L9907 datasheet(36/49 Pages) STMICROELECTRONICS

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SPI operation

L9907

36/49

DS11800 Rev 5

If EN1 and EN2 are both asserted while a SPI cycle CMD4 or CMD1 with WE=1 is ongoing,

then a SPI communication error is generated and the corresponding SPI command is

ignored.

The effect of any fault (except Shoot Through) can be selectively masked from Micro

Controller setting at '0' proper register. FS_FLAG status and SDO report are not affected

since fault detection always acts in the same way. Default value for these bits is '1' (fault

effect enabled). Once the fault effect is re-enabled with SPI communication the IC reacts to

fault as described in the specific paragraph if the fault is still present.

CMD4 SPI command register

SDI bit B12: REGOFF_EN

This bit is accessible for writing only if AND(EN1,EN2)='0': trying to write it without

lowering AND(EN1,EN2) will generate SPI error.

Once written, CMD4 B12 determines if the REG_OFF procedure is active or not

(default: not active).

REG_OFF procedure (active only if CMD4 B12 is set; refer also to Section 2.3)

Lowering EN1 external pin triggers the procedure to switch off regulators that supply

the HS and LS FET drivers: filter time, active only on the falling edge of the EN1 signal,

is implemented: 8*tosc

 TFILT  16*tosc.

Once the procedure has been triggered, the device behaves as follows:

REG_OFF = '1', EN_PWM = "000", FS_FLAG = '0', DIAG2 bit B6 set

In order to re-engage, the correct procedure is to toggle AND(EN1,EN2) then read the

DIAG2 SPI register (to verify that bit B6 is set).

Toggling of AND(EN1,EN2) will re-engage the output commands (EN_PWM = "111")

while subsequent reading of DIAG2 register will re-engage HS/LS drivers supply

(REG_OFF = '0') and release FS_FLAG.

In order to avoid activating output commands while regulators that supply the HS and

LS FET drivers are in power-up phase (this could generate current shape distortion)

Table 35. CMD4 SDI SPI bits vs. enabled fault

CMD4 SDI SPI BIT

Name

Description (Default value=’1’)

EN_VccOV

It enables VCCOV fault effect in case of VCCOV fault detection

EN_VccUV

It enables VCCUV fault effect in case of VCCUV fault detection

EN_UV_HS

It enables UV_HS fault effect in case of UV_HS fault detection

EN_UV_LS

It enables UV_LS fault effect in case of UV_LS fault detection

EN_VSCHS1

It enables VSCHS1 fault effect in case of VSCHS1 fault detection

EN_VSCHS2

It enables VSCHS2 fault effect in case of VSCHS2 fault detection

EN_VSCHS3

It enables VSCHS3 fault effect in case of VSCHS3 fault detection

EN_VSCLS1

It enables VSCLS1 fault effect in case of VSCLS1 fault detection

EN_VSCLS2

It enables VSCLS2 fault effect in case of VSCLS2 fault detection

EN_VSCLS3

It enables VSCLS3 fault effect in case of VSCLS3 fault detection

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