LT1206
250mA/60MHz Current
Feedback Amplifier
Features
n
n
n
n
n
n
n
n
n
n
n
Description
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 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.
The LT1206 is manufactured on Linear Technology’s proprietary complementary bipolar process.
Applications
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Video Amplifiers
n Cable Drivers
n RGB Amplifiers
n Test Equipment Amplifiers
n Buffers
n
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
5V
ENABLE
24k
74C906
1206 TA01
RG
*OPTIONAL, USE WITH CAPACITIVE LOADS
**GROUND SHUTDOWN PIN FOR
NORMAL OPERATION
VS = ±15V
RL = RG = 3k
RL = ∞
500ns/DIV
1206 TA01b
1206fb
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
Pin Configuration
TOP VIEW
TOP VIEW
+
1
8
V+
OUT
–IN 2
7
OUT
V–
+IN 3
6
V–
S/D* 4
5
COMP
NC 1
8
V
–IN 2
7
+IN 3
6
S/D* 4
5
COMP
V
+
S8 PACKAGE
8-LEAD PLASTIC SO
θJA = 60°C/W
N8 PACKAGE
8-LEAD PLASTIC DIP
θJA = 100°C/W
FRONT VIEW
TAB IS
V+
FRONT VIEW
7
6
5
4
3
2
1
OUT
V–
COMP
V+
S/D*
+IN
–IN
7
6
5
4
3
2
1
TAB IS
V+
OUT
V–
COMP
V+
S/D*
+IN
–IN
T7 PACKAGE
7-LEAD PLASTIC TO-220
θJA = 5°C/W
R PACKAGE
7-LEAD PLASTIC DD
θJA = 30°C/W
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC1206CN8#PBF
LTC1206CN8#TRPBF
LT1206
8-Lead Plastic DIP
–40°C to 85°C
LT1206CS8#PBF
LT1206CS8#TRPBF
1206
8-Lead Plastic SO
–40°C to 85°C
LT1206CR#PBF
LT1206CR#TRPBF
LT1206
7-Lead Plastic DD
–40°C to 85°C
LT1206CT7#PBF
LT1206CT7#TRPBF
LT1206
7-Lead Plastic TO-220
–40°C to 85°C
LEAD BASED FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC1206CN8†
LTC1206CN8#TR
LT1206
8-Lead Plastic DIP
–40°C to 85°C
LT1206CS8**
LT1206CS8#TR
1206
8-Lead Plastic SO
–40°C to 85°C
LT1206CR†
LT1206CR#TR
LT1206
7-Lead Plastic DD
–40°C to 85°C
LT1206CT7†
LT1206CT7#TR
LT1206
7-Lead Plastic TO-220
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
**Ground shutdown pin for normal operation. †See Note 3.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
1206fb
2
LT1206
Electrical
Characteristics
The
l 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
Input Offset Voltage
VOS
CONDITIONS
MIN
l
IIN+
Input Offset Voltage Drift
Noninverting Input Current
IIN–
Inverting Input Current
en
+in
–in
RIN
Input Noise Voltage Density
Input Noise Current Density
Input Noise Current Density
Input Resistance
CIN
Input Capacitance
Input Voltage Range
l
l
l
CMRR
PSRR
AV
ROL
VOUT
Common Mode Rejection Ratio
f = 10kHz, RF = 1k, RG = 10Ω, RS = 0Ω
f = 10kHz, RF = 1k, RG = 10Ω, RS = 10k
f = 10kHz, RF = 1k, RG = 10Ω, RS = 10k
VIN = ±12V, VS = ±15V
VIN = ±2V, VS = ±5V
VS = ±15V
VS = ±15V
VS = ±5V
VS = ±15V, VCM = ±12V
VS = ±5V, VCM = ±2V
VS = ±15V, VCM = ±12V
VS = ±5V, VCM = ±2V
VS = ±5V to ±15V
VS = ±5V to ±15V
Inverting Input Current Common Mode
Rejection
Power Supply Rejection Ratio
Noninverting Input Current Power Supply
Rejection
Inverting Input Current Power Supply Rejection VS = ±5V to ±15V
Large-Signal Voltage Gain
VS = ±15V, VOUT = ±10V, RL = 50Ω
VS = ±5V, VOUT = ±2V, RL = 25Ω
Transresistance, ΔVOUT /ΔIIN–
VS = ±15V, VOUT = ±10V, RL = 50Ω
VS = ±5V, VOUT = ±2V, RL = 25Ω
Maximum Output Voltage Swing
VS = ±15V, RL = 50Ω
l
l
1.5
0.5
l
l
±12
±2
55
50
l
l
l
l
l
l
l
l
l
l
l
VS = ±15V, RL = 25Ω
l
IOUT
IS
Maximum Output Current
Supply Current
RL = 1Ω
VS = ±15V, VS/D = 0V
SR
Supply Current, RS/D = 51k (Note 4)
Positive Supply Current, Shutdown
Output Leakage Current, Shutdown
Slew Rate (Note 5)
Differential Gain (Note 6)
Differential Phase (Note 6)
Small-Signal Bandwidth
VS = ±15V
VS = ±15V, VS/D = 15V
VS = ±15V, VS/D = 15V
AV = 2
VS = ±15V, RF = 560Ω, RG = 560Ω, RL = 30Ω
VS = ±15V, RF = 560Ω, RG = 560Ω, RL = 30Ω
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
l
l
55
55
100
75
±11.5
±10.0
±2.5
±2.0
250
TYP
±3
MAX
±10
±15
UNITS
mV
mV
10
µV/°C
±2
±8
µA
±25
µA
±10 ±60
µA
±100
µA
3.6
nV/√Hz
2
pA/√Hz
30
pA/√Hz
10
MΩ
5
MΩ
2
pF
±13.5
V
±3.5
V
62
dB
60
dB
0.1
10
µA/V
0.1
10
µA/V
77
dB
30
500
nA/V
0.7
71
68
260
200
±12.5
5
±3.0
500
20
l
BW
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.
12
l
l
400
900
0.02
0.17
60
52
43
27
1200
30
35
17
200
10
µA/V
dB
dB
kΩ
kΩ
V
V
V
V
mA
mA
mA
mA
µA
µA
V/µs
%
Deg
MHz
MHz
MHz
MHz
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.
1206fb
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
1206fb
4
LT1206
Typical Performance Characteristics
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
–3dB BANDWIDTH (MHz)
80
RF = 470Ω
70
RF = 560Ω
60
RF = 680Ω
50
40
RF = 750Ω
30
RF = 1k
20
10
40
RF = 560Ω
30
RF = 750Ω
20
RF = 1k
RF = 2k
10
16
14
12
10
8
SUPPLY VOLTAGE (±V)
6
100
0
18
4
16
14
12
10
8
SUPPLY VOLTAGE (±V)
6
RF =390Ω
RF = 330Ω
50
40
RF = 470Ω
30
RF = 680Ω
20
10
50
– 3dB BANDWIDTH (MHz)
70
10k
AV = 10
RL = 10Ω
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
30
RF = 560Ω
20
RF = 680Ω
16
14
12
10
8
SUPPLY VOLTAGE (±V)
6
RF = 1k
0
18
RF = 1.5k
4
14
12
10
8
SUPPLY VOLTAGE (±V)
6
1206 G04
0.10
RL = 15Ω
FEEDBACK RESISTOR
0
100
1
0.10
RL = 50Ω
0.06
RL = 30Ω
0.04
RL = 50Ω
0.02
RL = 150Ω
11
13
9
SUPPLY VOLTAGE (±V)
15
1206 G07
AV = +2
RL = ∞
VS = 15V
CCOMP = 0.01µF
1
10k
10
100
1k
CAPACITIVE LOAD (pF)
1206 G06
Spot Noise Voltage and Current
vs Frequency
RF = RG = 560Ω
AV = 2
N PACKAGE
RL = 15Ω
0.08
DIFFERENTIAL GAIN (%)
0.20
RL = 30Ω
7
10
Differential Gain
vs Supply Voltage
0.30
5
18
1k
1206 G05
Differential Phase
vs Supply Voltage
0.50 R = R = 560Ω
F
G
AV = 2
N PACKAGE
0.40
16
100
BANDWIDTH
40
10
1
10000
10 100
1000
CAPACITIVE LOAD (pF)
Bandwidth and Feedback Resistance
vs Capacitive Load for 5dB Peak
RF = 1.5k
4
1
1206 G03
Bandwidth vs Supply Voltage
80
60
100
18
–3dB BANDWIDTH (MHz)
–3dB BANDWIDTH (MHz)
FEEDBACK RESISTOR
AV = 2
RL = ∞
VS = 15V
CCOMP = 0.01µF
1206 G02
AV = 10
RL = 100Ω
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
90
DIFFERENTIAL PHASE (DEG)
10
1k
100
SPOT NOISE (nV/√Hz OR pA/√Hz)
4
Bandwidth vs Supply Voltage
0
BANDWIDTH
RF = 1.5k
1206 G01
0
100
10k
AV = 2
RL = 10Ω
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
FEEDBACK RESISTOR (Ω)
0
50
AV = 2
RL = 100Ω
–3dB BANDWIDTH (MHz)
– 3dB BANDWIDTH (MHz)
90
FEEDBACK RESISTOR (Ω)
100
Bandwidth and Feedback Resistance
vs Capacitive Load for 0.5dB Peak
Bandwidth vs Supply Voltage
Bandwidth vs Supply Voltage
–in
10
en
in
RL = 150Ω
0
5
7
11
13
9
SUPPLY VOLTAGE (±V)
15
1206 G08
1
10
100
1k
10k
FREQUENCY (Hz)
100k
1206 G09
1206fb
5
LT1206
Typical Performance Characteristics
Supply Current vs Ambient
Temperature, VS = ±5V
24
VS/D = 0V
TJ = –40°C
20
TJ = 25°C
18
16
TJ = 85°C
14
TJ = 125°C
12
10
RSD = 0Ω
20
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
22
25
4
16
14
12
10
8
SUPPLY VOLTAGE (±V)
6
15
RSD = 10.2k
10
RSD = 22.1k
5
0
–50 –25
18
50
25
0
75
TEMPERATURE (C)
100
COMMON-MODE RANGE (V)
SUPPLY CURRENT (mA)
12
10
8
6
4
100
300
400
200
SHUTDOWN PIN CURRENT (µA)
–1.5
–2.0
2.0
1.5
1.0
V–
–50
500
0
25
50
75
TEMPERATURE (C)
–25
RL = 50Ω
–3
–4
4
RL = 50Ω
3
2
RL = 2k
1
V–
–50
–25
0
25
50
75
TEMPERATURE (C)
100
125
0.9
0.8
SOURCING
0.7
0.6
100
125
1206 G16
SINKING
0.5
0.4
0.3
–50 –25
0
50
25
75
TEMPERATURE (C)
60
50
NEGATIVE
125
Supply Current vs Large-Signal
Output Frequency (No Load)
60
RL = 50Ω
VS = ±15V
RF = RG = 1k
POSITIVE
40
30
20
AV = 2
RL = ∞
V = ±15V
50 VS = 20V
OUT
P-P
40
30
20
10
0
10k
100
1206 G15
SUPPLY CURRENT (mA)
–2
70
RL = 2k
125
100
1206 G12
Power Supply Rejection Ratio
vs Frequency
POWER SUPPLY REJECTION (dB)
OUTPUT SATURATION VOLTAGE (V)
VS = ±15V
50
25
0
75
TEMPERATURE (C)
1206 G14
Output Saturation Voltage
vs Junction Temperature
–1
0
–50 –25
1.0
1206 G13
V+
RSD = 121k
Output Short-Circuit Current
vs Junction Temperature
0.5
0
RSD = 60.4k
10
Input Common Mode Limit
vs Junction Temperature
–1.0
2
0
15
125
– 0.5
14
20
OUTPUT SHORT-CIRCUIT CURRENT (A)
V+
VS = ±15V
16
AV = 1
RL = ∞
N PACKAGE
RSD = 0Ω
1206 G11
Supply Current
vs Shutdown Pin Current
18
Supply Current vs Ambient
Temperature, VS = ±15V
5
1206 G10
20
25
AV = 1
RL = ∞
N PACKAGE
SUPPLY CURRENT (mA)
Supply Current vs Supply Voltage
100k
1M
10M
FREQUENCY (Hz)
100M
1206 G17
10
10k
100k
1M
10M
FREQUENCY (Hz)
1206 G18
1206fb
6
LT1206
Typical Performance Characteristics
Output Impedance in Shutdown
vs Frequency
Output Impedance vs Frequency
100k
RS/D = 121k
10
RS/D = 0Ω
1
0.1
–30
AV = 1
RF = 1k
VS = ±15V
VS = ±15V
VO = 2VP-P
–40
2nd
RL = 10Ω
10k
DISTORTION (dBc)
VS = ±15V
IO = 0mA
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
1M
10M
100M
–90
10
100k
1M
FREQUENCY (Hz)
1
2
4 5
3
FREQUENCY (MHz)
6 7 8 9 10
1206 G21
Test Circuit for 3rd Order Intercept
VS = ±15V
RL = 50Ω
RF = 590Ω
RG = 64.9Ω
50
100M
1206 G20
3rd Order Intercept vs Frequency
60
10M
FREQUENCY (Hz)
1206 G19
3rd ORDER INTERCEPT (dBm)
0.01
100k
+
LT1206
PO
–
40
590Ω
30
65Ω
50Ω
MEASURE INTERCEPT AT PO
1206 TC01
20
10
0
5
10
15
20
FREQUENCY (MHz)
25
30
1206 G22
1206fb
7
LT1206
Simplified Schematic
V+
TO ALL
CURRENT
SOURCES
Q5
Q10
Q2
Q18
Q17
D1
Q6
Q1
Q9
V–
1.25k
+IN
SHUTDOWN
Q11
Q15
CC
–IN
V–
50Ω
COMP
RC
OUTPUT
V+
V+
Q12
Q3
Q8
Q16
Q14
D2
Q4
Q13
Q7
V–
1206 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
1206fb
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
1206 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
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
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
1206 F02
74C906
Figure 2. Shutdown Interface
VOUT
ENABLE
AV = 1
RF = 825Ω
RL = 50Ω
RPU = 24k
VIN = 1VP-P
1µs/DIV
1206 F03
Figure 3. Shutdown Operation
1206fb
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
RF = RG = 750Ω
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
10
1206 F05b
Figure 5b. Large-Signal Response, AV = –1
1206fb
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 G06
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
1206fb
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.
Calculating Junction Temperature
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.
TJ = Junction Temperature
TA = Ambient Temperature
PD = Device Dissipation
θJA = Thermal Resistance (Junction-to Ambient)
The junction temperature can be calculated from the
equation:
TJ = (PD × θJA) + TA
where:
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
+
Table 1. R Package, 7-Lead DD
COPPER AREA
TOPSIDE*
BACKSIDE
THERMAL RESISTANCE
BOARD AREA (JUNCTION-TO-AMBIENT)
2500 sq. mm 2500 sq. mm 2500 sq. mm
25°C/W
1000 sq. mm 2500 sq. mm 2500 sq. mm
27°C/W
125 sq. mm 2500 sq. mm 2500 sq. mm
35°C/W
330Ω
Table 2. S8 Package, 8-Lead Plastic SO
TOPSIDE*
BACKSIDE
THERMAL RESISTANCE
BOARD AREA (JUNCTION-TO-AMBIENT)
2500 sq. mm 2500 sq. mm 2500 sq. mm
60°C/W
1000 sq. mm 2500 sq. mm 2500 sq. mm
62°C/W
225 sq. mm 2500 sq. mm 2500 sq. mm
65°C/W
100 sq. mm 2500 sq. mm 2500 sq. mm
69°C/W
100 sq. mm 1000 sq. mm 2500 sq. mm
73°C/W
100 sq. mm 225 sq. mm 2500 sq. mm
80°C/W
100 sq. mm 100 sq. mm 2500 sq. mm
83°C/W
*Pins 1 and 8 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
LT1206
S/D
–
–15V
12V
0.01µF
2k
f = 2MHz
2k
–12V
300pF
1206 F07
Figure 7. Thermal Calculation Example
*Tab of device attached to topside copper.
COPPER AREA
39mA
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.
1206fb
12
LT1206
Applications Information
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
5V
3k
1206 TA03
–15V
10k
2N3904
10k
1206 TA02
OUTPUT OFFSET: < 500µV
SLEW RATE: 2V/µs
BANDWIDTH: 4MHz
STABLE WITH CL < 10nF
1k
Low Noise ×10 Buffered Line Driver
15V 1µF
+
75Ω
+
LT1115
–
1µF
–
1µF
68pF
560Ω
–15V
0.01µF
75Ω
LT1206
S/D
–
OUTPUT
LT1206
S/D
–15V
+
VIN
+
75Ω CABLE
75Ω
RF
75Ω
RL
1206 TA05
RG
+
+
Distribution Amplifier
15V 1µF
+
VIN
75Ω
560Ω
909Ω
1206 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*
RF**
*OPTIONAL, USE WITH CAPACITIVE LOADS
**VALUE OF RF DEPENDS ON SUPPLY
VOLTAGE AND LOADING. SELECT
FROM TYPICAL AC PERFORMANCE
TABLE OR DETERMINE EMPIRICALLY
1206 TA06
1206fb
13
LT1206
Package Description
N8 Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
.400*
(10.160)
MAX
8
7
6
5
1
2
3
4
.255 ± .015*
(6.477 ± 0.381)
.300 – .325
(7.620 – 8.255)
.008 – .015
(0.203 – 0.381)
(
+.035
.325 –.015
8.255
+0.889
–0.381
)
.045 – .065
(1.143 – 1.651)
.065
(1.651)
TYP
.100
(2.54)
BSC
.130 ± .005
(3.302 ± 0.127)
.120
(3.048) .020
MIN (0.508)
MIN
.018 ± .003
(0.457 ± 0.076)
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)
1206fb
14
LT1206
Package Description
R Package
Package
7-Lead R
Plastic
DD Pak
Plastic
DD Pak Rev E)
(Reference7-Lead
LTC DWG
# 05-08-1462
(Reference LTC DWG # 05-08-1462 Rev E)
.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
.050 ± .012
(1.270 ± 0.305)
.420
.080
.420
.013 – .023
(0.330 – 0.584)
.276
.350
.325
.205
.585
.585
.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
R (DD7) 0710 REV E
1206fb
15
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
8
.245
MIN
.160 ±.005
7
6
.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
.053 – .069
(1.346 – 1.752)
.008 – .010
(0.203 – 0.254)
5
.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
4
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)
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)
.095 – .115
(2.413 – 2.921)
.155 – .195*
(3.937 – 4.953)
.013 – .023
(0.330 – 0.584)
*MEASURED AT THE SEATING PLANE
T7 (TO-220) 0801
1206fb
16
LT1206
Revision History
(Revision history begins at Rev B)
REV
DATE
DESCRIPTION
PAGE NUMBER
B
3/11
Updated note on Table 2 in the Applications Information section.
12
1206fb
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.
17
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
1206fb
18 Linear Technology Corporation
LT 0311 REV B • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
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LINEAR TECHNOLOGY CORPORATION 1993
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