TDA8920C Datasheet, PDF (18/40 Pages) NXP Semiconductors – 2 X110 W class-D power amplifier

NXP Semiconductors
TDA8920C
2 × 110 W class-D power amplifier
13.3.2 Bridge-Tied Load (BTL)
Maximum output power:
P_o(0.5%) = ----^R--------^L---------^{+----------R--------D------S------o}------ⁿ------⁽--^R--^h----^s--^L----⁾------⁺----------^R--------^D-------^S-----o------ⁿ------⁽----^l---^s-----₂⁾---^×_R----_L-²---^V-----^P----^×-----⁽--¹-----^–----^t--^m----ⁱ--ⁿ----^×-----⁰---^.-⁵----^f---^o--^s---^c--⁾-----²-
(3)
Maximum output current internally limited to 9.2 A:
I_{o( peak)} = -_R----_L----₊----²-₍--_R-^V---_D-^P---_S--^×-_o--_n-⁽--₍-¹-_h---_s^–--₎---^t₊--^m---_R-ⁱ-ⁿ--_D--^×--_S---_o⁰---_n^.--⁵₍--_l--^f_s--₎-^o-₎-^s---^c₊--⁾---₂---_R----_s--_L-
(4)
Where:
• R_L: load impedance
• R_sL: series impedance of the filter coil
• R_DSon(hs): high-side R_DSon of power stage output DMOS (temperature dependent)
• R_DSon(ls): low-side R_DSson of power stage output DMOS (temperature dependent)
• f_osc: oscillator frequency
• t_min: minimum pulse width (typical 150 ns, temperature dependent)
• V_P: single-sided supply voltage or 0.5 × (V_DD + |V_SS|)
• P_{o(0.5 %)}: output power at the onset of clipping
Remark: Note that I_o(peak) should be below 9.2 A; see Section 8.3.2. I_o(peak) is the sum of
the current through the load and the ripple current. The value of the ripple current is
dependent on the coil inductance and voltage drop over the coil.
13.4 External clock
To ensure duty cycle independent operation of the device, the external clock input
frequency is internally divided by two. This implies that the external clock frequency is
twice the internal clock frequency (typically 2 × 345 kHz = 690 kHz).
If several class-D amplifiers are used together it is recommended that all devices run at
the same switching frequency. This can be achieved by connecting all OSC pins together
and feeding them from an external oscillator. When applying an external oscillator it is
necessary to force pin OSC to a DC level above SGND. This disables the internal
oscillator and causes the PWM to switch at half the external clock frequency.
The internal oscillator requires an external resistor R_OSC and capacitor C_OSC connected
between pin OSC and pin VSSA.
The noise contribution of the internal oscillator is supply voltage dependent. An external
low-noise oscillator is recommended for low-noise applications running at high supply
voltages.
TDA8920C_1
Preliminary data sheet
Rev. 01 — 29 September 2008
© NXP B.V. 2008. All rights reserved.
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