TDF8599 NXP Semiconductors, TDF8599 Datasheet - Page 9

• Manufacturer Part Number: TDF8599
• Description: I2C-bus controlled dual channel 43 W/2 W single channel 85 W/1 W class-D power amplifier
• Manufacturer: NXP Semiconductors

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NXP Semiconductors
TDF8599_1
Product data sheet
8.3.2 Spread spectrum mode (Master mode)
The value of the resistor R
In Master mode, Spread spectrum mode and frequency hopping can be enabled. In Slave
mode, phase staggering and phase lock operation can be selected. An external clock can
be used as the master-clock on pin OSCIO of the slave devices. When using an external
clock it must remain active during the shutdown sequence to ensure that all devices are
switched off and able to enter the off state as described in
Spread spectrum mode is a technique of modulating the oscillator frequency with a slow
varying signal to broaden the switching spectrum, thereby reducing the spectral density of
the EMI. Connecting a capacitor (C
Figure
The capacitor on pin SSM (C
mode is active. The current (I
gives a triangular voltage on pin SSM that sweeps around the voltage set by pin OSCSET
f
Fig 5.
Fig 6.
5 %. The voltage on pin SSM is used to modulate the oscillator frequency.
osc
=
7). When pin SSM is connected to pin AGND, Spread spectrum mode is disabled.
12.45 10
--------------------------- - Hz
Oscillator frequency as function of R
Master and slave configuration
R
osc
9
TDF8599
Master
OSCSET
Rev. 01 — 13 November 2008
R
(k )
OSCIO
osc
50
40
30
20
10
0
300
osc
SSM
SSM
sets the carrier frequency based on the following formula:
R osc
f
) sets the spreading frequency when Spread spectrum
) flowing in and out of pin SSM is typically 5 A. This
osc
350
SSM
C osc
) to pin SSM enables Spread spectrum mode (see
R
Class-D power amplifier with load diagnostics
400
TDF8599
Slave 1
osc
OSCSET
OSCIO
450
f
osc
001aai771
(kHz)
Section
TDF8599
Slave 2
500
OSCSET
OSCIO
001aai772
8.2.
TDF8599
© NXP B.V. 2008. All rights reserved.
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