L9907 datasheet(14/49 Pages) STMICROELECTRONICS

14 / 49 page

Functional description

L9907

14/49

DS11800 Rev 5

In order to unlatch also FS_FLAG status a SPI communication with diagnostic frame must

be performed.

2.5.3

Drain source monitoring

To monitor the external MOSFET a Drain Source monitoring for all HS and LS is

implemented. In case the drain source voltage exceeds a certain threshold (e.g. MOSFET

short) during gate ON mode, all drivers will be disabled and the fail will be reported via

FS_FLAG and SPI. In case the ShortPH bit of CMD2 SPI frame would be set to 1 (refer to

SPI mapping, Table 23), the device allows the switching off of the only phase for which the

drain-source short occurred.

2.6

Current Sense Amplifier (CSA)

L9907 is equipped with two SPI-programmable Current Sense Amplifiers to measure the

motor current by converting and amplifying the voltage drop across an external shunt

resistor. A simplified CSA circuit diagram is showed in Figure 6.

Figure 6. CSA simplified circuit diagram

Each CSA can be used for phase (bidirectional) or ground (unidirectional) current

monitoring by properly selecting the output zero-current offset via dedicated bits in the SPI

VCC

OFS

0.25*R

OFS

10*R

30*R

50*R

100*R

30*R

50*R

100*R

OFS1

OFS2

Sx-

Sx+

Isx+

-V

Isx-

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