TECHNICAL INFORMATION
B
pin to be pulled up through a large valued resistor (1MΩ recommended) to VDD. To disable SLEEP
mode, the sleep pin should be grounded.
Fault Pin
The FAULT pin is a 5V logic output that indicates various fault conditions within the device. These
conditions include: low supply voltage, low charge pump voltage, low 5V regulator voltage, over
current at any output, and junction temperature greater than approximately 155°C. The FAULT
output is capable of directly driving an LED through a series 200Ω. The FAULT output is capable of
directly driving an LED through a series 200Ω resistor. If the FAULT pin is connected directly to the
MUTE input an automatic reset will occur in the event of an over-current condition.
Heat Sink Requirements
In some applications it may be necessary to fasten the TA2020-020 to a heat sink. The determining
factor is that the 150°C maximum junction temperature, TJ(max) cannot be exceeded, as specified
by the following equation:
( ) PDISS = TJ(MAX ) − TA
θ JA
where…
PDISS = maximum power dissipation
TJMAX = maximum junction temperature of TA2020-020
TA = operating ambient temperature
θJC = junction-to-case thermal resistance of TA2020-020
Example:
What size heat sink is required to operate the TA2020-020 at 20W per channel continuously in a
70ºC ambient temperature?
PDISS is determined by:
η Efficiency =
=
POUT
PIN
=
POUT
POUT − PDISS
PDISS (per channel) = POUT
η
− POUT
=
20
0.8
−
20
=
5W
Thus, PDISS for two channels = 10W
( ) θJA =
TJ(MAX ) − TA
PDISS
=
150 − 70
10
=
8°C/W
10 of 13
TA2020-020, Rev. 4.0, 09.00