DATA TRANSFER AND OUTPUTS ACTIVAT-

ING (Figure 3)

The half bridges of OUT1, OUT2 and OUT3 can

be used with OUT4 to drive three bidirectional

motors in full bridge configuration as shown in

fig.1 Only one motor can be driven in the same

time. The

µC writes the corresponding word

status 1 till 10 at the bus and latch it with a low

pulse in the L9947. So the motor is activated. To

stop the motor it is useful to insert a braking

phase (status 9). In the braking condition there

are all low side DMOS of the half bridges

switched-on in this case the flyback currents flows

through the low side switches instead of the intrin-

sic diodes of the half bridges. After that, the half

bridges could be switched in tristate (T). The high

side driver, OUT5 can be switched only when all

the half bridges are in tristate status 10.

The

µC works always as master and the L9947

Power Interface as slave. That means: the

µC

starts the communication between the Power In-

terface and itself with low transition at the CSN

line. CSN = 0, R/WN= 0 the L9947 reads the data

at the bus and execute the command as shown in

tables 1,3,4 (write mode). The high slope of the

CSN stores the last command and execute it fur-

ther. All inputs are disabled if CSN= 1.

So the bus can be used for another device. With

CSN = 0 and R/WN = 1 the L9947 writes the

status of the diagnostic at the parallel bus until

CSN becomes high (table 2; status

µ + 15) (read

mode). The power outputs maintain the same

status as before.

Figure 3: Signal sequence for data transfer to switch M1 right, read the output status, brake the motor

and activate the standby mode.

L9947

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