LT1880CS5#TRM_技术文档

LT1880

SOT-23, Rail-to-Rail Output,

Picoamp Input Current

Precision Op Amp

U

FEATURES

DESCRIPTIO

The LT^®1880 op amp brings high accuracy input perfor-

mance and rail-to-rail output swing to the SOT-23 pack-

age.Inputoffsetvoltageistrimmedtolessthan150µVand

the low drift maintains this accuracy over the operating

temperature range. Input bias current is an ultra low

900pA maximum.

■

Offset Voltage: 150µV Max

■

Input Bias Current: 900pA Max

■

Offset Voltage Drift: 1.2µV/°C Max

■

Rail-to-Rail Output Swing

■

Operates with Single or Split Supplies

■

Open-Loop Voltage Gain: 1 Million Min

■

1.2mA Supply Current

The amplifier works on any total power supply voltage

between 2.7V and 36V (fully specified from 5V to ±15V).

Output voltage swings to within 55mV of the negative

supplyand250mVofthepositivesupply,whichmakesthe

amplifier a good choice for low voltage single supply

operation.

■

Slew Rate: 0.4V/µs

■

Gain Bandwidth: 1.1MHz

■

Low Noise: 13nV/√Hz at 1kHz

Low Profile (1mm) ThinSOT^TMPackage

■

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APPLICATIO S

Slew rates of 0.4V/µs with a supply current of 1.2mA give

superior response and settling time performance in a low

power precision amplifier.

■

Thermocouple Amplifiers

■

Bridge Transducer Conditioners

■

Instrumentation Amplifiers

The LT1880 is available in a 5-lead SOT-23 package.

■

Battery-Powered Systems

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

■

Photocurrent Amplifiers

ThinSOT is a trademark of Linear Technology Corporation.

U

TYPICAL APPLICATIO

Precision Photodiode Amplifier

Distribution of Input Offset Voltage

C1

39pF

35

30

25

20

15

10

5

R1

100k, 1%

+

V

S

V

λ

–

+

LT1880

OUT

S1

V

= 0.1V/µA

OUT

–

V

S

0

1880 TA01

20

100 140

–140 –100 –60 –20

60

320µV OUTPUT OFFSET, WORST CASE OVER 0°C TO 70°C

60kHz BANDWIDTH

INPUT OFFSET VOLTAGE (µV)

1880 TA01b

5.8µs RISE TIME, 10% TO 90%, 100mV OUTPUT STEP

52µV

OUTPUT NOISE, MEASURED ON A 100kHz BW

RMS

V

= ±1.5V TO ±18V

S

S1: SIEMENS INFINEON BPW21 PHOTODIODE (~580pF)

1

LT1880

W W U W

U

W

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ABSOLUTE AXI U RATI GS

PACKAGE/ORDER I FOR ATIO

(Note 1)

ORDER PART

Supply Voltage (V⁺to V^–) ....................................... 40V

Differential Input Voltage (Note 2) ......................... ±10V

Input Voltage .................................................... V⁺to V^–

Input Current (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 .......................... 150°C

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec).................. 300°C

NUMBER

TOP VIEW

LT1880CS5

LT1880IS5

+

OUT 1

–

5 V

V

2

+IN 3

4 –IN

S5 PART

MARKING

S5 PACKAGE

5-LEAD PLASTIC SOT-23

T_JMAX= 150°C, θ_JA= 250°C/W

LTUM

LTVW

Consult LTC Marketing for parts specified with wider operating temperature ranges.

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 5V, 0V; V_CM= 2.5V unless otherwise noted. (Note 5)

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

V

Input Offset Voltage

40

150

200

250

µV

OS

0°C < T < 70°C

●

A

–40°C < T < 85°C

A

Input Offset Voltage Drift

(Note 6)

0°C < T < 70°C

●

0.3

1.2

µV/°C

A

–40°C < T < 85°C

A

I

Input Offset Current

150

900

1200

1400

pA

OS

0°C < T < 70°C

●

A

–40°C < T < 85°C

A

Input Bias Current

150

900

1200

1500

pA

B

0°C < T < 70°C

●

A

–40°C < T < 85°C

A

Input Noise Voltage

0.1Hz to 10Hz

f = 1kHz

0.5

13

µV

P-P

e

Input Noise Voltage Density

Input Noise Current Density

Input Resistance

nV/√Hz

pA/√Hz

n

i

f = 1kHz

0.07

n

R

IN

Differential

Common Mode, V = 1V to 3.8V

380

210

MΩ

GΩ

CM

C

V

Input Capacitance

3.7

pF

V

IN

–

+

Input Voltage Range

●

(V + 1.0)

116

(V – 1.2)

CM

CMRR

PSRR

Common Mode Rejection Ratio

Power Supply Rejection Ratio

Minimum Operating Supply Voltage

Large Signal Voltage Gain

1V < V < 3.8V

135

2.4

dB

V

CM

–

+

V = 0V, V = 1.5V; 2.7V < V < 32V

110

CM

2.7

A

R = 10k; 1V < V < 4V

L OUT

500

400

300

250

1600

V/mV

VOL

●

R = 2k; 1V < V

< 4V

800

400

L

OUT

R = 1k; 1V < V

L

< 4V

V

Output Voltage Swing Low

No Load

●

20

35

130

55

65

200

mV

OL

I

= 100µA

= 1mA

SINK

2

LT1880

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 5V, 0V; V_CM= 2.5V unless otherwise noted. (Note 5)

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

+

V

Output Voltage Swing High

(Referred to V )

V = 5V; No Load

●

130

150

220

250

270

380

mV

OH

+

V = 5V; I

= 100µA

SOURCE

= 5V; I

+

V

= 1mA

SOURCE

+

I

Supply Current per Amplifier

V = 3V

1.2

1.8

2.2

mA

S

●

+

V = 5V

1.2

1.9

2.3

mA

+

V = 12V

1.35

2

2.4

mA

I

Short-Circuit Current

V

Short to GND

Short to V

●

10

18

20

mA

SC

OUT

+

GBW

Gain-Bandwidth Product

Settling Time

f = 20kHz

0.01%, V

0.8

1.1

10

MHz

t

= 1.5V to 3.5V

OUT

µs

S

A = –1, R = 2k

V

L

FPBW

THD

Full Power Bandwidth (Note 7)

V

= 4V

32

kHz

OUT

P-P

Total Harmonic Distortion and Noise

V = 2V , A = –1, f = 1kHz, R = 1k, BW = 22kHz

V = 2V , A = 1, f = 1kHz, R = 10k, BW = 22kHz

0.002

0.0008

%

O

P-P

V

f

O

P-P

V

L

+

SR

Slew Rate Positive

Slew Rate Negative

A = –1

0.25

0.2

0.4

V/µs

V

●

–

SR

A = –1

V

0.25

0.55

V/µs

The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T_A= 25°C.

V_S= ±15V, V_CM= 0V unless otherwise noted. (Note 5)

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

V

Input Offset Voltage

40

150

200

250

µV

OS

0°C < T < 70°C

●

A

–40°C < T < 85°C

A

Input Offset Voltage Drift

(Note 6)

0°C < T < 70°C

●

0.3

1.2

µV/°C

A

–40°C < T < 85°C

A

I

Input Offset Current

150

900

1200

1400

pA

OS

0°C < T < 70°C

●

A

–40°C < T < 85°C

A

Input Bias Current

150

900

1200

1500

pA

B

0°C < T < 70°C

●

A

–40°C < T < 85°C

A

Input Noise Voltage

0.1Hz to 10Hz

f = 1kHz

0.5

13

µV

P-P

e

Input Noise Voltage Density

Input Noise Current Density

Input Resistance

nV/√Hz

pA/√Hz

n

i

f = 1kHz

0.07

n

R

IN

Differential

Common Mode, V = –13.5V to 13.5V

380

190

MΩ

GΩ

CM

C

V

Input Capacitance

3.7

pF

V

IN

Input Voltage Range

●

–13.5

118

13.5

CM

CMRR

+PSRR

–PSRR

Common Mode Rejection Ratio

Positive Power Supply Rejection Ratio

Negative Power Supply Rejection Ratio

Minimum Operating Supply Voltage

–13.5V < V < 13.5V

135

±1.2

dB

V

CM

–

+

V = –15V, V = 0V; 1.5V < V < 18V

110

CM

+

–

V = 15V, V = 0V; –1.5V < V < –18V

110

CM

±1.35

3

LT1880

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= ±15V; V_CM= 0V unless otherwise noted. (Note 5)

SYMBOL PARAMETER

CONDITIONS

R = 10k; –13.5V < V < 13.5V

OUT

MIN

TYP

MAX

UNITS

A

Large Signal Voltage Gain

1000

700

500

300

1600

V/mV

VOL

L

●

R = 2k; –13.5V < V

< 13.5V

OUT

1000

L

V

Output Voltage Swing Low

No Load

●

25

35

130

65

75

200

mV

OL

OH

(Referred to V

)

EE

I

= 100µA

= 1mA

SINK

Output Voltage Swing High

(Referred to V

No Load

●

185

195

270

350

370

450

mV

)

CC

I

= 100µA

= 1mA

SOURCE

I

Supply Current per Amplifier

Short-Circuit Current

1.5

1.8

2.3

2.8

mA

S

●

–

V

Short to V

10

25

mA

SC

OUT

+

Short to V

10

20

mA

FPBW

GBW

THD

Full Power Bandwidth (Note 7)

Gain Bandwidth Product

= 14V

9

kHz

P-P

f = 20kHz

0.8

1.1

MHz

Total Harmonic Distortion and Noise V = 25V , A = –1, f = 100kHz, R = 10k, BW = 22kHz

0.00029

%

O

P-P

V

f

V = 25V , A = 1, f = 100kHz, R = 10k, BW = 22kHz

O

P-P

V

L

+

SR

Slew Rate Positive

Slew Rate Negative

A = –1

0.25

0.2

0.4

V/µs

V

●

–

SR

A = –1

V

0.25

0.2

0.55

V/µs

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired.

Note 2: The inputs are protected by back-to-back diodes. If the differential

input voltage exceeds 10V, see Application Information, the input current

should be limited to less than 10mA.

Note 5: The LT1880C is guaranteed to meet 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 LT1880I is guaranteed to meet specified performance

from –40°C to 85°C.

Note 6: This parameter is not 100% tested.

Note 3: A heat sink may be required to keep the junction temperature

below absolute maximum ratings.

Note 7: Full power bandwidth is calculated from the slew rate.

Note 4: The LT1880C and LT1880I are guaranteed functional over the

operating temperature range of –40°C to 85°C.

FPBW = SR/(2πV )

P

4

LT1880

U W

TYPICAL PERFOR A CE CHARACTERISTICS

Input Offset Voltage vs

Temperature

Input Bias Current vs Common

Mode Voltage

Input Bias Current vs Common

Mode Near V_CC

1000

500

1000

800

200

150

100

50

V

= ±15V

TEMPCO: –55°C TO 125°C

10 REPRESENTATIVE UNITS

T

= 25°C

= –40°C

= 85°C

S

A

–

I

B

600

400

–

I

B

200

0

+

I

B

–200

–400

–600

–800

–1000

–50

–100

–150

–200

+

I

B

–500

–1000

T

= –45°C

= 25°C

= 85°C

A

V

= ±15V

S

13.8

14.2

13.0

14.6

13.4

5

25

–55 –35 –15

45 65 85 105 125

–15

–10

0

5

10

15

–5

COMMON MODE VOLTAGE (V)

TEMPERATURE (°C)

1880 G02A

1880 G01

1880 G02

Output Voltage Swing

vs Load Current

Input Bias Current vs Common

Mode Near V_EE

Input Bias Current vs

Temperature

1000

500

200

150

100

50

V

= ±15V

V

= ±15V

S

T

= –40°C

A

–0.5

–

I

B

T

A

= 85°C

–1.0

–1.5

1.5

0

T

= 25°C

A

–

0

I

B

–50

–100

–150

–200

–250

–300

T

= 25°C

A

+

I

B

1.0

–500

–1000

+

T

= 85°C

I

B

A

T

= –40°C

= 25°C

= 85°C

A

0.5

T

= –40°C

A

–14.2

–13.8

–13.0

–14.6

–13.4

–10 –8

–4

0

2

4

6

8

10

–6

–2

–50

–25

25

50

75

100

0

COMMON MODE VOLTAGE (V)

OUTPUT CURRENT (mA)

TEMPERATURE (°C)

1880 G02B

1880 G04

1880 G03

Warm Up Drift

e_n, i_nvs Frequency

0.1 to 10Hz Noise

6

5

4

3

2

1

0

1000

100

10

V

= ±15V

= 25°C

T

= 25°C

S

A

T

CURRENT NOISE

V

= ±15V

S

VOLTAGE NOISE

V

= ±2.5V

S

V

= ±15V

= 25°C

S

A

T

1

0

1

2

3

4

5

1

10

100

1k

0

2

4

6

8

10

TIME AFTER POWER ON (MIN)

FREQUENCY (Hz)

TIME (SEC)

1880 G08

1880 G05

1880 G09a

5

LT1880

U W

TYPICAL PERFOR A CE CHARACTERISTICS

PSRR vs Frequency

0.01 to 1Hz Noise

Gain vs Frequency

160

140

120

100

80

140

120

100

80

V

S

= ±15V

V

= ±15V

S

–PSRR

60

40

+PSRR

60

20

40

0

20

V

= ±15V

= 25°C

–20

–40

S

A

T

0

20

40

60

80

100

1M

10M

0.1

1

10 100 1k 10k 100k 1M

FREQUENCY (Hz)

0.1

1

10 100 1k 10k 100k

FREQUENCY (Hz)

TIME (SEC)

1880 G11

1880 G09b

1880 G10

CMRR vs Frequency

Settling Time vs Output Step

Gain and Phase vs Frequency

70

60

100

10

8

160

140

120

100

80

V

S

A

V

= ±15V

= –1

V

= ±15V

V

= ±15V

S

80

50

60

6

0.1%

0.01%

40

4

PHASE SHIFT

30

20

2

20

0

10

–20

–40

–60

–80

–100

–2

–4

–6

–8

–10

60

GAIN

0

0.01%

40

0.1%

–10

–20

–30

20

0

10k

100k

1M

10M

0

20

SETTLING TIME (µs)

30 35

5

10 15

25

40

1

100

1k

10k

100k 1M

10

FREQUENCY (Hz)

1880 G13

1880 G14

1880 G12

Slew Rate, Gain-Bandwidth

Product and Phase Margin vs

Temperature

Slew Rate, Gain-Bandwidth

Product and Phase Margin vs

Power Supply

Settling Time vs Output Step

10

8

0.5

0.4

0.5

0.4

V

S

A

V

= ±15V

= 1

T

= 25°C

V

= ±15V

A

S

SLEW RATE

6

0.01%

SLEW RATE

0.1%

4

64

60

56

68

64

60

2

0.3

Φ

M

0

Φ

M

–2

–4

–6

–8

–10

1.12

1.11

1.10

1.14

1.12

1.10

0.01%

0.1%

10

GBW

0

20

30

35

5

15

25

0

2.5

7.5

10

12.5

15

5

–50

–25

25

50

75

100

0

SETTLING TIME (µs)

POWER SUPPLY (±V)

TEMPERATURE (°C)

1880 G15

1880 G17

1880 G16

6

LT1880

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TYPICAL PERFOR A CE CHARACTERISTICS

Gain vs Frequency

with C_LOAD, A_V= –1

Gain vs Frequency

with C_LOAD, A_V= 1

Output Impedance vs Frequency

100

10

0

10

0

V

= ±15V

S

1000pF

500pF

1000pF

500pF

A

= 100

–10

–20

–30

–40

A = 10

V

–10

–20

–30

–40

0pF

V

0pF

1.0

A

= 1

V

0.1

0.01

1k

10k

100k

1M

10M

100M

1k

10

10k

100k

FREQUENCY (Hz)

1M

10M

100M

0.01

0.1

1.0

FREQUENCY (MHz)

10

100

FREQUENCY (Hz)

1880 G19

1880 G17A

1880 G18

Total Harmonic Distortion + Noise

vs Frequency

Small Signal Response

V

= 5V, 0V

S

= 2.5V

G

CM

R = R = 1k

f

1.0

0.1

V

R

= 2V

OUT

P-P

= 10k

L

V

OUT

(20mV/DIV)

V

OUT

(20mV/DIV)

0.01

A

= –1

V

0.001

1880 G21

1880 G20

A

= 1

TIME (2µs/DIV)

V

A = –1

V

NO LOAD

TIME (2µs/DIV)

A

= 1

V

NO LOAD

0.0001

10

100

1k

FREQUENCY (Hz)

10k

100k

1880 G17B

Small Signal Response

Large Signal Response

V

OUT

(5V/DIV)

(20mV/DIV)

(5V/DIV)

1880 G23

1880 G22

1880 G24

A

= –1

TIME (50µs/DIV)

A

C

= 1

= 500pF

TIME (2µs/DIV)

A

= 1

V

TIME (50µs/DIV)

V

L

7

LT1880

W U U

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APPLICATIO S I FOR ATIO

The LT1880 single op amp features exceptional input moderangewillcausethegaintodroptozero, howeverno

precision with rail-to-rail output swing. Slew rate and gain reversal will occur.

small signal bandwidth are superior to other amplifiers

Input Protection

with comparable input precision. These characteristics

make the LT1880 a convenient choice for precision low

voltage systems and for improved AC performance in

higher voltage precision systems. Obtaining beneficial

advantage of the precision inherent in the amplifier de-

pends upon proper applications circuit design and board

layout.

The inverting and noninverting input pins of the LT1880

have limited on-chip protection. ESD protection is pro-

vided to prevent damage during handling. The input tran-

sistors have voltage clamping and limiting resistors to

protect against input differentials up to 10V. Short tran-

sients above this level will also be tolerated. If the input

pins can see a sustained differential voltage above 10V,

external limiting resistors should be used to prevent

Preserving Input Precision

Preserving the input voltage accuracy of the LT1880 damage to the amplifier. A 1k resistor in each input lead

requires that the applications circuit and PC board layout will provide protection against a 30V differential voltage.

do not introduce errors comparable to or greater than the

Capacitive Loads

40µV offset. Temperature differentials across the input

connections can generate thermocouple voltages of 10’s

of microvolts. PC board layouts should keep connections

to the amplifier’s input pins close together and away from

heat dissipating components. Air currents across the

board can also generate temperature differentials.

TheLT1880candrivecapacitiveloadsupto600pFinunity

gain. The capacitive load driving capability increases as

the amplifier is used in higher gain configurations, see the

graph labled Capacitive Load Response. Capacitive load

driving may be increased by decoupling the capacitance

from the output with a small resistance.

The extremely low input bias currents, 150pA, allow high

accuracy to be maintained with high impedance sources

and feedback networks. The LT1880’s low input bias

currents are obtained by using a cancellation circuit on-

Capacitance Load Response

30

V

T

= ±15V

= 25°C

S

A

25

20

15

10

5

+

–

chip. This causes the resulting I_BIASand I_BIASto be

uncorrelated, as implied by the l_OSspecification being

comparabletoI_BIAS. Theusershouldnottrytobalancethe

input resistances in each input lead, as is commonly

recommended with most amplifiers. The impedance at

either input should be kept as small as possible to mini-

mize total circuit error.

A

= 1

V

A

= 10

V

PC board layout is important to insure that leakage cur-

rents do not corrupt the low I_BIASof the amplifier. In high

precision, high impedance circuits, the input pins should

be surrounded by a guard ring of PC board interconnect,

with the guard driven to the same common mode voltage

as the amplifier inputs.

0

10

100

1000

10000

CAPACITIVE LOAD (pF)

1880 G25

Getting Rail-to-Rail Operation without Rail-to-Rail

Inputs

The LT1880 does not have rail-to-rail inputs, but for most

inverting applications and noninverting gain applications,

thisislargelyinconsequential.Figure1showsthebasicop

amp conﬁgurations, what happens to the op amp inputs,

and whether or not the op amp must have rail-to-rail

inputs.

Input Common Mode Range

The LT1880 output is able to swing nearly to each power

supply rail, but the input stage is limited to operating

between V^–+ 1V and V⁺– 1.2V. Exceeding this common

8

LT1880

W U U

APPLICATIO S I FOR ATIO

U

V

REF

IN

+

–

+

–

+

–

IN

R

G

V

IN

R

F

R

F

R

G

V

REF

INVERTING: A = –R /R

NONINVERTING: A = 1 + R /R

G

NONINVERTING: A = +1

V

INPUTS MOVE AS MUCH AS

OUTPUT

V

F

G

V

F

OP AMP INPUTS DO NOT MOVE,

BUT ARE FIXED AT DC BIAS

INPUTS MOVE BY AS MUCH AS

V

, BUT THE OUTPUT MOVES

IN

POINT V

MORE

REF

INPUT MUST BE RAIL-TO-

RAIL FOR OVERALL CIRCUIT

RAIL-TO-RAIL PERFORMANCE

INPUT DOES NOT HAVE TO BE

RAIL-TO-RAIL

INPUT MAY NOT HAVE TO BE

RAIL-TO-RAIL

Figure 1. Some Op Amp Configurations Do Not Require

Rail-to Rail Inputs to Achieve Rail-to-Rail Outputs

Precision Photodiode Ampliﬁer

The circuit of Figure 2 shows an extreme example of the

inverting case. The input voltage at the 1M resistor can

swing ±13.5V and the LT1880 will output an inverted,

divided-by-ten version of the input voltage. The input

accuracy is limited by the resistors to 0.2%. Output

referred, this error becomes 2.7mV. The 40µV input offset

voltage contribution, plus the additional error due to input

bias current times the ~100k effective source impedance,

contribute only negligibly to error.

Photodiode ampliﬁers usually employ JFET op amps be-

cause of their low bias current; however, when precision

is required, JFET op amps are generally inadequate due to

their relatively high input offset voltage and drift. The

LT1880 provides a high degree of precision with very low

bias current (I_B= 150pA typical) and is therefore appli-

cable to this demanding task. Figure 3 shows an LT1880

conﬁgured as a transimpedance photodiode ampliﬁer.

C

F

1.5V

±1.35V

OUTPUT

SWING

±13.5V SWINGS

WELL OUTSIDE

SUPPLY RAILS

WORST-CASE

OUTPUT OFFSET

R

51.1k

5V

F

≤196µV AT 25°C

≤262µV 0°C TO 70°C

≤323µV –40°C TO 85°C

+

–

LT1880

V

IN

–

+

1M, 0.1%

PHOTODIODE

(SEE TEXT)

LT1880

–5V

OUT

C

D

100k, 0.1%

–1.5V

Figure 2. Extreme Inverting Case: Circuit Operates Properly

with Input Voltage Swing Well Outside Op Amp Supply Rails.

Figure 3. Precision Photodiode Amplifier

9

LT1880

W U U

U

APPLICATIO S I FOR ATIO

The transimpedance gain is set to 51.1kΩ by R_F. The

feedback capacitor, C_F, may be as large as desired where

response time is not an issue, or it may be selected for

maximally ﬂat response and highest possible bandwidth

givenaphotodiodecapacitanceC_D. Figure4showsachart

of C_Fand rise time versus C_Dfor maximally ﬂat response.

Total output offset is below 262µV, worst-case, over

temperature (0°C–70°C). With a 5V output swing, this

guarantees a minimum 86dB dynamic range over

temperature (0°C–70°C), and a full-scale photodiode

current of 98µA.

connection. The LT1634 reference places 1.25V at the

noninvertinginputoftheLT1880,whichthenmaintainsits

inverting input at the same voltage by driving 1mA of

current through the RTD and the total 1.25kΩ of resis-

tance set by R1 and R2. Imprecise components R4 and C1

ensure circuit stability, which would otherwise be exces-

sively dependant on the cable characteristics. R5 is also

noncritical and is included to improve ESD immunity and

decoupleanycablecapacitancefromtheLT1880’soutput.

The 4-wire cable allows Kelvin sensing of the RTD voltage

while excluding the cable IR drops from the voltage

reading. With 1mA excitation, a 1kΩ RTD will have 1V

across it at 0°C, and +3.85mV/°C temperature response.

This voltage can be easily read in myriad ways, with the

best method depending on the temperature region to be

emphasized and the particular ADC that will be reading the

voltage.

Single-Supply Current Source for Platinum RTD

The precision, low bias current input stage of the LT1880

makesitidealforprecisionintegratorsandcurrentsources.

Figure 5 shows the LT1880 providing a simple precision

current source for a remote 1kΩ RTD on a 4-wire

R5

180Ω, 5%

+

100

V

OUT

= 1.00V AT 0°C + 3.85mV/°C

–50°C TO 600°C

1kΩ

AT 0°C

RTD*

–

C

F

10

1

C1

5V

0.1µF

R4

1k, 5%

–

R1

RISE TIME

LT1880

1.24K

0.1%

+

R2

10Ω

1%

R3

150k, 1%

100mV OUTPUT STEP

10 100 1000

0.1

1

C

D

(pF)

LT1634ACS8

-1.25

5V

Figure 4. Feedback C_Fand Rise Time vs Photodiode C_D

*OMEGA F3141 1kΩ, 0.1% PLATINUM RTD

(800) 826-6342

Figure 5. Single Supply Current Source for Platinum RTD

10

LT1880

W

SI PLIFIED SCHE ATIC

+

5

V

R3

R4

R5

R27

CX1

100µA

Q41

Q23

Q24

Q6

Q38

CM1

RCM1

Q5

Q4

Q3

OUT

1

Q47

B

A

35µA

Q48

CM2

Q58

Q59

RCM2

Q12

Q16

CM3

–

V

R1

Q46

Q14

500Ω

Q20

C

B

A

4

–IN

+IN

R22

500Ω

3

7µA

10µA

R2

500Ω

Q1

Q2

Q45

Q7

Q44

Q8

R38

21µA

1880 SD

–

2

V

U

PACKAGE DESCRIPTIO

S5 Package

5-Lead Plastic SOT-23

(Reference LTC DWG # 05-08-1633)

(Reference LTC DWG # 05-08-1635)

2.80 – 3.10

(.110 – .118)

(NOTE 3)

NOTE:

1. CONTROLLING DIMENSION: MILLIMETERS

MILLIMETERS

2. DIMENSIONS ARE IN

(INCHES)

SOT-23

(Original)

(ThinSOT)

3. DRAWING NOT TO SCALE

.90 – 1.45

(.035 – .057)

1.00 MAX

(.039 MAX)

4. DIMENSIONS ARE INCLUSIVE OF PLATING

5. DIMENSIONS ARE EXCLUSIVE OF MOLD

FLASH AND METAL BURR

A

A1

A2

L

2.60 – 3.00

(.102 – .118) (.059 – .069)

(NOTE 3)

1.50 – 1.75

.00 – .15

(.00 – .006)

.01 – .10

(.0004 – .004)

6. MOLD FLASH SHALL NOT EXCEED .254mm

7. PACKAGE EIAJ REFERENCE IS:

SC-74A (EIAJ) FOR ORIGINAL

.90 – 1.30

(.035 – .051)

.80 – .90

(.031 – .035)

JEDEL MO-193 FOR THIN

.35 – .55

(.014 – .021)

.30 – .50 REF

(.012 – .019 REF)

PIN ONE

.95

(.037)

REF

.25 – .50

(.010 – .020)

(5PLCS, NOTE 2)

.20

(.008)

A2

A

DATUM ‘A’

1.90

(.074)

REF

L

.09 – .20

(.004 – .008)

(NOTE 2)

A1

S5 SOT-23 0401

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 represen-

tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.

11

LT1880

U

TYPICAL APPLICATIO

All SOT-23 JFET Input Transimpedance Photodiode Amplifier

C4

1.2pF

1k

TIME DOMAIN

RESPONSE TRIM

+

R5

100k, 1%

V

C5

1.2pF

J1

R2

220k, 5%

C1

0.01µF

+

–

R7

47Ω

5%

U1

LT1880

U2

LT1806

V

OUT

R3

10k

5%

+

R1

220k, 5%

N1

J1: ON SEMI MMBF4416 JFET

C2

0.1µF

N1:ON SEMI MMBT3904 NPN

S1

R6

47Ω

5%

C3

0.01µF

S1: SIEMENS/INFINEON SFH213FA PHOTODIODE (~3pF)

V

= ±5V

SUPPLY

BANDWIDTH = 7MHz

NOISE FIGURE = 2dB AT 100kHz, 25°C

A

Z

= 100kΩ

–

V

1880 TA02

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

Rail-to-Rail I/O

4.2nV/√Hz

LT1782

Rugged, General Purpose SOT-23 Op Amp

Low Noise JFET Op Amp

LT1792

LT1881/LT1882

LTC2050

Dual/Quad Precision Op Amps

Zero Drift Op Amp in SOT-23

50µV V

, 200pA I

Rail-to-Rail Output

OS(MAX)

B(MAX)

3µV V

, Rail-to-Rail Output

OS(MAX)

1880f LT/TP 0801 2K • PRINTED IN USA

12 ^{LinearTechnology Corporation}

1630 McCarthy Blvd., Milpitas, CA 95035-7417

●

LINEAR TECHNOLOGY CORPORATION 2001

(408) 432-1900 FAX: (408) 434-0507 www.linear.com


型号：	LT1880CS5#TRM
厂家：	Linear
描述：	LT1880 - SOT-23, Rail-to-Rail Output, Picoamp Input Current Precision Op Amp; Package: SOT; Pins: 5; Temperature Range: 0°C to 70°C 运算放大器
文件：	总12页 (文件大小：234K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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