L9963E datasheet(17/184 Pages) STMICROELECTRONICS

17 / 184 page

A Soft RESET command received when in Normal state clears all registers except CommTimeout. The device is

kept in Normal and doesn’t move to Reset state.

4.1.4

Power up sequence

Final Normal state is reached through a power up sequence, which involves the turn ON of all regulators. The

following power up sequence is performed correctly if VBAT pin voltage lays in the operating range (refer to

Table 2):

•

VREG is the first regulator to turn ON

•

As soon as VREG reaches enough voltage dynamic (> 3 V), also VANA regulator starts to turn ON

•

When VANA regulator voltage reaches VVANA_UV threshold and related digital filter time TPOR_FILT +

TVTREF_DELAY expires, VTREF regulator is turned ON if VTREF_EN = 1. By default, VTREF is disabled

and will not be turned on during first power up sequence.

•

After TBOOT_DELAY in respect to VTREF enable, Bootstrap circuit is enabled in charge phase (CAP2

connected to VREG, CAP1 to GND)

•

After TVCOM_DELAY in respect to VTREF enable, VCOM regulator is turned ON

Normally, the power up sequence lasts TWAKEUP. In case it lasts longer than a specific timeout, the device moves

back to a low power state (Sleep or Silent Balancing, depending on the previous state). The following timeouts

are implemented:

•

timeout_VCOM_UP_first, valid only for the first power up

•

timeout_VCOM_UP, valid for each wake up

•

timeout_OSCI_MAIN, valid for each wake up

During power down:

•

VCOM, VTREF and Bootstrap are turned off at the same time

•

VREG is turned off after TVREG_OFF

•

When VREG falls below 4 V (typical value), VANA starts falling along with VREG.

Figure 8. Power up Sequence

L9963E

Device functional state

DS13636 - Rev 12

page 17/184

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