TLV1543CDBLE datasheet(17/26 Pages) TI

17 / 26 page

TLV1543C, TLV1543I, TLV1543M

3.3V 10BIT ANALOGTODIGITAL CONVERTERS

WITH SERIAL CONTROL AND 11 ANALOG INPUTS

SLAS072E − DECEMBER 1992 − REVISED JANUARY 2004

WWW.TI.COM

APPLICATION INFORMATION

simplified analog input analysis

Using the equivalent circuit in Figure 17, the time required to charge the analog input capacitance from 0 to VS

within 1/2 LSB can be derived as follows:

The capacitance charging voltage is given by

VC = VS 1−e

−t c/RtCi

(

)

(1)

Where:

Rt = Rs + ri

The final voltage to 1/2 LSB is given by

(2)

VC (1/2 LSB) = VS − (VS/2048)

Equating equation 1 to equation 2 and solving for time tc gives

VS −(VS/2048) = VS 1−e

(

)

(3)

−t c/RtCi

and

tc (1/2 LSB) = Rt × Ci × ln(2048)

(4)

Therefore, with the values given the time for the analog input signal to settle is

(5)

tc (1/2 LSB) = (Rs + 1 kΩ) × 60 pF × ln(2048)

This time must be less than the converter sample time shown in the timing diagrams.

1 k

Ω MAX

Driving Source†

TLV1543

VI = Input Voltage at A0 −A10

VS = External Driving Source Voltage

Rs = Source Resistance

ri = Input Resistance

Ci = Input Capacitance

† Driving source requirements:

• Noise and distortion for the source must be equivalent to the

resolution of the converter.

• Rs must be real at the input frequency.

Figure 17. Equivalent Input Circuit Including the Driving Source

60 pF MAX

TLV1543CDBLE bảng dữ liệu(PDF) 17 Page - Texas Instruments

TLV1543CDBLE bảng dữ liệu(HTML) 17 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

bảng dữ liệu tải về

Link URL