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TDF8590TH/N1TJ

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P21P22-P24P25-P27P28-P30
TDF8590TH_2 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 02 — 23 April 2007 16 of 30
NXP Semiconductors
TDF8590TH
2 × 80 W SE (4 Ω) or 1 × 160 W BTL (8 Ω) class-D amplifier
Peak output current, internally limited to 8 A:
SE: A
BTL: A
Variables:
R
L
= load resistance
R
s(L)
= series resistance of the filter coil
R
DSon(hs)
= high side drain source on-state resistance (temperature dependent)
R
DSon(ls)
= low side drain source on-state resistance (temperature dependent)
f
osc
= oscillator frequency
t
w(min)
= minimum pulse width (typical 150 ns, temperature dependent)
V
P
= supply voltage [or 0.5 (V
DD
+ V
SS
)]
P
o(0.5%)
= output power at the onset of clipping
I
OM
should be below 8 A (see Section 7). I
OM
is the sum of the current through the load
and the ripple current. The value of the ripple current is dependent on the coil inductance
and voltage drop over the coil.
12.3 External clock
If two or more class-D amplifiers are used it is recommended that all devices run at the
same switching frequency. This can be realized by connecting all OSC pins together and
feed them from an external oscillator.
The internal oscillator requires an external R
ext(OSC)
and C
ext(OSC)
between pins OSC and
V
SSA
. For application of an external oscillator it is necessary to force OSC to a DC level
above SGND. The internal oscillator is disabled and the PWM modulator will switch with
the external frequency. The duty cycle of the external clock should be between 47.5 %
and 52.5 %.
The noise contribution of the internal oscillator is supply voltage dependent. In low noise
applications running at high supply voltage an external low noise oscillator is
recommended.
12.4 Noise
Noise should be measured using a high-order low-pass filter with a cut-off frequency of
20 kHz. The standard audio band pass filters used in audio analyzers do not suppress the
residue of the carrier frequency sufficiently to ensure a reliable measurement of the
audible noise. Noise measurements should preferably be carried out using AES 17 (Brick
Wall) filters or the Audio Precision AUX 0025 filter, which was designed especially for
measuring switching (class-D) amplifiers.
I
OM
V
P
1t
w min()
– f
osc
×()×
R
L
R
DSon hs()
R
sL()
++
------------------------------------------------------------
=
I
OM
2V
P
1t
w min()
– f
osc
×()–
R
L
R
DSon hs()
R
DSon ls()
+()2R
sL()
++
-------------------------------------------------------------------------------------------
=
TDF8590TH_2 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 02 — 23 April 2007 17 of 30
NXP Semiconductors
TDF8590TH
2 × 80 W SE (4 Ω) or 1 × 160 W BTL (8 Ω) class-D amplifier
12.5 Heat sink requirements
In some applications it may be necessary to connect an external heat sink to the
TDF8590TH. The thermal foldback activates on T
j
= 140 °C. The expression below shows
the relationship between the maximum power dissipation before activation of the thermal
foldback and the total thermal resistance from junction to ambient:
Ω
The power dissipation is determined by the efficiency η of the TDF8590TH. The efficiency
measured as a function of output power is given in Figure 23. The power dissipation can
be derived as function of output power (see Figure 24).
Example of a heatsink calculation for the 8 Ω BTL application with ±27 V supply:
• An audio signal with a crest factor of 10 (the ratio between peak power and average
power is 10 dB), this means that the average output power is 1/10th of the peak power
• The peak RMS output power level is 130 W (0.5 % THD level)
• The average power is 0.1 × 130 W = 13 W
• The dissipated power at an output power of 13 W is approximately 5 W
• The total R
th(j-a)
= (140 − 85) / 5 = 11 K/W, if the maximum expected T
amb
= 85 °C
• The total thermal resistance R
th(j-a)
= R
th(j-c)
+ R
th(c-h)
+ R
th(h-a)
• R
th(j-c)
= 1.1 K/W, R
th(c-h)
= 0.5 K/W to 1 K/W (dependent on mounting), so R
th(h-a)
would then be: 11 − (1.1 + 1) = 8.9 K/W
12.6 Pumping effects
When the TDF8590TH is used in a SE configuration, a so-called pumping effect can
occur. During one switching interval, energy is taken from one supply (e.g. V
DDA1
), while a
part of that energy is delivered back to the other supply line (e.g. V
SSA1
) and visa versa.
When the voltage supply source cannot sink energy, the voltage across the output
capacitors of that voltage supply source will increase: the supply voltage is pumped to
higher levels. The voltage increase caused by the pumping effect depends on:
• Speaker impedance
• Supply voltage
• Audio signal frequency
• Value of decoupling capacitors on supply lines
• Source and sink currents of other channels
R
th j a–()
T
j
T
amb
–
P
------------------------
=
TDF8590TH_2 © NXP B.V. 2007. All rights reserved.
Product data sheet Rev. 02 — 23 April 2007 18 of 30
NXP Semiconductors
TDF8590TH
2 × 80 W SE (4 Ω) or 1 × 160 W BTL (8 Ω) class-D amplifier
The pumping effect should not cause a malfunction of either the audio amplifier and/or the
voltage supply source. For instance, this malfunction can be caused by triggering of the
UVP, OVP or UBP of the amplifier. Best remedy for pumping effects is to use the
TDF8590TH in a mono full-bridge application. In case of dual half-bridge application adapt
the power supply (e.g. increase supply decoupling capacitors).
12.7 Application schematics
For SE application (see Figure 10):
• A solid ground plane around the TDF8590TH is necessary to prevent emission
• 100 nF SMD capacitors must be placed as close as possible to the power supply pins
of the TDF8590TH
• The heatsink of the HSOP24 package of the TDF8590TH is connected to pin V
SSD
• The external heatsink must be connected to the ground plane
• Use a thermal conductive, electrically isolating Sil-Pad between the backside of the
TDF8590TH and the external heatsink
For BTL application (see Figure 11):
• A solid ground plane around the TDF8590TH is necessary to prevent emission
• 100 nF SMD capacitors must be placed as close as possible to the power supply pins
of the TDF8590TH
• The heatsink of the HSOP24 package of the TDF8590TH is connected to pin V
SSD
• The external heatsink must be connected to the ground plane
• Use a thermal conductive, electrically isolating Sil-Pad between the backside of the
TDF8590TH and the external heatsink
• The differential inputs enable the best system level audio performance with
unbalanced signal sources. In case of hum due to floating inputs connect the
shielding or source ground to the amplifier ground. The jumper J1 is open on set level
and is closed on the stand-alone demo board
• Minimum total required capacity per power supply line is 3300 µF
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TDF8590TH/N1TJ

Mfr. #:
Buy TDF8590TH/N1TJ
Manufacturer:
NXP Semiconductors
Description:
Audio Amplifiers 2 X 80 W SE (4 ) or 1 X 160 W BTL (8 ) class-D amplifier
Lifecycle:
New from this manufacturer.
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