AMIS-30624 Datasheet, PDF (33/56 Pages) AMI SEMICONDUCTOR – I2C Microstepping Motordriver

AMIS-30624
14.3.7. Electrical Defect on Coils, Detection and Confirmation
The principle relies on the detection of a voltage drop on at least one transistor of the H-bridge. Then the decision is taken to open the
transistors of the defective bridge.
This allows the detection of the following short circuits:
• External coil short circuit
• Short between one terminal of the coil and Vbat or Gnd
Open circuits are detected by a 100 percent PWM duty cycle value during a long time.
Table 23: Electrical Defect Detection
Pins
Yi or Xi
Yi or Xi
Yi or Xi
Y1 and Y2
X1 and X2
Xi and Yi
Fault Mode
Short circuit to GND
Short circuit to Vbat
Open
Short circuited
Short circuited
Short circuited
Remark: One cannot detect an internal short in the motor.
14.3.8. 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.
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