AMIS30421C4211G ONSEMI [ON Semiconductor], AMIS30421C4211G Datasheet - Page 24

• Manufacturer Part Number: AMIS30421C4211G
• Description: Micro-Stepping Stepper Motor Bridge Controller
• Manufacturer: ONSEMI [ON Semiconductor]

Watchdog
(Table 5). This can for instance be used to reset an external
microcontroller at power up.
function. When the watchdog is enabled (<WDEN> = ‘1’),
a timer will start counting up. When the counter reaches a
certain value (<WDT[3:0]>), the <WD> SPI bit will be set
and the WDb−pin will be pulled low for a time equal to t
to reset the external microcontroller. To avoid that the
microcontroller gets reset, the microcontroller needs to
re−enable the watchdog before the count value is reached (=
write ‘1’ to <WDEN> before <WDT[3:0]> is reached). This
functionality can be used to reset a “stuck” microcontroller.
boot. When powering the application (cold boot), <WD>
will be zero. If the microcontroller has been reset by the
WDb−pin (warm boot), <WD> bit will be ‘1’. The
microcontroller can use this information to detect a cold or
warm boot.
(minimum time between re−enabling must be above t
(see Figure 4)). One may also not enable the watchdog too
fast after power up (see t
noise on the VDD supply (t
When V
The WDb−pin also has a second function, a Watchdog
The SPI bit <WD> can be used to detect a cold or warm
It’s forbidden to re−enable the watchdog too fast
A small analogue filter avoids resetting due to spikes or
BB
is applied, the WDb−pin is kept low for t
DSPI
V
ERRb
rf
V
).
, Figure 4).
BB
Charge Pump Failure
during start up
Figure 23. Charge Pump Failure
http://onsemi.com
WDPR
POR
por
24
due to slow voltage slope Error is latched.
output. One can change this to a push−pull output by using
SPI bit <IO_OT>.
Error Output
is reported. Next errors will be reported:
•
•
•
•
•
•
will be reported during the first 250us but will not be latched
(see also Charge Pump Failure).
output. One can change this to a push−pull output with SPI
bit <IO_OT>.
Charge Pump Failure longer than 250 us
During and after power up the WDb−pin is an open drain
The error output (ERRb−pin) will be activated if an error
Keep in mind that during power up a charge pump failure
During and after power up the ERRb−pin is an open drain
Thermal Warning
Thermal Shutdown
Overcurrent
Open Coil
Charge Pump Failure
All errors except a Thermal Warning will disable the
H−bridge drivers to protect the motor driver
(<MOTEN> = ‘0’). To reset the error one needs to read
out the error. Only when all errors are reset it will be
possible to re−enable the motor driver (<MOTEN> =
‘1’).
t
t