TDA8929T Datasheet, PDF (16/36 Pages) NXP Semiconductors – Controller class-D audio amplifier

Philips Semiconductors
Controller class-D audio amplifier
Preliminary specification
TDA8929T
14 SWITCHING CHARACTERISTICS
V_P = ±25 V; T_amb = 25 °C; measured in Fig.10; unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX. UNIT
Switching frequency
f_osc
oscillator frequency
R_OSC = 30.0 kΩ
309
R_OSC = 27 kΩ;
−
see Fig.12
f_osc(r)
V_OSC
V_OSC(trip)
f_track
V_OSC(ext)
oscillator frequency range
note 1
210
maximum voltage at pin OSC frequency tracking −
trip level at pin OSC for tracking frequency tracking −
frequency range for tracking
frequency tracking 200
voltage at pin OSC for tracking note 2
−
317
329
kHz
360
−
kHz
−
600
kHz
−
SGND + 12 V
SGND + 2.5 −
V
−
600
kHz
5
−
V
Notes
1. Frequency set with R_OSC, according to the formula in the functional description.
2. For tracking the external oscillator has to switch around SGND + 2.5 V with a minimum voltage of V_OSC(ext).
14.1 Minimum pulse width
The minimum obtainable pulse width of the PWM output signal of a class-D system, sets the maximum output voltage
swing after the demodulation filter and also the maximum output power. Delays in the power stages are the main cause
for the minimum pulse width being not equal to zero. The TDA8926 and TDA8927 power stages have a minimum pulse
width of t_W(min) = 220 ns (typical). Using the TDA8929T controller, the effective minimum pulse is reduced by a factor of
two during clipping. For the calculation of the maximum output power at clipping the effective minimum pulse width during
clipping is 0.5t_W(min).
For the practical useable minimum and maximum duty factor (δ) which determines the maximum output power:
-t-^W-----⁽--^m---ⁱ-ⁿ--2-⁾---^×-----f--^o--^s--^c- × 100% < δ < _1 – ^t--W-----⁽-^m----ⁱ-ⁿ--2⁾---^×-----f--^o---^s--^c-_ × 100%
Using the typical values of the TDA8926 and TDA8927 power stages:
3.5% < δ < 96.5%.
2001 Dec 11
16