A6902D View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
A6902D
STMicroelectronics
'A6902D' PDF : 33 Pages View PDF
A6902D
Output overvoltage protection
where VD is the voltage drop across the diode, DCRL is the series resistance of the Inductor. In short-circuit
conditions VOUT is negligible so during TOFF the voltage across the inductor is very small as equal to the voltage
drop across parasitic components (typically the DCR of the inductor and the forward voltage of the freewheeling
diode) while during TON the voltage applied to the inductor is maximized as approximately equal to VIN.
In case a short circuit at the output is applied and VIN = 12 V the inductor current is controlled in most of the
applications. When the application must sustain the short-circuit condition for an extended period, the external
components (mainly the inductor and diode) must be selected based on this value.
In case the VIN is very high, it could occur that the ripple current during TOFF (Eq. (2)) does not compensate the
current increase during TON (Eq. (1)). In this case ΔILTON > ΔILTOFF so the current escalates and the balance
between Eq. (1) and Eq. (2) occurs at a current slightly higher than the current limit.
This must be taken into account in particular to avoid the risk of an abrupt inductor saturation.
6.3
Output overvoltage protection
Overvoltage protection, or OVP, is achieved by using an internal comparator connected to the feedback, which
turns OFF the power stage when the OVP threshold is reached. This threshold is typically 30% higher than the
feedback voltage.
6.4
Zero load operation
Due to the fact that the internal power is a PDMOS, no bootstrap capacitor is required and so the device works
properly even with no load at the output. In this case it works in burst mode, with a random burst repetition rate.
DS5503 - Rev 6
page 11/33
Share Link: 