LINER LT1206CR

LT1206
250mA/60MHz Current
Feedback Amplifier
FEATURES
DESCRIPTION
■
The LT®1206 is a current feedback amplifier with high
output current drive capability and excellent video characteristics. The LT1206 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 dissipation when the device is not in use. For
lower bandwidth applications, the supply current can be
reduced with a single external resistor. The low differential
gain and phase, wide bandwidth, and the 250mA minimum output current drive make the LT1206 well suited
to drive multiple cables in video systems.
■
■
■
■
■
■
■
■
■
■
250mA Minimum Output Drive Current
60MHz Bandwidth, AV = 2, RL = 100Ω
900V/µs Slew Rate, AV = 2, RL = 50Ω
0.02% Differential Gain, AV = 2, RL = 30Ω
0.17° Differential Phase, AV = 2, RL = 30Ω
High Input Impedance, 10MΩ
Wide Supply Range, ±5V to ±15V
Shutdown Mode: IS < 200µA
Adjustable Supply Current
Stable with CL = 10,000p
Available in 8-Pin DIP and SO and 7-Pin DD and
TO-220 Packages
The LT1206 is manufactured on Linear Technology’s
proprietary complementary bipolar process.
APPLICATIONS
■
■
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■
■
Video Amplifiers
Cable Drivers
RGB Amplifiers
Test Equipment Amplifiers
Buffers
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Noninverting Amplifier with Shutdown
Large-Signal Response, CL = 10,000pF
15V
VIN
+
VOUT
LT1206 COMP
CCOMP
– S/D**
0.01µF*
–15V
RF
15V
RG
5V
24k
*OPTIONAL, USE WITH CAPACITIVE LOADS
**GROUND SHUTDOWN PIN FOR
NORMAL OPERATION
ENABLE
74C906
LT1206 • TA01
VS = ±15V
RL = RG = 3k
RL = ∞
500ns/DIV
1206 TA02
1206fa
1
LT1206
ABSOLUTE MAXIMUM RATINGS
(Note 1)
Supply Voltage ........................................................±18V
Input Current........................................................±15mA
Output Short-Circuit Duration (Note 2) .........Continuous
Specified Temperature Range (Note 3) ........ 0°C to 70°C
Operating Temperature Range ................. –40°C to 85°C
Junction Temperature ........................................... 150°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
PACKAGE/OERDER INFORMATION
TOP VIEW
TOP VIEW
NC 1
8
V+
–IN 2
7
+IN 3
6
S/D* 4
5
COMP
V+ 1
8
V+
OUT
–IN 2
7
OUT
V–
+IN 3
6
V–
S/D* 4
5
COMP
S8 PACKAGE
8-LEAD PLASTIC SO
θJA = 60°C/W
N8 PACKAGE
8-LEAD PLASTIC DIP
θJA = 100°C/W
ORDER PART NUMBER
ORDER PART NUMBER
S8 PART MARKING
LT1206CN8**
LT1206CS8**
1206
FRONT VIEW
TAB IS
V+
FRONT VIEW
7
6
5
4
3
2
1
OUT
V–
COMP
V+
S/D*
+IN
–IN
OUT
V–
COMP
V+
S/D*
+IN
–IN
7
6
5
4
3
2
1
TAB IS
V+
T7 PACKAGE
7-LEAD PLASTIC TO-220
θJA = 5°C/W
R PACKAGE
7-LEAD PLASTIC DD
θJA = 30°C/W
ORDER PART NUMBER
ORDER PART NUMBER
LT1206CR**
LT1206CT7**
Order Options Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking: http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges. *Ground shutdown pin for normal operation. ** See Note 3.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCM = 0, ±5V ≤ VS ≤ 15V, pulse tested, VS/D = 0V, unless otherwise noted.
SYMBOL
PARAMETER
VOS
Input Offset Voltage
Input Offset Voltage Drift
IIN
+
IIN–
Noninverting Input Current
Inverting Input Current
CONDITIONS
MIN
●
●
●
●
TYP
MAX
UNITS
±3
±10
±15
mV
mV
µV/°C
±8
±25
±60
±100
µA
µA
µA
µA
10
±2
±10
1206fa
2
LT1206
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VCM = 0, ±5V ≤ VS ≤ 15V, pulse tested, VS/D = 0V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
en
Input Noise Voltage Density
f = 10kHz, RF = 1k, RG = 10Ω, RS = 0Ω
3.6
nV/√Hz
+in
Input Noise Current Density
f = 10kHz, RF = 1k, RG = 10Ω, RS = 10k
2
pA/√Hz
–in
Input Noise Current Density
f = 10kHz, RF = 1k, RG = 10Ω, RS = 10k
30
pA/√Hz
RIN
Input Resistance
●
●
1.5
0.5
CIN
Input Capacitance
VIN = ±12V, VS = ±15V
VIN = ±2V, VS = ±5V
VS = ±15V
10
5
2
MΩ
MΩ
pF
VS = ±15V
VS = ±5V
VS = ±15V, VCM = ±12V
VS = ±5V, VCM = ±2V
VS = ±15V, VCM = ±12V
VS = ±5V, VCM = ±2V
VS = ±5V to ±15V
●
●
±12
±2
55
50
±13.5
±3.5
62
60
0.1
0.1
77
V
V
dB
dB
µA/V
µA/V
dB
VS = ±5V to ±15V
●
30
500
nA/V
VS = ±5V to ±15V
●
0.7
5
µA/V
VS = ±15V, VOUT = ±10V, RL = 50Ω
VS = ±5V, VOUT = ±2V, RL = 25Ω
VS = ±15V, VOUT = ±10V, RL = 50Ω
VS = ±5V, VOUT = ±2V, RL = 25Ω
VS = ±15V, RL = 50Ω
●
●
500
1200
dB
dB
kΩ
kΩ
V
V
V
V
mA
20
30
35
17
mA
mA
mA
Input Voltage Range
CMRR
Common Mode Rejection Ratio
PSRR
Inverting Input Current Common Mode
Rejection
Power Supply Rejection Ratio
AV
Noninverting Input Current Power Supply
Rejection
Inverting Input Current Power Supply
Rejection
Large-Signal Voltage Gain
ROL
Transresistance, ΔVOUT/ΔIIN–
VOUT
Maximum Output Voltage Swing
MIN
VS = ±15V, RL = 25Ω
●
●
●
●
●
●
●
●
●
●
60
55
55
100
75
±11.5
±10.0
±2.5
±2.0
250
TYP
MAX
10
10
71
68
260
200
±12.5
±3.0
UNITS
IOUT
Maximum Output Current
RL = 1Ω
IS
Supply Current
VS = ±15V, VS/D = 0V
Supply Current, RS/D = 51k (Note 4)
VS = ±15V
Positive Supply Current, Shutdown
VS = ±15V, VS/D = 15V
●
200
µA
Output Leakage Current, Shutdown
VS = ±15V, VS/D = 15V
●
10
µA
Slew Rate (Note 5)
AV = 2
Differential Gain (Note 6)
SR
BW
●
12
900
V/µs
VS = ±15V, RF = 560Ω, RG = 560Ω, RL = 30Ω
0.02
%
Differential Phase (Note 6)
VS = ±15V, RF = 560Ω, RG = 560Ω, RL = 30Ω
0.17
Deg
Small-Signal Bandwidth
VS = ±15V, Peaking ≤ 0.5dB,
RF = RG = 620Ω, RL = 100Ω
VS = ±15V, Peaking ≤ 0.5dB,
RF = RG = 649Ω, RL = 50Ω
VS = ±15V, Peaking ≤ 0.5dB,
RF = RG = 698Ω, RL = 30Ω
VS = ±15V, Peaking ≤ 0.5dB,
RF = RG = 825Ω, RL = 10Ω
60
MHz
52
MHz
43
MHz
27
MHz
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
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.
400
Note 3: Commercial grade parts are designed to operate over the
temperature range of –40°C to 85°C but are neither tested nor guaranteed
beyond 0°C to 70°C. Industrial grade parts tested over –40°C to 85°C are
available on special request. Consult factory.
Note 4: RS/D is connected between the shutdown pin and ground.
Note 5: Slew rate is measured at ±5V on a ± 10V output signal while
operating on ±15V supplies with RF = 1.5k, RG = 1.5k and RL = 400Ω.
Note 6: NTSC composite video with an output level of 2V.
1206fa
3
LT1206
SMALL-SIGNAL BANDWIDTH
IS = 20mA Typical, Peaking ≤ 0.1dB
AV
RL
RF
RG
–3dB BW
(MHz)
–0.1dB BW
(MHz)
VS = ±5V, RS/D = 0Ω
AV
RL
RF
RG
–3dB BW
(MHz)
–0.1dB BW
(MHz)
VS = ±15V, RS/D = 0Ω
–1
150
30
10
562
649
732
562
649
732
48
34
22
21.4
17
12.5
–1
150
30
10
681
768
887
681
768
887
50
35
24
19.2
17
12.3
1
150
30
10
619
715
806
–
–
–
54
36
22.4
22.3
17.5
11.5
1
150
30
10
768
909
1k
–
–
–
66
37
23
22.4
17.5
12
2
150
30
10
576
649
750
576
649
750
48
35
22.4
20.7
18.1
11.7
2
150
30
10
665
787
931
665
787
931
55
36
22.5
23
18.5
11.8
10
150
30
10
442
511
649
48.7
56.2
71.5
40
31
20
19.2
16.5
10.2
10
150
30
10
487
590
768
536
64.9
84.5
44
33
20.7
20.7
17.5
10.8
–3dB BW
(MHz)
–0.1dB BW
(MHz)
AV
RL
RF
RG
–3dB BW
(MHz)
–0.1dB BW
(MHz)
IS = 10mA Typical, Peaking ≤ 0.1dB
AV
RL
RF
RG
VS = ±5V, RS/D = 10.2k
VS = ±15V, RS/D = 60.4k
–1
150
30
10
576
681
750
576
681
750
35
25
16.4
17
12.5
8.7
–1
150
30
10
634
768
866
634
768
866
41
26.5
17
19.1
14
9.4
1
150
30
10
665
768
845
–
–
–
37
25
16.5
17.5
12.6
8.2
1
150
30
10
768
909
1k
–
–
–
44
28
16.8
18.8
14.4
8.3
2
150
30
10
590
681
768
590
681
768
35
25
16.2
16.8
13.4
8.1
2
150
30
10
649
787
931
649
787
931
40
27
16.5
18.5
14.1
8.1
10
150
30
10
301
392
499
33.2
43.2
54.9
31
23
15
15.6
11.9
7.8
10
150
30
10
301
402
590
33.2
44.2
64.9
33
25
15.3
15.6
13.3
7.4
RG
–3dB BW
(MHz)
–0.1dB BW
(MHz)
AV
RL
RF
RG
–3dB BW
(MHz)
–0.1dB BW
(MHz)
IS = 5mA Typical, Peaking ≤ 0.1dB
AV
RL
RF
VS = ±5V, RS/D = 22.1k
VS = ±15V, RS/D = 121k
–1
150
30
10
604
715
681
604
715
681
21
14.6
10.5
10.5
7.4
6.0
–1
150
30
10
619
787
825
619
787
825
25
15.8
10.5
12.5
8.5
5.4
1
150
30
10
768
866
825
–
–
–
20
14.1
9.8
9.6
6.7
5.1
1
150
30
10
845
1k
1k
–
–
–
23
15.3
10
10.6
7.6
5.2
2
150
30
10
634
750
732
634
750
732
20
14.1
9.6
9.6
7.2
5.1
2
150
30
10
681
845
866
681
845
866
23
15
10
10.2
7.7
5.4
10
150
30
10
100
100
100
11.1
11.1
11.1
16.2
13.4
9.5
5.8
7.0
4.7
10
150
30
10
100
100
100
11.1
11.1
11.1
15.9
13.6
9.6
4.5
6
4.5
1206fa
4
LT1206
TYPICAL PERFORMANCE CHARACTERISTICS
100
RF = 560Ω
60
RF = 680Ω
50
40
RF = 750Ω
30
RF = 1k
20
10
40
FEEDBACK RESISTOR (Ω)
–3dB BANDWIDTH (MHz)
RF = 470Ω
RF = 560Ω
30
RF = 750Ω
20
RF = 1k
RF = 2k
10
1k
FEEDBACK RESISTOR
AV = 2
RL = ∞
VS = ±15V
CCOMP = 0.01µF
10
RF = 1.5k
0
100
0
4
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
4
18
6
14
12
10
8
SUPPLY VOLTAGE (±V)
LT1206 • TPC01
16
Bandwidth and Feedback Resistance
vs Capacitive Load for 5dB Peak
50
70
RF =390Ω
60
RF = 330Ω
50
40
RF = 470Ω
30
RF = 680Ω
20
10
AV = 10
RL = 10Ω
BANDWIDTH
40
30
RF = 560Ω
20
RF = 680Ω
RF = 1k
10
10
1k
FEEDBACK RESISTOR
RF = 1.5k
RF = 1.5k
0
4
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
100
0
0
4
18
6
14
12
10
8
SUPPLY VOLTAGE (±V)
LT1206 • TPC04
16
18
1
Spot Noise Voltage and Current
vs Frequency
100
0.10
0.20
RL = 30Ω
RL = 50Ω
0.10
RL = 15Ω
0.08
DIFFERENTIAL GAIN (%)
RF = RG = 560Ω
AV = 2
N PACKAGE
RF = RG = 560Ω
AV = 2
N PACKAGE
SPOT NOISE (nV/√Hz OR pA/√Hz)
RL = 15Ω
0.06
RL = 30Ω
0.04
RL = 50Ω
0.02
RL = 150Ω
0
7
11
13
9
SUPPLY VOLTAGE (±V)
15
LT1206 • TPC07
–in
10
en
in
RL = 150Ω
0
5
1
10k
LT1206 • TPC06
Differential Gain
vs Supply Voltage
0.50
0.30
10
100
1k
CAPACITIVE LOAD (pF)
LT1206 • TPC05
Differential Phase
vs Supply Voltage
0.40
AV = +2
RL = ∞
VS = ±15V
CCOMP = 0.01µF
–3dB BANDWIDTH (MHz)
– 3dB BANDWIDTH (MHz)
80
100
10k
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
AV = 10
RL = 100Ω
FEEDBACK RESISTOR (Ω)
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
1
10000
LT1206 • TPC03
Bandwidth vs Supply Voltage
100
90
100
10
1000
CAPACITIVE LOAD (pF)
1
18
LT1206 • TPC02
Bandwidth vs Supply Voltage
–3dB BANDWIDTH (MHz)
BANDWIDTH
AV = 2
RL = 10Ω
–3dB BANDWIDTH (MHz)
– 3dB BANDWIDTH (MHz)
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
AV = 2
RL = 100Ω
80
70
100
10k
50
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
90
DIFFERENTIAL PHASE (DEG)
Bandwidth and Feedback Resistance
vs Capacitive Load for 0.5dB Peak
Bandwidth vs Supply Voltage
Bandwidth vs Supply Voltage
5
7
11
13
9
SUPPLY VOLTAGE (±V)
15
LT1206 • TPC08
1
10
100
1k
10k
FREQUENCY (Hz)
100k
LT1206 • TPC09
1206fa
5
LT1206
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Ambient
Temperature, VS = ±5V
Supply Current vs Supply Voltage
24
25
25
TJ = –40˚C
22
RSD = 0Ω
SUPPLY CURRENT (mA)
20
20
TJ = 25˚C
18
16
TJ = 85˚C
14
TJ = 125˚C
AV = 1
RL = ∞
N PACKAGE
15
RSD = 10.2k
10
RSD = 22.1k
5
AV = 1
RL = ∞
N PACKAGE
RSD = 0Ω
20
SUPPLY CURRENT (mA)
VS/D = 0V
SUPPLY CURRENT (mA)
Supply Current vs Ambient
Temperature, VS = ±15V
15
RSD = 60.4k
10
RSD = 121k
5
12
0
–50 –25
10
4
16
14
12
10
8
SUPPLY VOLTAGE (±V)
6
18
50
25
0
75
TEMPERATURE (°C)
Supply Current vs Shutdown Pin
Current
OUTPUT SHORT-CIRCUIT CURRENT (A)
COMMON-MODE RANGE (V)
14
12
10
8
6
4
–1.0
–1.5
–2.0
2.0
1.5
1.0
0.5
2
100
300
400
200
SHUTDOWN PIN CURRENT (µA)
0
V–
–50
500
–25
LT1206 • TPC13
–2
–3
–4
4
RL = 50Ω
2
RL = 2k
1
V–
–50
–25
0.6
SINKING
0.5
0.4
0.3
–50 –25
0
75
25
50
TEMPERATURE (°C)
100
125
LT1206 • TPC16
50
25
75
0
TEMPERATURE (°C)
60
50
100
125
LT1206 • TPC15
Supply Current vs Large-Signal
Output Frequency (No Load)
60
70
RL = 2k
RL = 50Ω
3
SOURCING
0.7
Power Supply Rejection Ratio vs
Frequency
POWER SUPPLY REJECTION (dB)
OUTPUT SATURATION VOLTAGE (V)
–1
125
0.8
LT1206 • TPC14
Output Saturation Voltage vs
Junction Temperature
VS = ±15V
100
0
75
25
50
TEMPERATURE (°C)
0.9
NEGATIVE
RL = 50Ω
VS = ±15V
RF = RG = 1k
50
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
1.0
– 0.5
16
V+
Output Short-Circuit Current vs
Junction Temperature
V+
VS = ±15V
125
100
LT1206 • TPC12
Input Common Mode Limit vs
Junction Temperature
20
18
50
25
0
75
TEMPERATURE (°C)
LT1206 • TPC11
LT1206 • TPC10
0
0
–50 –25
125
100
POSITIVE
40
30
20
AV = 2
RL = ∞
VS = ±15V
VOUT = 20VP-P
40
30
20
10
0
10k
100k
1M
10M
FREQUENCY (Hz)
100M
10
10k
100k
1M
10M
FREQUENCY (Hz)
LT1206 • TPC17
LT1206 • TPC18
1206fa
6
LT1206
TYPICAL PERFORMANCE CHARACTERISTICS
Output Impedance in Shutdown vs
Frequency
Output Impedance vs Frequency
–30
100k
VS = ±15V
IO = 0mA
AV = 1
RF = 1k
VS = ±15V
RS/D = 0Ω
1
0.1
VS = ±15V
VO = 2VP-P
–40
2nd
RL = 10Ω
10k
DISTORTION (dBc)
RS/D = 121k
10
OUTPUT IMPEDANCE (Ω)
OUTPUT IMPEDANCE (Ω)
100
2nd and 3rd Harmonic Distortion
vs Frequency
1k
–50
3rd
2nd
–60
–70
RL = 30Ω
100
3rd
–80
10M
1M
100M
–90
10
100k
1M
FREQUENCY (Hz)
10M
100M
1
3
2
4 5
FREQUENCY (MHz)
FREQUENCY (Hz)
LT1206 • TPC19
Test Circuit for 3rd Order Intercept
VS = ±15V
RL = 50Ω
RF = 590Ω
RG = 64.9Ω
50
6 7 8 9 10
LT1206 • TPC21
LT1206 • TPC20
3rd Order Intercept vs Frequency
60
3rd ORDER INTERCEPT (dBm)
0.01
100k
+
PO
LT1206
–
40
590Ω
30
50Ω
65Ω
MEASURE INTERCEPT AT PO
LT1206 • TPC23
20
10
0
5
10
15
20
FREQUENCY (MHz)
25
30
LT1206 • TPC22
1206fa
7
LT1206
SIMPLIFIED SCHEMATIC
V+
TO ALL
CURRENT
SOURCES
Q5
Q10
Q2
Q18
Q17
D1
Q6
Q1
Q11
Q15
Q9
V–
1.25k
+IN
CC
–IN
V–
50Ω
COMP
RC
OUTPUT
V+
SHUTDOWN
V+
Q12
Q3
Q8
Q16
Q14
D2
Q4
Q13
Q7
V–
LT1206 • SS
APPLICATIONS INFORMATION
The LT1206 is a current feedback amplifier with high output
current drive capability. The device is stable with large
capacitive loads and can easily supply the high currents
required by capacitive loads. The amplifier will drive low
impedance loads such as cables with excellent linearity
at high frequencies.
Feedback Resistor Selection
The optimum value for the feedback resistors is a function
of the operating conditions of the device, the load impedance and the desired flatness of response. The Typical AC
Performance tables give the values which result in the
highest 0.1dB and 0.5dB bandwidths for various resistive
loads and operating conditions. If this level of flatness is
not required, a higher bandwidth can be obtained by use
of a lower feedback resistor. The characteristic curves of
Bandwidth vs Supply Voltage indicate feedback resistors
for peaking up to 5dB. These curves use a solid line when
the response has less than 0.5dB of peaking and a dashed
line when the response has 0.5dB to 5dB of peaking. The
curves stop where the response has more than 5dB of
peaking.
For resistive loads, the COMP pin should be left open (see
section on capacitive loads).
Capacitive Loads
The LT1206 includes an optional compensation network
for driving capacitive loads. This network eliminates most
of the output stage peaking associated with capacitive
loads, allowing the frequency response to be flattened.
Figure 1 shows the effect of the network on a 200pF load.
Without the optional compensation, there is a 5dB peak
at 40MHz caused by the effect of the capacitance on the
output stage. Adding a 0.01µF bypass capacitor between the
output and the COMP pins connects the compensation and
completely eliminates the peaking. A lower value feedback
resistor can now be used, resulting in a response which
1206fa
8
LT1206
APPLICATIONS INFORMATION
12
VS = ±15V
10
RF = 1.2k
COMPENSATION
VOLTAGE GAIN (dB)
8
6
4
RF = 2k
NO COMPENSATION
2
0
RF = 2k
COMPENSATION
–2
–4
–6
–8
1
10
FREQUENCY (MHz)
100
LT1206 • F01
Figure 1
is flat to 0.35dB to 30MHz. The network has the greatest
effect for CL in the range of 0pF to 1000pF. The graph of
Maximum Capacitive Load vs Feedback Resistor can be
used to select the appropriate value of feedback resistor.
The values shown are for 0.5dB and 5dB peaking at a gain
of 2 with no resistive load. This is a worst case condition,
as the amplifier is more stable at higher gains and with
some resistive load in parallel with the capacitance. Also
shown is the – 3dB bandwidth with the suggested feedback
resistor vs the load capacitance.
capacitor and the supply current is typically 100µA. The
shutdown pin is referenced to the positive supply through
an internal bias circuit (see the simplified schematic). An
easy way to force shutdown is to use open drain (collector) logic. The circuit shown in Figure 2 uses a 74C904
buffer to interface between 5V logic and the LT1206. The
switching time between the active and shutdown states
is less than 1µs. A 24k pull-up resistor speeds up the
turn-off time and insures that the LT1206 is completely
turned off. Because the pin is referenced to the positive
supply, the logic used should have a breakdown voltage
of greater than the positive supply voltage. No other
circuitry is necessary as the internal circuit limits the
shutdown pin current to about 500µA. Figure 3 shows
the resulting waveforms.
15V
VOUT
LT1206
– S/D
–15V
RF
15V
5V
Although the optional compensation works well with capacitive loads, it simply reduces the bandwidth when it is
connected with resistive loads. For instance, with a 30Ω
load, the bandwidth drops from 55MHz to 35MHz when the
compensation is connected. Hence, the compensation was
made optional. To disconnect the optional compensation,
leave the COMP pin open.
Shutdown/Current Set
+
VIN
RG
24k
ENABLE
LT1206 • F02
74C906
Figure 2. Shutdown Interface
VOUT
If the shutdown feature is not used, the SHUTDOWN pin
must be connected to ground or V –.
The shutdown pin can be used to either turn off the biasing for the amplifier, reducing the quiescent current to
less than 200µA, or to control the quiescent current in
normal operation.
The total bias current in the LT1206 is controlled by the current flowing out of the shutdown pin. When the shutdown
pin is open or driven to the positive supply, the part is shut
down. In the shutdown mode, the output looks like a 40pF
ENABLE
AV = 1
RF = 825Ω
RL = 50Ω
RPU = 24k
VIN = 1VP-P
1µs/DIV
1206 F03
Figure 3. Shutdown Operation
1206fa
9
LT1206
APPLICATIONS INFORMATION
For applications where the full bandwidth of the amplifier
is not required, the quiescent current of the device may be
reduced by connecting a resistor from the shutdown pin
to ground. The quiescent current will be approximately 40
times the current in the shutdown pin. The voltage across
the resistor in this condition is V + – 3VBE. For example, a
60k resistor will set the quiescent supply current to 10mA
with VS = ±15V.
The photos (Figures 4a and 4b) show the effect of reducing
the quiescent supply current on the large-signal response.
The quiescent current can be reduced to 5mA in the inverting configuration without much change in response. In
noninverting mode, however, the slew rate is reduced as
the quiescent current is reduced.
RF = 750Ω
RL = 50Ω
IQ = 5mA, 10mA, 20mA
VS = ±15V
50ns/DIV
Slew Rate
Unlike a traditional op amp, the slew rate of a current
feedback amplifier is not independent of the amplifier gain
configuration. There are slew rate limitations in both the
input stage and the output stage. In the inverting mode,
and for higher gains in the noninverting mode, the signal
amplitude on the input pins is small and the overall slew
rate is that of the output stage. The input stage slew rate
is related to the quiescent current and will be reduced as
the supply current is reduced. The output slew rate is set
by the value of the feedback resistors and the internal
capacitance. Larger feedback resistors will reduce the slew
rate as will lower supply voltages, similar to the way the
bandwidth is reduced. The photos (Figures 5a, 5b and 5c)
show the large-signal response of the LT1206 for various
gain configurations. The slew rate varies from 860V/µs
for a gain of 1, to 1400V/µs for a gain of – 1.
1206 F04a
Figure 4a. Large-Signal Response vs IQ, AV = –1
RF = 825Ω
RL = 50Ω
VS = ±15V
20ns/DIV
1206 F05a
Figure 5a. Large-Signal Response, AV = 1
RF = 750Ω
RL = 50Ω
IQ = 5mA, 10mA, 20mA
VS = ±15V
50ns/DIV
1206 F04b
Figure 4b. Large-Signal Response vs IQ, AV = 2
RF = RG = 750Ω
RL = 50Ω
VS = ±15V
20ns/DIV
1206 F05b
Figure 5a. Large-Signal Response, AV = –1
1206fa
10
LT1206
APPLICATIONS INFORMATION
the maximum allowable input voltage. To allow for some
margin, it is recommended that the input signal be less
than ±5V when the device is shut down.
Capacitance on the Inverting Input
RF = 750Ω
RL = 50Ω
20ns/DIV
1206 F05c
Figure 5c. Large-Signal Response, AV = 2
When the LT1206 is used to drive capacitive loads, the
available output current can limit the overall slew rate. In the
fastest configuration, the LT1206 is capable of a slew rate
of over 1V/ns. The current required to slew a capacitor at
this rate is 1mA per picofarad of capacitance, so 10,000pF
would require 10A! The photo (Figure 6) shows the large
signal behavior with CL = 10,000pF. The slew rate is about
60V/µs, determined by the current limit of 600mA.
Current feedback amplifiers require resistive feedback from
the output to the inverting input for stable operation. Take
care to minimize the stray capacitance between the output
and the inverting input. Capacitance on the inverting input
to ground will cause peaking in the frequency response
(and overshoot in the transient response), but it does not
degrade the stability of the amplifier.
Power Supplies
The LT1206 will operate from single or split supplies from
± 5V (10V total) to ±15V (30V total). It is not necessary to
use equal value split supplies, however the offset voltage
and inverting input bias current will change. The offset
voltage changes about 500µV per volt of supply mismatch.
The inverting bias current can change as much as 5µA
per volt of supply mismatch, though typically the change
is less than 0.5µA per volt.
Thermal Considerations
VS = ±15V
RL = RG = 3k
RL = ∞
500ns/DIV
1206 TA02
Figure 6. Large-Signal Response, CL = 10,000pF
Differential Input Signal Swing
The differential input swing is limited to about ± 6V by
an ESD protection device connected between the inputs.
In normal operation, the differential voltage between the
input pins is small, so this clamp has no effect; however,
in the shutdown mode the differential swing can be the
same as the input swing. The clamp voltage will then set
The LT1206 contains a thermal shutdown feature which
protects against excessive internal (junction) temperature.
If the junction temperature of the device exceeds the protection threshold, the device will begin cycling between
normal operation and an off state. The cycling is not
harmful to the part. The thermal cycling occurs at a slow
rate, typically 10ms to several seconds, which depends
on the power dissipation and the thermal time constants
of the package and heat sinking. Raising the ambient
temperature until the device begins thermal shutdown
gives a good indication of how much margin there is in
the thermal design.
For surface mount devices heat sinking is accomplished
by using the heat spreading capabilities of the PC board
and its copper traces. Experiments have shown that the
heat spreading copper layer does not need to be electrically connected to the tab of the device. The PCB material
can be very effective at transmitting heat between the pad
area attached to the tab of the device, and a ground or
1206fa
11
LT1206
APPLICATIONS INFORMATION
power plane layer either inside or on the opposite side of
the board. Although the actual thermal resistance of the
PCB material is high, the length/area ratio of the thermal
resistance between the layer is small. Copper board stiffeners and plated through holes can also be used to spread
the heat generated by the device.
Tables 1 and 2 list thermal resistance for each package.
For the TO-220 package, thermal resistance is given for
junction-to-case only since this package is usually mounted
to a heat sink. Measured values of thermal resistance for
several different board sizes and copper areas are listed
for each surface mount package. All measurements were
taken in still air on 3/32" FR-4 board with 1oz copper. This
data can be used as a rough guideline in estimating thermal
resistance. The thermal resistance for each application will
be affected by thermal interactions with other components
as well as board size and shape.
Table 1. R Package, 7-Lead DD
COPPER AREA
THERMAL RESISTANCE
TOPSIDE*
BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT)
2500 sq. mm 2500 sq. mm 2500 sq. mm
1000 sq. mm 2500 sq. mm 2500 sq. mm
125 sq. mm 2500 sq. mm 2500 sq. mm
*Tab of device attached to topside copper
Y Package, 7-Lead TO-220
Thermal Resistance (Junction-to-Case) = 5°C/W
N8 Package, 8-Lead DIP
Thermal Resistance (Junction-to-Ambient) = 100°C/W
The junction temperature can be calculated from the
equation:
TJ = (PD × θJA) + TA
where:
TJ = Junction Temperature
TA = Ambient Temperature
PD = Device Dissipation
θJA = Thermal Resistance (Junction-to Ambient)
As an example, calculate the junction temperature for the
circuit in Figure 7 for the N8, S8, and R packages assuming
a 70°C ambient temperature.
15V
I
39mA
+
330Ω
12V
LT1206
S/D
–
f = 2MHz
0.01µF
2k
25°C/W
27°C/W
35°C/W
–15V
–12V
300pF
2k
LT1206 • F07
Figure 7. Thermal Calculation Example
Table 2. S8 Package, 8-Lead Plastic SO
COPPER AREA
THERMAL RESISTANCE
TOPSIDE*
BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT)
2500 sq. mm 2500 sq. mm 2500 sq. mm
1000 sq. mm 2500 sq. mm 2500 sq. mm
225 sq. mm 2500 sq. mm 2500 sq. mm
100 sq. mm 2500 sq. mm 2500 sq. mm
100 sq. mm 1000 sq. mm 2500 sq. mm
100 sq. mm 225 sq. mm 2500 sq. mm
100 sq. mm 100 sq. mm 2500 sq. mm
*Pins 1 and 2 attached to topside copper
Calculating Junction Temperature
60°C/W
62°C/W
65°C/W
69°C/W
73°C/W
80°C/W
83°C/W
The device dissipation can be found by measuring the
supply currents, calculating the total dissipation, and
then subtracting the dissipation in the load and feedback
network.
PD = (39mA × 30V) – (12V)2/(2k||2k) = 1.03W
Then:
TJ = (1.03W × 100°C/W) + 70°C = 173°C
for the N8 package
TJ = (1.03W × 65°C/W) × + 70°C = 137°C
for the S8 with 225 sq. mm topside heat sinking
TJ = (1.03W × 35°C/W) × + 70°C = 106°C
for the R package with 100 sq. mm topside heat
sinking
Since the Maximum Junction Temperature is 150°C, the
N8 package is clearly unacceptable. Both the S8 and R
packages are usable.
1206fa
12
LT1206
TYPICAL APPLICATIONS
Precision ×10 Hi Current Amplifier
CMOS Logic to Shutdown Interface
15V
+
+
LT1097
LT1206
COMP
– S/D
–
+
OUT
330Ω
24k
LT1206
S/D
0.01µF
–
500pF
LT1206 • TA05
3k
5V
–15V
10k
2N3904
10k
LT1206 • TA03
OUTPUT OFFSET: < 500µV
SLEW RATE: 2V/µs
BANDWIDTH: 4MHz
STABLE WITH CL < 10nF
1k
Low Noise ×10 Buffered Line Driver
15V 1µF
+
+
75Ω
+
1µF
–
+
VIN
+
LT1115
–
Distribution Amplifier
15V 1µF
+
–
OUTPUT
LT1206
S/D
75Ω CABLE
75Ω
RF
75Ω
0.01µF
RL
LT1206 • TA06
RG
–15V
1µF
68pF
75Ω
LT1206
S/D
75Ω
+
VIN
–15V
560Ω
560Ω
909Ω
LT1206 • TA04
100Ω
RL = 32Ω
VO = 5VRMS
THD + NOISE = 0.0009% AT 1kHz
= 0.004% AT 20kHz
SMALL SIGNAL 0.1dB BANDWIDTH = 600kHz
Buffer AV = 1
VIN
+
LT1206
COMP
S/D
–
VOUT
0.01µF*
*OPTIONAL, USE WITH CAPACITIVE LOADS
**VALUE OF RF DEPENDS ON SUPPLY
VOLTAGE AND LOADING. SELECT
FROM TYPICAL AC PERFORMANCE
TABLE OR DETERMINE EMPIRICALLY
RF**
LT1206 • TA07
1206fa
13
LT1206
PACKAGE DESCRIPTION
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
.300 – .325
(7.620 – 8.255)
(
+0.889
8.255
–0.381
.130 ± .005
(3.302 ± 0.127)
.045 – .065
(1.143 – 1.651)
.065
(1.651)
TYP
.008 – .015
(0.203 – 0.381)
+.035
.325 –.015
.400*
(10.160)
MAX
8
7
6
5
1
2
3
4
.255 ± .015*
(6.477 ± 0.381)
)
.120
(3.048) .020
MIN (0.508)
MIN
.018 ± .003
(0.457 ± 0.076)
.100
(2.54)
BSC
N8 1002
NOTE:
1. DIMENSIONS ARE
INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
R Package
7-Lead Plastic DD Pak
(Reference LTC DWG # 05-08-1462)
.256
(6.502)
.060
(1.524)
TYP
.060
(1.524)
.390 – .415
(9.906 – 10.541)
.165 – .180
(4.191 – 4.572)
.045 – .055
(1.143 – 1.397)
15° TYP
.060
(1.524)
.183
(4.648)
+.008
.004 –.004
+0.203
0.102 –0.102
.059
(1.499)
TYP
.330 – .370
(8.382 – 9.398)
(
)
.095 – .115
(2.413 – 2.921)
.075
(1.905)
.300
(7.620)
+.012
.143 –.020
+0.305
3.632 –0.508
(
BOTTOM VIEW OF DD PAK
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
)
.026 – .035
(0.660 – 0.889)
TYP
.050
(1.27)
BSC
.013 – .023
(0.330 – 0.584)
.050 ± .012
(1.270 ± 0.305)
R (DD7) 0502
.420
.080
.420
.276
.350
.325
.205
.565
.565
.320
.090
.050
.035
RECOMMENDED SOLDER PAD LAYOUT
NOTE:
1. DIMENSIONS IN INCH/(MILLIMETER)
2. DRAWING NOT TO SCALE
.090
.050
.035
RECOMMENDED SOLDER PAD LAYOUT
FOR THICKER SOLDER PASTE APPLICATIONS
1206fa
14
LT1206
PACKAGE DESCRIPTION
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 ±.005
.050 BSC
7
8
.245
MIN
6
5
.160 ±.005
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
1
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
× 45°
(0.254 – 0.508)
3
2
4
.053 – .069
(1.346 – 1.752)
.008 – .010
(0.203 – 0.254)
.004 – .010
(0.101 – 0.254)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
.050
(1.270)
BSC
.014 – .019
(0.355 – 0.483)
TYP
NOTE:
1. DIMENSIONS IN
INCHES
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
SO8 0303
T7 Package
7-Lead Plastic TO-220 (Standard)
(Reference LTC DWG # 05-08-1422)
.390 – .415
(9.906 – 10.541)
.165 – .180
(4.191 – 4.572)
.147 – .155
(3.734 – 3.937)
DIA
.045 – .055
(1.143 – 1.397)
.230 – .270
(5.842 – 6.858)
.460 – .500
(11.684 – 12.700)
.570 – .620
(14.478 – 15.748)
.330 – .370
(8.382 – 9.398)
.620
(15.75)
TYP
.700 – .728
(17.780 – 18.491)
.095 – .115
(2.413 – 2.921)
.155 – .195*
(3.937 – 4.953)
SEATING PLANE
.152 – .202
.260 – .320 (3.860 – 5.130)
(6.604 – 8.128)
BSC
.050
(1.27)
.026 – .036
(0.660 – 0.914)
.135 – .165
(3.429 – 4.191)
.013 – .023
(0.330 – 0.584)
*MEASURED AT THE SEATING PLANE
T7 (TO-220) 0801
1206fa
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LT1206
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1010
High Speed Buffer
High Power, High Speed Buffer
LT1207
Dual 250mA Out, 900V/µs, 60MHz Current Feedback Amplifier
Adjustable Supply Current, Shutdown
LT1210
1.1A, 35MHz, 900V/µs Current Feedback Amplifier
Adjustable Supply Current, Shutdown
LT1395
Single 400MHz Current Feedback Amplifier
0.1dB Gain Flatness to 100MHz
LT1815
6.5mA, 220MHz, 1.5V/ns Operational Amplifier with
Programmable Current
S6 Version Features Programmable Supply Current
LT1818
400MHz, 2500V/µs, 9mA Single Operational Amplifier
High Speed, Low Noise, Low Distortion, Low Offset
1206fa
16 Linear Technology Corporation
LT 0307 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 1993