STWBC2-HP datasheet(46/96 Pages) STMICROELECTRONICS

46 / 96 page

Figure 48. DCM operation output voltage above target

2.2.7.7

CCM case

The drawing below shows a CCM case which happens because the coil current reached the maximum peak

current allowed for the coil. In this case, the charge time is not increased.

Figure 49. CCM Icoil reach max. peak

2.2.7.8

Discharge and Probing

As for the charge step, the discharge step is controlled by its duration. The discharge step is adjusted to target a

QR operation while ensuring that current in the coil is not reverting.

The current reversal detection during the discharge step is done using an additional probing step placed right

after the discharge step. During this probe step, the output stage of the converted is placed in high impedance

(both high- and low-side MOS are OFF):

•

If the current in the coil Icoil was still flowing to VOUT before the probe step, the switching node voltage Vsw

rises up to VOUT+0.7 V through the high-side MOS body diode.

•

If the current in the coil Icoil has reverted before the probe step, the switching node voltage Vsw drops down

to -0.7 V through the low-side MOS body diode.

STWBC2-HP

Digital AFE functions

DS13825 - Rev 1.0

page 46/96

STWBC2-HP Datasheet(PDF) 46 Page - STMicroelectronics