A6986H datasheet(32/71 Pages) STMICROELECTRONICS

Part #	A6986H

Description	Automotive 38 V, 2 A synchronous step-down switching regulator with 30 μA

PDF	71 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

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Figure 29. Valley current sense operation in overcurrent condition

Figure 29. Valley current sense operation in overcurrent condition shows the switching frequency reduction during

the valley current sense operation in case of extremely low duty cycle (VIN = 12 V, fSW = 2 MHz short-circuit

condition).

In a worst case scenario (like Figure 29. Valley current sense operation in overcurrent condition) of the

overcurrent protection the switch current is limited to:

IMAX=IVALLEYTH+VIN−VOUT

L ⋅TMASKHS

(15)

where IVALLEY_TH is the current threshold of the valley sensing circuitry (see Table 5. Electrical characteristics TJ

= - 40 to 135 °C, VIN = 12 V unless otherwise specified.) and TMASK_HS is the masking time of the high-side

switch 100 ns typ.).

In most of the overcurrent conditions the conduction time of the high-side switch is higher than the masking time

and so the peak current protection limits the switch current.

IMAX=IPEAK_TH

(16)

A6986H

Overcurrent protection

DS12861 - Rev 3

page 32/71

A6986H Datasheet(PDF) 32 Page - STMicroelectronics