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| TDA8933 Datasheet, PDF (8/47 Pages) NXP Semiconductors – Class-D audio amplifier | |||
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NXP Semiconductors
TDA8933
Class-D audio ampliï¬er
VP
POWERUP
DREF
HVPREF
HVP1, HVP2
0.43VENGAGE
ENGAGE 0.3VENGAGE
audio
OUT1, OUT2
PWM
AUDIO
PWM
AUDIO
AUDIO
PWM
0.17VENGAGE
DIAG
OSCIO
Fig 3. Start-up sequence
operating
mute
operating fault
operating
sleep
001aae788
8.3 Pulse width modulation frequency
The output signal of the ampliï¬er is a PWM signal with a carrier frequency of
approximately 320 kHz. Using a 2nd-order-low-pass ï¬lter in the application results in an
analog audio signal across the loudspeaker. The PWM switching frequency can be set by
an external resistor Rosc connected between pin OSCREF and VSSD(HW). The carrier
frequency can be set between 300 kHz and 500 kHz. Using an external resistor of 39 kâ¦,
the carrier frequency is set to an optimized value of 320 kHz (see Figure 4).
If two or more TDA8933 devices are used in the same audio application, it is
recommended to synchronize the switching frequency of all devices.This can be done by
connecting all the OSCIO pins together and conï¬guring one of the TDA8933 devices in
the application as the clock master. Conï¬gure the other TDA8933 devices as slaves.
Pin OSCIO is a 3-state input or output buffer. Pin OSCIO is conï¬gured in master mode as
oscillator output, and in slave mode as oscillator input. Master mode is enabled by
applying a resistor between pin OSCREF and VSSD(HW), while slave mode is enabled by
connecting pin OSCREF directly to VSSD(HW) (without any resistor).
The value of the resistor also sets the frequency of the carrier and can be calculated with
Equation 1:
TDA8933_1
Preliminary data sheet
Rev. 01 â 15 May 2007
© NXP B.V. 2007. All rights reserved.
8 of 47
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