EK76

EK76U Rev A

7

CURRENT SENSE

The optional current sense gain and offset circuit is designed to interface with various ADCs in closed-

loop current/torque control. Follow the below schematic and equations to determine the proper component

values.

After assembly of the EK76 including the above Current Sense circuit, R22 must be trimmed to reach the

desired value of VOS. To do this, attach a Voltmeter to measure the voltage between pins 11 (negative) and

13 (positive) of P2. Apply the low-voltage supply VCC (+VS should NOT be active). Adjust R22 until the desired

value for VOS is shown on the Voltmeter.

The following equation represents the Low-Side Phase Current (IPHASE) as a function of voltage measured

at IM_X (VM):

Value

Applicable Designators on

EVAL94

Equation

Default

Value

Units

Suggested

Tolerance

VOS

Bias

ADC min input (or higher)

1.65

V

-

VOUT_MAX -

ADC max input (or lower)

3.3

V

-

IOUT_MAX

-

< 80 A

33

A

-

Gain

-

(VOUT_MAX-VOS) / (IOUT_MAX*

10 mΩ)

5

V/V

-

RF

R9, 12, 13, 16, 17, 20

1.8k < RF < 100k

50k

Ω

0.1%

RIN

R10, 11, 14, 15, 18, 19

RF / Gain

10k

Ω

0.1%

RT

R22 (potentiometer)

1k < RT < 100k

10k

Ω

-

RL

R21

Roughly RT ((VCC/2VOS) – 1)

39k

Ω

-

C4

C4

C4 = 100n

100n

F

X7R

fFIL

-

Typically 200k < fFIL < 1M

∞

Hz

-

RFIL

R23, 24, 25

Typically 100 < RFIL < 1k

0

Ω

-

CFIL

C1, 2, 3

1 / (2π * fFIL * RFIL)

0

F

-

R1-3

10

RIN

RIN

+

-

RF

RF

BIAS

RFIL

CFIL

IM_X

PGND_X

3X

+

-

1X

BIAS

RL

RT

VCC

C4

PGND

DGND

DGND

Phase

Current

IPHASE

VM VOS

–

Gain 0.01



---------------------------------

=