SCBS881F january 2010 – june 2023 TMS3705
PRODUCTION DATA
The full bridge drives the antenna current at the carrier frequency during the charge phase and the active time of the write phase. The minimal load resistance the full bridge sees between its outputs in normal operation at the resonance frequency of the antenna is 43.3 Ω. When the full bridge is not active, the two driver outputs are switched to ground.
Both outputs of the full bridge are protected independently against short circuits to ground.
In case of an occurring short circuit, the full bridge is switched off in less than 10 µs to avoid a drop of the supply voltage. After a delay time of less than 10 ms the full bridge is switched on again to test if the short circuit is still there. An overcurrent due to a resistive short to ground that is higher than the maximum current in normal operation but lower than the current threshold for overcurrent protection does not need to be considered.