L6730CQ datasheet(23/50 Pages) STMICROELECTRONICS

No de pièce	L6730CQ

Description	Adjustable step-down controller with synchronous rectification

PDF	50 Pages

Scroll/Zoom	100%

Fabricant	STMICROELECTRONICS [STMicroelectronics]

Site Internet	http://www.st.com

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L6730C - L6730D

Device description

23/50

Using the L6730D there is the possibility to set the constant-current-protection also after the

soft-start. The following figures show the behaviour of the L6730D during an overcurrent event.

Figure 17. shows the intervention of the peak OCP: the high-side MOSFET(s) is turned-off

when the current exceeds the OCP threshold. In this way the duty-cycle is reduced, the VOUT is

reduced and so the maximum current can be fixed even if the output current is escalating.

Figure 18. shows the limit of this protection: the on-time can be reduced only to the masking

time and, if the output current continues to increase, the maximum current can increase too.

Notice how the Vout remains constant even if the output current increases because the on-time

cannot be reduced anymore.

Figure 16. Constant current and Hiccup Mode during an OCP (L6730C).

Figure 17. Peak overcurrent-protection in constant-current-protection (L6730D).

VSS

VCOMP

VOUT

TON

IOUT

Peak th

L6730CQ Fiches technique(PDF) 23 Page - STMicroelectronics