TDF8599 데이터 시트보기 (PDF) - NXP Semiconductors.
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TDF8599 Datasheet PDF : 52 Pages
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NXP Semiconductors
TDF8599
Class-D power amplifier with load diagnostics
The value of the resistor Rosc sets the carrier frequency based on the following formula:
f osc = 1----2---.-4-R--5--o---×s--c--1---0----9[Hz]
(1)
50
Rosc
(kΩ)
40
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30
20
10
0
300
350
400
Fig 5. Oscillator frequency as function of Rosc
450
500
fosc (kHz)
OSCSET
TDF8599
OSCIO
Master
OSCSET
Rosc
Cosc TDF8599
fosc
R
OSCIO
Slave 1
Fig 6. Master and slave configuration
OSCSET
TDF8599
OSCIO
Slave 2
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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 Section 8.2.
8.3.2 Spread spectrum mode (Master mode)
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 (CSSM) to pin SSM enables Spread spectrum mode (see
Figure 7). When pin SSM is connected to pin AGND, Spread spectrum mode is disabled.
TDF8599_1
Product data sheet
The capacitor on pin SSM (CSSM) sets the spreading frequency when Spread spectrum
mode is active. The current (ISSM) flowing in and out of pin SSM is typically 5 µA. This
gives a triangular voltage on pin SSM that sweeps around the voltage set by pin OSCSET
± 5 %. The voltage on pin SSM is used to modulate the oscillator frequency.
Rev. 01 — 13 November 2008
© NXP B.V. 2008. All rights reserved.
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