amis-30523 ON Semiconductor, amis-30523 Datasheet - Page 24

• Manufacturer Part Number: amis-30523
• Description: Amis-30523 Product Preview Can Micro-stepping Motor Driver
• Manufacturer: ON Semiconductor

coil during current decay, the coil voltage V
transient behavior. As this transient is not always desired in
application software, two operating modes can be selected
by means of the bit <SLAT> (see “SLA−transparency” in
Table 15 SPI Control Parameter Overview). The SLA pin
shows in “transparent mode” full visibility of the voltage
transient behavior. This allows a sanity−check of the
speed−setting versus motor operation and characteristics
and supply voltage levels. If the bit “SLAT” is cleared, then
only the voltage samples at the end of each coil current zero
crossing are visible on the SLA−pin. Because the transient
behavior of the coil voltage is not visible anymore, this mode
Warning, Error Detection and Diagnostics Feedback
Thermal Warning and Shutdown
warning bit <TW> is set (Table 17 SPI Status registers
Address SR0). If junction temperature increases above
thermal shutdown level, then the circuit goes in “Thermal
Shutdown” mode (<TSD>) and all driver transistors are
disabled (high impedance) (see Table 17 SPI Status registers
Address SR2). The conditions to reset flag <TSD> is to be
at a temperature lower than T
reading out Status Register 2.
Because of the relatively high recirculation currents in the
When junction temperature rises above T
SLA−Pin
PWMsh
V
Icoil=0
SLAT
COIL
V
PWMsh
SLAT = 1 => SLA−pin is “transparent” during
V
Crossing. SLA−pin is updated “real−time”.
COIL
Icoil=0
BEMF
sampling @ Coil Current Zero
div2
div4
TW
and to clear the <TSD> flag
Ssh
Figure 21. Timing Diagram of SLA−Pin
TW
COIL
Csh
, the thermal
shows a
http://onsemi.com
retained
Sh
is
sample
last
24
Ch
SLAT = 0 => SLA−pin is not “transparent”
during V
Crossing. SLA−pin is updated when leaving
current−less state.
V
generates smoother Back e.m.f. input for post−processing,
e.g. by software.
output level (0 to 5 V), the sampled coil voltage V
divided by 2 or by 4. This divider is set through an SPI bit
<SLAG> (see Table 15 SPI Control Parameter Overview).
SLA−pin and the transparency−bit. “PWMsh” and “I
are internal signals that define together with SLAT the
sampling and hold moments of the coil voltage.
AND8399/D.
Over−Current Detection
current in each activated output stage. If the load current
exceeds the over−current detection threshold, then the
over−current flag is set and the drivers are switched off to
reduce the power dissipation and to protect the integrated
circuit. Each driver transistor has an individual detection bit
in (see Table 17 SPI Status registers Address SR1 and SR2:
<OVCXij> and <OVCYij>). Error condition is latched
and the microcontroller needs to clear the status bits (by
reading Status Register 1 or 2) to reactivate the drivers.
SLAT
NOT (Icoil=0)
BEMF
In order to bring the sampled Back e.m.f. to a descent
The following drawing illustrates the operation of the
More information can be found in application note
The over−current detection circuit monitors the load
buf
BEMF
previous output is
kept at SLA pin
sampling @ Coil Current Zero
SLA−Pin
retain last sample
t
t
coil
COIL
= 0”
is