Datasheet

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LT1996

1996f

RESISTOR MATCHING (%)

PERCENTAGE OF UNITS (%)

0.04

1996 TA01b

–0.02

0.02

–0.04

LT1996A

G = 81

TYPICAL APPLICATIO

FEATURES

■

Pin Configurable as a Difference Amplifier,

Inverting and Noninverting Amplifier

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Difference Amplifier

Gain Range 9 to 117

CMRR >80dB

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Noninverting Amplifier

Gain Range 0.008 to 118

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Inverting Amplifier

Gain Range –0.08 to –117

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Gain Error: <0.05%

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Gain Drift: < 3ppm/°C

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Wide Supply Range: Single 2.7V to Split ±18V

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Micropower Operation: 100µA Supply

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Input Offset Voltage: 50µV (Max)

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Gain Bandwidth Product: 560kHz

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Rail-to-Rail Output

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Space Saving 10-Lead MSOP and DFN Packages

Precision, 100µA

Gain Selectable Amplifier

The LT

1996 combines a precision operational amplifier

with eight precision resistors to form a one-chip solution

for accurately amplifying voltages. Gains from –117 to

118 with a gain accuracy of 0.05% can be achieved without

any external components. The device is particularly well

suited for use as a difference amplifier, where the excellent

resistor matching results in a common mode rejection

ratio of greater than 80dB.

The amplifier features a 50µV maximum input offset

voltage and a gain bandwidth product of 560kHz. The

device operates from any supply voltage from 2.7V to 36V

and draws only 100µA supply current on a 5V supply. The

output swings to within 40mV of either supply rail.

The internal resistors have excellent matching character-

istics; variation is 0.05% over temperature with a guaran-

teed matching temperature coefficent of less than 3ppm/°C.

The resistors are also extremely stable over voltage,

exhibiting a nonlinearity of less than 10ppm.

The LT1996 is fully specified at 5V and ±15V supplies and

from –40°C to 85°C. The device is available in space

saving 10-lead MSOP and DFN packages. For an amplifier

with selectable gains from –13 to 14, see the LT1991 data

sheet.

DESCRIPTIO

APPLICATIO S

Rail-to-Rail Gain = 9 Difference Amplifier Distribution of Resistor Matching

–

15V

–15V

∆V

M(IN)

P(IN)

–

OUT

= V

REF

+ 9 •

∆V

SWING 40mV TO

EITHER RAIL

INPUT RANGE

±60V

= 100kΩ

LT1996

1996 TA01

450k/81

450k/27

450k/9

450k

450k/9

4pF

REF

, LTC and LT are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners. Patents Pending.

■

Handheld Instrumentation

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Medical Instrumentation

■

Strain Gauge Amplifiers

■

Differential to Single-Ended Conversion

Summary of content (24 pages)

PAGE 1
LT1996 Precision, 100µA Gain Selectable Amplifier U FEATURES DESCRIPTIO ■ The LT®1996 combines a precision operational amplifier with eight precision resistors to form a one-chip solution for accurately amplifying voltages. Gains from –117 to 118 with a gain accuracy of 0.05% can be achieved without any external components. The device is particularly well suited for use as a difference amplifier, where the excellent resistor matching results in a common mode rejection ratio of greater than 80dB.
PAGE 2
LT1996 W W U W ABSOLUTE AXI U RATI GS (Note 1) Total Supply Voltage (V + to V –) ............................... 40V Input Voltage (Pins P9/M9, Note 2) ....................... ±60V Input Current (Pins P27/M27/P81/M81, Note 2) .................. ±10mA Output Short-Circuit Duration (Note 3) ............ Indefinite Operating Temperature Range (Note 4) ...–40°C to 85°C Specified Temperature Range (Note 5) ....–40°C to 85°C Maximum Junction Temperature DD Package .........................................
PAGE 3
LT1996 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. Difference amplifier configuration, VS = 5V, 0V or ±15V; VCM = VREF = half supply, unless otherwise noted. SYMBOL PARAMETER CONDITIONS CMRR Common Mode Rejection Ratio (RTI) VS = ±15V; G = 81; VCM = –14.1V to 13.
PAGE 4
LT1996 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. Difference amplifier configuration, VS = 5V, 0V or ±15V; VCM = VREF = half supply, unless otherwise noted. SYMBOL PARAMETER CONDITIONS TYP MAX UNITS ∆R Resistor Matching (Note 9) G = 81; LT1996AMS G = 27; LT1996AMS G = 9; LT1996AMS ● ● ● MIN ±0.02 ±0.03 ±0.03 ±0.05 ±0.06 ±0.
PAGE 5
LT1996 ELECTRICAL CHARACTERISTICS Note 4: Both the LT1996C and LT1996I are guaranteed functional over the –40°C to 85°C temperature range. Note 5: The LT1996C is guaranteed to meet the specified performance from 0°C to 70°C and is designed, characterized and expected to meet specified performance from –40°C to 85°C but is not tested or QA sampled at these temperatures. The LT1996I is guaranteed to meet specified performance from –40°C to 85°C. Note 6: This parameter is not 100% tested.
PAGE 6
LT1996 U W TYPICAL PERFOR A CE CHARACTERISTICS Output Offset Voltage vs Difference Gain Gain Error vs Load Current 0.04 VS = 5V, 0V REPRESENTATIVE PARTS 7.5 5.0 0 –2.5 0 –0.01 –0.02 –7.5 –0.03 9 18 27 36 45 54 63 72 81 90 99 108 117 GAIN (V/V) REPRESENTATIVE UNITS –0.
PAGE 7
LT1996 U W TYPICAL PERFOR A CE CHARACTERISTICS Gain and Phase vs Frequency 40 VS = 5V, 0V TA = 25°C VS = 5V, 0V TA = 25°C –20 GAIN = 9 –40 PHASE (RIGHT AXIS) 40 GAIN = 81 30 30 GAIN = 27 20 0.01Hz to 1Hz Voltage Noise 0 GAIN (dB) 20 GAIN = 9 –80 GAIN (LEFT AXIS) –100 10 –120 PHASE (deg) GAIN (dB) –60 –140 0 10 –160 –180 0 0.5 1 10 100 FREQUENCY (kHz) 500 –10 0.
PAGE 8
LT1996 W BLOCK DIAGRA 10 M9 9 M27 8 7 M81 450k/81 6 VCC OUT 450k 4pF 450k/27 450k/9 450k/9 – OUT + LT1996 450k/27 450k/81 P9 2 P27 3 P81 450k 4 VEE 5 REF 1996 BD U 1 4pF W U U APPLICATIO S I FOR ATIO Introduction The LT1996 may be the last op amp you ever have to stock. Because it provides you with several precision matched resistors, you can easily configure it into several different classical gain circuits without adding external components.
PAGE 9
LT1996 U W U U APPLICATIO S I FOR ATIO maximum voltage allowed on the input and REF pins. The 50k resistors connected to the M9 and P9 inputs are isolated from the substrate, and can therefore be taken beyond the supply voltages. The naming of the pins “P9,” “P27,” “P81,” etc., is based on their admittances relative to the feedback and REF admittances. Because it has 9 times the admittance, the voltage applied to the P9 input has 9 times the effect of the voltage applied to the REF input.
PAGE 10
LT1996 U U W U APPLICATIO S I FOR ATIO Consider Figure 1. This shows the LT1996 configured as a gain of 117 difference amplifier on a single supply with RF VCC RG – 5V 7 8 450k/81 VEXT VINT 450k + RG VEE 4pF 9 450k/27 10 450k/9 – VDM 0V+ VCM 2.5V VREF RF 1 450k/9 2 450k/27 3 450k/81 Figure 2. Calculating CM Input Voltage Range – 6 VOUT = 117 • VDM + 4pF 450k REF 5 LT1996 4 1996 F02 1996 F01 Figure 1. Difference Amplifier Cannot Produce 0V on a Single Supply.
PAGE 11
LT1996 U U W U APPLICATIO S I FOR ATIO suggested in Figure 1: raise VREF, lower VEE, or provide some negative VMORE. The Classical Noninverting Amplifier: High Input Z representation of the circuit on the top. The LT1996 is shown on the bottom configured in a precision gain of 9.1. One of the benefits of the noninverting op amp configuration is that the input impedance is extremely high. The LT1996 maintains this benefit.
PAGE 12
LT1996 U U W U APPLICATIO S I FOR ATIO VS+ 8 M81 9 M27 10 M9 VIN VS+ 8 M81 9 M27 10 M9 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 6 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 VOUT VIN VS– 6 VOUT VIN 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 6 VS+ VS– 8 M81 9 M27 10 M9 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 VOUT 6 GAIN = 37 VS+ VIN GAIN = 9.
PAGE 13
LT1996 U U W U APPLICATIO S I FOR ATIO Attenuation Using the P Input Resistors Attenuation happens as a matter of fact in difference amplifier configurations, but it is also used for reducing peak signal level or improving input common mode range even in single ended systems. When signal conditioning indicates a need for attenuation, the LT1996 resistors are ready at hand. The four precision resistors can provide several attenuation levels, and these are tabulated in Table 2 as a design reference.
PAGE 14
LT1996 U U W U APPLICATIO S I FOR ATIO Inverting Configuration Table 3. Configuring the M Pins for Simple Inverting Gains The inverting amplifier, shown in Figure 8, is another classical op amp configuration. The circuit is actually identical to the noninverting amplifier of Figure 4, except that VIN and GND have been swapped. The list of available gains is shown in Table 3, and some of the circuits are shown in Figure 9. Noise gain is 1+|Gain|, as is the usual case for inverting amplifiers.
PAGE 15
LT1996 U U W U APPLICATIO S I FOR ATIO VS + 8 M81 9 M27 10 M9 VIN VS + 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 6 8 M81 9 M27 10 M9 VIN 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 VOUT 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 6 VIN VS+ VIN 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 VOUT 6 8 M81 9 M27 10 M9 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 VOUT VS– VS– VS– GAIN = –27 GAIN = –36 GAIN = –8.
PAGE 16
LT1996 U W U U APPLICATIO S I FOR ATIO Difference Amplifiers RF The resistors in the LT1996 allow it to easily make difference amplifiers also. Figure 10 shows the basic 4-resistor difference amplifier and the LT1996. A difference gain of 27 is shown, but notice the effect of the additional dashed connections. By connecting the 50k resistors in parallel, the gain is reduced by a factor of 10. Of course, with so many resistors, there are many possible gains.
PAGE 17
LT1996 U U W U APPLICATIO S I FOR ATIO VS + VIN 8 M81 9 M27 10 M9 – 7 VCC LT1996 VIN 1 P9 2 P27 VEE 3 P81 4 + VS + OUT REF 5 6 VIN – VIN + 8 M81 9 M27 10 M9 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 VOUT VS– VIN+ 7 VCC VIN– LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 6 VIN+ 6 VOUT VIN+ 8 M81 9 M27 10 M9 LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 6 VOUT VS– VS+ 7 VCC 6 VOUT VIN+ 8 M81 9 M27 10 M9 VIN+ VOUT GAIN = 90 VS + VS + VIN– 7 VCC LT1996 OUT 1 REF P9 2 5 P2
PAGE 18
LT1996 U U W U APPLICATIO S I FOR ATIO VIN– RF VIN – VIN+ RG RG CROSSCOUPLING – VOUT + VIN+ + RF 8 450k/81 450k 9 450k/27 10 450k/9 1 450k/9 2 450k/27 4pF 3 450k/81 450k 4pF – 6 VOUT + – VOUT = GAIN • (VIN – VIN ) GAIN = RF/RG 5 LT1996 CLASSICAL DIFFERENCE AMPLIFIER IMPLEMENTED WITH LT1991. RF = 450k, RG = 16.7k, GAIN = 27. GAIN CAN BE ADJUSTED BY "CROSS COUPLING." MAKING THE DASHED CONNECTIONS REDUCE THE GAIN FROM 3 T0 2.
PAGE 19
LT1996 U W U U APPLICATIO S I FOR ATIO High Voltage CM Difference Amplifiers This class of difference amplifier remains to be discussed. Figure 14 shows the basic circuit on the top. The effective input voltage range of the circuit is extended by the fact that resistors RT attenuate the common mode voltage seen by the op amp inputs.
PAGE 20
LT1996 U W U U APPLICATIO S I FOR ATIO 3V 8 M81 9 M27 10 M9 VIN – 3V 7 VCC 6 VOUT LT1996 OUT 1 REF P9 2 5 P27 VEE 1.25V 3 P81 4 VIN + VIN – VIN + VCM = 0.97V TO 1.86V 8 M81 9 M27 10 M9 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 VIN – 1 P9 2 P27 VEE 3 P81 4 VIN + VOUT 6 VOUT OUT REF 5 1.25V VIN – 8 M81 9 M27 10 M9 LT1996 VIN + 1 P9 2 P27 VEE 3 P81 4 6 VOUT OUT REF 5 1.25V 6 VOUT VCM = –.78V TO 1.
PAGE 21
LT1996 U U W U APPLICATIO S I FOR ATIO 5V 8 M81 9 M27 10 M9 VIN – 5V 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 2.5V 3 P81 4 VIN + 6 VIN – VOUT VIN + VCM = –0.83V TO 3.9V 8 M81 9 M27 10 M9 7 VCC LT1996 OUT 1 REF P9 2 5 P27 VEE 3 P81 4 VIN – 1 P9 2 P27 VEE 3 P81 4 VIN + VOUT OUT REF 5 2.5V 6 VIN – VOUT 8 M81 9 M27 10 M9 VIN + 1 P9 2 P27 VEE 3 P81 4 6 VOUT VCM = –0.56V TO 3.
PAGE 22
LT1996 U U W U APPLICATIO S I FOR ATIO 5V 8 M81 9 M27 10 M9 VIN – 5V 7 VCC LT1996 OUT REF 5 1 P9 2 P27 VEE 3 P81 4 VIN + 6 8 M81 9 M27 10 M9 VIN – VOUT 7 VCC LT1996 1 P9 2 P27 VEE 3 P81 4 VIN + –5V 5V VIN – 7 VCC OUT REF 5 1 P9 2 P27 VEE 3 P81 4 2.5V 6 8 M81 9 M27 10 M9 VIN – VOUT 1 P9 2 P27 VEE 3 P81 4 VIN + 1 P9 2 P27 VEE 3 P81 4 OUT REF 5 6 VIN – VOUT LT1996 OUT REF 5 –5V VCM = –52.4V TO 49.8V 6 VIN – VOUT –5V VOUT VCM = –31.4V TO 0.
PAGE 23
LT1996 U PACKAGE DESCRIPTIO DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1699) R = 0.115 TYP 6 0.38 ± 0.10 10 0.675 ±0.05 3.50 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) 3.00 ±0.10 (4 SIDES) PACKAGE OUTLINE 1.65 ± 0.10 (2 SIDES) PIN 1 TOP MARK (SEE NOTE 6) (DD10) DFN 1103 5 0.50 BSC 2.38 ±0.05 (2 SIDES) 2.38 ±0.10 (2 SIDES) 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1.
PAGE 24
LT1996 U TYPICAL APPLICATIO Micropower AV = 90 Instrumentation Amplifier 10 9 8 VOUT 6 450k 450k/81 + VM 7 4pF 450k/27 1/2 LT6011 – 450k/9 – 450k/9 + VP + LT1996 450k 450k/27 1/2 LT6011 450k/81 – 1 2 4pF 3 4 5 1996 TA02 Bidirectional Controlled Current Source AC Coupled Amplifier VS + VIN – VIN + 8 M81 9 M27 10 M9 VS + VS + 8 M81 9 M27 10 M9 7 6 LT1996 5 R1 10k 0.