795 G11
Third Harmonic Distortion vs
Frequency
–40
A
V
= 2 DIFFERENTIAL
V
OUT
= 4V
P-P
V
S
=
±12V
R
LOAD
= 50Ω
I
Q
PER AMPLIFIER
Second Harmonic Distortion vs
Frequency
A
V
= 10 DIFFERENTIAL
V
OUT
= 4V
P-P
V
S
=
±12V
R
LOAD
= 50Ω
I
Q
PER AMPLIFIER
I
Q
= 10mA
I
Q
= 5mA
I
Q
= 20mA
I
Q
= 15mA
I
Q
= 5mA
–50
–60
–70
–80
–90
I
Q
= 10mA
I
Q
= 15mA
I
Q
= 20mA
1M
–100
10k
100k
FREQUENCY (Hz)
1M
LT1795 G14
–100
10k
100k
FREQUENCY (Hz)
1M
LT1795 G15
1795fa
5
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