ZHCSIH0A December 2017 – July 2018 LP87702-Q1
A short-circuit protection feature allows the LP87702-Q1 to protect itself and external components against short circuit at the output or against overload during start-up. During start-up, short-circuit at buck converter output is detected when the output voltage is below 350mV (typical) 1 ms after the buck converter is enabled. For boost the fault threshold is 150mV (typical) below input voltage level. Boost converter is disabled if the output voltage is below the threshold level 1 ms after the boost converter is enabled.
In a similar way the overload situation is protected during normal operation. If the feedback-pin voltage of the buck converter falls below 0.35 V and remains below the threshold level for 1 ms the buck converter is disabled. If the output voltage of the boost converter decreases 150 mV below input voltage level, converter is disabled after 1 ms. If the output voltage decreases to 2.5 V, boost is disabled immediately.
In the Buck converter short-circuit and overload situations the BUCKx_SC_INT and the BUCK_INT bits are set to 1, the BUCKx_STAT bit is set to 0 and the nINT signal is pulled low. In the boost converter short-circuit and overload situations the BOOST_SC_INT and the BOOST_INT bits are set to 1, the BOOST_STAT bit is set to 0 and the nINT signal is pulled low. The host processor clears the interrupt by writing 1 to the BUCKx_SC_INT or BOOST_SC_INT bit. Upon clearing the interrupt the converter makes a new start-up attempt if the converter is in enabled state.