5

LTC1250

CC

HARA TERISTICS

A

TYPICALPERFOR

CE

Output Swing vs Output Current,

±5V Supply

Short-Circuit Current

vs Temperature

Output Swing vs Output Current,

Single 5V Supply

TEST CIRCUITS

Offset Test Circuit

–

+

5V

100pF

100k

7

6

4

3

2

–5V

OUTPUT

1250 TC01

LTC1250

10

Ω

S

APPLICATI

I FOR ATIO

Input Noise

The LTC1250, like all CMOS amplifiers, exhibits two types

of low frequency noise: thermal noise and 1/f noise. The

LTC1250 uses several design modifications to minimize

these noise sources. Thermal noise is minimized by rais-

high bias levels and using large transistor geometries. 1/f

noise is combated by optimizing the zero-drift nulling loop

to run at twice the 1/f corner frequency, allowing it to

reduce the inherently high CMOS 1/f noise to near thermal

levels at low frequencies. The resultant noise spectrum is

quite low at frequencies below the internal 5kHz clock

Figure 1. Voltage Noise vs Frequency

FREQUENCY (Hz)

20

30

40

50

80

0.01

1

LTC1250 F01

0

0.1

70

60

10

LTC1250

OP-07

OP-27

OUTPUT CURRENT (mA)

0.01

–1

0

1

2

3

0.1

1

10

LTC1250 G16

–2

–3

–4

–5

4

5

OUTPUT CURRENT (mA)

0.01

2

3

4

5

0.1

1

10

LTC1250 G17

1

0

6

TEMPERATURE (°C)

–50

0

10

20

25

LTC1250 G18

–10

–20

–25

0

50

–30

–40

40

75

100

125

30

–

+

DC to 10Hz Noise Test Circuit

(for DC to 1Hz Multiply All Capacitor Values by 10)

100pF

100k

OUTPUT

1250 TC02

–

+

5V

7

6

4

3

2

–5V

LTC1250

10

Ω

–

+

7

5

6

0.02

µF

800k

–

+

3

2

800k

800k

0.04

µF

0.01

µF

1/2

LT1057

5V

8

1

4

–5V

1/2

LT1057