LTC2483 datasheet(23/32 Pages) LINER

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LTC2483

2483f

Second, the increase in clock frequency will increase

proportionally the amount of sampling charge trans-

ferred through the input and the reference pins. If large

external input and/or reference capacitors (CIN, CREF) are

used, the previous section provides formulae for evaluat-

ing the effect of the source resistance upon the converter

performance for any value of fEOSC. If small external input

and/or reference capacitors (CIN, CREF) are used, the

effect of the external source resistance upon the LTC2483

typical performance can be inferred from Figures 9, 10,

11 and 12 in which the horizontal axis is scaled by

307200/fEOSC.

APPLICATIO S I FOR ATIO

Third, an increase in the frequency of the external oscillator

above 1MHz (a more than 3+ increase in the output data

rate) will start to decrease the effectiveness of the internal

autocalibration circuits. This will result in a progressive

degradation in the converter accuracy and linearity.

Typical measured performance curves for output data

rates up to 100 readings per second are shown in Fig-

ures 16 to 23. In order to obtain the highest possible level

of accuracy from this converter at output data rates above

20 readings per second, the user is advised to maximize

the power supply voltage used and to limit the maximum

ambient operating temperature. In certain circumstances,

a reduction of the differential reference voltage may

be beneficial.

OUTPUT DATA RATE (READINGS/SEC)

–10

–5

2483 F21

90 100

20 30

VCC = 5V, VREF = 2.5V

VCC = VREF = 5V

VIN(CM) = VREF(CM)

VIN = 0V

CA0/F0 = EXT CLOCK

TA = 25°C

Figure 21. Offset Error vs Output

Data Rate and Reference Voltage

Figure 23. Resolution (INLMAX ≤ 1LSB)

vs Output Data Rate and Reference Voltage

OUTPUT DATA RATE (READINGS/SEC)

2483 F23

90 100

20 30

VIN(CM) = VREF(CM)

VIN = 0V

CA0/F0 = EXT CLOCK

TA = 25°C

RES = LOG 2 (VREF/INLMAX)

VCC = 5V, VREF = 2.5V

VCC = VREF = 5V

OUTPUT DATA RATE (READINGS/SEC)

2483 F20

90 100

20 30

TA = 85°C

TA = 25°C

VIN(CM) = VREF(CM)

VCC = VREF = 5V

CA0/F0 = EXT CLOCK

RES = LOG 2 (VREF/INLMAX)

Figure 20. Resolution (INLMAX ≤ 1LSB)

vs Output Data Rate and Temperature

Figure 22. Resolution (NoiseRMS ≤ 1LSB)

vs Output Data Rate and Reference Voltage

OUTPUT DATA RATE (READINGS/SEC)

2483 F22

90 100

20 30

VIN(CM) = VREF(CM)

VIN = 0V

CA0/F0 = EXT CLOCK

TA = 25°C

RES = LOG 2 (VREF/NOISERMS)

VCC = 5V, VREF = 2.5V

VCC = VREF = 5V

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