AN273

Rev. 0.1

5

Equation 5.

4.3. Condition 3: TIP to GND Fault

Resistive faults from TIP to GND are also detected in the TIP-OPEN linefeed state. In this case, the resistive fault

Figure 4. TIP-OPEN Linefeed State with TIP to GND Resistive Fault

From the voltages measured at TIP and RING, the resistive fault from TIP to GND may be expressed as follows:

Equation 6.

ACTIVE linefeed state. By applying a high common-mode voltage to TIP and keeping the differential voltage to 0 V

FORWARD ACTIVE state (see Figure 5).

–

()

1.5

+

---------------------------------------------------------

=

TIP

RING

1.5 V

–

×

×

+

() R

–

()

–

-------------------------------------------------------------------------------------------------------------

=