AMIS-30624 Datasheet, PDF (21/56 Pages) AMI SEMICONDUCTOR – I2C Microstepping Motordriver

AMIS-30624 I²C Microstepping Motordriver
Data Sheet
As illustrated in Table 15, the state is depending on the previous state, the condition of the two switch controls (DriveLS and DriveHS)
and the output of HW_Cmp. Figure 11 shows an example of a practical case where a connection to VBAT is interrupted.
Condition
DriveHS
R2VBAT
Tsw = 1024 µs
OPEN
R2VBAT
R2GND
t
t
DriveLS
Tsw_on = 128 µs
t
"R"-Comp
R_th
t
HW_Cmp
t
State
PC20060926.2
t
Figure 11: Timing Diagram Showing the Change in States for HW Comparator
R2VBAT
A resistor is connected between VBAT and HW. Every 1024µs S_BOT is closed for a period of 128µs and a current is sensed. The output
of the I Æ R converter is low and the HW_Cmp output is high. Assuming the previous state was floating, the internal LOGIC will
interpret this as a change of state and the new state will be High (see also Table 15). The next time S_BOT is closed the same condition is
observed. The previous state was high, so based on Table 15 the new state remains unchanged. This high state will be interpreted as
HW address = 1.
OPEN
In case the HW connection is lost (broken wire, bad contact in connector) the next time S_BOT is closed this will be sensed. There will be
no current, the output of the corresponding I Æ R converter is high and the HW_Cmp will be low. The previous state was High. Based
on Table 15 one can see that the state changes to float. This will trigger a motion to secure position after a debounce time of 64 ms.
This prevents false triggering in case of micro interruptions of the power supply. See also Electrical Transient Conduction Along Supply
Lines.
R2GND
If a resistor is connected between HW and the GND, a current is sensed every 1024µs when S_TOP is closed. The output of the top I Æ R
converter is low and as a result the HW_Cmp output switches to high. Again based on the stated diagram in Table 15 one can see that
the state will change to low. This low state will be interpreted as HW address = 0.
AMI Semiconductor – Apr. 2007, Rev 3.1, M-20664-003
21
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