LT1880IS5#TR_技术文档

LT1880

SOT-23, Rail-to-Rail Output,

Picoamp Input Current

Precision Op Amp

DESCRIPTION

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

manceandrail-to-railoutputswingtotheSOT-23package.

Input offset voltage is trimmed to less than 150μV and

the low drift maintains this accuracy over the operating

temperaturerange.Inputbiascurrentisanultralow900pA

maximum.

FEATURES

n

Offset Voltage: 150μV Max

n

Input Bias Current: 900pA Max

n

Offset Voltage Drift: 1.2μV/°C Max

n

Rail-to-Rail Output Swing

n

Operates with Single or Split Supplies

n

Open-Loop Voltage Gain: 1 Million Min

n

1.2mA Supply Current

The ampliﬁer works on any total power supply voltage

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

Output voltage swings to within 55mV of the negative

supply and 250mV of the positive supply, which makes

the ampliﬁer a good choice for low voltage single supply

operation.

n

Slew Rate: 0.4V/μs

n

Gain Bandwidth: 1.1MHz

n

Low Noise: 13nV/√Hz at 1kHz

™

n

Low Proﬁle (1mmꢀ ThinSOT Package

APPLICATIONS

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.

n

Thermocouple Ampliﬁers

n

Bridge Transducer Conditioners

n

Instrumentation Ampliﬁers

n

Battery-Powered Systems

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

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other

trademarks are the property of their respective owners.

n

Photocurrent Ampliﬁers

TYPICAL APPLICATION

Precision Photodiode Ampliﬁer

Distribution of Input Offset Voltage

C1

35

30

25

20

15

10

5

39pF

R1

100k, 1%

+

V

S

V

L

–

+

LT1880

–

OUT

S1

V

OUT

= 0.1V/μA

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 (μVꢀ

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 (~580pFꢀ

1880fa

1

LT1880

ABSOLUTE MAXIMUM RATINGS

PIN CONFIGURATION

(Note 1)

TOP VIEW

+

–

Supply Voltage (V to V ꢀ.........................................40V

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

+

OUT 1

–

5 V

V

2

+

–

Input Voltage......................................................V to V

+IN 3

4 –IN

Input Current (Note 2ꢀ.......................................... 10mA

Output Short-Circuit Duration (Note 3ꢀ............ Indeﬁnite

Operating Temperature Range (Note 4ꢀ ...–40°C to 85°C

Speciﬁed Temperature Range (Note 5ꢀ ....–40°C to 85°C

Maximum Junction Temperature .......................... 150°C

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

Lead Temperature (Soldering, 10 secꢀ...................300°C

S5 PACKAGE

5-LEAD PLASTIC TSOT-23

T

JMAX

= 150°C, θ = 250°C/W

JA

ORDER INFORMATION

LEAD FREE FINISH

LT1880CS5#PBF

LT1880IS5#PBF

TAPE AND REEL

PART MARKING

LTUM

PACKAGE DESCRIPTION

5-Lead Plastic TSOT-23

SPECIFIED TEMPERATURE RANGE

0°C to 70°C

LT1880CS5#TRPBF

LT1880IS5#TRPBF

LTVW

–40°C to 85°C

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

Consult LTC Marketing for information on non-standard lead based ﬁnish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/

For more information on tape and reel speciﬁcations, go to: http://www.linear.com/tapeandreel/

ELECTRICAL CHARACTERISTICS

The l 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

OS

Input Offset Voltage

40

150

200

250

μV

l

0°C < T < 70°C

A

–40°C < T < 85°C

A

l

Input Offset Voltage Drift

(Note 6ꢀ

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

l

0°C < T < 70°C

A

–40°C < T < 85°C

A

Input Bias Current

150

900

1200

1500

pA

B

l

0°C < T < 70°C

A

–40°C < T < 85°C

A

Input Noise Voltage

0.1Hz to 10Hz

f = 1kHz

0.5

13

μVp-p

nV/√Hz

pA/√Hz

e

n

Input Noise Voltage Density

Input Noise Current Density

Input Resistance

i

n

f = 1kHz

0.07

R

IN

Differential

Common Mode, V = 1V to 3.8V

380

210

MΩ

GΩ

CM

C

V

Input Capacitance

3.7

pF

V

IN

–

+

l

Input Voltage Range

(V + 1.0ꢀ

(V – 1.2ꢀ

CM

1880fa

2

LT1880

ELECTRICAL CHARACTERISTICS

The l 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

116

110

TYP

135

2.4

MAX

UNITS

dB

l

CMRR

PSRR

Common Mode Rejection Ratio

1V < V < 3.8V

CM

–

+

Power Supply Rejection Ratio

Minimum Operating Supply Voltage

Large Signal Voltage Gain

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

dB

CM

2.7

V

A

VOL

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

L OUT

500

400

300

250

1600

V/mV

l

R = 2k; 1V < V

L

< 4V

800

400

OUT

R = 1k; 1V < V

L

< 4V

l

V

Output Voltage Swing Low

Output Voltage Swing High

No Load

20

35

55

65

mV

OL

I

= 100μA

= 1mA

SINK

+

130

200

l

V = 5V; No Load

130

150

220

250

270

380

mV

OH

+

(Referred to V ꢀ

V = 5V; I

= 100μA

= 1mA

SOURCE

+

V

= 5V; I

SOURCE

+

I

Supply Current per Ampliﬁer

V = 3V

1.2

1.8

2.2

mA

S

l

+

V = 5V

1.2

1.9

2.3

mA

+

V = 12V

1.35

2

2.4

mA

l

I

SC

Short-Circuit Current

V

OUT

V

OUT

Short to GND

10

18

20

mA

+

Short to V

GBW

Gain-Bandwidth Product

Settling Time

f = 20kHz

0.8

1.1

10

MHz

μs

t

S

0.01%, V

= 1.5V to 3.5V

OUT

A = –1, R = 2k

V

L

FPBW

THD

Full Power Bandwidth (Note 7ꢀ

V

= 4V

32

kHz

OUT

P-P

Total Harmonic Distortion and Noise

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

0.002

0.0008

%

O

P-P

V

f

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

O

L

+

SR

Slew Rate Positive

Slew Rate Negative

A = –1

0.25

0.2

0.4

V/μs

V

l

–

SR

A = –1

V

0.25

0.55

V/μs

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

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

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

V

OS

Input Offset Voltage

40

150

200

250

μV

l

0°C < T < 70°C

A

–40°C < T < 85°C

A

l

Input Offset Voltage Drift

(Note 6ꢀ

0°C < T < 70°C

0.3

1.2

μV/°C

A

–40°C < T < 85°C

A

I

Input Offset Current

Input Bias Current

Input Noise Voltage

150

0.5

900

1200

1400

pA

OS

l

0°C < T < 70°C

A

–40°C < T < 85°C

A

900

1200

1500

pA

B

l

0°C < T < 70°C

A

–40°C < T < 85°C

A

0.1Hz to 10Hz

μV/p-p

1880fa

3

LT1880

ELECTRICAL CHARACTERISTICS

The l denotes the speciﬁcations which apply over the full operating

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

SYMBOL PARAMETER

CONDITIONS

f = 1kHz

MIN

TYP

13

MAX

UNITS

nV/√Hz

pA/√Hz

e

n

Input Noise Voltage Density

Input Noise Current Density

Input Resistance

i

n

f = 1kHz

0.07

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

l

Input Voltage Range

–13.5

118

13.5

1.35

CM

CMRR

Common Mode Rejection Ratio

–13.5V < V < 13.5V

135

dB

CM

–

+

+PSRR

Positive Power Supply Rejection

Ratio

V = –15V, V = 0V; 1.5V < V < 18V

110

CM

+

–

l

–PSRR

Negative Power Supply Rejection

Ratio

V = 15V, V = 0V; –1.5V < V < –18V

110

135

dB

CM

Minimum Operating Supply Voltage

Large Signal Voltage Gain

1.2

V

A

VOL

R = 10k; –13.5V < V < 13.5V

L OUT

1000

700

500

300

1600

V/mV

l

R = 2k; –13.5V < V

L

< 13.5V

OUT

1000

l

V

Output Voltage Swing Low

No Load

SINK

25

35

65

75

mV

OL

(Referred to V

ꢀ

I

= 100μA

= 1mA

EE

130

200

l

Output Voltage Swing High

(Referred to V

No Load

185

195

270

350

370

450

mV

OH

ꢀ

CC

I

= 100μA

= 1mA

SINK

I

Supply Current per Ampliﬁer

Short-Circuit Current

1.5

1.8

2.3

2.8

mA

S

l

–

+

V

Short to V

10

25

mA

SC

OUT

10

20

mA

FPBW

GBW

THD

Full Power Bandwidth (Note 7ꢀ

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

L

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

P-P

V

+

SR

Slew Rate Positive

Slew Rate Negative

A = –1

0.25

0.2

0.4

V/μs

V

l

–

SR

A = –1

V

0.25

0.2

0.55

V/μs

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

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 4: The LT1880C and LT1880I are guaranteed functional over the

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

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

Note 6: This parameter is not 100% tested.

below absolute maximum ratings.

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

FPBW = SR/(2πV ꢀ

P

1880fa

4

LT1880

TYPICAL PERFORMANCE CHARACTERISTICS

Input Offset Voltage

vs Temperature

Input Bias Current

vs Common Mode Voltage

vs Common Mode Near V_CC

1000

800

1000

500

200

150

100

50

TEMPCO: –55°C TO 125°C

10 REPRESENTATIVE UNITS

T

= 25°C

= –40°C

= 85°C

V

S

= 15V

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

–10

S

5

25

–55 –35 –15

45 65 85 105 125

13.8

COMMON MODE VOLTAGE (Vꢀ

–15

0

5

10

15

13.0

13.4

14.2

14.6

–5

COMMON MODE VOLTAGE (Vꢀ

TEMPERATURE (°Cꢀ

1880 G01

1880 G02

1880 G02A

Input Bias Current

vs Common Mode Near V_EE

Output Voltage Swing

vs Load Current

Input Bias Current vs Temperature

200

150

100

50

1000

500

V

=

15V

V

=

15V

S

T

= –40°C

A

–

–0.5

–1.0

–1.5

1.5

I

B

T

= 85°C

A

0

T

= 25°C

A

–

–50

–100

–150

–200

–250

–300

0

I

B

T

= 25°C

A

+

I

B

1.0

–500

–1000

+

T

= 85°C

A

I

B

T

= –40°C

= 25°C

= 85°C

A

0.5

T

= –40°C

A

–14.2

–13.8

–13.0

–50

–25

0

25

50

75

100

–10

10

–14.6

–13.4

–8 –6 –4 –2

0

2

4

6

8

TEMPERATURE (°Cꢀ

OUTPUT CURRENT (mAꢀ

COMMON MODE VOLTAGE (Vꢀ

1880 G03

1880 G02B

1880 G04

Warm Up Drift

e_n, i_nvs Frequency

0.± to ±0Hz Noise

6

5

4

3

2

1

0

1000

100

10

V

S

T

A

=

15V

T

= 25°C

A

= 25°C

CURRENT NOISE

V

S

= 15V

VOLTAGE NOISE

V

S

= 2.5V

V

T

=

15V

S

A

= 25°C

1

0

2

4

6

8

10

1

10

100

1k

0

1

2

3

4

5

FREQUENCY (Hzꢀ

TIME AFTER POWER ON (MINꢀ

TIME (SECꢀ

1880 G08

1880 G09a

1880 G05

1880fa

5

LT1880

TYPICAL PERFORMANCE CHARACTERISTICS

0.0± to ±Hz Noise

Gain vs Frequency

PSRR vs Frequency

160

140

120

100

80

140

120

100

80

V

S

= 15V

V

S

= 15V

–PSRR

60

40

+PSRR

60

20

40

0

20

V

T

=

15V

–20

–40

S

A

= 25°C

0

20

40

60

80

100

0.1

1

100 1k 10k 100k 1M

10

FREQUENCY (Hzꢀ

1M

10M

0.1

1

10 100 1k 10k 100k

FREQUENCY (Hzꢀ

TIME (SECꢀ

1880 G11

1880 G09b

1880 G10

CMRR vs Frequency

Gain and Phase vs Frequency

Settling Time vs Output Step

10

8

160

140

120

100

80

70

60

100

80

V

A

=

15V

V

= 15V

V

S

= 15V

S

V

S

= –1

6

50

60

0.1%

0.01%

4

40

PHASE SHIFT

2

30

20

0

20

0

–2

–4

–6

–8

–10

10

–20

–40

–60

–80

–100

60

GAIN

0

0.01%

40

0.1%

–10

–20

–30

20

0

10k

100k

FREQUENCY (Hzꢀ

1M

10M

0

5

10 15 20 25 30

SETTLING TIME (μsꢀ

35

40

1

100

1k

10k

100k 1M

10

FREQUENCY (Hzꢀ

1880 G12

1880 G13

1880 G14

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

A

=

= 1

15V

V

S

= 15V

T

= 25°C

S

V

A

SLEW RATE

6

0.01%

0.1%

SLEW RATE

4

68

64

60

56

2

0.3

&

M

0

64

60

&

M

–2

–4

–6

–8

1.14

1.12

1.10

1.12

1.11

1.10

0.01%

0.1%

10

GBW

–10

0

20

30

35

5

15

25

–50

–25

25

50

75

100

0

2.5

7.5

10

12.5

15

5

SETTLING TIME (μsꢀ

TEMPERATURE (°Cꢀ

POWER SUPPLY ( Vꢀ

1880 G15

1880 G16

1880 G17

1880fa

6

LT1880

TYPICAL PERFORMANCE CHARACTERISTICS

Gain vs Frequency

with C_LOAD, A_V= –±

Gain vs Frequency

with C_LOAD, A_V= ±

Output Impedance vs Frequency

100

10

0

10

0

V

S

= 15V

1000pF

500pF

1000pF

500pF

A

V

= 100

–10

–20

–30

–40

–10

–20

–30

–40

A = 10

V

0pF

1.0

A

V

= 1

0.1

0.01

1k

10k

100k

1M

10M

100M

1k

10k

100k

1M

10M

100M

0.01

0.1

1.0

FREQUENCY (MHzꢀ

10

100

FREQUENCY (Hzꢀ

1880 G17A

1880 G18

1880 G19

Total Harmonic Distortion + Noise

vs Frequency

Small Signal Response

10

V

= 5V, 0V

S

= 2.5V

CM

R = R = 1k

f

G

1.0

0.1

V

R

= 2V

OUT

P-P

= 10k

L

V

OUT

(20mV/DIVꢀ

0.01

A

V

= –1

0.001

1880 G21

1880 G20

A = 1

V

NO LOAD

TIME (2μs/DIVꢀ

A

= –1

TIME (2μs/DIVꢀ

V

A

V

= 1

NO LOAD

0.0001

10

100

1k

FREQUENCY (Hzꢀ

10k

100k

1880 G17B

Small Signal Response

Large Signal Response

V

OUT

(20mV/DIVꢀ

(5V/DIVꢀ

1880 G22

1880 G24

1880 G23

A

C

= 1

= 500pF

TIME (2μs/DIVꢀ

A

V

= 1

TIME (50μs/DIVꢀ

A

V

= –1

TIME (50μs/DIVꢀ

V

L

1880fa

7

LT1880

APPLICATIONS INFORMATION

The LT1880 single op amp features exceptional input

precisionwithrail-to-railoutputswing.Slewrateandsmall

signal bandwidth are superior to other ampliﬁers with

comparable input precision. These characteristics make

the LT1880 a convenient choice for precision low voltage

systemsandforimprovedACperformanceinhighervoltage

precision systems. Obtaining beneﬁcial advantage of the

precision inherent in the ampliﬁer depends upon proper

applications circuit design and board layout.

Input Protection

The inverting and noninverting input pins of the LT1880

havelimitedon-chipprotection.ESDprotectionisprovided

to prevent damage during handling. The input transistors

have voltage clamping and limiting resistors to protect

against input differentials up to 10V. Short transients

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 damage to

the ampliﬁer. A 1k resistor in each input lead will provide

protection against a 30V differential voltage.

Preserving Input Precision

Preserving the input voltage accuracy of the LT1880

requires that the applications circuit and PC board layout

do not introduce errors comparable to or greater than the

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

heatdissipatingcomponents.Aircurrentsacrosstheboard

can also generate temperature differentials.

Capacitive Loads

The LT1880 can drive capacitive loads up to 600pF in unity

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.

Capacitance Load Response

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

accuracytobemaintainedwithhighimpedancesourcesand

feedback networks. The LT1880’s low input bias currents

are obtained by using a cancellation circuit on-chip. This

30

V

=

15V

S

A

T

= 25°C

25

20

15

10

5

+

–

causestheresultingI

andI

tobeuncorrelated,as

BIAS

implied by the l speciﬁcation being comparable to I

.

BIAS

OS

A

= 1

V

The user should not try to balance the 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 minimize total circuit error.

A

V

= 10

0

PCboardlayoutisimportanttoinsurethatleakagecurrents

10

100

1000

10000

CAPACITIVE LOAD (pFꢀ

do not corrupt the low I

of the ampliﬁer. In high

BIAS

1880 G25

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.

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,

this is largely inconsequential. Figure 1 shows the basic

op 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

mode range will cause the gain to drop to zero, however

no gain reversal will occur.

1880fa

8

LT1880

APPLICATIONS INFORMATION

V

IN

V

IN

REF

+

–

+

–

+

–

R

G

V

IN

R

F

R

G

V

REF

INVERTING: A = –R /R

NONINVERTING: A = 1 +R /R

G

NONINVERTING: A = +1

V

F

G

V

F

OP AMP INPUTS DO NOT MOVE,

BUT ARE FIXED AT DC BIAS

INPUTS MOVE BY AS MUCH AS

INPUTS MOVE AS MUCH AS

OUTPUT

V

IN

, BUT THE OUTPUT MOVES

POINT V

MORE

REF

INPUT MUST BE

INPUT DOES NOT HAVE TO BE

RAIL-TO-RAIL

INPUT MAY NOT HAVE TO BE

RAIL-TO-RAIL

RAIL-TO-RAIL FOR OVERALL

CIRCUIT RAIL-TO-RAIL

PERFORMANCE

1880 F01

Figure ±. Some Op Amp Conﬁgurations Do Not Require

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

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.

Precision Photodiode Ampliﬁer

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 = 150pA typicalꢀ and is therefore appli-

B

cable to this demanding task. Figure 3 shows an LT1880

conﬁgured as a transimpedance photodiode ampliﬁer.

1.5V

1.35V

OUTPUT

SWING

C

F

13.5V SWINGS

WELL OUTSIDE

SUPPLY RAILS

WORST-CASE

OUTPUT OFFSET

≤196μV AT 25°C

R

51.1k

5V

+

–

F

LT1880

≤262μV 0°C TO 70°C

≤323μV –40°C TO 85°C

V

IN

1M, 0.1%

–

+

PHOTODIODE

(SEE TEXTꢀ

LT1880

OUT

100k, 0.1%

–1.5V

C

D

1880 F02

–5V

1880 F02

Figure 2. Extreme Inverting Case: Circuit Operates Properly with

Input Voltage Swing Well Outside Op Amp Supply Rails.

Figure 3. Precision Photodiode Ampliﬁer

1880fa

9

LT1880

APPLICATIONS INFORMATION

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

connection. The LT1634 reference places 1.25V at the

noninverting input of the LT1880, which then maintains

its inverting input at the same voltage by driving 1mA

of current through the RTD and the total 1.25kΩ of

resistance set by R1 and R2. Imprecise components R4

and C1 ensure circuit stability, which would otherwise be

excessively dependant on the cable characteristics. R5 is

also noncritical and is included to improve ESD immunity

and decouple any cable capacitance from the LT1880’s

output. The 4-wire cable allows Kelvin sensing of the RTD

voltagewhileexcludingthecableIRdropsfromthevoltage

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.

F

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

F

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

maximally ﬂat response and highest possible bandwidth

given a photodiode capacitance C . Figure 4 shows a

D

chart of C and rise time versus C for maximally ﬂat

F

D

response. Total output offset is below 262μV, worst-case,

over temperature (0°C to 70°Cꢀ. With a 5V output swing,

this guarantees a minimum 86dB dynamic range over

temperature (0°C to 70°Cꢀ, and a full-scale photodiode

current of 98μA.

Single-Supply Current Source for Platinum RTD

The precision, low bias current input stage of the LT1880

makes it ideal for precision integrators and current

sources. Figure 5 shows the LT1880 providing a simple

precisioncurrentsourceforaremote1kΩRTDona4-wire

R5

180Ω, 5%

100

+

C

F

10

1

V

= 1.00V AT 0°C + 3.85mV/°C

–50°C TO 600°C

OUT

1kΩ

AT 0°C

RTD*

–

C1

RISE TIME

5V

0.1μF

R4

1k, 5%

–

R1

1.24K

0.1%

100mV OUTPUT STEP

10 100 1000

LT1880

0.1

+

0.1

1

C

D

(pFꢀ

R2

10Ω

1%

1880 F04

R3

150k, 1%

Figure 4. Feedback C_Fand Rise Time vs Photodiode C_D

LT1634ACS8

-1.25

5V

*OMEGA F3141 1kΩ, 0.1% PLATINUM RTD

(800ꢀ 826-6342

1880 F05

Figure 5. Single Supply Current Source for Platinum RTD

1880fa

10

LT1880

SIMPLIFIED SCHEMATIC

+

5

V

R3

R4

CX1

100μA

R5

R27

Q41

Q23

Q24

Q6

Q38

CM1

RCM1

RCM2

Q5

Q4

Q3

OUT

1

Q47

B

A

35μA

CM2

Q48

Q58

Q59

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

PACKAGE DESCRIPTION

S5 Package

5-Lead Plastic TSOT-23

(Reference LTC DWG # 05-08-1635ꢀ

0.62

MAX

0.95

REF

2.90 BSC

(NOTE 4ꢀ

1.22 REF

1.50 – 1.75

(NOTE 4ꢀ

2.80 BSC

1.4 MIN

3.85 MAX 2.62 REF

PIN ONE

RECOMMENDED SOLDER PAD LAYOUT

PER IPC CALCULATOR

0.30 – 0.45 TYP

5 PLCS (NOTE 3ꢀ

0.95 BSC

0.80 – 0.90

0.20 BSC

DATUM ‘A’

0.01 – 0.10

1.00 MAX

0.30 – 0.50 REF

1.90 BSC

0.09 – 0.20

(NOTE 3ꢀ

S5 TSOT-23 0302 REV B

NOTE:

1. DIMENSIONS ARE IN MILLIMETERS

2. DRAWING NOT TO SCALE

3. DIMENSIONS ARE INCLUSIVE OF PLATING

4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR

5. MOLD FLASH SHALL NOT EXCEED 0.254mm

6. JEDEC PACKAGE REFERENCE IS MO-193

1880fa

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 representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

11

LT1880

TYPICAL APPLICATION

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 (~3pFꢀ

V

= 5V

SUPPLY

BANDWIDTH = 7MHz

NOISE FIGURE = 2dB AT 100kHz, 25°C

A

= 100kΩ

–

Z

V

1880 TA02

RELATED PARTS

PART NUMBER

LT1782

DESCRIPTION

COMMENTS

Rugged, General Purpose SOT-23 Op Amp

Low Noise JFET Op Amp

Rail-to-Rail I/O

LT1792

4.2nV/√Hz

LT1881/LT1882

LTC2050

Dual/Quad Precision Op Amps

50μV V

, 200pA I

Rail-to-Rail Output

OS(MAXꢀ

B(MAXꢀ

Zero Drift Op Amp in SOT-23

3μV V

, Rail-to-Rail Output

OS(MAXꢀ

LT6010

135μA Rail-to-Rail Output Precision Op Amp

Lower Power Version of LT1880

1880fa

LT 0909 REV A • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

12

●

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


型号：	LT1880IS5#TR
厂家：	Linear
描述：	LT1880 - SOT-23, Rail-to-Rail Output, Picoamp Input Current Precision Op Amp; Package: SOT; Pins: 5; Temperature Range: -40°C to 85°C 放大器光电二极管
文件：	总12页 (文件大小：218K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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