SA53 Datasheet, PDF (12/14 Pages) Cirrus Logic – Switching Amplifier

SA53
Product Innova tionFrom
Typically, the current sense pins source _{Figure 8. Current Limit Waveforms}
current into grounded resistors which pro-
vide voltages to the current limit compara-
tors. If instead the current limit resistors are _{It INPUT}
connected to a voltage output DAC, the
current limit can be controlled dynamically
from the system controller. This technique
essentially reduces the current limit thresh-
V_th
old voltage to (Vth-VDAC). During expect-
ed conditions of high torque demand, such
as start-up or reversal, the DAC can adjust
I1
the current limit dynamically to allow pe-
riods of high current. In normal operation
when low current is expected, the DAC
output voltage can increase, reducing the
current limit setting to provide more con-
servative fault protection.
OUT 1
2.6 EXTERNAL FLYBACK
DIODES
External fly-back diodes will offer superior
reverse recovery characteristics and low- I_LIM/DIS1
er forward voltage drop than the internal
back-body diodes. In high current applica-
tions, external flyback diodes can reduce power dissipation and heat-
ing during commutation of the motor current. Reverse recovery time
and capacitance are the most important parameters to consider when
selecting these diodes. Ultra-fast rectifiers offer better reverse recovery
time and Schottky diodes typically have low capacitance. Individual ap-
plication requirements will be the guide when determining the need for
these diodes and for selecting the component which is most suitable.
Figure 9. Schottky Diodes
V_S V_S
SA53
OUT 1
OUT 2
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