Maximum Input and Common-Mode Voltages. ETAS ES650

ETAS

3.6

Hardware Description

Maximum Input and Common-Mode Voltages

The maximum input voltage between two inputs and the maximum voltage between an input and case ground is 60 V DC / 30 V AC.

For an explanation of the maximum input and common-mode voltages, see the illustration and example below.

U in+ r

Å

U in-

U inx

C

C r

`jñó

+

channel x galvanically isolated

U in+

U in-

U iny

C

C r

`jóò

+

channel y galvanically isolated

C

U in+

U inr

Å

U inz

C

+

channel z case potential

Fig. 3 5 Maximum input and common-mode voltages

All capacitors between the inputs (U in+

and U in-

) and case ground have the same capacity. The maximum voltage between any input and case ground is

60 V DC / 30 V AC.

Example

For the given input voltages U inx

, U iny

, U inz

and the common-mode voltage

U

CMxy

, the maximum allowed common-mode voltage U

CMyz

is to be calculated.

U inx

= 10 V

U iny

= 5 V

U inz

= 10 V

U

CMxy

= 15 V max(U inx

+ U iny

+ U inz

+ U

CMxy

+ U

CMyz

) = 2 U c

= 60 V

10 V + 5 V + 10 V + 15 V + max(U

CMyz

) = 60 V max(U

CMyz

) = 60 V - 40 V = 20 V

ES650.1 - User Guide 19