TFA9843J Просмотр технического описания (PDF) - NXP Semiconductors.

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TFA9843J

2-channel audio amplifier (SE: 1 W to 20 W or BTL: 4 W to 40 W)

NXP Semiconductors. 

Philips Semiconductors

TFA9843J

2-channel audio amplifier (2 x SE or 1 x BTL)

Standby — In this mode the current consumption is very low and the outputs are

floating. The device is in standby mode when VMODE < 0.8 V, or when pin MODE is

grounded.

Mute — In this mode the amplifier is DC-biased but not operational (no audio output).

This allows the input coupling capacitors to be charged to avoid pop-noise. The

device is in mute mode when 4.5 V < VMODE < (VCC − 3.5 V).

On — In this mode the amplifier is operating normally. The operating mode is

activated at VMODE > (VCC − 2.0 V).

standby

all mute

1/2 on

0.8

4.5

Fig 3. Mode selection.

VCC−3.5 VCC−2.0 VCC

VMODE (V)

MCE502

8.4 Supply voltage ripple rejection

The supply voltage ripple rejection (SVRR) is measured with an electrolytic capacitor

of 150 µF on pin SVR using a bandwidth of 20 Hz to 22 kHz. Figure 17 illustrates the

SVRR as function of the frequency. A larger capacitor value on pin SVR improves the

ripple rejection behavior at the lower frequencies.

8.5 Built-in protection circuits

The TFA9843J contains two types of temperature sensors; one measures local

temperatures of the power stages and one measures the global chip temperature. At

a local temperature of the power stage of approximately 185 oC or a global

temperature of approximately 150 oC this detection circuit switches off the power

stages for 2 ms. High impedance of the outputs is the result. After this time period the

power stages switch on automatically and the detection will take place again; still a

too high temperature switches off the power stages immediately. This protects the

TFA9843J against shorts to ground, to the supply voltage, across the load and too

high chip temperatures.

The protection will only be activated when necessary, so even during a short-circuit

condition, a certain amount of (pulsed) current will still be flowing through the short,

just as much as the power stage can handle without exceeding the critical

temperature level.

9397 750 12587

Preliminary data

Rev. 02 — 19 January 2004

© Koninklijke Philips Electronics N.V. 2004. All rights reserved.

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