TDF8599A NXP Semiconductors, TDF8599A Datasheet - Page 15

• Manufacturer Part Number: TDF8599A
• Description: The TDF8599A is a dual Bridge-Tied Load (BTL) car audio amplifier comprising anNDMOST-NDMOST output stage based on SOI BCDMOS technology
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDF8599A_2
Product data sheet
8.5.1 Thermal foldback
8.5.2 Overtemperature protection
8.5.3 Overcurrent protection
8.5.4 Window protection
Table 9.
Thermal Foldback Protection (TFP) is tripped when the average junction temperature
exceeds the threshold level (145 C). TFP decreases amplifier gain such that the
combination of power dissipation and R
threshold level. The device will not completely switch off but remains operational at the
lower output power levels. If the average junction temperature continues to increase, a
second built-in temperature protection threshold level shuts down the amplifier completely.
If the average junction temperature (T
tripped and the power stage shuts down immediately.
OverCurrent Protection (OCP) is tripped when the output current exceeds the maximum
output current of 8 A. OCP regulates the output voltage such that the maximum output
current is limited to 8 A. The amplifier outputs keep switching and the amplifier is NOT
shutdown completely. This is called current limiting.
OCP also detects when the loudspeaker terminals are short circuited or one of the
amplifier’s demodulated outputs is short circuited to one of the supply lines. In either case,
the shorted channel(s) are switched off.
The amplifier can distinguish between loudspeaker impedance drops and a low-ohmic
short across the load or one of the supply lines. This impedance threshold depends on the
supply voltage used. When a short is made across the load causing the impedance to
drop below the threshold level, the shorted channel(s) are switched off. They try to restart
every 50 ms. If the short circuit condition is still present after 50 ms, the cycle repeats. The
average power dissipation will be low because of this reduced duty cycle.
When a channel is switched off due to a short circuit on one of the supply lines, Window
Protection (WP) is activated. WP ensures the amplifier does not start-up after 50 ms until
the supply line short circuit is removed.
Window Protection (WP) checks the PWM output voltage before switching from Standby
mode to Mute mode (with both outputs switching) and is activated as follows:
Protection type
Thermal foldback
Overtemperature
Overcurrent
Window
DC Offset
Undervoltage
Overvoltage
Overview of protection types
Rev. 02 — 30 June 2009
I
2
C-bus controlled dual channel class-D power amplifier
j
) > 160 C, OverTemperature Protection (OTP) is
th(j-a)
create a junction temperature around the
Reference
Section 8.5.1
Section 8.5.2
Section 8.5.3
Section 8.5.4
Section 8.5.5
Section 8.5.6
Section 8.5.6
TDF8599A
© NXP B.V. 2009. All rights reserved.
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