Board schematics

UM0580

18/24

The voltage at node "OPOUT2" can be computed as the sum of a bias and a signal

component, respectively equal to:

Equation 4

Equation 5

With the default values this gives:

●

●

As such, the maximum current amplifiable without distortion is equal to:

Equation 6

resistors.

8.4

Brake function

The STEVAL-IHM021V1 board provides a brake function that through the pull-up of a single

brake signal simultaneously turns the three low side switches ON , shorting the 3-phase

load. The feature is accessed using one single small-signal bipolar transistor (Q7), whose

function is to pull down the cathodes of six small signal diodes connected to each of the six

logic inputs (HIN1,

, HIN2,

, HIN3,

) of the L6390 gate drivers. The in-

series resistors together with the input lines avoid any conflict with the external controller

input signals, giving priority to the brake signal (see Figure 12).

⎟

⎠

⎞

⎜

⎝

⎛

+

+

+

=

R42

R39

R38

1

R41//R43

R36

R41//R43

3.3

V

BIAS

⎟

⎠

⎞

⎜

⎝

⎛

+

+

+

⋅

⋅

=

R42

R39

R38

1

R36//R43

R41

R36//R43

R

I

V

SHUNT

SIGN

V

1.86

I

R

2.91

V

SHUNT

SIGN

⋅

⋅

=

A

1

.

1

R

495

.

0

R

91

.

2

86

.

1

3

.

3

I

SHUNT

SHUNT

MAX

=

=

⋅

−

=

LIN 1

LIN 2

LIN 3