High-Power Stereo Class-D Audio Power Amplifier
SGM4703 with Adjustable Power Limit and Automatic Level Control
23
DECEMBER 2022
SG Micro Corp
www.sg-micro.com
APPLICATION INFORMATION (continued)
Startup and Shutdown
The SGM4703 requires a power-up sequence (see
Figure 12). Please hold EN low at least 10ms after
PVDD and AVDD supply voltages are turned on.
The SGM4703 employs the EN pin to minimize power
consumption when not in use. When the EN pin is
pulled low, the SGM4703 is forced into shutdown mode.
At this time, all the analog circuitry is de-biased and the
supply current is reduced to the minimum level, and the
differential outputs are shorted to ground through an
on-chip resistor (5kΩ) individually. Once in shutdown
mode, the EN pin must remain low for at least 10ms (t
SD
)
for the shutdown settling time before it can be pulled
high again. When the EN pin is asserted high, the
device exits out of shutdown mode and enters into
normal operation after the startup time (t
STARTUP
) of
45ms.
An on-chip pull-down resistor of 250kΩ is included onto
the EN pin. Thus, shutdown mode is the state when the
power supply is first applied to the device. Whenever
possible, please hold the EN pin low until the device is
properly powered up and the audio signals at the inputs
are stable. Also, for best power-off pop performance,
place the device in shutdown mode prior to removing
the power supply voltage.
Note that the setting at the MODS pin is latched during
startup and cannot be changed while the device is in
operation. To change the setting of the MODS pin, the
device must be first brought into shutdown mode by
pulling the EN pin low for at least 10ms before it can be
restored to its normal operation.
t
EN _ D ELA Y
> 10 ms
> t
SD
t
SD
t
Fade-In
t
Fade-Out
PVDD
AVDD
GVDD
EN
VOP /N
t
ST AR TUP
t
ST AR TUP
Figure 12. Startup Timming
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