LINER LT1210CS 1.1a, 35mhz current feedback amplifier Datasheet

LT1210
1.1A, 35MHz Current
Feedback Amplifier
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DESCRIPTIO
FEATURES
■
■
■
■
■
■
■
■
■
1.1A Minimum Output Drive Current
35MHz Bandwidth, AV = 2, RL = 10Ω
900V/µs Slew Rate, AV = 2, RL = 10Ω
High Input Impedance: 10MΩ
Wide Supply Range: ±5V to ±15V
(TO-220 and DD Packages)
Enhanced θJA SO-16 Package for ±5V Operation
Shutdown Mode: IS < 200µA
Adjustable Supply Current
Stable with CL = 10,000pF
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APPLICATIONS
■
■
■
■
■
Cable Drivers
Buffers
Test Equipment Amplifiers
Video Amplifiers
ADSL Drivers
The LT ®1210 is a current feedback amplifier with high
output current and excellent large-signal characteristics.
The combination of high slew rate, 1.1A output drive and
±15V operation enables the device to deliver significant
power at frequencies in the 1MHz to 2MHz range. Shortcircuit protection and thermal shutdown ensure the
device’s ruggedness. The LT1210 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 and low
supply 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 LT1210 is available in the TO-220 and DD packages
for operation with supplies up to ±15V. For ±5V applications the device is also available in a low thermal resistance SO-16 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
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TYPICAL APPLICATIO S
Twisted Pair Driver
Total Harmonic Distortion vs Frequency
15V
–50
4.7µF*
100nF
RT
11Ω
2.5W
+
VIN
LT1210
SD
–
+
T1**
1
4.7µF*
–15V
3
RL
100Ω
2.5W
100nF
845Ω
* TANTALUM
** MIDCOM 671-7783 OR EQUIVALENT
TOTAL HARMONIC DISTORTION (dB)
+
VS = ±15V
VOUT = 20VP-P
AV = 4
–60
–70
RL = 12.5Ω
–80
RL = 10Ω
RL = 50Ω
–90
–100
1k
274Ω
10k
100k
FREQUENCY (Hz)
1M
1210 TA01
1210 TA02
1
LT1210
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 ............... –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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PACKAGE/ORDER INFORMATION
TOP VIEW
FRONT VIEW
TAB
IS V +
7
6
5
4
3
2
1
OUT
V–
COMP
V+
SHUTDOWN
+IN
–IN
R PACKAGE
7-LEAD PLASTIC DD
θJA ≈ 25°C/W
V+
1
16 V +
V+
2
15 NC
OUT 3
14 V –
V+ 4
13 COMP
NC 5
12 SHUTDOWN
–IN 6
11 +IN
NC 7
10 NC
V+ 8
9
FRONT VIEW
7
6
5
4
3
2
1
TAB
IS V +
OUT
V–
COMP
V+
SHUTDOWN
+IN
–IN
T7 PACKAGE
7-LEAD TO-220
V+
S PACKAGE
16-LEAD PLASTIC SO
θJC = 5°C/W
θJA ≈ 40°C/W (Note 3)
ORDER PART NUMBER
ORDER PART NUMBER
ORDER PART NUMBER
LT1210CR
LT1210CS
LT1210CT7
Consult factory for Industrial and Military grade parts.
ELECTRICAL CHARACTERISTICS
VCM = 0V, ±5V ≤ VS ≤ ±15V, pulse tested, VSD = 0V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
VOS
Input Offset Voltage
TA = 25°C
MIN
TYP
MAX
UNITS
±3
±15
±20
mV
mV
●
Input Offset Voltage Drift
IIN+
Noninverting Input Current
±2
±5
±20
µA
µA
±10
±60
±100
µA
µA
●
IIN–
Inverting Input Current
µV/°C
10
●
TA = 25°C
TA = 25°C
●
en
Input Noise Voltage Density
f = 10kHz, RF = 1k, RG = 10Ω, RS = 0Ω
3.0
nV/√Hz
+ in
Input Noise Current Density
f = 10kHz, RF = 1k, RG = 10Ω, RS = 10k
2.0
pA/√Hz
– in
Input Noise Current Density
f = 10kHz, RF = 1k, RG = 10Ω, RS = 10k
40
pA/√Hz
RIN
Input Resistance
VIN = ±12V, VS = ±15V
VIN = ±2V, VS = ±5V
10
5
MΩ
MΩ
CIN
Input Capacitance
VS = ±15V
2
pF
Input Voltage Range
VS = ±15V
VS = ±5V
±13.5
±3.5
V
V
2
●
●
●
●
1.50
0.25
±12
±2
LT1210
ELECTRICAL CHARACTERISTICS
VCM = 0V, ±5V ≤ VS ≤ ±15V, pulse tested, VSD = 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
●
Inverting Input Current
Power Supply Rejection
VS = ±5V to ±15V
●
Large-Signal Voltage Gain
TA = 25°C, VS = ±15V, VOUT = ±10V,
RL = 10Ω (Note 3)
PSRR
AV
ROL
VOUT
Transresistance, ∆VOUT/∆IIN–
Maximum Output Voltage Swing
MIN
TYP
55
50
62
60
µA/V
µA/V
30
500
nA/V
0.7
5
µA/V
77
dB
55
71
dB
●
55
68
dB
VS = ±5V, VOUT = ±2V, RL = 10Ω
●
55
68
dB
100
260
kΩ
75
200
kΩ
kΩ
TA = 25°C, VS = ±15V, VOUT = ±10V,
RL = 10Ω (Note 3)
VS = ±15V, VOUT = ±8.5V, RL = 10Ω (Note 3)
●
VS = ±5V, VOUT = ±2V, RL = 10Ω
●
75
200
±11.5
●
±10.0
±8.5
V
V
±2.5
±2.0
±3.0
●
V
V
●
1.1
2.0
TA = 25°C, VS = ±15V, RL = 10Ω (Note 3)
IOUT
Maximum Output Current (Note 3)
VS = ±15V, RL = 1Ω
IS
Supply Current (Note 3)
TA = 25°C, VS = ±15V, VSD = 0V
Supply Current, RSD = 51k (Notes 3, 4)
TA = 25°C, VS = ±15V
Positive Supply Current, Shutdown
VS = ±15V, VSD = 15V
●
●
Output Leakage Current, Shutdown
VS = ±15V, VSD = 15V
Slew Rate (Note 5)
Slew Rate (Note 3)
TA = 25°C, AV = 2, RL = 400Ω
TA = 25°C, AV = 2, RL = 10Ω
Differential Gain (Notes 3, 6)
A
35
50
65
mA
mA
15
30
mA
200
µA
●
BW
dB
dB
VS = ±15V, VOUT = ±8.5V, RL = 10Ω (Note 3)
TA = 25°C, VS = ±5V, RL = 10Ω
SR
UNITS
10
10
0.1
0.1
60
MAX
10
µA
900
900
V/µs
V/µs
VS = ±15V, RF = 750Ω, RG = 750Ω, RL = 15Ω
0.3
%
Differential Phase (Notes 3, 6)
VS = ±15V, RF = 750Ω, RG = 750Ω, RL = 15Ω
0.1
DEG
Small-Signal Bandwidth
AV = 2, VS = ±15V, Peaking ≤ 1dB,
RF = RG = 680Ω, RL = 100Ω
55
MHz
AV = 2, VS = ±15V, Peaking ≤ 1dB,
RF = RG = 576Ω, RL = 10Ω
35
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 ≤ TA ≤ 85°C, but are neither tested nor
guaranteed beyond 0°C ≤ TA ≤ 70°C. Industrial grade parts tested over
– 40°C ≤ TA ≤ 85°C are available on special request. Consult factory.
Note 3: SO package is recommended for ±5V supplies only, as the power
dissipation of the SO package limits performance on higher supplies. For
400
supply voltages greater than ±5V, use the TO-220 or DD package. See
“Thermal Considerations” in the Applications Information section for
details on calculating junction temperature. If the maximum dissipation of
the package is exceeded, the device will go into thermal shutdown.
Note 4: RSD 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.
3
LT1210
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SMALL-SIGNAL BANDWIDTH
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RSD = 0Ω, IS = 30mA, VS = ±5V, Peaking ≤ 1dB
RSD = 0Ω, IS = 35mA, VS = ±15V, Peaking ≤ 1dB
AV
RL
RF
RG
– 3dB BW
(MHz)
–1
150
30
10
150
30
10
150
30
10
150
30
10
549
590
619
604
649
619
562
590
576
392
383
215
549
590
619
–
–
–
562
590
576
43.2
42.2
23.7
52.5
39.7
26.5
53.5
39.7
27.4
51.8
38.8
27.4
48.4
40.3
36.0
1
2
10
RSD = 7.5k, IS = 15mA, VS = ±5V, Peaking ≤ 1dB
RL
RF
RG
– 3dB BW
(MHz)
–1
150
30
10
150
30
10
150
30
10
150
30
10
562
619
604
634
681
649
576
604
576
324
324
210
562
619
604
–
–
–
576
604
576
35.7
35.7
23.2
39.7
28.9
20.5
41.9
29.7
20.7
40.2
29.6
21.6
39.5
32.3
27.7
2
10
RSD = 15k, IS = 7.5mA, VS = ±5V, Peaking ≤ 1dB
RL
RF
RG
– 3dB BW
(MHz)
–1
150
30
10
150
30
10
150
30
10
150
30
10
536
549
464
619
634
511
536
549
412
150
118
100
536
549
464
–
–
–
536
549
412
16.5
13.0
11.0
28.2
20.0
15.0
28.6
19.8
14.9
28.3
19.9
15.7
31.5
27.1
19.4
2
10
4
RF
RG
– 3dB BW
(MHz)
–1
150
30
10
150
30
10
150
30
10
150
30
10
604
649
665
750
866
845
665
715
576
453
432
221
604
649
665
–
–
–
665
715
576
49.9
47.5
24.3
66.2
48.4
46.5
56.8
35.4
24.7
52.5
38.9
35.0
61.5
43.1
45.5
1
2
10
AV
RL
RF
RG
– 3dB BW
(MHz)
–1
150
30
10
150
30
10
150
30
10
150
30
10
619
698
698
732
806
768
634
698
681
348
357
205
619
698
698
–
–
–
634
698
681
38.3
39.2
22.6
47.8
32.3
22.2
51.4
33.9
22.5
48.4
33.0
22.5
46.8
36.7
31.3
1
2
10
RSD = 82.5k, IS = 9mA, VS = ±15V, Peaking ≤ 1dB
AV
1
RL
RSD = 47.5k, IS = 18mA, VS = ±15V, Peaking ≤ 1dB
AV
1
AV
AV
RL
RF
RG
– 3dB BW
(MHz)
–1
150
30
10
150
30
10
150
30
10
150
30
10
590
649
576
715
768
649
590
665
549
182
182
100
590
649
576
–
–
–
590
665
549
20.0
20.0
11.0
34.8
22.5
16.3
35.5
22.5
16.1
35.3
22.5
16.8
37.2
28.9
22.5
1
2
10
LT1210
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TYPICAL PERFOR A CE CHARACTERISTICS
50
100
–3dB BANDWIDTH (MHz)
70
RF = 560Ω
60
50
RF = 750Ω
40
RF = 680Ω
30
RF = 1k
40
RF = 560Ω
30
RF = 750Ω
RF = 1k
20
RF = 2k
10
20
FEEDBACK RESISTANCE
AV = 2
RL = ∞
VS = ±15V
CCOMP = 0.01µF
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
Bandwidth vs Supply Voltage
1210 G03
Bandwidth and Feedback Resistance
vs Capacitive Load for Peaking ≤ 5dB
Bandwidth vs Supply Voltage
50
PEAKING ≤ 1dB
PEAKING ≤ 5dB
90
50
– 3dB BANDWIDTH (MHz)
RF =390Ω
60
RF = 330Ω
RF = 470Ω
40
RF = 680Ω
30
30
20
10
RF = 560Ω
RF = 1k
10
20
BANDWIDTH
40
RF = 680Ω
100
AV = 10
RL = 10Ω
1k
AV = +2
RL = ∞
VS = ±15V
CCOMP = 0.01µF
RF = 1.5k
RF = 1.5k
100
0
0
0
4
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
4
18
14
12
10
8
SUPPLY VOLTAGE (±V)
6
16
1
18
1210 G06
Differential Gain vs
Supply Voltage
Differential Phase vs
Supply Voltage
Spot Noise Voltage and Current
vs Frequency
100
0.5
0.6
RF = RG = 750Ω
AV = 2
RL = 10Ω
DIFFERENTIAL GAIN (%)
0.4
0.4
RF = RG = 750Ω
AV = 2
0.3
RL = 15Ω
0.2
RL = 50Ω
RL = 10Ω
0.3
RL = 15Ω
0.2
0.1
0.1
RL = 50Ω
RL = 30Ω
RL = 30Ω
0
5
7
11
13
9
SUPPLY VOLTAGE (±V)
15
1210 G07
1
10000
10
100
1000
CAPACITIVE LOAD (pF)
1210 G05
1210 G04
0.5
10
FEEDBACK
RESISTANCE
–3dB BANDWIDTH (MHz)
80
70
10k
PEAKING ≤ 1dB
AV = 10
RL = 100Ω
FEEDBACK RESISTANCE (Ω)
100
1
10000
10
100
1000
CAPACITIVE LOAD (pF)
1210 G02
1210 G01
–3dB BANDWIDTH (MHz)
10
1k
RF = 1.5k
10
DIFFERENTIAL PHASE (DEG)
BANDWIDTH
SPOT NOISE (nV/√Hz OR pA/√Hz)
– 3dB BANDWIDTH (MHz)
RF = 470Ω
AV = 2
RL = 10Ω
–3dB BANDWIDTH (MHz)
80
100
10k
PEAKING ≤ 1dB
PEAKING ≤ 5dB
AV = 2
RL = 100Ω
FEEDBACK RESISTANCE (Ω)
PEAKING ≤ 1dB
PEAKING ≤ 5dB
90
0
Bandwidth and Feedback Resistance
vs Capacitive Load for Peaking ≤ 1dB
Bandwidth vs Supply Voltage
Bandwidth vs Supply Voltage
5
7
11
13
9
SUPPLY VOLTAGE (±V)
15
1210 G08
– in
10
en
+in
1
10
100
1k
10k
FREQUENCY (Hz)
100k
1210 G09
5
LT1210
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TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs
Ambient Temperature, VS = ±5V
Supply Current vs Supply Voltage
40
40
40
RSD = 0Ω
35
SUPPLY CURRENT (mA)
TA = 25°C
36
TA = 85°C
34
32
30
TA = –40°C
28
TA = 125°C
26
AV = 1
RL = ∞
RSD = 0Ω
35
30
25
SUPPLY CURRENT (mA)
38
SUPPLY CURRENT (mA)
Supply Current vs
Ambient Temperature, VS = ±15V
RSD = 7.5k
20
15
RSD = 15k
10
RSD = 0Ω
30
25
RSD = 47.5k
20
15
RSD = 82.5k
10
24
5
22
0
–50 –25
20
4
16
12
14
8
10
SUPPLY VOLTAGE (±V)
6
18
50
25
0
75
TEMPERATURE (°C)
– 0.5
COMMON MODE RANGE (V)
35
SUPPLY CURRENT (mA)
3.0
OUTPUT SHORT-CIRCUIT CURRENT (A)
VS = ±15V
20
15
10
5
–1.0
–1.5
–2.0
2.0
1.5
1.0
0.5
V–
–50
0
100
300
400
200
SHUTDOWN PIN CURRENT (µA)
0
500
–25
0
25
50
75
TEMPERATURE (°C)
1210 G13
–3
–4
RL = 10Ω
4
3
2
RL = 2k
1
V–
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
1210 G16
6
2.2
2.0
1.8
50
25
75
0
TEMPERATURE (°C)
125
Supply Current vs Large-Signal
Output Frequency (No Load)
100
60 NEGATIVE
50
100
1210 G15
70
RL = 2k
RL = 10Ω
–2
SINKING
2.4
1.6
–50 –25
125
RL = 50Ω
VS = ±15V
RF = RG = 1k
POSITIVE
40
30
20
10
0
10k
90
SUPPLY CURRENT (mA)
VS = ±15V
SOURCING
2.6
Power Supply Rejection Ratio
vs Frequency
POWER SUPPLY REJECTION (dB)
OUTPUT SATURATION VOLTAGE (V)
–1
100
2.8
1210 G14
Output Saturation Voltage vs
Junction Temperature
125
Output Short-Circuit Current vs
Junction Temperature
V+
40
100
1210 G12
Input Common Mode Limit vs
Junction Temperature
25
50
25
0
75
TEMPERATURE (°C)
1210 G11
Supply Current vs
Shutdown Pin Current
V+
0
–50 –25
125
100
1210 G10
30
AV = 1
RL = ∞
5
80
AV = 2
RL = ∞
VS = ±15V
VOUT = 20VP-P
70
60
50
40
30
100k
1M
10M
FREQUENCY (Hz)
100M
1210 G17
20
10k
100k
1M
FREQUENCY (Hz)
10M
1210 G18
LT1210
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TYPICAL PERFOR A CE CHARACTERISTICS
Output Impedance in Shutdown
vs Frequency
Output Impedance vs Frequency
10k
OUTPUT IMPEDANCE (Ω)
10
RSD = 82.5k
RSD = 0Ω
1
0.1
0.01
100k
10M
1M
FREQUENCY (Hz)
100M
18
LARGE-SIGNAL VOLTAGE GAIN (dB)
VS = ±15V
IO = 0mA
1k
100
10
1
100k
10M
1M
FREQUENCY (Hz)
3rd Order Intercept vs Frequency
56
52
AV = 4, RL = 10Ω
RF = 680Ω, RG = 220Ω
VS = ±15V, VIN = 5VP-P
12
9
6
3
0
103
104
105
106
FREQUENCY (Hz)
107
108
1210 G21
Test Circuit for 3rd Order Intercept
VS = ±15V
RL = 10Ω
RF = 680Ω
RG = 220Ω
54
100M
15
1210 G20
1210 G19
3RD ORDER INTERCEPT (dBm)
OUTPUT IMPEDANCE (Ω)
100
Large-Signal Voltage Gain vs
Frequency
+
LT1210
50
PO
–
48
680Ω
46
220Ω
44
10Ω
MEASURE INTERCEPT AT PO
42
1210 TC01
40
0
2
4
6
FREQUENCY (MHz)
8
10
1210 G22
7
LT1210
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S I FOR ATIO
The LT1210 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 less
than 1dB of peaking 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 1dB of peaking and a dashed line when the
response has 1dB to 5dB of peaking. The curves stop
where the response has more than 5dB of peaking.
14
VS = ±15V
CL = 200pF
12
RF = 3.4k
NO COMPENSATION
10
VOLTAGE GAIN (dB)
APPLICATI
8
RF = 1.5k
COMPENSATION
6
4
2
0
–2
RF = 3.4k
COMPENSATION
–4
–6
1
10
FREQUENCY (MHz)
100
1210 F01
Figure 1
tance. Also shown is the – 3dB bandwidth with the suggested feedback resistor vs the load capacitance.
For resistive loads, the COMP pin should be left open (see
Capacitive Loads section).
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 10Ω
load, the bandwidth drops from 35MHz to 26MHz when
the compensation is connected. Hence, the compensation
was made optional. To disconnect the optional compensation, leave the COMP pin open.
Capacitive Loads
Shutdown/Current Set
The LT1210 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 6dB 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 greatly reduces the peaking. A lower value feedback
resistor can now be used, resulting in a response which is
flat to ±1dB to 40MHz. The network has the greatest effect
for CL in the range of 0pF to 1000pF. The graphs of
Bandwidth and Feedback Resistance vs Capacitive Load
can be used to select the appropriate value of feedback
resistor. The values shown are for 1dB 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 capaci-
If the shutdown feature is not used, the SHUTDOWN pin
must be connected to ground or V –.
8
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 LT1210 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 70pF capacitor and the supply current is typically less
than 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
LT1210. The switching time between the active and shutdown states is about 1µs. A 24k pull-up resistor speeds
LT1210
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15V
VIN
+
VOUT
LT1210
– SD
response. The quiescent current can be reduced to 9mA 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
–15V
5V
74C906
RG
24k
15V
ENABLE
1210 F02
Figure 2. Shutdown Interface
RF = 750Ω
RL = 10Ω
IQ = 9mA, 18mA, 36mA
VS = ±15V
1210 F04a
Figure 4a. Large-Signal Response vs IQ, AV = –1
ENABLE
VOUT
up the turn-off time and ensures that the LT1210 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.
RF = 750Ω
RL = 10Ω
AV = 1
RF = 825Ω
RL = 50Ω
RPULL-UP = 24k
VIN = 1V P-P
VS = ±15V
1210 F03
IQ = 9mA, 18mA, 36mA
VS = ±15V
1210 F04b
Figure 4b. Large-Signal Response vs IQ, AV = 2
Slew Rate
Figure 3. Shutdown Operation
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 65
times the current in the Shutdown pin. The voltage across
the resistor in this condition is V + – 3VBE. For example, a
82k resistor will set the quiescent supply current to 9mA
with VS = ±15V.
The photos in Figures 4a and 4b show the effect of
reducing the quiescent supply current on the large-signal
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
9
LT1210
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the bandwidth is reduced. The photos in Figures 5a, 5b and
5c show the large-signal response of the LT1210 for
various gain configurations. The slew rate varies from
770V/µs for a gain of 1, to 1100V/µs for a gain of – 1.
RF = 825Ω
RL = 10Ω
VS = ±15V
When the LT1210 is used to drive capacitive loads, the
available output current can limit the overall slew rate. In
the fastest configuration, the LT1210 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 150V/µs, determined by the current limit of
1.5A.
1210 F05a
Figure 5a. Large-Signal Response, AV = 1
RF = RG = 3k
RL = ∞
VS = ±15V
1210 F06
Figure 6. Large-Signal Response, CL = 10,000pF
Differential Input Signal Swing
RF = RG = 750Ω
RL = 10Ω
VS = ±15V
1210 F05b
Figure 5b. Large-Signal Response, AV = –1
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 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 = RG = 750Ω
RL = 10Ω
VS = ±15V
1210 F05c
Figure 5c. Large-Signal Response, AV = 2
10
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.
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Power Supplies
The LT1210 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.
Power Supply Bypassing
To obtain the maximum output and the minimum distortion from the LT1210, the power supply rails should be
well bypassed. For example, with the output stage pouring
1A current peaks into the load, a 1Ω power supply impedance will cause a droop of 1V, reducing the available
output swing by that amount. Surface mount tantalum and
ceramic capacitors make excellent low ESR bypass elements when placed close to the chip. For frequencies
above 100kHz, use 1µF and 100nF ceramic capacitors.
If significant power must be delivered below 100kHz,
capacitive reactance becomes the limiting factor. Larger
ceramic or tantalum capacitors, such as 4.7µF, are recommended in place of the 1µF unit mentioned above.
Inadequate bypassing is evidenced by reduced output
swing and “distorted” clipping effects when the output is
driven to the rails. If this is observed, check the supply pins
of the device for ripple directly related to the output
waveform. Significant supply modulation indicates poor
bypassing.
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
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 2 oz 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
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
*Tab of device attached to topside copper
Thermal Considerations
The LT1210 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.
Table 2. Fused 16-Lead SO Package
COPPER AREA
TOPSIDE
BACKSIDE
2500 sq. mm
1000 sq. mm
600 sq. mm
180 sq. mm
180 sq. mm
180 sq. mm
180 sq. mm
180 sq. mm
180 sq. mm
2500 sq. mm
2500 sq. mm
2500 sq. mm
2500 sq. mm
1000 sq. mm
600 sq. mm
300 sq. mm
100 sq. mm
0 sq. mm
BOARD AREA
THERMAL RESISTANCE
(JUNCTION-TO-AMBIENT)
5000 sq. mm
3500 sq. mm
3100 sq. mm
2680 sq. mm
1180 sq. mm
780 sq. mm
480 sq. mm
280 sq. mm
180 sq. mm
40°C/W
46°C/W
48°C/W
49°C/W
56°C/W
58°C/W
59°C/W
60°C/W
61°C/W
11
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5V
T7 Package, 7-Lead TO-220
Thermal Resistance (Junction-to-Case) = 5°C/W
76mA
A
Calculating Junction Temperature
The junction temperature can be calculated from the
equation:
+
LT1210
–
TJ = (PD)(θJA) + TA
2V
0V
–2V
VO
SD
10Ω
VO = 1.4VRMS
where:
TJ = Junction Temperature
TA = Ambient Temperature
PD = Device Dissipation
θJA = Thermal Resistance (Junction-to-Ambient)
–5V
220Ω
680Ω
1210 F07
Figure 7
then:
As an example, calculate the junction temperature for the
circuit in Figure 7 for the SO and R packages assuming a
70°C ambient temperature.
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.
TJ = (0.56W)(46°C/W) + 70°C = 96°C
for the SO package with 1000 sq. mm topside
heat sinking
TJ = (0.56W)(27°C/W) + 70°C = 85°C
for the R package with 1000 sq. mm topside heat
sinking
Since the maximum junction temperature is 150°C,
both packages are clearly acceptable.
PD = (76mA)(10V) – (1.4V)2/ 10 = 0.56W
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TYPICAL APPLICATIONS
Precision × 10 High Current Amplifier
VIN
CMOS Logic to Shutdown Interface
15V
+
+
LT1097
LT1210
COMP
– SD
–
+
OUT
LT1210
SD
0.01µF
–
500pF
3k
330Ω
24k
5V
–15V
10k
2N3904
9.09k
OUTPUT OFFSET: < 500µV
SLEW RATE: 2V/µs
BANDWIDTH: 4MHz
STABLE WITH CL < 10nF
12
1210 TA04
1k
1210 TA03
LT1210
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TYPICAL APPLICATIONS
Buffer AV = 1
Distribution Amplifier
+
VIN
75Ω
75Ω
+
VIN
75Ω CABLE
LT1210
COMP
SD
LT1210
SD
–
–
75Ω
RF
VOUT
0.01µF*
75Ω
RF**
* OPTIONAL, USE WITH CAPACITIVE LOADS
** VALUE OF R F DEPENDS ON SUPPLY
VOLTAGE AND LOADING. SELECT
FROM TYPICAL AC PERFORMANCE
TABLE OR DETERMINE EMPIRICALLY
RG
1210 TA06
75Ω
1210 TA05
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
Q7
Q13
V–
1210 SS
13
LT1210
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PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
R Package
7-Lead Plastic DD Pak
(LTC DWG # 05-08-1462)
0.256
(6.502)
0.060
(1.524)
0.060
(1.524)
TYP
0.390 – 0.415
(9.906 – 10.541)
0.165 – 0.180
(4.191 – 4.572)
0.045 – 0.055
(1.143 – 1.397)
15° TYP
0.060
(1.524)
0.183
(4.648)
0.059
(1.499)
TYP
0.330 – 0.370
(8.382 – 9.398)
(
+0.203
0.102 –0.102
BOTTOM VIEW OF DD PAK
HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
(
+0.012
0.143 –0.020
+0.305
3.632 –0.508
0.040 – 0.060
(1.016 – 1.524)
0.026 – 0.036
(0.660 – 0.914)
)
0.013 – 0.023
(0.330 – 0.584)
0.050 ± 0.012
(1.270 ± 0.305)
R (DD7) 0396
S Package
16-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.386 – 0.394*
(9.804 – 10.008)
16
15
14
13
12
11
10
9
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
5
0.053 – 0.069
(1.346 – 1.752)
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.014 – 0.019
(0.355 – 0.483)
6
7
8
0.004 – 0.010
(0.101 – 0.254)
0° – 8° TYP
0.016 – 0.050
0.406 – 1.270
14
)
0.095 – 0.115
(2.413 – 2.921)
0.075
(1.905)
0.300
(7.620)
+0.008
0.004 –0.004
0.050
(1.270)
TYP
S16 0695
LT1210
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PACKAGE DESCRIPTION
Dimensions in inches (millimeters) unless otherwise noted.
T7 Package
7-Lead Plastic TO-220 (Standard)
(LTC DWG # 05-08-1422)
0.390 – 0.415
(9.906 – 10.541)
0.165 – 0.180
(4.293 – 4.572)
0.147 – 0.155
(3.734 – 3.937)
DIA
0.045 – 0.055
(1.143 – 1.397)
0.230 – 0.270
(5.842 – 6.858)
0.460 – 0.500
(11.684 – 12.700)
0.570 – 0.620
(14.478 – 15.748)
0.330 – 0.370
(8.382 – 9.398)
0.620
(15.75)
TYP
0.700 – 0.728
(17.780 – 18.491)
0.152 – 0.202
0.260 – 0.320 (3.860 – 5.130)
(6.604 – 8.128)
0.040 – 0.060
(1.016 – 1.524)
0.095 – 0.115
(2.413 – 2.921)
0.013 – 0.023
(0.330 – 0.584)
0.026 – 0.036
(0.660 – 0.914)
0.135 – 0.165
(3.429 – 4.191)
0.155 – 0.195
(3.937 – 4.953)
T7 (TO-220) (FORMED) 0695
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
LT1210
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TYPICAL APPLICATION
Wideband 9W Bridge Amplifier
15V
INPUT
5VP-P
Frequency Response
+
LT1210
SD
–
PO
9W
26
T1*
10nF
1
RL
50Ω
9W
23
20
1
17
GAIN (dB)
680Ω
–15V
1
100nF
220Ω
910Ω
+
LT1210
SD
–
11
8
5
1
15V
14
1
1
2
–1
–4
10k
100k
10nF
1M
10M
FREQUENCY (Hz)
100M
1210 TA08
* COILTRONICS Versa-PacTM CTX-01-13033-X2
OR EQUIVALENT
1210 TA07
–15V
Versa-Pac is a trademark of Coiltronics, Inc.
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1010
Fast ±150mA Power Buffer
20MHz Bandwidth, 75V/µs Slew Rate
LT1166
Power Output Stage Automatic Bias System
Sets Class AB Bias Currents for High Voltage/High Power
Output Stages
LT1206
Single 250mA, 60MHz Current Feedback Amplifier
Shutdown Function, Stable with CL = 10,000pF, 900V/µs
Slew Rate
LT1207
Dual 250mA, 60MHz Current Feedback Amplifier
Dual Version of LT1206
LT1227
Single 140MHz Current Feedback Amplifier
Shutdown Function, 1100V/µs Slew Rate
LT1360
Single 50MHz, 800V/µs Op Amp
Voltage Feedback, Stable with CL = 10,000pF
LT1363
Single 70MHz, 1000V/µs Op Amp
Voltage Feedback, Stable with CL = 10,000pF
16
Linear Technology Corporation
LT/GP 0796 7K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977
 LINEAR TECHNOLOGY CORPORATION 1996