TA0104A Tripath Technology Inc., TA0104A Datasheet - Page 16

• Manufacturer Part Number: TA0104A
• Manufacturer: Tripath Technology Inc.

Efficiency Of A TA0104A Amplifier
The efficiency, K, of an amplifier is:
The power dissipation of a TA0104A amplifier is primarily determined by the on resistance, R
the output transistors used, and the switching losses of these transistors, P
amplifier, P
For an 400W RMS per channel, 8: load amplifier using STW38NB20 MOSFETs, and an R
50m:,
In the above calculation the R
to account for some temperature rise of the MOSFETs. (R
as for a typical MOSFET as temperature increases from 25ºC to 170ºC.)
So,
This compares to the 90% measured efficiency (see Typical Performance graphs).
Technical Documentation
Please
(http://www.tripath.com/html/tech.htm#appnotes) for more information regarding evaluation, test and
design of Class-T amplifiers.
16
K = P
P
where:
P
P
R
P
K = P
IN
DRIVER
SW
IN
COIL
refer
IN
= P
= P
= 1.6 + 2 x (0.015) x (95) + 400 x ((0.025 + 0.11 + 0.05 + 8)/8)
= 423W
= 1 . 6 + 2 . 8 5 + 4 1 9
= 2 x (0.015) x Q
(per channel) is approximated by:
OUT
OUT
= Resistance of the output filter inductor (typically around 50m:)
DRIVER
DRIVER
= Power dissipated in the TA0104A = 1.6W/channel
/P
/P
to
IN
IN
= 400/423 = 94%
+ P
+ P
the
SW
SW
+ P
+ P
g
DS (ON)
Tripath
(Q
OUT
OUT
g
is the gate charge of M, in nano-coulombs)
((R
((R
of 0.065: was multiplied by a factor of 1.7 to obtain R
S
S
+ R
+ R
“Application
ON
ON
+ R
+ R
COIL
COIL
+ R
+ R
Notes”
L
L
)/R
)/R
DS (ON)
T r i p a t h T e c h n o l o g y , I n c . - T e c h n i c a l I n f o r m a t i o n
L
L
)
)
2
2
typically increases by a factor of 1.7
section
2
on
TA104A – Rev. 3.1/06.00
SW
our
. For a TA0104A
web
ON
in order
ON
page
S
, of
of