MB90F548GPF datasheet(59/70 Pages) CYPRESS

59 / 70 page

Document Number: 002- 07696 Rev. *A

Page 59 of 70

MB90540G/545G Series

(Continued)

11.5.3 Notes on Using A/D Converter

Select the output impedance value for the external circuit of analog input according to the following conditions, :

 Output impedance values of the external circuit of 15 k

 or lower are recommended.

 When capacitors are connected to external pins, the capacitance of several thousand times the internal capacitor value is

recommended to minimized the effect of voltage distribution between the external capacitor and internal capacitor.

Note : When the output impedance of the external circuit is too high, the sampling period for analog voltages may not be sufficient

(sampling period

 4.00 s @machine clock of 16 MHz) .

11.5.4 Error

The smaller the | AVRH

 AVRL |, the greater the error would become relatively.

3FF

3FE

3FD

004

003

002

001

AVRL

AVRH

AVRL

AVRH

+ 1

− 1

− 2

VNT

V (N + 1) T

VOT

VFST

{1 LSB

× (N − 1) + VOT }

Linearity error

Differential linearity error

Analog input

Actual conversion

value

(measured value)

Actual conversion

characteristics

Theoretical

characteristics

(measured value)

Theorential characteristics

Actual conversion value

(measured value)

Acturel conversion

value

Linearity error of

digital output N

[LSB]

VNT

 {1 LSB  (N  1)  V

}

1 LSB

[V]

VFST

 V

1022

1 LSB

 1 LSB [LSB]

V (N



) T

 V

1 LSB

Differential linearity error

of digital N

VOT : Voltage at transition of digital output from “000H” to “001H”

VFST : Voltage at transition of digital output from “3FEH” to “3FFH”



3.2 k

Ω Max

30 pF Max

Analog input

Comparator

 Equipment of analog input circuit model

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