TDF8599TH datasheet(8/52 Pages) NXP

8 / 52 page

TDF8599_1

Product data sheet

Rev. 01 — 13 November 2008

8 of 52

NXP Semiconductors

TDF8599

Class-D power ampliﬁer with load diagnostics

[1]

X = do not care

8.3 Pulse-width modulation frequency

The output signal from the ampliﬁer is a PWM signal with a switching frequency of fosc.

This frequency is set by connecting a resistor (Rosc) between pins OSCSET and AGND.

The optimal clock frequency setting is between 300 kHz and 400 kHz. Connecting a

resistor with a value of 39 k

Ω, for example, sets the clock frequency to 320 kHz. The

external capacitor (Cosc) has no inﬂuence on the oscillator frequency. It does however,

reduce jitter and sensitivity to disturbance. Using a 2nd order LC demodulation ﬁlter in the

application generates an analog audio signal across the loudspeaker.

8.3.1 Master and slave mode selection

In a master and slave conﬁguration, multiple TDF8599 devices are daisy-chained together

in one audio application with a single device providing the clock frequency signal for the

other devices. In this situation, it is recommended that the oscillators of all devices are

synchronized for optimum EMI behavior as follows:

All OSCIO pins are connected together and one TDF8599 in the application is conﬁgured

as the clock-master. All other TDF8599 devices are conﬁgured as clock-slaves (see

Figure 6).

• The clock-master pin OSCIO is conﬁgured as the oscillator output. When a resistor

(Rosc) is connected between pins OSCSET and AGND, the TDF8599 is in Master

mode.

• The clock-slave pins OSCIO are conﬁgured as the oscillator inputs. When pin

OSCSET is directly connected to pin AGND (see Table 6), the TDF8599 is in Slave

mode.

Table 4.

I2C-bus mode operation

Pin EN

Bit IB1[D0]

Bit IB2[D0]

Mode

S2 closed

Operating mode

Mute mode

0X[1]

Standby mode

S2 open

X[1]

off

Table 5.

Non-I2C-bus mode operation

Pin EN

Bit IB2[D0]

Mode

S2 closed

S1 open

Operating mode

S2 closed

Mute mode

S2 open

do not care

off

Table 6.

Mode setting OSCIO

Mode

Settings

Pin OSCSET

Pin OSCIO

Master

Rosc > 26 kΩ

output

Slave

Rosc =0kΩ; shorted to AGND

input

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