Datasheet

LM4951A
SNAS453C –AUGUST 2008–REVISED APRIL 2013 www.ti.com
The gain of the internal amplifiers remains unity until the voltage on the bypass pin reaches V
DD
/2. As soon as
the voltage on the bypass pin is stable, there is a delay to prevent undesirable output transients (“click and
pops”). After this delay, the device becomes fully functional.
THERMAL SHUTDOWN AND SHORT CIRCUIT PROTECTION
The LM4951A has thermal shutdown and short circuit protection to fully protect the device. The thermal
shutdown circuit is activated when the die temperature exceeds a safe temperature. The short circuit protection
circuitry senses the output current. When the output current exceeds the threshold under a short condition, a
short will be detected and the output deactivated until the short condition is removed. If the output current is
lower than the threshold then a short will not be detected and the outputs will not be deactivated. Under such
conditions the die temperature will increase and, if the condition persist to raise the die temperature to the
thermal shutdown threshold, initiate a thermal shutdown response. Once the die cools the outputs will become
active.
RECOMMENDED PRINTED CIRCUIT BOARD LAYOUT
Figures 2–4 show the recommended two-layer PC board layout that is optimized for the SD10A. This circuit is
designed for use with an external 7.5V supply 8Ω (min) speakers.
Demonstration Board Circuit
Figure 35. Demo Board Circuit
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