If there is a short between OUT1 and OUT2, then a short circuit current (I_SC) flows from AVDD. A successful OLD flag in an H-bridge short depends on the I_SC. I_SC will depend on AVDD, on the high-side resistor (R_{OL_HS} = 12 kΩ) and on the low-side resistor (R_{OL_LS} = 15 kΩ). The I_SC equation is as follows:

Equation 1.

Hence the I_SC is calculated using Equation 1 as,

Equation 2.

This OLD example will show how an OLD flag cannot occur when there is a short on the H-bridge. The voltage changes due to an H-bridge short on the positive terminal of OL1_HS (V_{OL1_HS}(+)) and on the negative terminal of OL2_LS (V_{OL1_HS}) will be as follows:

High-side comparator of OUT1's half-bridge (OL1_HS)

I_SC (155.56 µA) is flowing from AVDD. Therefore, the voltage on the positive terminal of OL1_HS is calculated as,

Equation 3.

Using Equation 3, the V_{OL1_HS}(+) is calculated as,

Equation 4.

Since V_{OL1_HS}(+) (2.33 V) is greater than V_{OL1_HS} (2.3 V), the output of OL1_HS is set to "1".

Low-side comparator of OUT2's half-bridge (OL2_LS)

The pull down current of I_SC (155.56 µA) is flowing from AVDD to the SW2_LS switch. Therefore, the voltage on the negative terminal of OL2_LS (V_{OL2_LS}(-)) is calculated as,

Equation 5.

Using Equation 5, the V_{OL2_LS}(-) value is,

Equation 6.

Since V_{OL2_LS}(-) (2.33 V) is greater than V_{OL_LS} (1.2 V), the output of OL2_LS is set to"0". The output of OL1_HS is set to "1" and the output of OL2_LS is set to "0". Therefore, this case is not considered as an OLD.