L6730D datasheet(27/50 Pages) STMICROELECTRONICS

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L6730C - L6730D

Device description

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5.12

Thermal shutdown

When the junction temperature reaches 150°C ±10°C the device enters in thermal shutdown.

Both MOSFETs are turned OFF and the soft-start capacitor is rapidly discharged with an

internal switch. The device does not restart until the junction temperature goes down to 120°C

and, in any case, until the voltage at the soft-start pin reaches 500mV.

5.13

Minimum on-time (TON, MIN)

The device can manage minimum on-times lower than 100ns. This feature comes from the

control topology and from the particular over-current-protection system of the L6730C -

L6730D. In fact, in a voltage mode controller the current has not to be sensed to perform the

regulation and, in the case of L6730C - L6730D, neither for the over-current protection, given

that during the off-time the valley-current-protection can operate. The first advantage related to

this feature is the possibility to realize extremely low conversion ratios. Figure 22. shows a

conversion from 14V to 0.5V at 820KHz with a TON of about 50ns. The on-time is limited by the

turn-on and turn-off times of the MOSFETs.

Figure 22. 14V -> 0.5V@820KHz, 5A

50ns

L6730D Arkusz danych(PDF) 27 Page - STMicroelectronics