MB90F482 datasheet(104/113 Pages) FUJITSU

104 / 113 page

MB90480/485 Series

104

(Continued)

• A/D converter with sample and hold circuit. If the external impedance is too high to keep sufficient sampling

time, the analog voltage charged to the internal sample and hold capacitor is insufficient, adversely affecting

A/D conversion precision.

• To satisfy the A/D conversion precision standard, consider the relationship between the external impedance

and minimum sampling time and either adjust the resistor value and operating frequency or decrease the

external impedance so that the sampling time is longer than the minimum value.

The relationship between external impedance and minimum sampling time

• If the sampling time cannot be sufficient, connect a capacitor of about 0.1

µF to the analog input pin.

As |AVRH

− AVSS| becomes smaller, values of relative errorsgrow larger.

Note : Concerning sampling time, and compare time When 3.6 V

≥ AVCC ≥ 2.7 V, then

Sampling time : 1.92

µs, compare time : 1.1 µs

Settings should ensure that actual values do not go below these values due to operating frequency changes.

During sampling : ON

Analog input

Comparator

Note: The values are reference values.

• Analog input circuit model

MB90487

2.5 k

Ω (Max) 31.0 pF (Max)

MB90F481/F482

1.9 k

Ω (Max) 25.0 pF (Max)

MB90F488

1.9 k

Ω (Max) 25.0 pF (Max)

MB90F481/F482

MB90F488

MB90487

100

MB90F481/F482

MB90F488

MB90487

0123456

External impedance

= 0 kΩ to 100 kΩ

External impedance

= 0 kΩ to 100 kΩ

→ Minimum sampling time [µs]

MB90F482 Scheda tecnica(PDF) 104 Page - fujitsu semiconductor

MB90F482 Scheda tecnica(HTML) 104 Page - fujitsu semiconductor

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 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Scheda tecnica Scarica

Link URL