AMIS-30624 Datasheet, PDF (34/56 Pages) AMI SEMICONDUCTOR – I2C Microstepping Motordriver

AMIS-30624
Tj ≥ Tsd or
Vbb ≤ UV2 or
<ElDef> = ‘1’ or
<CpFail> = ‘1’
SetPosition
frame
GetFullStatus1
frame
GetFullStatus1
frame
↓
- The circuit is driven in
motor shutdown
mode
- The application is not
aware of this
↑
- The position set-point
is updated by the
I²C Master
- Motor shutdown
mode ⇒ no motion
- The application is still
unaware
↑
↑…
- The application is
- Possible confirmation
aware of a problem
of the problem
- Reset <TW> or <TSD> or <UV2> or <StepLoss>
or <ElDef> or <CPFail> by the application
- Possible new detection of over temperature or
low voltage or electrical problem ⇒ Circuit
sets <TW> or <TSD> or <UV2> or
<StepLoss> or <ElDef> or <CPFail>
again at ‘1’
Figure 21: Example of Possible Sequence Used to Detect and Determine Cause of Motor Shutdown
Important: While in shutdown mode, since there is no hold current in the coils, the mechanical load can cause a step loss, which
cannot be flagged by the AMIS-30624.
Warning: The application should limit the number of consecutive GetFullStatus1 commands to try to get the AMIS-30624 out of
shutdown mode. When this proves to be unsuccessful, for example if there is a permanent defect, the reliability of the circuit could be
altered since GetFullStatus1 attempts to disable the protection of the H-bridges.
14.4 Motion Detection
Motion detection is based on the back emf generated internally in the running motor. When the motor is blocked, for example when it
hits the end-position, the velocity and as a result also the generated back emf, is disturbed. The AMIS-30624 senses the back emf,
calculates a moving average and compares the value with two independent threshold levels: Absolute threshold (AbsThr[3:0] ) and
Delta threshold (DelThr[3:0] ). Instructions for the correct use of these two levels in combination with three additional parameters
(MinSamples, FS2StallEn and DC100SDis) are outside the scope of this datasheet. Detailed information is available in a dedicated
white paper “Robust Motion Control with AMIS-3062x Stepper Motor Drivers”, available on http://www.amis.com/.
If the motor is accelerated by a pulling or propelling force and the resulting back emf increases above the Delta threshold (+ ΔTHR),
then <DelStallHi> is set. When the motor is slowing down and the resulting back emf decreases below the Delta threshold
(- ΔTHR), then <DelStallLo> is set. When the motor is blocked and the velocity is zero after the acceleration phase, the back emf is
low or zero. When this value is below the Absolute threshold, <AbsStall> is set. The <Stall> flag is the OR function of
<DelStallLo> OR <DelStallHi> OR <AbsStall>.
Rev. 4 | Page 34 of 56 | www.onsemi.com