4 Proposed initialization sequences L9904:

AN2229

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4

Proposed initialization sequences L9904:

Alternative 1:

Vs > 7V

EN = High

for >50

μs

PWM = Low Pulse

after 50

μs of EN

PWM = 1

for >10

μs

Alternative 2:

Vs > 7V

EN = High

for >50

μs

PWM = Edge

positive Edge after min 50

μs of EN

PWM = 1

for >10

μs

Alternative 3:

Vs > 7V

EN = High

for >50

μs

PWM = 1

for >10

μs after Edge of DIR 50μs of EN

DIR=Edge

after 50

μs of EN

Figure 5.

Three possible solutions. Important is that PWM=1 will be detected after enabling the L9904 to switch on

both LS transistors (break mode). Therefore an edge at PWM or DIR input has to be present 50

μs (or

more) after EN was set HI. The 50

μs delay are needed for the internal circuit to setup. A signal change

within the 50

100nF) to charge the CBx bootsstrap capacitors (depending on value of capacitor)

EN

VS

EN

PWM

VS should be>7V before EN=HI

>50us

>10us

PWM

>10us

>10us

PWM

DIR

Alternativ 1:

Pulse at PWM

Alternative 2:

pos. Edge PWM

Alternative 3:

Edge at DIR

with PWM=1