TDA8954 NXP Semiconductors, TDA8954 Datasheet - Page 8

• Manufacturer Part Number: TDA8954
• Description: The TDA8954 is a stereo or mono high–efficiency Class D audio power amplifier in asingle IC featuring low power dissipation
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDA8954_1
Product data sheet
8.2 Diagnostics
8.3 Pulse-width modulation frequency
The TDA8954 provides two diagnostic signals on pins DIAG1 and DIAG2. Both are
open-drain outputs that can be pulled up via a resistor (10 kΩ recommended) to a
maximum of 5 V relative to the GND pin. The maximum input current on these pins is
1 mA.
Pin DIAG1 provides a TFB warning signal. Pin DIAG2 can be used to monitor the OCP
status and the protection status (whether one of the protection circuits has switched off the
amplifier).
Details of the timing of these signals can be found in
see also
The amplifier output signal is a PWM signal with a typical carrier frequency of between
250 kHz and 450 kHz. A second-order LC demodulation filter on the output converts the
PWM signal into an analog audio signal. The carrier frequency, f
external resistor, R
frequency setting is between 250 kHz and 450 kHz.
The carrier frequency is set to 335 kHz by connecting an external 30 kΩ resistor between
pins OSC and OSCREF (see
If two or more Class D amplifiers are used in the same audio application, an external clock
circuit must be used to synchronize all amplifiers (see
they operate at the same switching frequency, thus avoiding beat tones (if the switching
frequencies are different, audible interference known as ‘beat tones’ can be generated).
Fig 6.
(kHz)
f
OSC
500
400
300
200
Table
Carrier frequency as a function of R
20
5.
OSC
Rev. 01 — 24 December 2009
, connected between pins OSC and OSCREF. The optimal carrier
25
Figure
6).
30
OSC
35
Section 8.4.1.1
2 × 210 W class-D power amplifier
Section
14.4). This will ensure that
40
OSC
R
, is determined by an
OSC
and
TDA8954
010aaa596
© NXP B.V. 2009. All rights reserved.
(kΩ)
Section
45
8.4.2;
8 of 46