Functional description

STSPIN820

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DocID031065 Rev 2

When the full-step mode is set, the reference value of the PWM current controllers and the

direction of the currents are set as listed in Table 8.

When the step mode is different from the full-step mode the values listed in Table 9 are

used.

The DECAY input determinates the behavior of the PWM current control as described in

Section 5.3.

When the EN\FAULT input is forced low the power stage is immediately disabled (all

MOSFETs are turned off). The pin is also used as FAULT indication through the integrated

open-drain MOSFET as described in Section 5.4 on page 19 and Section 5.5 on page 22.

Table 10 shows the target reference and sequencer values for the 1/2-, 1/4- and 1/8-step

operation. Higher microstepping resolutions follow the same pattern. The reset state (home

state) for all stepping mode is entered at power-up or when the device exits the standby

status.

Table 8. Target reference and current direction according to sequencer value (full-step mode)

Sequencer value

Phase A

Phase B

Reference voltage Current direction Reference voltage Current direction

0 0 X X X X XXX X

A1 → A2

B1 → B2

0 1 X X X X XXX X

A1 → A2

B1 ← B2

1 0 X X X X XXX X

A1 ← A2

B1 ← B2

1 1 X X X X XXX X

A1 ← A2

B1 → B2

Table 9. Target reference and current direction according to sequencer value (not full-step mode)

Sequencer value

Phase A

Phase B

Reference voltage

Current

direction

Reference voltage

Reference

voltage

0 0 0 0 0 0 0 0 0 0 Zero (power bridge disabled)

-

B1 → B2

00

N

A1 → A2

-

B1 → B2

0 1 0 0 0 0 0 0 0 0

A1 → A2 Zero (power bridge disabled)

-

01

N

Sin (π/2 + N/256 × π/2) ×

A1 → A2

Cos (π/2 + N/256 × π/2) ×

B1 ← B2

1 0 0 0 0 0 0 0 0 0 Zero (power bridge disabled)

-

B1 ← B2

10

N

A1 ← A2

B1 ← B2

1 1 0 0 0 0 0 0 0 0

A1 ← A2 Zero (power bridge disabled)

-

11

N

Sin (π/2 + N/256 × π/2) ×

A1 ← A2

Cos (π/2 + N/256 × π/2) ×

B1 → B2