Datasheet

I
t
I
TRIP
0mA
Fast
Mixed
25%
Slow
PWM cycle
PWM on PWM off (t
OFF
)
25% 50% 75% 100%
DRV8834
www.ti.com SLVSB19C –FEBRUARY 2012–REVISED JUNE 2013
Figure 3 illustrates the current waveforms in slow, 25% mixed, and fast decay modes.
Figure 3. Current Decay Modes
Decay mode is selected by the voltage present on the xDECAY pins. Internal current sources of 10 µA (typical)
are connected to the pins, which allows setting of the decay mode by a resistor connected to ground if desired.
It is possible to drive the xDECAY pin with a tri-state GPIO pin and also place the resistor to ground. This allows
a microcontroller to select fast, slow, or mixed decay modes by driving the pin high, low, or high-impedance.
Note that the logic-low voltage must be less than 0.1 V with 10-µA of current sourced from the DRV8834 to attain
slow decay.
In indexer mode, only the ADECAY pin is used, and slow decay mode is always used when at any point in the
step table where the current is increasing. When current is decreasing or remaining constant, the decay mode
used will be fast, slow, or mixed, as commanded by the ADECAY pin.
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