Patent ID: 8270135

Claim:
A circuit for driving a transistor half bridge that comprises a series circuit of a first transistor and a second transistor each having a respective intrinsic or external free-wheeling diode coupled in parallel, the circuit comprising: an over-current detection circuit configured to signal an over-current condition when a load current flowing through the first transistor exceeds a first threshold; a protection circuit coupled to the over-current detection circuit and configured to disable an activation of the first transistor in response to a detected over-current and to re-activate the first transistor after a first time interval has elapsed; an evaluation circuit coupled to the over-current detection circuit and configured to check whether a further over-current condition is detected within a second time interval that follows the first time interval, wherein, in response to an over-current event, the first transistor is switched off during the first time interval in order to stop current flow and protect the circuit from thermal breakdown; and wherein, after the re-activation of the first transistor, the load current starts to flow again, and, if a second over-current event occurs during the second time interval, then active free-wheeling is not used during following over-current switch-offs, otherwise passive free-wheeling is used.