TDA8933 Datasheet, PDF (28/47 Pages) NXP Semiconductors – Class-D audio amplifier

NXP Semiconductors
TDA8933
Class-D audio amplifier
R1 = series resistors (Ω)
R2 = series resistors (Ω)
R_EQ = -_RR----₃₃----₊^×-----^ZZ----ⁱⁱ
(9)
Where:
R_EQ = equivalent resistance (Ω)
R3 = parallel resistor (Ω)
Z_i = internal input impedance (Ω)
Example:
Substituting R1 = R2 = 4.7 kΩ, Z_i = 100 kΩ and R3 = 22 kΩ in Equation 8 and Equation 9
results in a gain of G_v(tot) = 26.3 dB.
14.6 Device synchronization
If two or more TDA8933 devices are used in one application it is recommended that all
devices are synchronized at the same switching frequency to avoid beat tones.
Synchronization can be realized by connecting all OSCIO pins together and configuring
one of the TDA8933 devices as master, while the other TDA8933 devices are configured
as slaves (see Figure 10).
A device is configured as master when a resistor R_osc is connected between pin OSCREF
and pin V_SSD(HW), setting the carrier frequency. Pin OSCIO of the master is then
configured as an oscillator output for synchronization. The OSCREF pins of the slave
devices should be shorted to pin V_SSD(HW), configuring pin OSCIO as an input.
master
IC1
TDA8933
OSCREF ^VSSD(HW) OSCIO
slave
IC2
TDA8933
OSCIO ^VSSD(HW) OSCREF
Cosc
100 nF
Rosc
39 kΩ
Fig 10. Master/slave concept in two-chip application
010aaa138
TDA8933_1
Preliminary data sheet
Rev. 01 — 15 May 2007
© NXP B.V. 2007. All rights reserved.
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