PM6670AS evaluation tests

AN2798

28/38

Latched thermal shutdown

If the junction temperature rises up to 150 deg, the thermal protection circuit turns off the

device and discharges the output rails by performing the non-tracking discharge soft-end.

8.9

VDDQ current limit

The valley current limit avoids any high side turning on if the inductor current is higher than

the programmed value. This current limit can be designed with the following equation:

The current sensing is performed by comparing the voltage drop in the low-side MOSFET,

during the TOFF period, with the voltage drop given by an injected current and the current

limit resistor.

Figure 31.

VDDQ, VTT, VTTREF and inductor current, thermal shutdown, pulse-skip mode

DSon

LS

ILIM

CL

R

R

I

,

100µA x

=

DSon

LS

ILIM

CL

R

R

I

,

100µA x

=