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LT1210 1.1A, 35MHz Current Feedback Amplifier
FEATURES
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DESCRIPTIO
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1.1A Minimum Output Drive Current 35MHz Bandwidth, AV = 2, RL = 10 900V/s Slew Rate, AV = 2, RL = 10 High Input Impedance: 10M Wide Supply Range: 5V to 15V (TO-220 and DD Packages) Enhanced JA SO-16 Package for 5V Operation Shutdown Mode: IS < 200A Adjustable Supply Current Stable with CL = 10,000pF
APPLICATIONS
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Cable Drivers Buffers Test Equipment Amplifiers Video Amplifiers ADSL Drivers
The LT (R)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.
TYPICAL APPLICATIO S
Twisted Pair Driver
15V
Total Harmonic Distortion vs Frequency
+
TOTAL HARMONIC DISTORTION (dB) 4.7F* 100nF RT 11 2.5W
-50 VS = 15V VOUT = 20VP-P AV = 4
-60
VIN
+
LT1210 SD
T1** RL 100 2.5W
-70 RL = 12.5 -80 RL = 10 RL = 50 -90
-
4.7F* -15V 100nF 845
1
3
* TANTALUM ** MIDCOM 671-7783 OR EQUIVALENT 274
1210 TA01
-100 1k 10k 100k FREQUENCY (Hz) 1M
1210 TA02
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1
LT1210 ABSOLUTE AXI U RATI GS
Operating Temperature Range ............... -40C to 85C Junction Temperature ......................................... 150C Storage Temperature Range ................. - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C Supply Voltage ..................................................... 18V Input Current .................................................... 15mA Output Short-Circuit Duration (Note 1) ....... Continuous Specified Temperature Range (Note 2) ...... 0C to 70C
PACKAGE/ORDER INFORMATION
TOP VIEW V+ 1 2 16 V + 15 NC 14 V - 13 COMP 12 SHUTDOWN 11 +IN 10 NC 9 V+ V+
FRONT VIEW 7 6 5 4 3 2 1 OUT V- COMP V+ SHUTDOWN +IN -IN
OUT 3 V+ 4 NC 5 -IN 6 NC 7 V+ 8
TAB IS V +
R PACKAGE 7-LEAD PLASTIC DD
JA 25C/W
S PACKAGE 16-LEAD PLASTIC SO
JA 40C/W (Note 3)
ORDER PART NUMBER LT1210CR
Consult factory for Industrial and Military grade parts.
ORDER PART NUMBER LT1210CS
ELECTRICAL CHARACTERISTICS
VCM = 0V, 5V VS 15V, pulse tested, VSD = 0V, unless otherwise noted.
SYMBOL VOS PARAMETER Input Offset Voltage Input Offset Voltage Drift IIN+ IIN- en + in - in RIN CIN Noninverting Input Current Inverting Input Current Input Noise Voltage Density Input Noise Current Density Input Noise Current Density Input Resistance Input Capacitance Input Voltage Range TA = 25C
q
CONDITIONS TA = 25C
q q
TA = 25C
q
f = 10kHz, RF = 1k, RG = 10, RS = 0 f = 10kHz, RF = 1k, RG = 10, RS = 10k f = 10kHz, RF = 1k, RG = 10, RS = 10k VIN = 12V, VS = 15V VIN = 2V, VS = 5V VS = 15V VS = 15V VS = 5V
q q q q
2
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FRONT VIEW 7 6 5 4 3 2 1 T7 PACKAGE 7-LEAD TO-220
JC = 5C/W
TAB IS V +
OUT V- COMP V+ SHUTDOWN +IN -IN
ORDER PART NUMBER LT1210CT7
MIN
TYP 3 10 2 10 3.0 2.0 40
MAX 15 20 5 20 60 100
UNITS mV mV V/C A A A A nV/Hz pA/Hz pA/Hz M M pF V V
1.50 0.25 12 2
10 5 2 13.5 3.5
LT1210
ELECTRICAL CHARACTERISTICS
VCM = 0V, 5V VS 15V, pulse tested, VSD = 0V, unless otherwise noted.
SYMBOL CMRR PARAMETER Common Mode Rejection Ratio Inverting Input Current Common Mode Rejection PSRR Power Supply Rejection Ratio Noninverting Input Current Power Supply Rejection Inverting Input Current Power Supply Rejection AV Large-Signal Voltage Gain CONDITIONS VS = 15V, VCM = 12V VS = 5V, VCM = 2V VS = 15V, VCM = 12V VS = 5V, VCM = 2V VS = 5V to 15V VS = 5V to 15V VS = 5V to 15V TA = 25C, VS = 15V, VOUT = 10V, RL = 10 (Note 3) VS = 15V, VOUT = 8.5V, RL = 10 (Note 3) VS = 5V, VOUT = 2V, RL = 10 ROL Transresistance, VOUT/IIN- TA = 25C, VS = 15V, VOUT = 10V, RL = 10 (Note 3) VS = 15V, VOUT = 8.5V, RL = 10 (Note 3) VS = 5V, VOUT = 2V, RL = 10 VOUT Maximum Output Voltage Swing TA = 25C, VS = 15V, RL = 10 (Note 3)
q q q q q q q q q q q q
MIN 55 50
TYP 62 60 0.1 0.1
MAX
UNITS dB dB
10 10 500 5
A/V A/V dB nA/V A/V dB dB dB k k k V V V V A
60
77 30 0.7
55 55 55 100 75 75 10.0 8.5 2.5 2.0 1.1
71 68 68 260 200 200 11.5 3.0 2.0 35 50 65 30 200 10
TA = 25C, VS = 5V, RL = 10
q
IOUT IS
Maximum Output Current (Note 3) Supply Current (Note 3) Supply Current, RSD = 51k (Notes 3, 4) Positive Supply Current, Shutdown Output Leakage Current, Shutdown
VS = 15V, RL = 1 TA = 25C, VS = 15V, VSD = 0V
q q
mA mA mA A A V/s V/s % DEG MHz MHz
TA = 25C, VS = 15V VS = 15V, VSD = 15V VS = 15V, VSD = 15V TA = 25C, AV = 2, RL = 400 TA = 25C, AV = 2, RL = 10 VS = 15V, RF = 750, RG = 750, RL = 15 VS = 15V, RF = 750, RG = 750, RL = 15 AV = 2, VS = 15V, Peaking 1dB, RF = RG = 680, RL = 100 AV = 2, VS = 15V, Peaking 1dB, RF = RG = 576, RL = 10
q q
15
SR
Slew Rate (Note 5) Slew Rate (Note 3) Differential Gain (Notes 3, 6) Differential Phase (Notes 3, 6)
400
900 900 0.3 0.1 55 35
BW
Small-Signal Bandwidth
The q denotes specifications which apply for 0C TA 70C. 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 - 40C TA 85C, but are neither tested nor guaranteed beyond 0C TA 70C. Industrial grade parts tested over - 40C TA 85C 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
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 = 400. Note 6: NTSC composite video with an output level of 2V.
3
LT1210
SMALL-SIGNAL BANDWIDTH
RSD = 0, IS = 30mA, VS = 5V, Peaking 1dB
AV -1 RL 150 30 10 150 30 10 150 30 10 150 30 10 RF 549 590 619 604 649 619 562 590 576 392 383 215 RG 549 590 619 - - - 562 590 576 43.2 42.2 23.7 - 3dB BW (MHz) 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
AV -1 RL 150 30 10 150 30 10 150 30 10 150 30 10 RF 562 619 604 634 681 649 576 604 576 324 324 210 RG 562 619 604 - - - 576 604 576 35.7 35.7 23.2 - 3dB BW (MHz) 39.7 28.9 20.5 41.9 29.7 20.7 40.2 29.6 21.6 39.5 32.3 27.7
1
2
10
RSD = 15k, IS = 7.5mA, VS = 5V, Peaking 1dB
AV -1 RL 150 30 10 150 30 10 150 30 10 150 30 10 RF 536 549 464 619 634 511 536 549 412 150 118 100 RG 536 549 464 - - - 536 549 412 16.5 13.0 11.0 - 3dB BW (MHz) 28.2 20.0 15.0 28.6 19.8 14.9 28.3 19.9 15.7 31.5 27.1 19.4
1
2
10
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RSD = 0, IS = 35mA, VS = 15V, Peaking 1dB
AV -1 RL 150 30 10 150 30 10 150 30 10 150 30 10 RF 604 649 665 750 866 845 665 715 576 453 432 221 RG 604 649 665 - - - 665 715 576 49.9 47.5 24.3 - 3dB BW (MHz) 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
RSD = 47.5k, IS = 18mA, VS = 15V, Peaking 1dB
AV -1 RL 150 30 10 150 30 10 150 30 10 150 30 10 RF 619 698 698 732 806 768 634 698 681 348 357 205 RG 619 698 698 - - - 634 698 681 38.3 39.2 22.6 - 3dB BW (MHz) 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 150 30 10 150 30 10 150 30 10 150 30 10 RF 590 649 576 715 768 649 590 665 549 182 182 100 RG 590 649 576 - - - 590 665 549 20.0 20.0 11.0 - 3dB BW (MHz) 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
TYPICAL PERFOR A CE CHARACTERISTICS
Bandwidth vs Supply Voltage
100 90 PEAKING 1dB PEAKING 5dB RF = 470 RF = 560 RF = 750 RF = 680 RF = 1k RF = 1.5k AV = 2 RL = 100 -3dB BANDWIDTH (MHz)
FEEDBACK RESISTANCE ()
- 3dB BANDWIDTH (MHz)
80 70 60 50 40 30 20 10 0 4 6 14 12 10 8 SUPPLY VOLTAGE (V) 16 18
Bandwidth vs Supply Voltage
100 90
-3dB BANDWIDTH (MHz)
50
PEAKING 1dB PEAKING 5dB
AV = 10 RL = 100
- 3dB BANDWIDTH (MHz)
40
FEEDBACK RESISTANCE ()
80 70 60 50 40 30 20 10 0 4 6 14 12 10 8 SUPPLY VOLTAGE (V) 16 18 RF = 1.5k RF =390 RF = 330
RF = 470 RF = 680
Differential Phase vs Supply Voltage
0.6 0.5 0.4 0.3 0.2 0.1 0 RF = RG = 750 AV = 2 RL = 15 RL = 50 RL = 30 RL = 10
DIFFERENTIAL PHASE (DEG)
0.4
DIFFERENTIAL GAIN (%)
RL = 10 0.3 RL = 15
SPOT NOISE (nV/Hz OR pA/Hz)
5
7
11 13 9 SUPPLY VOLTAGE (V)
UW
1210 G01
Bandwidth vs Supply Voltage
50 PEAKING 1dB PEAKING 5dB 40 RF = 560 30 RF = 750 RF = 1k AV = 2 RL = 10
10k
Bandwidth and Feedback Resistance vs Capacitive Load for Peaking 1dB
100 BANDWIDTH
-3dB BANDWIDTH (MHz)
1k FEEDBACK RESISTANCE AV = 2 RL = VS = 15V CCOMP = 0.01F 1 10 100 1000 CAPACITIVE LOAD (pF)
10
20
10
RF = 2k
0 4 6 14 12 10 8 SUPPLY VOLTAGE (V) 16 18
100
1 10000
1210 G03
1210 G02
Bandwidth vs Supply Voltage
10k
Bandwidth and Feedback Resistance vs Capacitive Load for Peaking 5dB
100 BANDWIDTH
PEAKING 1dB
AV = 10 RL = 10
-3dB BANDWIDTH (MHz)
30 RF = 680 20 RF = 560 RF = 1k RF = 1.5k
1k
FEEDBACK RESISTANCE AV = +2 RL = VS = 15V CCOMP = 0.01F 1 10 100 1000 CAPACITIVE LOAD (pF)
10
10
0 4 6 14 12 10 8 SUPPLY VOLTAGE (V) 16 18
100 0
1 10000
1210 G06
1210 G04
1210 G05
Differential Gain vs Supply Voltage
0.5 RF = RG = 750 AV = 2
100
Spot Noise Voltage and Current vs Frequency
- in
10
0.2
en +in 1 10 100 1k 10k FREQUENCY (Hz) 100k
1210 G09
0.1
RL = 50
RL = 30 15
1210 G08
0
15
1210 G07
5
7
11 13 9 SUPPLY VOLTAGE (V)
5
LT1210
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage
40 38 36
SUPPLY CURRENT (mA)
RSD = 0 TA = 25C
SUPPLY CURRENT (mA)
34 32 30 28 26 24 22 20 4 6
TA = 85C
25 20 15 10 5 0 -50 -25
SUPPLY CURRENT (mA)
TA = -40C TA = 125C
12 14 8 10 SUPPLY VOLTAGE (V)
Supply Current vs Shutdown Pin Current
40 VS = 15V 35
- 0.5 COMMON MODE RANGE (V) -1.0 -1.5 -2.0 2.0 1.5 1.0 0.5
OUTPUT SHORT-CIRCUIT CURRENT (A)
SUPPLY CURRENT (mA)
30 25 20 15 10 5 0 0 100 300 400 200 SHUTDOWN PIN CURRENT (A) 500
1210 G13
Output Saturation Voltage vs Junction Temperature
V+
OUTPUT SATURATION VOLTAGE (V)
-1 -2 -3 -4
VS = 15V
RL = 2k RL = 10 POWER SUPPLY REJECTION (dB)
60 NEGATIVE 50 40 30 20 10 0 10k POSITIVE
SUPPLY CURRENT (mA)
4 3 2 1 V- -50 -25
RL = 10
RL = 2k
0 25 50 75 TEMPERATURE (C)
6
UW
16 18
1210 G10
Supply Current vs Ambient Temperature, VS = 5V
40 35 30 RSD = 7.5k RSD = 0 AV = 1 RL = 40 35 30 25 20 15
Supply Current vs Ambient Temperature, VS = 15V
RSD = 0
RSD = 47.5k
RSD = 15k
RSD = 82.5k 10 5 AV = 1 RL = 50 25 0 75 TEMPERATURE (C) 100 125
50 25 0 75 TEMPERATURE (C)
100
125
0 -50 -25
1210 G11
1210 G12
Input Common Mode Limit vs Junction Temperature
V+
Output Short-Circuit Current vs Junction Temperature
3.0 2.8 2.6 SINKING 2.4 2.2 2.0 1.8 1.6 -50 -25 SOURCING
V- -50
-25
0 25 50 75 TEMPERATURE (C)
100
125
50 25 75 0 TEMPERATURE (C)
100
125
1210 G14
1210 G15
Power Supply Rejection Ratio vs Frequency
70 RL = 50 VS = 15V RF = RG = 1k
Supply Current vs Large-Signal Output Frequency (No Load)
100 90 80 70 60 50 40 30 AV = 2 RL = VS = 15V VOUT = 20VP-P
100
125
100k
1M 10M FREQUENCY (Hz)
100M
1210 G17
20 10k
100k 1M FREQUENCY (Hz)
10M
1210 G18
1210 G16
LT1210
TYPICAL PERFOR A CE CHARACTERISTICS
Output Impedance vs Frequency
100 VS = 15V IO = 0mA OUTPUT IMPEDANCE ()
LARGE-SIGNAL VOLTAGE GAIN (dB)
OUTPUT IMPEDANCE ()
10 RSD = 82.5k 1 RSD = 0
0.1
0.01 100k
10M 1M FREQUENCY (Hz)
3rd Order Intercept vs Frequency
56 54
3RD ORDER INTERCEPT (dBm)
52 50 48 46
44 42
40
0
2
UW
1210 G19
Output Impedance in Shutdown vs Frequency
10k
18 15 12 9 6 3
Large-Signal Voltage Gain vs Frequency
AV = 4, RL = 10 RF = 680, RG = 220 VS = 15V, VIN = 5VP-P
1k
100
10
100M
1 100k
10M 1M FREQUENCY (Hz)
100M
1210 G20
0 103
104
105 106 FREQUENCY (Hz)
107
108
1210 G21
Test Circuit for 3rd Order Intercept
VS = 15V RL = 10 RF = 680 RG = 220
+
LT1210 PO
-
680 220 MEASURE INTERCEPT AT PO
1210 TC01
10
4 6 FREQUENCY (MHz)
8
10
1210 G22
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LT1210
APPLICATI 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. For resistive loads, the COMP pin should be left open (see Capacitive Loads section). Capacitive Loads 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 0.01F 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-
VOLTAGE GAIN (dB)
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1210 F01
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VS = 15V CL = 200pF
RF = 3.4k NO COMPENSATION
RF = 1.5k COMPENSATION
RF = 3.4k COMPENSATION
Figure 1
tance. Also shown is the - 3dB bandwidth with the suggested feedback resistor vs the load capacitance. 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 10 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. Shutdown/Current Set 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 200A, 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 100A. 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 1s. A 24k pull-up resistor speeds
LT1210
APPLICATI S I FOR ATIO
15V VIN
+
LT1210 VOUT RF -15V
- SD
5V 74C906 ENABLE 24k 15V RG
1210 F02
Figure 2. Shutdown Interface
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 500A. Figure 3 shows the resulting waveforms.
ENABLE
VOUT
AV = 1 RF = 825 RL = 50
RPULL-UP = 24k VIN = 1V P-P VS = 15V
1210 F03
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
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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 = 750 RL = 10 IQ = 9mA, 18mA, 36mA VS = 15V
1210 F04a
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Figure 4a. Large-Signal Response vs IQ, AV = -1
RF = 750 RL = 10
IQ = 9mA, 18mA, 36mA VS = 15V
1210 F04b
Figure 4b. Large-Signal Response vs IQ, AV = 2
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
9
LT1210
APPLICATI
S I FOR ATIO
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/s for a gain of 1, to 1100V/s for a gain of - 1.
RF = 825 RL = 10
VS = 15V
1210 F05a
Figure 5a. Large-Signal Response, AV = 1
VS = 15V
RF = RG = 750 RL = 10
VS = 15V
1210 F05b
Figure 5b. Large-Signal Response, AV = -1
RF = RG = 750 RL = 10
VS = 15V
1210 F05c
Figure 5c. Large-Signal Response, AV = 2
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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/s, determined by the current limit of 1.5A.
RF = RG = 3k RL =
1210 F06
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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 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 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.
LT1210
APPLICATI
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 500V per volt of supply mismatch. The inverting bias current can change as much as 5A per volt of supply mismatch, though typically the change is less than 0.5A 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 1 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 1F 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 4.7F, are recommended in place of the 1F 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. 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.
S I FOR ATIO
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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 2500 sq. mm 2500 sq. mm 1000 sq. mm 2500 sq. mm 125 sq. mm 2500 sq. mm THERMAL RESISTANCE BOARD AREA (JUNCTION-TO-AMBIENT) 2500 sq. mm 2500 sq. mm 2500 sq. mm 25C/W 27C/W 35C/W *Tab of device attached to topside copper
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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 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 THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 40C/W 46C/W 48C/W 49C/W 56C/W 58C/W 59C/W 60C/W 61C/W
11
LT1210
APPLICATI S I FOR ATIO
T7 Package, 7-Lead TO-220 Thermal Resistance (Junction-to-Case) = 5C/W
Calculating Junction Temperature The junction temperature can be calculated from the equation: TJ = (PD)(JA) + TA where: TJ = Junction Temperature TA = Ambient Temperature PD = Device Dissipation JA = Thermal Resistance (Junction-to-Ambient) As an example, calculate the junction temperature for the circuit in Figure 7 for the SO and R packages assuming a 70C 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. PD = (76mA)(10V) - (1.4V)2/ 10 = 0.56W
220 -5V 680
1210 F07
TYPICAL APPLICATIONS
Precision x 10 High Current Amplifier
+
LT1097
VIN
+
LT1210 COMP - SD 500pF 330 3k
5V 10k
-
0.01F
9.09k OUTPUT OFFSET: < 500V SLEW RATE: 2V/s BANDWIDTH: 4MHz STABLE WITH CL < 10nF 1k
1210 TA03
12
U
5V
W
U
U
UO
A
76mA
+
LT1210 SD
VO
-
2V 0V -2V 10 VO = 1.4VRMS
Figure 7
then: TJ = (0.56W)(46C/W) + 70C = 96C for the SO package with 1000 sq. mm topside heat sinking TJ = (0.56W)(27C/W) + 70C = 85C for the R package with 1000 sq. mm topside heat sinking Since the maximum junction temperature is 150C, both packages are clearly acceptable.
CMOS Logic to Shutdown Interface
15V
OUT
+ -
LT1210 SD 24k
-15V 2N3904
1210 TA04
LT1210
TYPICAL APPLICATIONS
Distribution Amplifier
VIN 75
+ -
LT1210 SD RF
RG 75
1210 TA05
SI PLIFIED SCHE ATIC
TO ALL CURRENT SOURCES Q2 Q18 Q17 1.25k +IN -IN Q1
SHUTDOWN V+
U
Buffer AV = 1
+ -
LT1210 COMP SD VOUT 0.01F* * OPTIONAL, USE WITH CAPACITIVE LOADS ** VALUE OF R F DEPENDS ON SUPPLY VOLTAGE AND LOADING. SELECT FROM TYPICAL AC PERFORMANCE TABLE OR DETERMINE EMPIRICALLY
1210 TA06
75
75 CABLE
VIN
75 75
RF**
W
W
V+
Q5 D1 Q6 Q9 V- RC Q15
Q10 Q11
V- CC
50 COMP OUTPUT
V+ Q12 Q8 Q4 Q7 D2 Q13 Q16 Q14
Q3
V-
1210 SS
13
LT1210
PACKAGE DESCRIPTION
0.256 (6.502)
0.060 (1.524)
0.060 (1.524)
0.183 (4.648)
0.075 (1.905) 0.300 (7.620) BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED COPPER HEAT SINK +0.012 0.143 -0.020 0.040 - 0.060 (1.016 - 1.524) 0.026 - 0.036 (0.660 - 0.914) 0.013 - 0.023 (0.330 - 0.584)
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
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 0.254) 0 - 8 TYP
0.016 - 0.050 0.406 - 1.270 *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
14
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Dimensions in inches (millimeters) unless otherwise noted. R Package 7-Lead Plastic DD Pak
(LTC DWG # 05-08-1462)
0.060 (1.524) TYP
0.390 - 0.415 (9.906 - 10.541) 15 TYP
0.165 - 0.180 (4.191 - 4.572)
0.045 - 0.055 (1.143 - 1.397) +0.008 0.004 -0.004
0.330 - 0.370 (8.382 - 9.398)
0.059 (1.499) TYP
(
+0.203 0.102 -0.102
)
0.095 - 0.115 (2.413 - 2.921) 0.050 0.012 (1.270 0.305)
(
+0.305 3.632 -0.508
)
R (DD7) 0396
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
1 0.053 - 0.069 (1.346 - 1.752)
2
3
4
5
6
7
8
0.004 - 0.010 (0.101 - 0.254)
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) TYP
S16 0695
LT1210
PACKAGE DESCRIPTION
0.390 - 0.415 (9.906 - 10.541)
0.460 - 0.500 (11.684 - 12.700)
0.040 - 0.060 (1.016 - 1.524)
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.
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Dimensions in inches (millimeters) unless otherwise noted.
T7 Package 7-Lead Plastic TO-220 (Standard)
(LTC DWG # 05-08-1422)
0.147 - 0.155 (3.734 - 3.937) DIA 0.230 - 0.270 (5.842 - 6.858) 0.570 - 0.620 (14.478 - 15.748) 0.330 - 0.370 (8.382 - 9.398)
0.165 - 0.180 (4.293 - 4.572)
0.045 - 0.055 (1.143 - 1.397)
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) 0.026 - 0.036 (0.660 - 0.914) 0.135 - 0.165 (3.429 - 4.191)
0.095 - 0.115 (2.413 - 2.921)
0.013 - 0.023 (0.330 - 0.584) 0.155 - 0.195 (3.937 - 4.953)
T7 (TO-220) (FORMED) 0695
15
LT1210
TYPICAL APPLICATION
Wideband 9W Bridge Amplifier
15V INPUT 5VP-P
+ -
LT1210 SD 10nF 1 -15V 680 100nF 220 1 15V 910 1 1 T1* 1
GAIN (dB)
+ -
LT1210 SD 10nF
-15V
* COILTRONICS Versa-PacTM CTX-01-13033-X2 OR EQUIVALENT 1210 TA07
RELATED PARTS
PART NUMBER LT1010 LT1166 LT1206 LT1207 LT1227 LT1360 LT1363 DESCRIPTION Fast 150mA Power Buffer Power Output Stage Automatic Bias System Single 250mA, 60MHz Current Feedback Amplifier Dual 250mA, 60MHz Current Feedback Amplifier Single 140MHz Current Feedback Amplifier Single 50MHz, 800V/s Op Amp Single 70MHz, 1000V/s Op Amp COMMENTS 20MHz Bandwidth, 75V/s Slew Rate Sets Class AB Bias Currents for High Voltage/High Power Output Stages Shutdown Function, Stable with CL = 10,000pF, 900V/s Slew Rate Dual Version of LT1206 Shutdown Function, 1100V/s Slew Rate Voltage Feedback, Stable with CL = 10,000pF Voltage Feedback, Stable with CL = 10,000pF
16
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 q FAX: (408) 434-0507 q TELEX: 499-3977
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Frequency Response
PO 9W
26
RL 50 9W
23 20 17 14 11 8 5
1
2 -1 -4 10k 100k 1M 10M FREQUENCY (Hz) 100M
1210 TA08
Versa-Pac is a trademark of Coiltronics, Inc.
LT/GP 0796 7K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1996

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