TC1765T datasheet(71/88 Pages) INFINEON

71 / 88 page

TC1765

Data Sheet

V1.2, 2002-12

Preliminary

Figure 22

Equivalent Circuitry of Analog Input

Note: This equivalent circuitry for an analog input is also valid for the reference inputs

VAREF and VAGND.

9) The overload coupling factor (k

A) defines the worst case relation of an overload condition (IOV) at one pin to

the resulting leakage current (

Ileak) into an adjacent pin: |Ileak| = kA × |IOV|.

Thus under overload conditions an additional error leakage voltage (

VAEL) will be induced onto an adjacent

analog input pin due to the resistance of the analog input source (

RAIN). That means VAEL = RAIN × |Ileak|.

See also section 7.1.6 “Error Through Overload Conditions” in the TC1765 Peripheral Units User’s Manual for

further explanations.

10) This represents an equivalent switched capacitance. This capacitance is not switched to the reference voltage

at once. Instead of this smaller capacitances are successively switched to the reference voltage. Alternatively,

the redistributed charge could be specified.

11) The switched capacitance at the analog voltage input must be charged within the sampling time. Alternatively,

the redistributed charge could be specified.

M C S 04879

AIN , So u rce

AIN

AIN , Blo ck

AIN , O n

AIN T O T - C AIN S W

AIN S W

A /D C o nv erte r

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