TDA8931T View Datasheet(PDF) - Philips Electronics

Part Name

Description

Manufacturer

TDA8931T

Power comparator 1×20 W

Philips Electronics 

Philips Semiconductors

TDA8931

Power comparator 1 × 20 W

14.2 Output current limiting

The output current is limited by the OCP with a threshold level of 3.3 A (minimum). During

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

output signal is distorted. The peak output current should stay below 3.3 A and can be

estimated using the following equation:

IO ≤ 2-----×-----(--R----D----S---o--n----+-----R---V-L---P-+-----R----c--o---i-l---+-----R----E---S---R---) ≤ 3.3

(4)

Where:

IO = output current in the load in

VP = supply voltage (VDDP − VSSP)

RDSon = on-resistance power switch

RL = load impedance

Rcoil = series resistance output coil

RESR = ESR of the single-ended capacitor

Example: With a 4 Ω load the OCP will be triggered below a supply voltage of 28 V. This

will result in an absolute maximum output power of Po = 26 W at THD = 10 %.

14.3 Low pass filter considerations

For a flat frequency response (second order Butterworth filter) it is necessary to change

the LC-filter components (L1 and C14) according to the speaker impedance. Table 12

shows the required components values in case of a 4 W, 6 W or 8 W speaker impedance.

Table 12: Filter components values

Speaker impedance

(Ω)

L1 value

(µH)

4

22

6

33

8

47

C14 value

(nF)

680

470

330

14.4 Thermal behavior (printed-circuit board considerations)

The SO20 package of the TDA8931T has special thermal corner leads, significantly

increasing the power capability (reducing Rth). The corner leads (pins 1, 10, 11 and 20)

should be attached to a copper area (VSS) on the PCB for cooling.

The typical thermal resistance Rth(j-a) of the TDA8931T is 24 K/W (free air and natural

convection) when soldered on a double sided FR4 PCB with 35 µm copper layer and

cooling area of approximately of 28 cm2.

9397 750 13847

Preliminary data sheet

Rev. 01 — 14 January 2004

© Koninklijke Philips Electronics N.V. 2005. All rights reserved.

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