AMIS-30624 Datasheet, PDF (36/56 Pages) AMI SEMICONDUCTOR – I2C Microstepping Motordriver

AMIS-30624 I²C Microstepping Motordriver
Data Sheet
15.3.8. Motor Shutdown Mode
A motor shutdown occurs when:
• The chip temperature rises above the thermal shutdown threshold Ttsd (see Thermal Shutdown Mode)
• The battery voltage goes below UV2 (see Battery Voltage Management)
• Flag <ElDef> = ‘1’, meaning an electrical problem is detected on one or both coils, e.g. a short circuit
• Flag <CPFail> = ‘1’, meaning there is a charge pump failure
A motor shutdown leads to the following:
• H-bridges in high impedance mode
• The TagPos register is loaded with the ActPos (to avoid any motion after leaving the motor shutdown mode)
The I²C interface remains active, being able to receive orders or send status.
The conditions to get out of a motor shutdown mode are:
• Reception of a GetFullStatus1 command AND
• The four causes above are no longer detected
This leads to H-bridges in Ihold mode, hence the circuit is ready to execute any positioning command.
This can be illustrated in the following sequence given as an application tip. The master can check whether there is a problem or not
and decide which application strategy to adopt.
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.
AMI Semiconductor – Apr. 2007, Rev 3.1, M-20664-003
36
www.amis.com