LINER LT1206CY

LT1206
250mA/60MHz Current
Feedback Amplifier
U
DESCRIPTIO
FEATURES
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■
■
■
■
■
■
■
■
■
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 = 10,000pF
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APPLICATIO S
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The LT1206 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.
Video Amplifiers
Cable Drivers
RGB Amplifiers
Test Equipment Amplifiers
Buffers
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TYPICAL APPLICATIO S
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 = ∞
RF = RG = 3k
LT1206 • TA02
1
LT1206
W W
W
AXI U
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ABSOLUTE
RATI GS
Supply Voltage ..................................................... ±18V
Input Current .................................................... ±15mA
Output Short-Circuit Duration (Note 1) ....... Continuous
Specified Temperature Range (Note 2) ...... 0°C to 70°C
Operating Temperature Range
LT1206C ........................................... – 40°C to 85°C
Junction Temperature ......................................... 150°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
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W
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PACKAGE/ORDER I FOR ATIO
TOP VIEW
+
NC 1
8
V
–IN 2
7
OUT
+IN 3
6
V–
S/D* 4
5
COMP
TOP VIEW
ORDER PART
NUMBER
LT1206CN8**
V+
–IN 2
7
OUT
+IN 3
6
V–
S/D* 4
5
COMP
OUT
V–
COMP
V+
S/D*
+IN
–IN
ORDER PART
NUMBER
LT1206CS8**
PART MARKING
1206
ORDER PART
NUMBER
FRONT VIEW
OUT
V–
COMP
V+
S/D*
+IN
–IN
7
6
5
4
3
2
1
LT1206CR**
TAB IS
V+
LT1206CY**
Y PACKAGE
7-LEAD TO-220
R PACKAGE
7-LEAD PLASTIC DD
θJA ≈ 30°C/W
*Ground shutdown pin for normal operation
ORDER PART
NUMBER
θJA ≈ 60°C/W
FRONT VIEW
TAB IS
V+
8
S8 PACKAGE
8-LEAD PLASTIC SO
N8 PACKAGE
8-LEAD PLASTIC DIP
θJA = 100°C/W
7
6
5
4
3
2
1
V+ 1
θJC = 5°C/W
**See Note 2
ELECTRICAL CHARACTERISTICS VCM = 0, ±5V ≤ VS ≤ ±15V, pulse tested, VS/D = 0V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
VOS
Input Offset Voltage
TA = 25°C
MIN
TYP
MAX
UNITS
±3
±10
±15
mV
mV
●
Input Offset Voltage Drift
+
IIN
Noninverting Input Current
TA = 25°C
±2
±5
±20
µA
µA
±10
±60
±100
µA
µA
●
IIN–
Inverting Input Current
µV/°C
10
●
TA = 25°C
●
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
VIN = ±12V, VS = ±15V
VIN = ±2V, VS = ±5V
CIN
Input Capacitance
VS = ±15V
Input Voltage Range
VS = ±15V
VS = ±5V
2
●
●
1.5
0.5
10
5
MΩ
MΩ
2
pF
●
●
±12
±2
±13.5
±3.5
V
V
LT1206
ELECTRICAL CHARACTERISTICS VCM = 0, ±5V ≤ VS ≤ ±15V, pulse tested, VS/D = 0V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
CMRR
Common-Mode Rejection Ratio
VS = ±15V, VCM = ±12V
VS = ±5V, VCM = ±2V
●
●
Inverting Input Current
Common-Mode Rejection
VS = ±15V, VCM = ±12V
VS = ±5V, VCM = ±2V
●
●
Power Supply Rejection Ratio
VS = ±5V to ±15V
●
Noninverting Input Current
Power Supply Rejection
VS = ±5V to ±15V
●
30
500
nA/V
Inverting Input Current
Power Supply Rejection
VS = ±5V to ±15V
●
0.7
5
µA/V
AV
Large-Signal Voltage Gain
VS = ±15V, VOUT = ±10V, RL = 50Ω
VS = ±5V, VOUT = ±2V, RL = 25Ω
●
●
55
55
71
68
dB
dB
ROL
Transresistance, ∆VOUT/∆IIN–
VS = ±15V, VOUT = ±10V, RL = 50Ω
VS = ±5V, VOUT = ±2V, RL = 25Ω
●
●
100
75
260
200
kΩ
kΩ
VOUT
Maximum Output Voltage Swing
VS = ±15V, RL = 50Ω, TA = 25°C
PSRR
VS = ±5V, RL = 25Ω, TA = 25°C
IOUT
Maximum Output Current
RL = 1Ω
IS
Supply Current
VS = ±15V, VS/D = 0V, TA = 25°C
MIN
TYP
55
50
62
60
0.1
0.1
60
●
±11.5
±10.0
±2.5
±2.0
●
250
●
SR
BW
VS = ±15V, TA = 25°C
UNITS
dB
dB
10
10
77
µA/V
µA/V
dB
±12.5
V
V
V
V
±3.0
500
1200
mA
20
30
35
mA
mA
12
17
mA
●
Supply Current, RS/D = 51k (Note 3)
MAX
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 4)
AV = 2, TA = 25°C
900
V/µs
Differential Gain (Note 5)
VS = ±15V, RF = 560Ω, RG = 560Ω, RL = 30Ω
0.02
%
Differential Phase (Note 5)
VS = ±15V, RF = 560Ω, RG = 560Ω, RL = 30Ω
0.17
DEG
Small-Signal Bandwidth
VS = ±15V, Peaking ≤ 0.5dB
RF = RG = 620Ω, RL = 100Ω
60
MHz
VS = ±15V, Peaking ≤ 0.5dB
RF = RG = 649Ω, RL = 50Ω
52
MHz
VS = ±15V, Peaking ≤ 0.5dB
RF = RG = 698Ω, RL = 30Ω
43
MHz
VS = ±15V, Peaking ≤ 0.5dB
RF = RG = 825Ω, RL = 10Ω
27
MHz
The ● denotes specifications which apply for 0°C ≤ TA ≤ 70°C.
Note 1: 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 2: Commercial grade parts are designed to operate over the
temperature range of – 40°C to 85°C but are neither tested nor guaranteed
400
beyond 0°C to 70°C. Industrial grade parts tested over – 40°C to 85°C are
available on special request. Consult factory.
Note 3: RS/D is connected between the shutdown pin and ground.
Note 4: 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 5: NTSC composite video with an output level of 2V.
3
LT1206
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W
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S ALL-SIG AL BA DWIDTH
IS = 20mA Typical, Peaking ≤ 0.1dB
AV
RL
VS = ±5V, RSD = 0Ω
–1
150
30
10
1
150
30
10
2
150
30
10
10
150
30
10
RF
562
649
732
619
715
806
576
649
750
442
511
649
RG
562
649
732
–
–
–
576
649
750
48.7
56.2
71.5
– 3dB BW
(MHz)
– 0.1dB BW
(MHz)
48
34
22
54
36
22.4
48
35
22.4
40
31
20
21.4
17
12.5
22.3
17.5
11.5
20.7
18.1
11.7
19.2
16.5
10.2
RG
– 3dB BW
(MHz)
– 0.1dB BW
(MHz)
576
681
750
–
–
–
590
681
768
33.2
43.2
54.9
35
25
16.4
37
25
16.5
35
25
16.2
31
23
15
17
12.5
8.7
17.5
12.6
8.2
16.8
13.4
8.1
15.6
11.9
7.8
– 3dB BW
(MHz)
– 0.1dB BW
(MHz)
AV
RL
VS = ±5V, RSD = 0Ω
–1
150
30
10
1
150
30
10
2
150
30
10
10
150
30
10
RF
RG
– 3dB BW
(MHz)
– 0.1dB BW
(MHz)
681
768
887
768
909
1k
665
787
931
487
590
768
681
768
887
–
–
–
665
787
931
536
64.9
84.5
50
35
24
66
37
23
55
36
22.5
44
33
20.7
19.2
17
12.3
22.4
17.5
12
23
18.5
11.8
20.7
17.5
10.8
RF
RG
– 3dB BW
(MHz)
– 0.1dB BW
(MHz)
634
768
866
–
–
–
649
787
931
33.2
44.2
64.9
41
26.5
17
44
28
16.8
40
27
16.5
33
25
15.3
19.1
14
9.4
18.8
14.4
8.3
18.5
14.1
8.1
15.6
13.3
7.4
RG
– 3dB BW
(MHz)
– 0.1dB BW
(MHz)
IS = 10mA Typical, Peaking ≤ 0.1dB
AV
RL
RF
VS = ±5V, RSD = 10.2k
–1
150
576
30
681
10
750
1
150
665
30
768
10
845
2
150
590
30
681
10
768
10
150
301
30
392
10
499
AV
RL
VS = ±15V, RSD = 60.4k
–1
150
634
30
768
10
866
1
150
768
30
909
10
1k
2
150
649
30
787
10
931
10
150
301
30
402
10
590
IS = 5mA Typical, Peaking ≤ 0.1dB
AV
RL
RF
RG
VS = ±5V, RSD = 22.1k
AV
RL
RF
VS = ±15V, RSD = 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
4
LT1206
W U
TYPICAL PERFOR A CE CHARACTERISTICS
Bandwidth vs Supply Voltage
–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
1k
FEEDBACK RESISTOR
AV = 2
RL = ∞
VS = ±15V
CCOMP = 0.01µF
10
RF = 1.5k
100
0
0
4
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
4
18
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
Bandwidth vs Supply Voltage
LT1206 • TPC03
Bandwidth and Feedback Resistance
vs Capacitive Load for 5dB Peak
Bandwidth vs Supply Voltage
50
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
90
70
RF =390Ω
RF = 330Ω
50
40
RF = 470Ω
30
RF = 680Ω
20
10
BANDWIDTH
40
30
RF = 560Ω
20
RF = 680Ω
RF = 1k
10
100
AV = 10
RL = 10Ω
1k
10
FEEDBACK RESISTOR
RF = 1.5k
RF = 1.5k
0
100
0
0
4
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
4
18
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
18
1
Differential Phase
vs Supply Voltage
Spot Noise Voltage and Current
vs Frequency
100
0.10
RF = RG = 560Ω
AV = 2
N PACKAGE
0.20
RL = 30Ω
RL = 50Ω
0.10
RL = 15Ω
0.08
DIFFERENTIAL GAIN (%)
0.30
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
0.40
10
100
1k
CAPACITIVE LOAD (pF)
LT1206 • TPC05
LT1206 • TPC04
AV = +2
RL = ∞
VS = ±15V
CCOMP = 0.01µF
–3dB BANDWIDTH (MHz)
– 3dB BANDWIDTH (MHz)
80
60
10k
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
AV = 10
RL = 100Ω
FEEDBACK RESISTOR (Ω)
100
1
10000
100
10
1000
CAPACITIVE LOAD (pF)
1
18
LT1206 • TPC02
LT1206 • TPC01
–3dB BANDWIDTH (MHz)
BANDWIDTH
AV = 2
RL = 10Ω
–3dB BANDWIDTH (MHz)
– 3dB BANDWIDTH (MHz)
90
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
AV = 2
RL = 100Ω
FEEDBACK RESISTOR (Ω)
PEAKING ≤ 0.5dB
PEAKING ≤ 5dB
100
10k
50
100
DIFFERENTIAL PHASE (DEG)
Bandwidth and Feedback Resistance
vs Capacitive Load for 0.5dB Peak
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
5
LT1206
W U
TYPICAL PERFOR A CE 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
10
4
16
14
12
10
8
SUPPLY VOLTAGE (±V)
6
0
–50 –25
18
50
25
0
75
TEMPERATURE (°C)
LT1206 • TPC10
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 • TPC11
POWER SUPPLY REJECTION (dB)
OUTPUT SATURATION VOLTAGE (V)
–3
–4
4
RL = 50Ω
2
RL = 2k
1
V–
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
LT1206 • TPC16
6
0.6
SINKING
0.5
0.4
50
25
75
0
TEMPERATURE (°C)
60
50
100
125
LT1206 • TPC15
Supply Current vs Large Signal
Output Frequency (No Load)
60
RL = 2k
RL = 50Ω
3
SOURCING
0.7
0.3
–50 –25
125
70
–2
0.8
Power Supply Rejection Ratio
vs Frequency
V+
VS = ±15V
0.9
LT1206 • TPC14
Output Saturation Voltage
vs Junction Temperature
–1
100
0
25
50
75
TEMPERATURE (°C)
NEGATIVE
RL = 50Ω
VS = ±15V
RF = RG = 1k
50
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
1.0
– 0.5
16
125
Output Short-Circuit Current
vs Junction Temperature
V+
VS = ±15V
100
LT1206 • TPC12
Input Common-Mode Limit
vs Junction Temperature
20
18
50
25
0
75
TEMPERATURE (°C)
LT1206 • TPC11
Supply Current
vs Shutdown Pin Current
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
LT1206 • TPC17
10
10k
100k
1M
10M
FREQUENCY (Hz)
LT1206 • TPC18
LT1206
W U
TYPICAL PERFOR A CE CHARACTERISTICS
Output Impedance in Shutdown
vs Frequency
Output Impedance vs Frequency
100
–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)
2nd and 3rd Harmonic Distortion
vs Frequency
1k
–50
3rd
2nd
–60
–70
RL = 30Ω
3rd
100
–80
1M
10M
100M
–90
10
100k
1M
FREQUENCY (Hz)
10M
100M
2
4 5
3
FREQUENCY (MHz)
1
FREQUENCY (Hz)
LT1206 • TPC19
LT1206 • TPC21
LT1206 • TPC20
3rd Order Intercept vs Frequency
6 7 8 9 10
Test Circuit for 3rd Order Intercept
60
3rd ORDER INTERCEPT (dBm)
0.01
100k
VS = ±15V
RL = 50Ω
RF = 590Ω
RG = 64.9Ω
50
+
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
7
LT1206
W
W
SI PLIFIED SCHE ATIC
V+
TO ALL
CURRENT
SOURCES
Q5
Q10
Q2
Q18
D1
Q6
Q1
Q17
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 • TC
U
W
U
UO
APPLICATI
S I FOR ATIO
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
8
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
LT1206
U
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VS = ±15V
10
RF = 1.2k
COMPENSATION
8
VOLTAGE GAIN (dB)
W
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APPLICATI
6
4
RF = 2k
NO COMPENSATION
2
0
RF = 2k
COMPENSATION
–2
–4
–6
–8
1
10
FREQUENCY (MHz)
100
LT1206 • F01
Figure 1.
which 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.
a 40pF 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
+
VIN
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.
RG
24k
ENABLE
74C906
LT1206 • F02
Figure 2. Shutdown Interface
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
ENABLE
If the shutdown feature is not used, the SHUTDOWN pin
must be connected to ground or V –.
VOUT
Shutdown/Current Set
AV = 1
RF = 825Ω
RL = 50Ω
RPU = 24k
VIN = 1VP-P
LT1206 • F3
Figure 3. Shutdown Operation
9
LT1206
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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
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.
LT1206 • F04a
Figure 4a. Large-Signal Response vs IQ, AV = –1
RF = 825Ω
RL = 50Ω
VS = ±15V
LT1206 • F05a
Figure 5a. Large-Signal Response, AV = 1
RF = 750Ω
RL = 50Ω
IQ = 5mA, 10mA, 20mA
VS = ±15V
LT1206 • F04b
Figure 4b. Large-Signal Response vs IQ, AV = 2
RF = RG = 750Ω
RL = 50Ω
VS = ±15V
LT1206 • F05b
Figure 5b. Large-Signal Response, AV = –1
10
LT1206
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APPLICATI
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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
LT1206 • F04c
RF = 750Ω
RL = 50Ω
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.
Figure 5c. Large-Signal Response, AV = 2
Power Supplies
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.
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
RF = RG = 3k
RL = ∞
LT1206 • F06
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
11
LT1206
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APPLICATI
S I FOR ATIO
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.
Calculating Junction Temperature
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
+
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
35°C/W
2500 sq. mm
330Ω
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
12
–
f = 2MHz
0.01µF
–15V
–12V
300pF
2k
LT1206 • F07
Figure 7. Thermal Calculation Example
Table 2. S8 Package, 8-Lead Plastic SOIC
COPPER AREA
12V
LT1206
S/D
2k
*Tab of device attached to topside copper
TOPSIDE*
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.
LT1206
U
TYPICAL APPLICATIO S
Precision ×10 Hi Current Amplifier
CMOS Logic to Shutdown Interface
15V
+
+
LT1097
LT1206
COMP
– S/D
–
+
OUT
24k
LT1206
S/D
–
0.01µF
500pF
LT1206 • TA05
330Ω
5V
3k
–15V
10k
2N3904
10k
LT1206 • TA03
OUTPUT OFFSET: < 500µV
SLEW RATE: 2V/µs
BANDWIDTH: 4MHz
STABLE WITH CL < 10nF
1k
Distribution Amplifier
75Ω
+
LT1206 • TA06
+
LT1115
1µF
–
75Ω CABLE
75Ω
RF
15V 1µF
+
–
75Ω
LT1206
S/D
75Ω
–
15V 1µF
+
+
VIN
Low Noise ×10 Buffered Line Driver
+
RG
OUTPUT
LT1206
S/D
0.01µF
75Ω
RL
–15V
1µF
68pF
+
VIN
Buffer AV = 1
–15V
560Ω
560Ω
VIN
909Ω
LT1206 • TA04
100Ω
RL = 32Ω
VO = 5VRMS
THD + NOISE = 0.0009% AT 1kHz
= 0.004% AT 20kHz
SMALL SIGNAL 0.1dB BANDWIDTH = 600kHz
+
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
13
LT1206
PACKAGE DESCRIPTIO
U
Dimensions in inches (millimeters) unless otherwise noted.
N8 Package
8-Lead Plastic DIP
0.400
(10.160)
MAX
8
7
6
5
0.250 ± 0.010
(6.350 ± 0.254)
1
0.300 – 0.320
(7.620 – 8.128)
0.009 – 0.015
(0.229 – 0.381)
(
+0.025
0.325 –0.015
8.255
+0.635
–0.381
)
2
3
4
0.130 ± 0.005
(3.302 ± 0.127)
0.045 – 0.065
(1.143 – 1.651)
0.065
(1.651)
TYP
0.125
(3.175)
MIN
0.045 ± 0.015
(1.143 ± 0.381)
0.020
(0.508)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
0.100 ± 0.010
(2.540 ± 0.254)
N8 0392
R Package
7-Lead Plastic DD
0.060
(1.524)
0.401 ± 0.015
(10.185 ± 0.381)
0.175 ± 0.008
(4.445 ± 0.203)
15° TYP
(
+0.012
0.331 –0.020
+0.305
8.407 –0.508
0.059
(1.499)
TYP
)
0.050 ± 0.008
(1.270 ± 0.203)
(
+0.008
0.004 –0.004
+0.203
0.102 –0.102
)
0.105 ± 0.008
(2.667 ± 0.203)
(
+0.012
0.143 –0.020
+0.305
3.632 –0.508
14
)
0.050 ± 0.010
(1.270 ± 0.254)
0.030 ± 0.008
(0.762 ± 0.203)
0.022 ± 0.005
(0.559 ± 0.127)
0.050 ± 0.012
(1.270 ± 0.305)
DD7 0693
LT1206
PACKAGE DESCRIPTIO
U
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package
8-Lead Plastic SOIC
0.189 – 0.197
(4.801 – 5.004)
8
7
6
5
0.150 – 0.157
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
2
3
4
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0°– 8° TYP
0.016 – 0.050
0.406 – 1.270
0.014 – 0.019
(0.355 – 0.483)
0.050
(1.270)
BSC
SO8 0392
Y Package
7-Lead TO-220
0.390 – 0.410
(9.91 – 10.41)
0.147 – 0.155
(3.73 – 3.94)
DIA
0.169 – 0.185
(4.29 – 4.70)
0.045 – 0.055
(1.14 – 1.40)
0.235 – 0.258
(5.97 – 6.55)
0.103 – 0.113
(2.62 – 2.87)
0.560 – 0.590
(14.22 – 14.99)
0.620
(15.75)
TYP
0.700 – 0.728
(17.78 – 18.49)
0.152 – 0.202
(3.86 – 5.13)
0.260 – 0.320
(6.60 – 8.13)
0.026 – 0.036
(0.66 – 0.91)
0.045 – 0.055
(1.14 – 1.40)
0.016 – 0.022
(0.41 – 0.56)
0.135 – 0.165
(3.43 – 4.19)
0.095 – 0.115
(2.41 – 2.92)
0.155 – 0.195
(3.94 – 4.95)
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 circuits as described herein will not infringe on existing patent rights.
Y7 0893
15
LT1206
U.S. Area Sales Offices
NORTHEAST REGION
Linear Technology Corporation
One Oxford Valley
2300 E. Lincoln Hwy.,Suite 306
Langhorne, PA 19047
Phone: (215) 757-8578
FAX: (215) 757-5631
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Linear Technology Corporation
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Dallas, TX 75248
Phone: (214) 733-3071
FAX: (214) 380-5138
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Phone: (818) 703-0835
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Phone: (508) 658-3881
FAX: (508) 658-2701
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Addison, IL 60101
Phone: (708) 620-6910
FAX: (708) 620-6977
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Linear Technology Corporation
782 Sycamore Dr.
Milpitas, CA 95035
Phone: (408) 428-2050
FAX: (408) 432-6331
International Sales Offices
FRANCE
Linear Technology S.A.R.L.
Immeuble "Le Quartz"
58 Chemin de la Justice
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France
Phone: 33-1-41079555
FAX: 33-1-46314613
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Korea
Phone: 82-2-792-1617
FAX: 82-2-792-1619
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D-85386 Eching
Germany
Phone: 49-89-3197410
FAX: 49-89-3194821
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Linear Technology Pte. Ltd.
101 Boon Keng Road
#02-15 Kallang Ind. Estates
Singapore 1233
Phone: 65-293-5322
FAX: 65-292-0398
TAIWAN
Linear Technology Corporation
Rm. 801, No. 46, Sec. 2
Chung Shan N. Rd.
Taipei, Taiwan, R.O.C.
Phone: 886-2-521-7575
FAX: 886-2-562-2285
UNITED KINGDOM
Linear Technology (UK) Ltd.
The Coliseum, Riverside Way
Camberley, Surrey GU15 3YL
United Kingdom
Phone: 44-276-677676
FAX: 44-276-64851
JAPAN
Linear Technology KK
5F YZ Bldg.
4-4-12 Iidabashi, Chiyoda-Ku
Tokyo, 102 Japan
Phone: 81-3-3237-7891
FAX: 81-3-3237-8010
World Headquarters
Linear Technology Corporation
1630 McCarthy Blvd.
Milpitas, CA 95035-7487
Phone: (408) 432-1900
FAX: (408) 434-0507
06/24/93
16
Linear Technology Corporation
LT/GP 0993 10K REV 0 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977
 LINEAR TECHNOLOGY CORPORATION 1993