LTC6910-3CTS8#TRPBF_技术文档

LTC6910-1

LTC6910-2/LTC6910-3

Digitally Controlled

Programmable

Gain Amplifiers in SOT-23

U

FEATURES

DESCRIPTIO

The LTC^®6910 family are low noise digitally program-

mable gain amplifiers (PGAs) that are easy to use and

occupy very little PC board space. The inverting gain is

adjustable using a 3-bit digital input to select gains of 0, 1,

2, 5, 10, 20, 50 and 100V/V in the LTC6910-1; 0, 1, 2, 4,

8, 16, 32 and 64V/V in the LTC6910-2; and 0, 1, 2, 3, 4, 5,6

and 7V/V in the LTC6910-3.

■

3-Bit Digital Gain Control in Three Gain-Code

Options

■

Rail-to-Rail Input Range

Rail-to-Rail Output Swing

■

Single or Dual Supply: 2.7V to 10.5V Total

■

11MHz Gain Bandwidth Product

■

Input Noise Down to 8nV/√Hz

■

System Dynamic Range to 120dB

The LTC6910-Xs are inverting amplifiers with rail-to-rail

output. When operated with unity gain, they will also

process rail-to-rail input signals. A half-supply reference

generated internally at the AGND pin supports single

power supply applications. Operating from single or split

supplies from 2.7V to 10.5V, the LTC6910-X family is

offered in an 8-lead SOT-23 package.

■

Input Offset Voltage: 1.5mV

■

8-Pin Low Profile (1mm) SOT-23

(ThinSOT™) Package

U

APPLICATIO S

■

Data Acquisition Systems

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

ThinSOT is a trademark of Linear Technology Corporation.

■

Dynamic Gain Changing

U.S. Patent Number 6121908.

■

Automatic Ranging Circuits

Automatic Gain Control

■

U

TYPICAL APPLICATIO

Single Supply Programmable Amplifier

Frequency Response (LTC6910-1)

50

+

V

= 10V, V = 5mV

IN

S

RMS

2.7V TO 10.5V

GAIN OF 100 (DIGITAL INPUT 111)

0.1µF

40

30

DIGITAL INPUTS GAIN IN VOLTS/VOLT

G2 G1 G0 6910-1 6910-2 6910-3

GAIN OF 50 (DIGITAL INPUT 110)

8

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

4

–1

–2

–3

–4

–5

–6

–7

GAIN OF 20 (DIGITAL INPUT 101)

GAIN OF 10 (DIGITAL INPUT 100)

GAIN OF 5 (DIGITAL INPUT 011)

3

1

–2

–5

–10

–20

–50

–100

–2

20

10

V

= GAIN • V

LTC6910-X

IN

OUT IN

–4

2

–8

5

–16

–32

–64

AGND

1µF OR LARGER

6

7

GAIN OF 2 (DIGITAL INPUT 010)

GAIN OF 1 (DIGITAL INPUT 001)

G2 G1 G0

6910 TA01

0

PIN 2 (AGND) PROVIDES BUILT-IN HALF-SUPPLY

REFERENCE WITH INTERNAL RESISTANCE OF 5k.

AGND CAN ALSO BE DRIVEN BY A SYSTEM ANALOG

GROUND REFERENCE NEAR HALF SUPPLY

–10

100

1k

10k

100k

1M

10M

FREQUENCY (Hz)

6910 TA01b

6910123fa

1

LTC6910-1

LTC6910-2/LTC6910-3

W W U W

U W

U

ABSOLUTE AXI U RATI GS

(Note 1)

PACKAGE/ORDER I FOR ATIO

Total Supply Voltage (V+ to V–) ............................. 11V

Input Current ..................................................... ±25mA

Operating Temperature Range (Note 2)

LTC6910-1C, -2C, -3C ........................ –40°C to 85°C

LTC6910-1I, -2I, -3I ........................... –40°C to 85°C

LTC6910-1H, -2H, -3H .................... –40°C to 125°C

Specified Temperature Range (Note 3)

LTC6910-1C, -2C, -3C ........................ –40°C to 85°C

LTC6910-1I, -2I, -3I ........................... –40°C to 85°C

LTC6910-1H, -2H, -3H .................... –40°C to 125°C

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

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

ORDER PART NUMBER

LTC6910-1CTS8

LTC6910-1ITS8

LTC6910-1HTS8

LTC6910-2CTS8

LTC6910-2ITS8

LTC6910-2HTS8

LTC6910-3CTS8

LTC6910-3ITS8

LTC6910-3HTS8

TOP VIEW

+

OUT 1

AGND 2

8 V

7 G2

6 G1

5 G0

IN 3

–

V

4

TS8 PACKAGE

8-LEAD PLASTIC TSOT-23

T_JMAX= 150°C, θ_JA= 230°C/W

TS8 PART MARKING*

LTB5 (6910-1)

LTACQ (6910-2)

LTACS (6910-3)

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

*The temperature grades are identified by a label on the shipping container.

U

GAI SETTI GS A D PROPERTIES

Table 1. LTC6910-1

NOMINAL

NOMINAL LINEAR INPUT RANGE (V

)

P-P

INPUT

IMPEDANCE

(kΩ)

VOLTAGE GAIN

Dual 5V

Supply

Single 5V

Supply

Single 3V

Supply

G2

0

G1

0

G0

0

Volts/Volt

0

(dB)

–120

0

10

5

3

(Open)

0

1

–1

3

10

5

0

1

0

–2

6

2.5

1

1.5

0.6

0.3

0.15

0.06

0.03

0

1

–5

14

20

26

34

40

2

1

0

–10

–20

–50

–100

1

0.5

0.25

0.1

0.05

1

0

1

0.5

0.2

0.1

1

0

1

6910123fa

2

LTC6910-1

LTC6910-2/LTC6910-3

U

GAI SETTI GS A D PROPERTIES

Table 2. LTC6910-2

NOMINAL

NOMINAL LINEAR INPUT RANGE (V

)

P-P

INPUT

IMPEDANCE

(kΩ)

VOLTAGE GAIN

Dual 5V

Supply

Single 5V

Supply

Single 3V

Supply

G2

0

G1

0

G0

0

Volts/Volt

0

(dB)

–120

0

10

5

3

(Open)

10

0

1

–1

5

3

0

1

0

–2

6

5

2.5

1.5

5

0

1

–4

12

2.5

1.25

0.625

0.313

0.156

0.078

0.75

0.375

0.188

0.094

0.047

2.5

1

0

–8

18.1

24.1

30.1

36.1

1.25

0.625

0.313

0.156

1.25

1

0

1

–16

–32

–64

1

0

1

Table 3. LTC6910-3

NOMINAL

INPUT

IMPEDANCE

(kΩ)

NOMINAL

VOLTAGE GAIN

Volts/Volt

NOMINAL LINEAR INPUT RANGE (V

)

P-P

Dual 5V

Supply

Single 5V

Supply

Single 3V

Supply

G2

0

G1

0

G0

0

(dB)

–120

0

10

5

3

(Open)

10

0

1

–1

–2

–3

–4

–5

–6

–7

5

0

1

0

6

5

2.5

1.67

1.25

1

1.5

1

5

0

1

9.5

12

3.33

2.5

2

3.3

2.5

2

1

0

0.75

0.6

0.5

0.43

1

0

1

14

1

0

15.6

16.9

1.67

1.43

0.83

0.71

1.7

1.4

1

6910123fa

3

LTC6910-1

LTC6910-2/LTC6910-3

ELECTRICAL CHARACTERISTICS

to midsupply point, unless otherwise noted.

The ● denotes the specifications that apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), R_L= 10k

C, I SUFFIXES

MIN TYP MAX

H SUFFIX

MIN TYP MAX

PARAMETER

CONDITIONS

UNIT

Specifications for the LTC6910-1, LTC6910-2 and LTC6910-3

Total Supply Voltage

●

2.7

10.5

2.7

10.5

V

Supply Current

V = 2.7V, V = 1.35V

●

2

3

2

3

mA

S

IN

V = 5V, V = 2.5V

2.4

3

3.5

4.5

4.9

2.4

3

3.5

4.5

4.9

S

IN

V = ±5V, V = 0V, Pins 5, 6, 7 = –5V or 5V

S

IN

V = ±5V, V = 0V, Pin 5 = 4.5V,

3.5

S

IN

Pins 6, 7 = 0.5V (Note 4)

Output Voltage Swing LOW (Note 5)

V = 2.7V, R = 10k to Midsupply Point

●

12

50

30

100

12

50

30

100

mV

S

L

V = 2.7V, R = 500Ω to Midsupply Point

S

L

V = 5V, R = 10k to Midsupply Point

●

20

90

40

160

20

90

40

160

mV

S

L

V = 5V, R = 500Ω to Midsupply Point

S

L

V = ±5V, R = 10k to 0V

●

30

50

30

50

mV

S

L

V = ±5V, R = 500Ω to 0V

180 250

180 270

S

L

Output Voltage Swing HIGH (Note 5)

V = 2.7V, R = 10k to Midsupply Point

●

10

50

20

80

10

50

20

85

mV

S

L

V = 2.7V, R = 500Ω to Midsupply Point

S

L

V = 5V, R = 10k to Midsupply Point

●

10

80

30

150

10

80

30

150

mV

S

L

V = 5V, R = 500Ω to Midsupply Point

S

L

V = ±5V, R = 10k to 0V

●

20

40

20

40

mV

S

L

V = ±5V, R = 500Ω to 0V

180 250

S

L

Output Short-Circuit Current (Note 6)

AGND Open-Circuit Voltage

V = 2.7V

S

±27

±35

±27

±35

mA

S

V = ±5V

V = 5V

S

●

2.45 2.5 2.55

V

AGND Rejection (i.e., Common Mode

Rejection or CMRR)

V = 2.7V, V

V = ±5V, V

S

= 1.1V to Upper AGND Limit

= –2.5V to 2.5V

●

55

80

75

50

80

75

dB

S

AGND

Power Supply Rejection Ratio (PSRR)

Signal Attenuation at Gain = 0 Setting

Slew Rate

V = 2.7V to ±5V

●

60

80

60

80

dB

S

Gain = 0 (Digital Inputs 000), f = 20kHz

V = 5V, V = 2.8V

–122

12

16

12

16

V/µs

S

OUT

P-P

V = ±5V, V

S

= 2.8V

OUT

P-P

Digital Input “High” Voltage

V = 2.7V

●

2.43

4.5

2.43

4.5

V

S

V = 5V

S

V = ±5V

S

Digital Input “Low” Voltage

V = 2.7V

●

0.27

0.5

0.27

0.5

V

S

V = 5V

S

V = ±5V

S

–

+

Digital Input Leakage Current Magnitude

V ≤ (Digital Input) ≤ V

2

µA

6910123fa

4

LTC6910-1

LTC6910-2/LTC6910-3

ELECTRICAL CHARACTERISTICS

to midsupply point, unless otherwise noted.

The ● denotes the specifications that apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), R_L= 10k

LTC6910-1C/LTC6910-1I

MIN TYP MAX

LTC6910-1H

MIN TYP MAX

PARAMETER

CONDITIONS

UNIT

Specifications for LTC6910-1 Only

Voltage Gain (Note 7)

V = 2.7V, Gain = 1, R = 10k

●

–0.05

0

0.07 –0.06

0

0.07

dB

S

L

V = 2.7V, Gain = 1, R = 500Ω

–0.1 –0.02 0.06 –0.12 –0.02 0.08

S

L

V = 2.7V, Gain = 2, R = 10k

●

5.96 6.02 6.08 5.96 6.02 6.08

13.85 13.95 14.05 13.83 13.95 14.05

dB

S

L

V = 2.7V, Gain = 5, R = 10k

S

L

V = 2.7V, Gain = 10, R = 10k

●

19.7 19.9 20.1

19.6 19.85 20.1

19.7 19.9 20.1

19.4 19.85 20.1

dB

S

L

V = 2.7V, Gain = 10, R = 500Ω

S

L

V = 2.7V, Gain = 20, R = 10k

●

25.7 25.9 26.1

33.5 33.8 34.1

25.65 25.9 26.1

33.4 33.8 34.1

dB

S

L

V = 2.7V, Gain = 50, R = 10k

S

L

V = 2.7V, Gain = 100, R = 10k

●

39 39.6 40.2

37.4 39 40.1

38.7 39.6 40.2

36.4 39 40.1

dB

S

L

V = 2.7V, Gain = 100, R = 500Ω

S

L

V = 5V, Gain = 1, R = 10k

●

–0.05

0

0.07 –0.05

0

0.07

dB

S

L

V = 5V, Gain = 1, R = 500Ω

–0.1 –0.01 0.08 –0.11 –0.01 0.08

S

L

V = 5V, Gain = 2, R = 10k

●

5.96 6.02 6.08

13.8 13.95 14.1

5.955 6.02 6.08

13.75 13.95 14.1

dB

S

L

V = 5V, Gain = 5, R = 10k

S

L

V = 5V, Gain = 10, R = 10k

●

19.8 19.9 20.1

19.6 19.85 20.1

19.75 19.9 20.1

19.45 19.85 20.1

dB

S

L

V = 5V, Gain = 10, R = 500Ω

S

L

V = 5V, Gain = 20, R = 10k

●

25.8 25.9 26.1

33.5 33.8 34.1

25.70 25.9 26.1

33.4 33.8 34.1

dB

S

L

V = 5V, Gain = 50, R = 10k

S

L

V = 5V, Gain = 100, R = 10k

●

39.3 39.7 40.1

38 39.2 40.1

39.1 39.7 40.1

37 39.2 40.1

dB

S

L

V = 5V, Gain = 100, R = 500Ω

S

L

V = ±5V, Gain = 1, R = 10k

●

–0.05

0

0.07 –0.05

0

0.07

dB

S

L

V = ±5V, Gain = 1, R = 500Ω

–0.1 –0.01 0.08

5.96 6.02 6.08

13.80 13.95 14.1

–0.1 –0.01 0.08

5.96 6.02 6.08

13.80 13.95 14.1

S

L

V = ±5V, Gain = 2, R = 10k

●

dB

S

L

V = ±5V, Gain = 5, R = 10k

S

L

V = ±5V, Gain = 10, R = 10k

●

19.8 19.9 20.1

19.7 19.9 20.1

19.75 19.9 20.1

19.6 19.9 20.1

dB

S

L

V = ±5V, Gain = 10, R = 500Ω

S

L

V = ±5V, Gain = 20, R = 10k

●

25.8 25.95 26.1

33.7 33.85 34

25.75 25.95 26.1

33.6 33.85 34

dB

S

L

V = ±5V, Gain = 50, R = 10k

S

L

V = ±5V, Gain = 100, R = 10k

●

39.4 39.8 40.2

38.8 39.6 40.1

39.25 39.8 40.2

38 39.6 40.1

dB

S

L

V = ±5V, Gain = 100, R = 500Ω

S

L

Offset Voltage Magnitude (Internal Op Amp)

●

1.5

9

1.5

11

mV

(V ) (Note 8)

OS(OA)

Offset Voltage Drift (Internal Op Amp) (Note 8)

6

8

µV/°C

Offset Voltage Magnitude

Gain = 1

Gain = 10

●

3

1.7

15

10

3

1.7

18

12

mV

(Referred to “IN” Pin) (V

)

OS(IN)

DC Input Resistance (Note 9)

DC V = 0V

Gain = 0

Gain = 1

Gain = 2

Gain = 5

Gain = 10, 20, 50, 100

IN

>100

10

5

2

1

>100

10

5

2

1

MΩ

kΩ

●

6910123fa

5

LTC6910-1

LTC6910-2/LTC6910-3

ELECTRICAL CHARACTERISTICS

to midsupply point, unless otherwise noted.

The ● denotes the specifications that apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), R_L= 10k

LTC6910-1C/LTC6910-1I

MIN TYP MAX

LTC6910-1H

MIN TYP MAX

PARAMETER

CONDITIONS

UNIT

Specifications for LTC6910-1 Only

DC Small-Signal Output Resistance

Gain = 0

Gain = 1

Gain = 2

Gain = 5

Gain = 10

Gain = 20

Gain = 50

Gain = 100

0.4

0.7

1

1.9

3.4

6.4

15

30

0.4

0.7

1

1.9

3.4

6.4

15

30

Ω

Gain-Bandwidth Product

Gain = 100, f = 200kHz

8

6

11

14

16

8

5

11

14

16

MHz

IN

●

Wideband Noise (Referred to Input)

f = 1kHz to 200kHz

Gain = 0 Output Noise

Gain = 1

Gain = 2

Gain = 5

Gain = 10

Gain = 20

Gain = 50

Gain = 100

3.8

10.7

7.3

5.2

4.5

4.2

3.9

3.4

3.8

10.7

7.3

5.2

4.5

4.2

3.9

3.4

µV

RMS

µV

Voltage Noise Density (Referred to Input)

f = 50kHz

Gain = 1

Gain = 2

24

16

12

24

16

12

nV/√Hz

Gain = 5

Gain = 10

Gain = 20

Gain = 50

Gain = 100

10

9.4

8.7

7.6

9.4

8.7

7.6

Total Harmonic Distortion

Gain = 10, f = 10kHz, V

= 1V

RMS

–90

0.003

–90

0.003

dB

%

IN

OUT

Gain = 10, f = 100kHz, V

= 1V

RMS

–77

0.014

–77

0.014

dB

%

IN

OUT

AGND (Common Mode) Input Voltage Range V = 2.7V

●

0.55

0.7

–4.3

1.6

3.65

3.5

0.7

1

–4.3

1.5

3.25

3.35

V

S

(Note 10)

V = 5V

S

V = ±5V

S

6910123fa

6

LTC6910-1

LTC6910-2/LTC6910-3

ELECTRICAL CHARACTERISTICS

to midsupply point, unless otherwise noted.

The ● denotes the specifications that apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), R_L= 10k

LTC6910-2C/LTC6910-2I

MIN TYP MAX

LTC6910-2H

MIN TYP MAX

PARAMETER

CONDITIONS

UNIT

Specifications for LTC6910-2 Only

Voltage Gain (Note 7)

V = 2.7V, Gain = 1, R = 10k

●

–0.06

0

0.08 –0.07

0

0.08

dB

S

L

V = 2.7V, Gain = 1, R = 500Ω

–0.1 –0.02 0.06 –0.11 –0.02 0.06

S

L

V = 2.7V, Gain = 2, R = 10k

●

5.96 6.02 6.1 5.95 6.02 6.1

dB

S

L

V = 2.7V, Gain = 4, R = 10k

11.9 12.02 12.12 11.9 12.02 12.12

S

L

V = 2.7V, Gain = 8, R = 10k

●

17.8 17.98 18.15 17.8 17.98 18.15

17.65 17.95 18.15 17.55 17.95 18.15

dB

S

L

V = 2.7V, Gain = 8, R = 500Ω

S

L

V = 2.7V, Gain = 16, R = 10k

●

23.75 24 24.2

29.7 30 30.2

23.75 24 24.2

29.65 30 30.2

dB

S

L

V = 2.7V, Gain = 32, R = 10k

S

L

V = 2.7V, Gain = 64, R = 10k

●

35.3 35.75 36.2

34.2 35.3 36.2

35.2 35.75 36.2

33.7 35.3 36.2

dB

S

L

V = 2.7V, Gain = 64, R = 500Ω

S

L

V = 5V, Gain = 1, R = 10k

●

–0.06

–0.1 –0.01 0.08 –0.11 –0.01 0.08

5.96 6.02 6.1 5.96 6.02 6.1

0

0.08 –0.06

0

0.08

dB

S

L

V = 5V, Gain = 1, R = 500Ω

S

L

V = 5V, Gain = 2, R = 10k

●

dB

S

L

V = 5V, Gain = 4, R = 10k

11.85 12.02 12.15 11.85 12.02 12.15

S

L

V = 5V, Gain = 8, R = 10k

●

17.85 18 18.15 17.85 18 18.15

17.65 17.9 18.15 17.6 17.9 18.15

dB

S

L

V = 5V, Gain = 8, R = 500Ω

S

L

V = 5V, Gain = 16, R = 10k

●

23.85 24 24.15 23.78 24 24.15

dB

S

L

V = 5V, Gain = 32, R = 10k

29.7 30 30.2

S

L

V = 5V, Gain = 64, R = 10k

●

35.6 35.9 36.2

34.8 35.5 36

35.5 35.9 36.2

34.2 35.5 36

dB

S

L

V = 5V, Gain = 64, R = 500Ω

S

L

V = ±5V, Gain = 1, R = 10k

●

–0.05

–0.1 –0.01 0.08

0

0.07 –0.05

0

0.07

dB

S

L

V = ±5V, Gain = 1, R = 500Ω

–0.1 –0.01 0.08

S

L

V = ±5V, Gain = 2, R = 10k

●

5.96 6.02 6.1

dB

S

L

V = ±5V, Gain = 4, R = 10k

11.9 12.02 12.15 11.9 12.02 12.15

17.85 18 18.15 17.85 18 18.15

17.80 17.95 18.1

S

L

V = ±5V, Gain = 8, R = 10k

●

dB

S

L

V = ±5V, Gain = 8, R = 500Ω

17.72 17.95 18.1

S

L

V = ±5V, Gain = 16, R = 10k

●

23.85 24 24.15 23.8 24 24.15

29.85 30 30.15 29.78 30 30.15

dB

S

L

V = ±5V, Gain = 32, R = 10k

S

L

V = ±5V, Gain = 64, R = 10k

●

35.7 35.95 36.2

35.2 35.8 36.2

35.7 35.95 36.2

34.8 35.8 36.2

dB

S

L

V = ±5V, Gain = 64, R = 500Ω

S

L

Offset Voltage Magnitude (Internal Op Amp)

●

1.5

9

1.5

11

mV

(V ) (Note 8)

OS(OA)

Offset Voltage Drift (Internal Op Amp) (Note 8)

●

6

8

µV/°C

Offset Voltage Magnitude

Gain = 1

Gain = 8

●

3

2

15

10

3

2

17

12

mV

(Referred to “IN” Pin) (V

)

OS(IN)

DC Input Resistance (Note 9)

DC V = 0V

Gain = 0

Gain = 1

Gain = 2

Gain = 4

Gain = 8, 16, 32, 64

IN

>100

10

5

2.5

1.25

>100

10

5

2.5

1.25

MΩ

kΩ

●

6910123fa

7

LTC6910-1

LTC6910-2/LTC6910-3

ELECTRICAL CHARACTERISTICS

to midsupply point, unless otherwise noted.

The ● denotes the specifications that apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), R_L= 10k

LTC6910-2C/LTC6910-2I

MIN TYP MAX

LTC6910-2H

MIN TYP MAX

PARAMETER

CONDITIONS

UNIT

Specifications for LTC6910-2 Only

DC Small-Signal Output Resistance

Gain = 0

Gain = 1

Gain = 2

Gain = 4

Gain = 8

Gain = 16

Gain = 32

Gain = 64

0.4

0.7

1

1.6

2.8

5

0.4

0.7

1

1.6

2.8

5

Ω

10

20

10

20

Gain-Bandwidth Product

Gain = 64, f = 200kHz

9

7

13

16

19

9

7

13

16

19

MHz

IN

●

Wideband Noise (Referred to Input)

f = 1kHz to 200kHz

Gain = 0 Output Noise

Gain = 1

Gain = 2

Gain = 4

Gain = 8

Gain = 16

Gain = 32

Gain = 64

3.8

10.7

7.3

5.3

4.6

4.2

4

3.8

10.7

7.3

5.3

4.6

4.2

4

µV

RMS

µV

3.6

Voltage Noise Density (Referred to Input)

f = 50kHz

Gain = 1

Gain = 2

Gain = 4

Gain = 8

Gain = 16

Gain = 32

Gain = 64

24

16

12

10.3

9.4

9

24

16

12

10.3

9.4

9

nV/√Hz

8.1

Total Harmonic Distortion

Gain = 8, f = 10kHz, V

= 1V

RMS

–90

0.003

–90

0.003

dB

%

IN

OUT

Gain = 8, f = 100kHz, V

= 1V

RMS

–77

0.014

–77

0.014

dB

%

IN

OUT

AGND (Common Mode) Input Voltage Range V = 2.7V

●

0.85

0.7

–4.3

1.55

3.6

3.4

0.85

0.7

–4.3

1.55

3.6

3.4

V

S

(Note 10)

V = 5V

S

V = ±5V

S

6910123fa

8

LTC6910-1

LTC6910-2/LTC6910-3

ELECTRICAL CHARACTERISTICS

to midsupply point, unless otherwise noted.

The ● denotes the specifications that apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), R_L= 10k

LTC6910-3C/LTC6910-3I

MIN TYP MAX

LTC6910-3H

MIN TYP MAX

PARAMETER

CONDITIONS

UNIT

Specifications for LTC6910-3 Only

Voltage Gain (Note 7)

V = 2.7V, Gain = 1, R = 10k

●

–0.05

0

0.07 –0.05

0

0.09

dB

S

L

V = 2.7V, Gain = 1, R = 500Ω

–0.1 –0.02 0.06 –0.11 –0.02 0.06

S

L

V = 2.7V, Gain = 2, R = 10k

●

5.93 6.02 6.08

9.35 9.5 9.7

5.93 6.02 6.09

9.35 9.5 9.75

dB

S

L

V = 2.7V, Gain = 3, R = 10k

S

L

V = 2.7V, Gain = 4, R = 10k

●

11.9 11.98 12.2

11.8 11.98 12.2

11.9 11.98 12.2

11.75 11.98 12.2

dB

S

L

V = 2.7V, Gain = 4, R = 500Ω

S

L

V = 2.7V, Gain = 5, R = 10k

●

13.85 13.92 14.05 13.8 13.92 14.05

dB

S

L

V = 2.7V, Gain = 6, R = 10k

15.4 15.5 15.6

S

L

V = 2.7V, Gain = 7, R = 10k

●

16.7 16.85 17

16.55 16.8 17

16.7 16.85 17

16.47 16.8 17

dB

S

L

V = 2.7V, Gain = 7, R = 500Ω

S

L

V = 5V, Gain = 1, R = 10k

●

–0.05

0

0.07 –0.05

0

0.07

dB

S

L

V = 5V, Gain = 1, R = 500Ω

–0.1 –0.01 0.08

5.96 6.02 6.08

9.45 9.54 9.65

–0.1 –0.01 0.08

5.96 6.02 6.08

9.45 9.54 9.65

S

L

V = 5V, Gain = 2, R = 10k

●

dB

S

L

V = 5V, Gain = 3, R = 10k

S

L

V = 5V, Gain = 4, R = 10k

●

11.85 12.02 12.15 11.85 12.02 12.15

11.8 11.95 12.15 11.75 11.95 12.15

dB

S

L

V = 5V, Gain = 4, R = 500Ω

S

L

V = 5V, Gain = 5, R = 10k

●

13.8 13.95 14.05 13.8 13.95 14.05

15.35 15.5 15.65 15.35 15.5 15.65

dB

S

L

V = 5V, Gain = 6, R = 10k

S

L

V = 5V, Gain = 7, R = 10k

●

16.7 16.85 17

16.6 16.8 17

16.7 16.85 17

16.5 16.8 17

dB

S

L

V = 5V, Gain = 7, R = 500Ω

S

L

V = ±5V, Gain = 1, R = 10k

●

–0.06

0

0.07 –0.06

0

0.07

dB

S

L

V = ±5V, Gain = 1, R = 500Ω

–0.1 –0.01 0.08 –0.12 –0.01 0.08

S

L

V = ±5V, Gain = 2, R = 10k

●

5.96 6.02 6.08

9.4 9.54 9.65

5.96 6.02 6.08

9.4 9.54 9.65

dB

S

L

V = ±5V, Gain = 3, R = 10k

S

L

V = ±5V, Gain = 4, R = 10k

●

11.85 12 12.2

11.8 12 12.2

11.85 12 12.2

11.8 12 12.2

dB

S

L

V = ±5V, Gain = 4, R = 500Ω

S

L

V = ±5V, Gain = 5, R = 10k

●

13.8 13.95 14.1

15.35 15.5 15.7

13.8 13.95 14.1

15.35 15.5 15.7

dB

S

L

V = ±5V, Gain = 6, R = 10k

S

L

V = ±5V, Gain = 7, R = 10k

●

16.7 16.85 17.05 16.7 16.85 17.05

16.65 16.8 17 16.6 16.8 17

dB

S

L

V = ±5V, Gain = 7, R = 500Ω

S

L

Offset Voltage Magnitude (Internal Op Amp)

●

1.5

8

1.5

8

mV

(V ) (Note 8)

OS(OA)

Offset Voltage Drift (Internal Op Amp) (Note 8)

●

6

8

µV/°C

Offset Voltage Magnitude

Gain = 1

Gain = 4

●

3

1.9

15

10

3

1.9

15

10

mV

(Referred to “IN” Pin) (V

)

OS(IN)

DC Input Resistance (Note 9)

DC V = 0V

IN

Gain = 0

Gain = 1

Gain = 2

Gain = 3

Gain = 4

Gain = 5

Gain = 6

Gain = 7

>100

10

5

3.3

2.5

2

1.7

1.4

>100

10

5

3.3

2.5

2

1.7

1.4

MΩ

kΩ

●

6910123fa

9

LTC6910-1

LTC6910-2/LTC6910-3

ELECTRICAL CHARACTERISTICS

to midsupply point, unless otherwise noted.

The ● denotes the specifications that apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 5V, AGND = 2.5V, Gain = 1 (Digital Inputs 001), R_L= 10k

LTC6910-3C/LTC6910-3I

MIN TYP MAX

LTC6910-3H

MIN TYP MAX

PARAMETER

CONDITIONS

UNIT

Specifications for LTC6910-3 Only

DC Small-Signal Output Resistance

Gain = 0

Gain = 1

Gain = 2

Gain = 3

Gain = 4

Gain = 5

Gain = 6

Gain = 7

0.4

0.7

1

1.3

1.6

1.9

2.2

2.5

0.4

0.7

1

1.3

1.6

1.9

2.2

2.5

Ω

Gain-Bandwidth Product

Gain = 7, f = 200kHz

●

11

MHz

IN

Wideband Noise (Referred to Input)

f = 1kHz to 200kHz

Gain = 0 Output Noise

Gain = 1

Gain = 2

Gain = 3

Gain = 4

Gain = 5

Gain = 6

Gain = 7

3.8

10.7

7.3

6.1

5.3

5.2

4.9

4.7

3.8

10.7

7.3

6.1

5.3

5.2

4.9

4.7

µV

RMS

µV

Voltage Noise Density (Referred to Input)

f = 50kHz

Gain = 1

Gain = 2

Gain = 3

Gain = 4

Gain = 5

Gain = 6

Gain = 7

24

16

14

24

16

14

nV/√Hz

12

11.6

11.2

10.5

11.6

11.2

10.5

Total Harmonic Distortion

Gain = 4, f = 10kHz, V

= 1V

RMS

–90

0.003

–90

0.003

dB

%

IN

OUT

Gain = 4, f = 100kHz, V

= 1V

RMS

–80

0.01

–80

0.01

dB

%

IN

OUT

AGND (Common Mode) Input Voltage Range V = 2.7V

●

0.85

0.7

–4.3

1.55

3.6

3.4

0.85

0.7

–4.3

1.55

3.6

3.4

V

S

(Note 10)

V = 5V

S

V = ±5V

S

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

of the device may be impaired.

Note 2: The LTC6910-XC and LTC6910-XI are guaranteed functional over

the operating temperature range of –40°C to 85°C. The LTC6910-XH are

guaranteed functional over the operating temperature range of –40°C to

125°C.

Note 3: The LTC6910-XC are guaranteed to meet specified performance

from 0°C to 70°C. The LTC6910-XC are designed, characterized and

expected to meet specified performance from –40°C to 85°C but are not

tested or QA sampled at these temperatures. LTC6910-XI are guaranteed

to meet specified performance from –40°C to 85°C. The LTC6910-XH are

guaranteed to meet specified performance from –40°C to 125°C.

Note 4: Operating all three logic inputs at 0.5V causes the supply current

to increase typically 0.1mA from this specification.

Note 5: Output voltage swings are measured as differences between the

output and the respective supply rail.

Note 6: Extended operation with output shorted may cause junction

temperature to exceed the 150°C limit and is not recommended.

Note 7: Gain is measured with a DC large-signal test using an output

excursion between approximately 30% and 70% of supply voltage.

Note 8: Offset voltage referred to “IN” pin is (1 + 1/G) times offset voltage

of the internal op amp, where G is nominal gain magnitude. See Applica-

tions Information.

Note 9: Input resistance can vary by approximately ±30% part-to-part at a

given gain setting.

Note 10: At limits of AGND input range, open-loop gain of internal op amp

may be greater than, or as much as 15dB below, its value at nominal

AGND value.

6910123fa

10

LTC6910-1

LTC6910-2/LTC6910-3

U W

TYPICAL PERFOR A CE CHARACTERISTICS _(LTC6910-1)

LTC6910-1 Gain Shift

LTC6910-1 –3dB Bandwidth

vs Gain Setting

vs Temperature

LTC6910-1 Frequency Response

50

8.0

7.5

7.0

6.5

6.0

5.5

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

0.2

0.1

0

V

= ±5V, V = 5mV

IN

V

IN

V

•

V

•

= 5mV

RMS

V

= ±2.5V

S

RMS

S

•

= 2.7V

OUTPUT UNLOADED

S

GAIN OF 100

GAIN OF 50

= ±5V

40

30

GAIN = 100

GAIN = 10

GAIN OF 20

GAIN OF 10

GAIN OF 5

•

20

10

GAIN = 1

GAIN OF 2

GAIN OF 1

•

–0.1

0

•

–10

–0.2

100

1k

10k

100k

1M

10M

1

10

100

–50

0

50

100

150

FREQUENCY (Hz)

GAIN

TEMPERATURE (°C)

6910 G02

6910 G03

6910 G01

LTC6910-1 Output Voltage Swing

vs Load Current

LTC6910-1 Power Supply

Rejection vs Frequency

LTC6910-1 Noise Density

vs Frequency

90

80

70

60

50

40

30

20

10

0

+V

100

S

V

= ±2.5V

S

INPUT-REFERRED

V

S

= ±2.5V

125°C

25°C

GAIN = 1

+V – 0.5

S

V

T

= ±2.5V

= 25°C

S

A

SOURCE

+V – 1.0

S

–40°C

GAIN = 1

+SUPPLY

+V – 1.5

S

–SUPPLY

+V – 2.0

S

GAIN = 10

10

–V + 2.0

S

GAIN = 100

–V + 1.5

S

–V + 1.0

S

SINK

10

–V + 0.5

S

–V

S

1

0.01

0.1

1

100

0.1

1

10

FREQUENCY (kHz)

100

1000

10

FREQUENCY (kHz)

1

100

OUTPUT CURRENT (mA)

6910 G04

6910 G05

6910 G06

LTC6910-1 Distortion with Light

Loading (R_L= 10k)

LTC6910-1 Distortion with Heavy

LTC6910-1 THD + Noise

vs Input Voltage

Loading (R_L= 500Ω)

–30

3

–30

–40

–50

3

1

–20

V

= ±2.5V

f

= 1kHz

= ±5V

S

IN

S

= 1V

(2.83V )

P-P

V

–30

–40

–50

–60

–70

–80

–90

–100

–110

OUT

RMS

–40

–50

1

THD MEASURES HD2 AND HD3

NOISE BW = 22kHz

GAIN SETTING = 100

GAIN SETTING = 10

GAIN =100

GAIN =10

0.3

–60

–70

0.1

–60

–70

0.1

GAIN =100

GAIN =10

GAIN =1

0.03

0.01

0.003

0.001

0.03

0.01

0.003

0.001

GAIN =1

–80

V

= ±2.5V

S

–90

= 1V

(2.83V )

P-P

OUT

RMS

GAIN SETTING = 1

0.1

INPUT VOLTAGE (V

THD MEASURES HD2 AND HD3

–100

50

100

200

0

150

50

100

200

0.01

1

10

0

150

FREQUENCY (kHz)

)

P-P

6910 G09

6910 G08

6910 G07

6910123fa

11

LTC6910-1

LTC6910-2/LTC6910-3

U W

TYPICAL PERFOR A CE CHARACTERISTICS _(LTC6910-2)

LTC6910-2 Gain Shift

LTC6910-2 –3dB Bandwidth

vs Gain Setting

vs Temperature

LTC6910-2 Frequency Response

50

8.0

7.5

7.0

6.5

6.0

5.5

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

0.2

0.1

0

V

= ±5V

IN

V

IN

V

•

V

•

= 10mV

RMS

V

S

= ±2.5V

S

•

= 10mV

= 2.7V

OUTPUT UNLOADED

RMS

S

= ±5V

40

30

S

GAIN OF 64

GAIN OF 32

GAIN OF 16

GAIN OF 8

GAIN OF 4

GAIN OF 2

GAIN = 64

GAIN = 8

•

20

10

GAIN = 1

•

–0.1

GAIN OF 1

•

0

•

–10

100

–0.2

1k

10k

100k

1M

10M

1

10

GAIN

100

–50

0

50

100

150

FREQUENCY (Hz)

TEMPERATURE (°C)

6910 G11

6910 G12

6910 G10

LTC6910-2 Output Voltage Swing

vs Load Current

LTC6910-2 Power Supply

Rejection vs Frequency

LTC6910-2 Noise Density

vs Frequency

90

80

70

60

50

40

30

20

10

0

+V

100

S

V

= ±2.5V

S

INPUT-REFERRED

V

S

= ±2.5V

125°C

25°C

+SUPPLY

GAIN = 1

+V – 0.5

S

V

T

= ±2.5V

= 25°C

S

A

SOURCE

+V – 1.0

S

–40°C

GAIN = 1

+V – 1.5

S

–SUPPLY

+V – 2.0

S

GAIN = 8

10

–V + 2.0

S

GAIN = 64

–V + 1.5

S

–V + 1.0

S

SINK

10

–V + 0.5

S

–V

S

1

0.01

0.1

1

100

0.1

1

10

100

1000

10

FREQUENCY (kHz)

1

100

OUTPUT CURRENT (mA)

FREQUENCY (kHz)

6910 G13

6910 G14

6910 G15

LTC6910-2 Distortion with Light

Loading (R_L= 10k)

LTC6910-2 Distortion with Heavy

LTC6910-2 THD + Noise

vs Input Voltage

Loading (R_L= 500Ω)

–30

3

–30

–40

–50

3

1

–20

V

= ±2.5V

S

GAIN

SETTING = 64

= 1V

(2.83V )

P-P

–30

–40

–50

–60

–70

–80

–90

–100

–110

OUT

RMS

–40

–50

1

THD MEASURES HD2 AND HD3

GAIN = 64

GAIN = 8

0.3

–60

–70

0.1

–60

–70

0.1

GAIN = 64

GAIN

0.03

0.01

0.003

0.001

0.03

0.01

0.003

0.001

SETTING = 8

GAIN = 8

GAIN =1

–80

V

= ±2.5V

f

= 1kHz

S

IN

S

–90

= 1V

(2.83V )

P-P

V

= ±5V

OUT

RMS

THD MEASURES HD2 AND HD3

NOISE BW = 22kHz

GAIN SETTING = 1

–100

50

100

200

0

150

50

100

200

0.01

0.1

1

10

0

150

FREQUENCY (kHz)

INPUT VOLTAGE (V

)

P-P

6910 G18

6910 G17

6910 G16

6910123fa

12

LTC6910-1

LTC6910-2/LTC6910-3

U W

TYPICAL PERFOR A CE CHARACTERISTICS _(LTC6910-3)

LTC6910-3 Gain Shift

LTC6910-3 –3dB Bandwidth

vs Gain Setting

vs Temperature

LTC6910-3 Frequency Response

20

8.0

7.0

6.0

5.0

4.0

3.0

2.0

1.0

0

0.02

0.01

0

V

•

= 10mV

RMS

V

= ±2.5V

IN

V

S

GAIN OF 7 GAIN OF 6

= 2.7V

OUTPUT UNLOADED

•

S

V

= ±5V

15

10

GAIN OF 5

GAIN OF 4

GAIN = 7

GAIN OF 3

GAIN OF 2

GAIN OF 1

•

GAIN = 4

5

0

•

GAIN = 1

•

–0.01

•

–5

V

= ±5V

IN

S

= 10mV

RMS

–10

–0.02

100

1k

10k

100k

1M

10M

1

3

6

9 10

7 8

2

4

5

–50

0

50

100

150

FREQUENCY (Hz)

GAIN

TEMPERATURE (°C)

6910 G20

6910 G21

6910 G19

LTC6910-3 Output Voltage Swing

vs Load Current

LTC6910-3 Power Supply

Rejection vs Frequency

LTC6910-3 Noise Density

vs Frequency

90

80

70

60

50

40

30

20

10

0

+V

100

S

V

= ±2.5V

S

INPUT-REFERRED

V

S

= ±2.5V

125°C

25°C

+SUPPLY

GAIN = 1

+V – 0.5

S

V

T

= ±2.5V

= 25°C

S

A

SOURCE

+V – 1.0

S

–40°C

GAIN = 1

+V – 1.5

S

–SUPPLY

GAIN = 4

GAIN = 7

+V – 2.0

S

10

–V + 2.0

S

–V + 1.5

S

–V + 1.0

S

SINK

10

–V + 0.5

S

–V

S

1

0.01

0.1

1

100

0.1

1

10

100

1000

10

FREQUENCY (kHz)

1

100

OUTPUT CURRENT (mA)

FREQUENCY (kHz)

6910 G22

6910 G23

6910 G24

LTC6910-3 Distortion with Light

Loading (R_L= 10k)

LTC6910-3 Distortion with Heavy

LTC6910-3 THD + Noise

vs Input Voltage

Loading (R_L= 500Ω)

–30

3

–30

–40

–50

3

1

–20

V

= ±2.5V

f

= 1kHz

S

IN

S

= 1V

(2.83V )

P-P

V

= ±5V

–30

–40

–50

–60

–70

–80

–90

–100

–110

OUT

RMS

–40

–50

1

THD MEASURES HD2 AND HD3

NOISE BW = 22kHz

0.3

GAIN SETTING = 7

GAIN SETTING = 4

0.3

GAIN = 7

GAIN = 4

–60

–70

0.1

–60

–70

0.1

GAIN = 7

GAIN = 4

0.03

0.01

0.003

0.001

0.03

0.01

0.003

0.001

GAIN =1

–80

GAIN =1

–80

V

= ±2.5V

S

–90

= 1V

(2.83V )

P-P

OUT

RMS

THD MEASURES HD2 AND HD3

GAIN SETTING = 1

–100

50

100

200

0

150

50

100

200

0.01

0.1

1

10

0

150

FREQUENCY (kHz)

INPUT VOLTAGE (V

)

P-P

6910 G27

6910 G26

6910 G25

6910123fa

13

LTC6910-1

LTC6910-2/LTC6910-3

U

PI FU CTIO S

Recommended analog ground plane connection depends

on how power is applied to the LTC6910-X (Figures 1, 2,

and 3). Single power supply applications typically use V^–

for the system signal ground. The analog ground plane in

single-supply applications should therefore tie to V^–, and

the AGND pin should be bypassed to this ground plane by

a high quality capacitor of at least 1µF (Figure 1). The

AGND pin then provides an internal analog reference

voltage at half the supply voltage (with internal resistance

of approximately 5kΩ) which is the center of the swing

range for both input and output. Dual supply applications

with symmetrical supplies (such as ±5V) have a natural

system ground at zero volts, which can drive the analog

ground plane; AGND then connects directly to the ground

plane, making zero volts the input and output reference

voltage for the LTC6910-X (Figure 2). Finally, if a dual

power supply is asymmetrical, the supply ground is still

the natural ground plane voltage. To maximize signal

swing capability with an asymmetrical supply, however, it

is often desirable to refer the LTC6910-X’s analog input

and output to a voltage equidistant from the two supply

rails V⁺and V^–. The AGND pin will provide such a potential

when open-circuited and bypassed with a capacitor (Fig-

ure 3), just as with a single power supply, but now the

ground plane connection is different and the LTC6910-X’s

V⁺and V^–pins are both isolated from this ground plane.

OUT (Pin 1): Analog Output. This is the output of an

internal operational amplifier and swings to near the

powersupplyrails(V⁺andV^–)asspecifiedintheElectrical

Characteristics table. The internal op amp remains active

at all times, including the zero gain setting (digital input

000).Aswithotheramplifiercircuits,loadingtheoutputas

lightly as possible will minimize signal distortion and gain

error. The Electrical Characteristics table shows perfor-

mance at output currents up to 10mA and current limits

thatoccurwhentheoutputisshortedtomidsupplyat2.7V

and ±5V supplies. Signal outputs above 10mA are pos-

sible but current-limiting circuitry will begin to affect

amplifierperformanceatapproximately20mA.Long-term

operation above 20mA output is not recommended. Do

not exceed maximum junction temperature of 150°C. The

outputwilldrivecapacitiveloadsupto50pF. Capacitances

higher than 50pF should be isolated by a series resistor to

preserve AC stability.

AGND (Pin 2): Analog Ground. The AGND pin is at the

midpoint of an internal resistive voltage divider, develop-

ing a potential halfway between the V⁺and V^–pins, with an

equivalent series resistance to the pin of nominally 5kΩ

(Figure 4). AGND is also the noninverting input of the

internal op amp, which makes it the ground reference

voltage for the IN and OUT pins. Because of this, very

“clean”groundingisimportant,includingananalogground

plane surrounding the package.

+

V

0.1µF

8

7

6

5

8

7

6

5

4

8

1

7

6

5

4

LTC6910-X

1

2

3

4

1

2

3

2

3

0.1µF

MID-SUPPLY

REFERENCE

ANALOG

GROUND

PLANE

ANALOG

GROUND

PLANE

ANALOG

GROUND

PLANE

+

V

1µF

REFERENCE

2

1µF

–

V

SINGLE-POINT

SYSTEM GROUND

SINGLE-POINT

SYSTEM GROUND

SINGLE-POINT

SYSTEM GROUND

DIGITAL GROUND PLANE

(IF ANY)

DIGITAL GROUND PLANE

(IF ANY)

DIGITAL GROUND PLANE

(IF ANY)

6910 F02

6910 F03

6910 F01

Figure 1. Single Supply

Ground Plane Connection

Figure 2. Symmetrical Dual Supply

Ground Plane Connection

Figure 3. Asymmetrical Dual

Supply Ground Plane Connection

6910123fa

14

LTC6910-1

LTC6910-2/LTC6910-3

U

PI FU CTIO S

Where AGND does not connect to a ground plane, as in

Figures1and3,itisimportanttoAC-bypasstheAGNDpin.

This is especially true when AGND is used as a reference

voltage for other circuitry. Also, without a bypass capaci-

tor, wideband noise will enter the signal path from the

internalvoltagedividerresistorsthatsettheDCvoltageon

AGND. This noise can reduce SNR by 3dB at high gain

settings. The resistors present a Thévenin equivalent of

approximately 5k to the AGND pin. An external capacitor

from AGND to the ground plane, whose impedance is well

below 5k at frequencies of interest, will suppress this

noise.A1µFhighqualitycapacitoriseffectiveinsuppress-

ing resistor noise for frequencies down to 1kHz. Larger

capacitors extend this suppression to proportionately

lower frequencies. This issue does not arise in symmetri-

cal dual supply applications (Figure 2) because AGND

goes directly to ground.

tance.Theinputmayvaryfromrailtorailinthe“zero”gain

settingbuttheoutputisinsensitivetoitandremainsatthe

AGNDpotential.CircuitrydrivingtheINpinmustconsider

the LTC6910-X’s input resistance and the variation of this

resistance when used at multiple gain settings. Signal

sources with significant output resistance may introduce

a gain error as the source’s output resistance and the

LTC6910-X’sinputresistanceformavoltagedivider. This

is especially true at the higher gain settings where the

input resistance is lowest.

In single supply voltage applications at elevated gain

settings (digital input 010 or higher), it is important to

remember that the LTC6910-X’s DC ground reference for

both input and output is AGND, not V^–. With increasing

gains, the LTC6910-X’s input voltage range for unclipped

output is no longer rail-to-rail but shrinks toward AGND.

The OUT pin also swings positive or negative with respect

toAGND. Atunitygain(digitalinput001), bothINandOUT

voltages can swing from rail to rail (Tables 1, 2, 3).

Inapplicationsrequiringananaloggroundreferenceother

than halfway between the supply rails, the user can over-

ride the built-in analog ground reference by tying the

AGND pin to a reference voltage within the AGND voltage

range specified in the Electrical Characteristics table. The

AGND pin will load the external reference with approxi-

mately 5k returned to the mid-supply potential. AGND

should still be capacitively bypassed to a ground plane as

noted above. Do not connect the AGND pin to the V^–pin.

G2

7

G1

6

G0

5

CMOS LOGIC

IN (Pin 3): Analog Input. The input signal to the amplifier

in the LTC6910-X is the voltage difference between the IN

andAGNDpins.TheINpinconnectsinternallytoadigitally

controlled resistance whose other end is a current sum-

ming point at the same potential as the AGND pin (Fig-

ure 4). At unity gain (digital input 001), the value of this

inputresistanceisapproximately10kΩandtheINvoltage

range is rail-to-rail (V⁺to V^–). At gain settings above unity

(digital input 010 or higher), the input resistance falls.

Also, thelinearinputvoltagerangefallsininversepropor-

tiontogain.(Thehighergainsaredesignedtoboostlower

level signals with good noise performance.) Tables 1, 2,

and 3 summarize this behavior. In the “zero” gain state

(digital input 000), analog switches disconnect the IN pin

internally and this pin presents a very high input resis-

IN

3

INPUT R ARRAY

FEEDBACK R ARRAY

–

MOS-INPUT

1

OUT

OP AMP

+

10k

+

–

V

8

2

4

6910 F04

+

–

V

AGND

V

Figure 4. Block Diagram

6910123fa

15

LTC6910-1

LTC6910-2/LTC6910-3

U

PI FU CTIO S

V^–, V⁺(Pins 4, 8): Power Supply Pins. The V⁺and V^–pins

should be bypassed with 0.1µF capacitors to an adequate

analog ground plane using the shortest possible wiring.

Electrically clean supplies and a low impedance ground

are important for the high dynamic range available from

the LTC6910-X (see further details under AGND). Low

noise linear power supplies are recommended. Switching

power supplies require special care to prevent switching

noise coupling into the signal path, reducing dynamic

range.

Table1,Table2andTable3).Digitalinputcode000causes

a“zero”gainwithverylowoutputnoise. Inthis“zero”gain

state the IN pin is disconnected internally, but the OUT pin

remains active and forced by the internal op amp to the

voltage present on the AGND pin. Note that the voltage

gain from IN to OUT is inverting: OUT and IN pins always

swing on opposite sides of the AGND potential. The G pins

are high impedance CMOS logic inputs and must be

connected(theywillfloattounpredictablevoltagesifopen

circuited). No speed limitation is associated with the

digital logic because it is memoryless and much faster

than the analog signal path.

G0, G1, G2 (Pins 5, 6, 7): CMOS-Level Digital Gain-

ControlInputs. G2isthemostsignificantbit(MSB). These

pins control the voltage gain from IN to OUT pins (see

6910123fa

16

LTC6910-1

LTC6910-2/LTC6910-3

W U U

APPLICATIO S I FOR ATIO

U

Functional Description

with finite speed, toward a differently scaled version of the

input signal. Varying the gain faster than the output can

settle produces a garbled output signal. The LTC6910-X

analog path settles with a characteristic time constant or

time scale, τ, that is roughly the standard value for a first

order band limited response:

The LTC6910 family are small outline, wideband inverting

DC amplifiers whose voltage gain is digitally program-

mable. Each delivers a choice of eight voltage gains,

controlled by the 3-bit digital inputs to the G pins, which

accept CMOS logic levels. The gain code is always mono-

tonic; an increase in the 3-bit binary number (G2 G1 G0)

causesanincreaseinthegain. Table1, Table2andTable 3

list the nominal voltage gains for LTC6910-1, LTC6910-2

and LTC6910-3 respectively. Gain control within each

amplifier occurs by switching resistors from a matched

array in or out of a closed-loop op amp circuit using MOS

analog switches (Figure 4). Bandwidth depends on gain

setting. CurvesintheTypicalPerformanceCharacteristics

section show measured frequency responses.

τ = 1 / (2 π f_-3dB),

where f_-3dBis the –3dB bandwidth of the amplifier. For

example, when the upper –3dB frequency is 1MHz, τ is

about 160ns. The bandwidth, and therefore τ, varies with

gain(seeFrequencyResponseand–3dBBandwidthcurves

inTypicalPerformanceCharacteristics).Afteragainchange

it is the new gain value that determines the settling time

constant.Exactsettlingtimingdependsonthegainchange,

the input signal and the possibility of slew limiting at the

output.Howeverasabasicguideline,therangeofτ is20ns

to 1400ns for the LTC6910-1, 20ns to 900ns for the

LTC6910-2 and 20ns to 120ns for the LTC6910-3. These

numbers correspond to the ranges of –3dB Bandwidth in

theplotsofthattitleunderTypicalPerformanceCharacter-

istics.

Digital Control

Logic levels for the LTC6910-X digital gain control inputs

(Pins5,6,7)arenominallyrail-to-railCMOS.Logic1isV⁺,

logic 0 is V^–or alternatively 0V when using ±5V supplies.

The part is tested with the values listed in the Electrical

Characteristics table (Digital Input “High” and “Low” Volt-

ages), which are 10% and 90% of full excursion on the

inputs. That is, the tested logic levels are 0.27V and 2.43V

with a 2.7V supply, 0.5V and 4.5V levels with 0V and 5V

supply rails, and 0.5V and 4.5V logic levels at ±5V sup-

plies. Do not attempt to drive the digital inputs with TTL

logic levels (such as HCT or LS logic), which normally do

not swing near +5V. TTL sources should be adapted with

CMOS drivers or suitable pull-up resistors to 5V so that

they will swing to the positive rail.

Offset Voltage vs Gain Setting

The electrical tables list DC offset (error) voltage at the

inputs of the internal op-amp in Figure 4, V_OS(OA), which

is the source of DC offsets in the LTC6910-X. The tables

also show the resulting, gain dependent offset voltage

referred to the IN pin, V_OS(IN). These two measures are

related through the feedback/input resistor ratio, which

equals the nominal gain-magnitude setting, G:

V_OS(IN)= (1 + 1/G) V_OS(OA)

Timing Constraints

Offsetvoltagesatanygainsettingcanbeinferredfromthis

relationship. For example, an internal offset V_OS(OA)of

1mV will appear referred to the IN pin as 2mV at a gain

settingGof1, or1.5mVatagainsettingof2. Athighgains,

V_OS(IN)approaches V_OS(OA). (Offset voltage can be of

either polarity; it is a statistical parameter centered on

zero.) The MOS input circuitry of the internal op amp in

Figure 4 draws negligible input currents (unlike some op

amps), so only V_OS(OA)and G affect the overall amplifier’s

offset.

Settling time in the CMOS gain-control logic is typically

several nanoseconds and faster than the analog signal

path. When amplifier gain changes, the limiting timing is

analog, not digital, because the effects of digital input

changes are observed only through the analog output

(Figure 4). The LTC6910-X’s logic is static (not latched)

and therefore lacks bus timing requirements. However, as

with any programmable-gain amplifier, each gain change

causesanoutputtransientastheamplifier’soutputmoves,

6910123fa

17

LTC6910-1

LTC6910-2/LTC6910-3

W U U

U

APPLICATIO S I FOR ATIO

Offset Nulling and Drift

these internal 10k resistors also have an absolute toler-

ance of up to ±30% and a temperature coefficient of

typically –30ppm/°C.) Also, as described under Pin Func-

tions for AGND, a bypass capacitor C1 is always advisable

when AGND is not connected directly to a ground plane.

Because internal op amp offset voltage V_OS(OA)is gain

independent as noted above, offset trimming can be

readilyaddedattheAGNDpin,whichdrivesthenoninverting

input of the internal op amp. Such a trim shifts the AGND

voltage slightly from the system’s analog ground refer-

ence, where AGND would otherwise connect directly. This

is convenient when a low resistance analog ground poten-

tial or analog ground reference exists, for the return of a

voltage divider as in Figure 5a. When adjusted for zero DC

output voltage when the LTC6910-X has zero DC input

voltage,thisDCnullingwillholdatothergainsettingsalso.

With this trim technique in place, the remaining DC offset

sources are drifts with temperature (typically 6µV/°C

referred to V_OS(OA)), shifts in the LTC6910-X’s supply

voltage divided by the PSRR factors, supply voltage shifts

coupling through the two 10k internal resistors of

Figure 4, and of course any shifts in the reference voltages

that supply +V_REFand –V_REFin Figure 5a.

Figure 5a shows the basic arrangement for dual-supply

applications. A voltage divider (R1 and R2) scales external

reference voltages +V_REFand –V_REFto a range equaling or

slightly exceeding the approximately ±10mV op amp off-

set-voltage range. Resistor R1 is chosen to drop the

±10mV maximum trim voltage when the potentiometer is

set to either end. Thus if V_REFis 5V, R1 should be about

100Ω. Note also that the two internal 10k resistors in

Figure 4 tend to bias AGND toward the mid-point of V⁺and

V^–. TheexternalvoltagedividerwillswampthiseffectifR1

is much less than 5kΩ. When considering the effect of the

internal 10k resistors, note that they form a Thévenin

equivalent of 5k in series with an open-circuit voltage at

thehalfwaypotential(V⁺+V^–)/2.(Althoughtightlymatched,

Figure 5b illustrates how to make an offset voltage adjust-

ment relative to the mid-supply potential in single supply

applications. Resistor values shown provide at least a

±10mV adjustment range assuming the minimum values

for the internal resistors at pin 2 and a supply potential of

5V. For single supply systems where all circuitry is DC

referenced to some other fixed bias potential, an offset

adjustment scheme is shown in Figure 5c. A low value for

R1 overrides the internal resistors at pin 2 and applies the

system DC bias to the LTC6910. Actual values for the

adjustment components depend on the magnitude of the

DC bias voltage. Offset adjustment component values

shown are an example with a single 5V V_CCsupply and a

1.25V system DC reference voltage.

1.25V

SYSTEM DC REFERENCE

VOLTAGE

5V

V

5V

CC

V

5V

CC

V

CC

8

+V

REF

R1

100Ω

LTC6910-X

AGND

17.4k

LTC6910-X

AGND

4.64k

500Ω

976Ω

R2

49.9k

2

AGND

20k

500Ω

1µF

R1

C1

≥1µF

17.4k

–V

REF

6910 F05a

6910 F05b

6910 F05c

4

ANALOG GROUND

REFERENCE

Figure 5a. Offset Nulling

(Dual Supplies)

Figure 5b. Offset Nulling

(Single Supply, Half Supply Reference)

Figure 5c. Offset Nulling

(Single Supply, External Reference)

6910123fa

18

LTC6910-1

LTC6910-2/LTC6910-3

W U U

APPLICATIO S I FOR ATIO

U

Analog Input and DC Levels

demands some care if employed with a series input

capacitor. When the chip enters the zero gain mode, the

opened IN pin tends to freeze the voltage across the

capacitorto the value itheld just beforethe zerogainstate.

This can place the IN pin at or near the DC potential of a

supply rail (the IN pin may also drift to a supply potential

in this state due to small junction leakage currents). To

prevent driving the IN pin outside the supply limit and

potentially damaging the chip, avoid AC input signals in

the zero gain state with a series capacitor. Also, switching

later to a nonzero gain value will cause a transient pulse at

the output of the LTC6910-X (with a time constant set by

the capacitor value and the new LTC6910-X input resis-

tance value). This occurs because the IN pin returns to the

AGND potential and transient current flows to charge the

capacitor to a new DC drop.

As described in Tables 1, 2 and 3 and under Pin Functions,

the IN pin presents a variable input resistance returned

internally to a potential equal to that at the AGND pin

(within a small offset-voltage error). This input resistance

varies with digital gain setting, becoming infinite (open

circuit)at“zero”gain(digitalinput000),andaslowas1kΩ

at high gain settings. It is important to allow for this

input-resistance variation with gain, when driving the

LTC6910-X from other circuitry. Also, as the gain in-

creases above unity, the DC linear input-voltage range

(correspondingtorail-to-railswingattheOUTpin)shrinks

toward the AGND potential. The output swings positive or

negative around the AGND potential (in the opposite

direction from the input, because the gain is inverting).

AC-Coupled Operation

SNR and Dynamic Range

Adding a capacitor in series with the IN pin makes the

LTC6910-X into an AC-coupled amplifier, suppressing the

source’s DC level (and even minimizing the offset voltage

from the LTC6910-X itself). No further components are

required because the input of the LTC6910-X biases itself

correctly when a series capacitor is added. The IN pin

connects to an internal variable resistor (and floats when

DC open-circuited to a well defined voltage equal to the

AGND input voltage at nonzero gain settings). The value of

this internal input resistor varies with gain setting over a

total range of about 1k to 10k, depending on version (the

rightmost columns of Table 1, Table 2 and Table 3).

Therefore, with a series input capacitor the low frequency

cutoff will also vary with gain. For example, for a low

frequency corner of 1kHz or lower, use a series capacitor

of 0.16µF or larger. A 0.16µF capacitor has a reactance of

1kΩ at 1kHz, giving a 1kHz lower –3dB frequency for gain

settings of 10V/V through 100V/V in the LTC6910-1. If the

LTC6910-1 is operated at lower gain settings with an

0.16µF input capacitor, the higher input resistance will

reducethelowercornerfrequencydownto100Hzatagain

setting of 1V/V. These frequencies scale inversely with the

value of the input capacitor.

The term “dynamic range” is much used (and abused)

with signal paths. Signal-to-noise ratio (SNR) is an unam-

biguous comparison of signal and noise levels, measured

in the same way and under the same operating conditions.

In a variable gain amplifier, however, further characteriza-

tion is useful because both noise and maximum signal

level in the amplifier will vary with the gain setting, in

general. In the LTC6910-X, maximum output signal is

independent of gain (and is near the full power supply

voltage, as detailed in the Swing sections of the Electrical

Characteristics table). The maximum input level falls with

increasing gain, and the input-referred noise falls as well

(aslistedalsointhetable). Tosummarizetheusefulsignal

rangeinsuchanamplifier, wedefineDynamicRange(DR)

as the ratio of maximum input (at unity gain) to minimum

input-referred noise (at maximum gain). (These two num-

bers are measured commensurately, in RMS Volts.

For deterministic signals such as sinusoids, 1V_RMS

=

2.828V_P-P.) This DR has a physical interpretation as the

range of signal levels that will experience an SNR above

unity V/V or 0dB. At a 10V total power supply, DR in the

LTC6910-1 (gains 0V to 100V/V) is typically 120dB (the

ratio of a nominal 9.9V_P-P, or 3.5V_RMS, maximum input to

the 3.4µV_RMShigh gain input noise). The corresponding

DR for the LTC6910-2 (gains 0V to 64V) is also 120dB; for

Note that operating the LTC6910-X in zero gain mode

(digital inputs 000) open circuits the IN pin and this

6910123fa

19

LTC6910-1

LTC6910-2/LTC6910-3

U

TYPICAL APPLICATIO S

the LTC6910-3 (gains 0V to 7V/V) it is 117dB. The SNR

from an amplifier is the ratio of input level to input-

referrednoise, andcanbe110dBwiththeLTC6910family

at unity gain.

8-lead MSOP. This ADC has 16-bit resolution and a maxi-

mum sampling rate of 250ksps. An LTC6910-1, for ex-

ample, expands the ADC’s input amplitude range by 40dB

whileoperatingfromthesamesingle5Vsupply. The499Ω

resistor and 270pF capacitor couple cleanly between the

LTC6910-X’s output and the switched-capacitor input of

the LTC1864. The 270pF capacitor should be an NPO or

X7R type, and lead length and inductance in the connec-

tions to the LTC1864 inputs must be minimized, to achieve

the full performance capability of this circuit. (See LTC

1864 data sheet for further general information.)

Construction and Instrumentation Cautions

Electricallycleanconstructionisimportantinapplications

seeking the full dynamic range of the LTC6910-X ampli-

fier. Short, direct wiring will minimize parasitic capaci-

tance and inductance. High quality supply bypass capaci-

tors of 0.1µF near the chip provide good decoupling from

a clean, low inductance power source. But several cm of

wire (i.e., a few microhenrys of inductance) from the

power supplies, unless decoupled by substantial capaci-

tance (≥10µF) near the chip, can cause a high-Q LC

resonance in the hundreds of kHz in the chip’s supplies or

ground reference. This may impair circuit performance at

those frequencies. A compact, carefully laid out printed

circuit board with a good ground plane makes a

significant difference in minimizing distortion. Finally,

equipment to measure amplifier performance can itself

introduce distortion or noise floors. Checking for these

limits with a wire replacing the chip is a prudent routine

procedure.

At a gain setting of 10V/V in an LTC6910-1 (digital input

100)anda250kspssamplingrateintheLTC1864, a10kHz

input signal at 60% of full scale shows a THD of

–87dB at the digital output of the ADC. 100kHz input

signals under the same conditions produce THD values

around –75dB. Noise effects (both random and quantiza-

tion) in the ADC are divided by the gain of the amplifier

when referred to V_INin Figure 4. Because of this, the circuit

can acquire a signal that is 40dB down from full scale of

5V_P-Pwith an SNR of over 70dB. Such performance from

an ADC alone (70 + 40 = 110dB of useful dynamic range at

250ksps), if available, would be far more expensive.

Low Noise AC Amplifier with Programmable Gain

and Bandwidth

Expanding an ADC’s Dynamic Range

Figure 6 shows a compact data acquisition system for

wide ranging input levels. This figure combines an

LTC6910-X programmable amplifier (8-lead TSOT-23)

with an LTC1864 analog-to-digital converter (ADC) in an

Analog data acquisition can exploit band limiting as well as

gain to suppress unwanted signals or noise. Tailoring an

analog front end to both the level and bandwidth of each

source maximizes the resulting SNR.

1µF

5V

0.1µF

LTC1864

8

4

V

CC

REF

+

499Ω

1

3

IN

SCK

SDO

V

LTC6910-X

IN

5

–

270pF

6

7

GND CONV

2

6910 F04

AGND

1µF

GAIN

CONTROL

ADC

CONTROL

Figure 6. Expanding an ADC’s Dynamic Range

6910123fa

20

LTC6910-1

LTC6910-2/LTC6910-3

U

TYPICAL APPLICATIO

Figure 7 shows a block diagram and Figure 8 the practical

circuit for a low noise amplifier with gain and bandwidth

independently programmable over 100:1 ranges. One

LTC6910-X controls the gain and another controls the

bandwidth. An LT1884 dual op amp forms an integrating

lowpass loop with capacitor C2 to set the programmable

uppercornerfrequency.TheLT1884alsosupportsrail-to-

rail output swings over the total supply voltage range of

2.7V to 10.5V. AC coupling through capacitor C1 estab-

lishes a fixed low frequency corner of 1Hz, which can be

adjustedbychangingC1.Alternatively,shortingC1makes

the amplifier DC coupled. (If DC gain is not needed,

however,theACcouplingsuppressesseveralerrorsources:

any shifts in DC levels, low frequency noise and all

amplifier DC offset voltages other than the low internally

trimmed LT1884 offset in the integrating amplifier. If

desired,anothercouplingcapacitorinserieswiththeinput

can relax the requirements on DC input level as well.)

R2

C2

–

C1

V

IN

R1

–

+

–

+

GAIN CONTROL PGA

(GAIN A)

V

OUT

6910 F05

+

BANDWIDTH CONTROL PGA

(GAIN B)

GAIN = –1

1

V

= (GAIN A)V

≤ BANDWIDTH ≤

2πR1C1

OUT

IN

R2

2π

C2

(GAIN B)

Figure 7. Block Diagram of an AC Amplifier with Programmable Gain and Bandwidth

6910123fa

21

LTC6910-1

LTC6910-2/LTC6910-3

U

TYPICAL APPLICATIO S

Measured frequency responses in Figure 8 with

LTC6910-1PGAsdemonstratebandwidthsettingsof10Hz,

100Hz and 1kHz, with digital codes at the BW inputs of

respectively001, 100and111, andunitygainineachcase.

By scaling C2, this circuit can serve other bandwidths,

such as a maximum of 10kHz with 0.1µF using LT1884

(gain-bandwidth product around 1MHz). Noise floor from

internalsourcesyieldsanoutputSNRof76dBwith10mV_P-

_Pinput, gain of 100 and 100Hz bandwidth; for 100mV_P-P

input, gain of 10 and 1000Hz bandwidth it is 64dB.

+

–

+

–

V

OUT

0.1µF

R2

15.8k

C2

1µF

+

V

0.1µF

8

LT1884

8

C1

1

2

3

4

8

7

6

5

+

R1

15.8k

4

10µF

1

V

R4 15.8k

–

+

–

3

1

V

LTC6910-1

6

LTC6910-1

6

IN

5

–

+

R3

15.8k

7

V

2

0.1µF

–

V

GAIN

CONTROL

BANDWIDTH

CONTROL

GN2 GN1 GN0

BW2BW1BW0

0

1

0

1

0

1

0

1

0

1

0

1

GAIN = 1

BANDWIDTH 1Hz TO 10Hz

BANDWIDTH 1Hz TO 20Hz

BANDWIDTH 1Hz TO 50Hz

BANDWIDTH 1Hz TO 100Hz

BANDWIDTH 1Hz TO 200Hz

BANDWIDTH 1Hz TO 500Hz

BANDWIDTH 1Hz TO 1000Hz

0

1

0

1

0

1

0

1

0

1

0

1

GAIN = 2

GAIN = 5

GAIN = 10

GAIN = 20

GAIN = 50

GAIN = 100

Gain vs Frequency

10

0

GN2 GN1 GN0 = 001

BW2 BW1 BW0

–10

–20

–30

–40

–50

–60

–70

–80

1

BW2 BW1 BW0

0

1

BW2 BW1 BW0

1

0

1

10

100

1k

10k

100k

FREQUENCY (Hz)

6910 F06b

Figure 8. Low Noise AC Amplifier with Programmable Gain and Bandwidth

6910123fa

22

LTC6910-1

LTC6910-2/LTC6910-3

U

PACKAGE DESCRIPTIO

TS8 Package

8-Lead Plastic TSOT-23

(Reference LTC DWG # 05-08-1637)

2.90 BSC

(NOTE 4)

0.52

MAX

0.65

REF

1.22 REF

1.50 – 1.75

(NOTE 4)

2.80 BSC

1.4 MIN

3.85 MAX 2.62 REF

PIN ONE ID

RECOMMENDED SOLDER PAD LAYOUT

PER IPC CALCULATOR

0.22 – 0.36

8 PLCS (NOTE 3)

0.65 BSC

0.80 – 0.90

0.09 – 0.20

(NOTE 3)

0.20 BSC

NOTE:

0.01 – 0.10

1.00 MAX

DATUM ‘A’

0.30 – 0.50 REF

TS8 TSOT-23 0802

1.95 BSC

1. DIMENSIONS ARE IN MILLIMETERS

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

2. DRAWING NOT TO SCALE

3. DIMENSIONS ARE INCLUSIVE OF PLATING

6910123fa

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.

23

LTC6910-1

LTC6910-2/LTC6910-3

U

TYPICAL APPLICATIO

AC-Coupled Single Supply Amplifiers

+

V

2.7V TO 10.5V

0.1µF

LTC6910-1

LTC6910-2

LTC6910-3

DIGITAL INPUTS PASSBAND LOWER –3dB

PASSBAND LOWER –3dB

G2 G1 G0

GAIN

FREQ (C1 = 1µF)

GAIN

FREQ (C1 = 1µF)

GAIN

FREQ (C1 = 1µF)

8

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

–1

—

0

–1

—

0

–1

–2

–3

–4

–5

–6

–7

—

4

C1

16Hz

32Hz

48Hz

64Hz

80Hz

95Hz

111Hz

3

1

V

V = GAIN • V

OUT IN

LTC6910-X

–2

32Hz

80Hz

160Hz

–2

32Hz

64Hz

127Hz

IN

–5

–4

–8

–16

–32

–64

2

5

–10

–20

–50

–100

AGND

1µF OR LARGER

6

7

G2 G1 G0

6910 TA02

C1 VALUE SETS LOWER CORNER FREQUENCY.

THE TABLE SHOWS THIS FREQUENCY WITH

C1 = 1µF. THIS FREQUENCY SCALES INVERSELY

WITH C1

PIN 2 (AGND) SETS DC OUTPUT VOLTAGE AND HAS

BUILT-IN HALF-SUPPLY REFERENCE WITH INTERNAL

RESISTANCE OF 5k. AGND CAN ALSO BE DRIVEN BY A

SYSTEM ANALOG GROUND REFERENCE NEAR HALF SUPPLY

Frequency Response, LTC6910-1

Frequency Response, LTC6910-2

Frequency Response, LTC6910-3

50

40

30

20

10

0

20

G2, G1, G0 = 110

G2, G1, G0 = 111

G2, G1, G0 = 110

G2, G1, G0 = 111

40

15

G2, G1, G0 = 110

G2, G1, G0 = 101

G2, G1, G0 = 100

G2, G1, G0 = 101

G2, G1, G0 = 100

G2, G1, G0 = 011

G2, G1, G0 = 010

G2, G1, G0 = 001

30

10

G2, G1, G0 = 101

G2, G1, G0 = 011

G2, G1, G0 = 100

20

5

G2, G1, G0 = 010

G2, G1, G0 = 011

10

0

G2, G1, G0 = 010

G2, G1, G0 = 001

0

–5

V

= 10V

S

IN

V

= 10V, V = 5mV

IN RMS

V

= 10V, V = 5mV

= 10mV

S

IN RMS

RMS

1k

C1 = 1µF

–10

100

–10

1k

10k

100k

1M

100

1k

10k

100k

1M

10

100

10k 100k

1M

10M

FREQUENCY (Hz)

6910 TA03

6910 TA04

6910 TA05

RELATED PARTS

PART NUMBER

LT^®1228

DESCRIPTION

COMMENTS

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10kHz to 150kHz Digitally Controlled Filter and PGA

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Zero Drift Instrumentation Amplifier with Programmable Gain Zero Drift, Digitally Programmable Gain Up to 4096 V/V

6910123fa

LT/TP 0404 1K REV A • PRINTED IN USA

24 ^{Linear Technology Corporation}

1630 McCarthy Blvd., Milpitas, CA 95035-7417

●

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

LINEAR TECHNOLOGY CORPORATION 2002


型号：	LTC6910-3CTS8#TRPBF
厂家：	Linear
描述：	LTC6910 - Digitally Controlled Programmable Gain Amplifiers in SOT-23; Package: SOT; Pins: 8; Temperature Range: 0°C to 70°C 仪表放大器放大器电路光电二极管
文件：	总24页 (文件大小：251K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LTC6910-3CTS8#TRPBF [Linear]

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