7106

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

8 of 18

www.unisonic.com.tw

QW-R502-018.E

DETAILED DESCRIPTION(Cont.)

DIFFERENTIAL REFERENCE

The reference voltage can be generated anywhere within the power supply voltage of the converter. The main

source of common mode error is a roll-over voltage caused by the reference capacitor losing or gaining charge to

stray capacity on its nodes. If there is a large common mode voltage, the reference capacitor can gain charge

(increase voltage) when called up to de-integrate a positive signal but lose charge (decrease voltage) when called up

to de-integrate a negative input signal. This difference in reference for positive or negative input voltage will give a

roll-over error. However, by selecting the reference capacitor such that it is large enough in comparison to the stray

capacitance, this error can be held to less than 0.5 count worst case. (See Component Value Selection)

COMMON

IN LO

30

32

31

V+

A-Z

INT

INT

A-Z AND DE(±)

V-

Fig.1 Analog Section

DE+

DE-

DE-

DE+

A-Z

A-Z

REF HI

REF LO

STRAY

34

36

35

33

28

1

2.8V

-

+

-

+

-

+

29

27

INT

A-Z

INTEGRATOR

V+

STRAY

TO

DIGITAL

SECTION

A-Z

COMPARATOR

INPUT

LOW

-

+

N

INPUT

HIGH

6.2V

10 A

IN HI

μ

BUFFER