Datasheet

LT6015/LT6016/LT6017
16
601567fd
For more information www.linear.com/LT6015
Distortion
There are two main contributors of distortion in op amps:
output crossover distortion as the output transitions
from sourcing to sinking current and distortion caused
by nonlinear common mode rejection. If the op amp is
operating in an inverting configuration there is no com
-
mon mode induced distortion. If the op amp is operating
in the noninverting configuration within the normal input
common mode range (V
–
to V
+
–1.5V) the CMRR is very
good, typically over 120dB. When the LT6015/LT6016/
LT6017 transitions input stages going from the normal
input stage to the Over-The-Top input stage or vice-versa,
there will be a significant degradation in linearity due to
the change in input circuitry.
Lower load resistance increases distortion due to a net
decrease in loop gain, and greater voltage swings internal
to the amp necessary to drive the load, but has no effect on
the input stage transition distortion. The lowest distortion
can be achieved with the LT6015/LT6016/LT6017 sourcing
in class-A operation in an inverting configuration, with the
input common mode biased mid-way between the supplies.
Power Dissipation Considerations
Because of the ability of the LT6015/LT6016/
LT6017 to
operate
on power supplies up to ±25V and to drive heavy
loads, there is a need to ensure the die junction tempera
-
ture does not exceed 150°C. The LT6015 is housed in a
5-lead TSOT-23 package (θ
JA
= 250°C/W). The LT6016
is housed in an 8-lead MSOP package (θ
JA
= 273°C/W).
The LT6017 is housed in a 22 pin leadless DFN package
(DJC22, θ
JA
= 31.8°C/W).
In general, the die junction temperature (T
J
) can be esti-
mated from the ambient temperature T
A
, and the device
power dissipation P
D
:
T
J
= T
A
+ P
D
• θ
JA
The power dissipation in the IC is a function of supply
voltage and load resistance. For a given supply voltage,
the worst-case power dissipation P
D(MAX)
occurs at the
maximum supply current with the output voltage at half
of either supply voltage (or the maximum swing is less
than one-half the supply voltage). P
D(MAX)
is given by:
P
D(MAX)
= (V
S
• I
S(MAX)
) + (V
S
/2)
2
/R
LOAD
Example: An LT6016 in a MSOP package mounted on a PC
board has a thermal resistance of 273°C/W. Operating on
±25V supplies with both
amplifiers simultaneously driving
2.5kΩ
loads, the worst-case IC power dissipation for the
given load occurs when driving 12.5V
PEAK
and is given by:
P
D(MAX)
= 2 • 50 • 0.6mA + 2 • (12.5)
2
/2500 = 0.185W
With a thermal resistance of 273°C/W, the die temperature
will experience approximately a 50°C rise above ambient.
This implies the maximum ambient temperate the LT6016
should ever operate under the assumed conditions:
T
A
= 150°C – 50°C = 100°C
To operate to higher ambient temperatures, use two chan-
nels of
the
LT6017 quad which has lower thermal resistance
θ
JA
= 31.8°C/W, and an exposed pad which may be soldered
down to a copper plane (connected to V
–
) to further lower
the thermal resistance below θ
JA
= 31.8°C/W.
applicaTions inForMaTion