TDA8933B 查看數據表（PDF） - NXP Semiconductors.

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TDA8933B

Class-D audio amplifer

NXP Semiconductors. 

NXP Semiconductors

TDA8933B

Class D audio amplifier

14.2 Output current limitation

The peak output current IO(max) is internally limited to a minimum value of 2 A. During

normal operation the output current should not exceed this threshold level, otherwise the

signal will be distorted. The peak output current in SE or BTL configurations can be

calculated using Equation 5 and Equation 6.

SE configuration:

IO(max) ≤ -R----L----+-----R---D---0-S--.-o5--n---×-+---V--R---P-s---+-----R----E---S---R- ≤ 2 A

(5)

BTL configuration:

IO(max) ≤ -R----L----+----2-----×-----(-V-R----PD----S--o---n----+-----R----s--) ≤ 2 A

(6)

Where:

• VP = supply voltage VDDP1 − VSSP1 (V) or VDDP2 − VSSP2 (V)

• RL = load resistance (Ω)

• RDSon = drain-source on-state resistance (Ω)

• Rs = series resistance output inductor (Ω)

• RESR = Equivalent Series Resistance SE capacitance (Ω)

Example:

An 8 Ω speaker in the BTL configuration can be used up to a supply voltage of 18 V

without running into current limiting. Current limiting (clipping) will avoid audio holes but

produces a similar distortion to voltage clipping.

14.3 Speaker configuration and impedance

For a flat frequency response (second-order Butterworth filter with an output frequency of

40 kHz) it is necessary to change the low-pass filter components LLC and CLC according

to the speaker configuration and impedance. Table 14 shows the values required in

practice.

Table 14. Filter component values

Configuration

SE

RL (Ω)

4

6

8

BTL

8

16

LLC (µH)

22

33

47

22

47

CLC (nF)

680

470

330

680

330

TDA8933B_1

Preliminary data sheet

Rev. 01 — 23 October 2008

© NXP B.V. 2008. All rights reserved.

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