AMIS30421C4211G ONSEMI [ON Semiconductor], AMIS30421C4211G Datasheet - Page 23

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

Thermal Warning and Shutdown
through SPI bits <TR[1:0]> and <TSD>. Thermal Range 1
goes from −40°C up to T
to T
T
level is reached which is the thermal warning range.
ERRb−pin will be activated. If junction temperature
increases above thermal shutdown level (T
circuit goes in Thermal Shutdown Mode and all driver
transistors are disabled (high impedance). The condition to
get out of the Thermal Shutdown Mode is to be at a
temperature lower than T
bit.
Over−Current Detection
current in each activated output stage. If the load current
exceeds the over−current detection threshold, the ERRb−pin
will be activated and the drivers are switched off (motor
driver disabled) to reduce the power dissipation and to
protect the H−bridge. Each driver has an individual
detection bit (see Status Register 1 and 2). The error
condition is latched and the microcontroller needs to read
out the error to reset the error and to be able to re−enable the
motor driver again.
T
3
AMIS−30421 has 4 thermal ranges which can be read out
When junction temperature rises above T
The over−current detection circuit monitors the load
3
can be found in Table 4). Once above T
− 40°C
= T
2
and Thermal Range 3 goes from T
T
TW
TSD
T
T
2
1
Ï Ï
 Â
È È È È
Ï Ï
 Â
Ç Ç Ç Ç
È È
À À
Ç Ç
À À À À
Figure 22. Thermal Ranges
Thermal Range 4 = Thermal Warning (ERRb−pin active)
Thermal Range 3
Thermal Range 2
Thermal Range 1
WARNING, ERROR DETECTION AND DIAGNOSTICS FEEDBACK
TW
1
. Thermal Range 2 goes from T
and by clearing the <TSD> SPI
2
up to T
3
the 4
TW
TSD
3
(T
(= T
), then the
th
1
thermal
, T
http://onsemi.com
3
), the
2
and
1
23
Note: Successive resetting the motor driver in case of a short
circuit condition may damage the drivers.
Open Coil/Current Not Reached Detection
duty cycle of the PWM regulator. If in a coil 100% duty cycle
is detected for a certain time, an open coil will be latched (see
Status Register 1 and 2) and the ERRb−pin will be activated
(drivers are disabled). The time this 100% duty cycle needs
to
<OPEN_COIL[1:0]>. A short time will result in fast
detection of an open−coil but could also trigger unwanted
open−coil errors. Increase the timing if this is the case.
supply voltage is low, it can happen that the motor driver is
not able to deliver the requested current to the motor. Under
these conditions the PWM controller duty cycle will be
100% and the ERRb−pin will flag this situation. This feature
can be used to test if the operating conditions (supply
voltage, motor coil resistance) still allow reaching the
requested coil−current or else the coil current should be
reduced.
Note: A short circuit could trigger an open coil.
Charge Pump Failure
low R
supply voltages. If supply voltage is too low or external
components are not properly connected to guarantee a low
R
(<CPFAIL>), the ERRb−pin is activated and the driver is
disabled (<MOTEN> = ‘0’). One needs to read Status
Register 1 to clear the charge pump failure.
need some time to exceed the required threshold. During that
time the ERRb−pin will be active but not latched for 250us.
If the slope of the power supply V
up (charge pump not started after 250 ms), a charge pump
failure will be latched and the ERRb−pin is activated (see
also Figure 23).
DS(on)
Open coil detection is based on the observation of 100%
When the resistance of a motor coil is very large and the
The charge pump is an important circuit that guarantees
After power on reset (POR) the charge pump voltage will
be
DS(on)
of the drivers, a charge pump failure is latched
present
for all external MOSFET’s, especially for low
is
adjustable
BB
is slow during power
with
SPI
bits