MCP654 MICROCHIP [Microchip Technology], MCP654 Datasheet - Page 26

• Manufacturer Part Number: MCP654
• Description: 50 MHz, 6 mA Op Amps with mCal
• Manufacturer: MICROCHIP [Microchip Technology]

MCP651/2/4/5/9
4.3.0.3
Since the output short circuit current (I
at ±100 mA (typical), these op amps are capable of
both delivering and dissipating significant power. Two
common loads, and their impact on the op amp’s power
dissipation, will be discussed.
Figure 4-7
voltage (V
ground (0V) and I
currents are assumed to be negligible.
FIGURE 4-7:
Power Calculations.
The DC currents are:
EQUATION 4-1:
The DC op amp power is:
EQUATION 4-2:
The maximum op amp power, for resistive loads at DC,
occurs when V
halfway between V
EQUATION 4-3:
DS22146B-page 26
Where:
max P
P
(
V
OA
MCP65X
OUT
OA
I
OUT
Q
=
)
shows a resistive load (R
=
I
= Quiescent supply current for one
= A DC value (V)
Power Dissipation
DD
). V
OUT
I
I
I
I
DD
op amp (mA/amplifier)
OUT
DD
SS
(
V
L
OUT
≈
DD
SS
(
is R
V
V
is halfway between V
≈
V
DD
I –
SS
DD
=
I
and V
–
Q
Diagram for Resistive Load
is the output current. The input
Q
L
V
I
’s ground point, V
I
V
------------------------- -
+
DD
–
SS
+
OUT
+
OUT
max 0 I
V
min 0 I
max
----------------------------------------------------------------- -
SS
R
L
:
I
L
)
)
–
OUT
(
(
+
2
V
,
,
(
I
L
SS
V
OUT
OUT
DD
(
L
V
V
) with a DC output
L
SS
4R
–
)
)
SC
R
V
–
L
L
DD
L
) is specified
SS
V
,
OUT
V
V
and V
L
is usually
OUT
–
)
V
SS
L
)
or
Figure 4-7
driven by a sine wave with DC offset. The capacitive
load causes the op amp to output higher currents at
higher frequencies. Because the output rectifies I
the op amp’s dissipated power increases (even though
the capacitor does not dissipate power).
FIGURE 4-8:
Power Calculations.
The output voltage is assumed to be:
EQUATION 4-4:
The op amp’s currents are:
EQUATION 4-5:
The op amp’s instantaneous power, average power
and peak power are:
EQUATION 4-6:
The power dissipated in a package depends on the
powers dissipated by each op amp in that package:
Where:
Where:
P
ave P
max P
OA
I
I
I
MCP65X
V
V
OUT
DD
SS
(
DC
AC
(
I
ω = Radian frequency (2π f) (rad/s)
Q
≈
=
OA
≈
shows a capacitive load (C
OA
I –
=
I
I
= DC offset (V)
= Peak output swing (V
= Quiescent supply current for one
V
DD
)
Q
Q
)
OUT
C
=
+
+
op amp (mA/amplifier)
=
(
L
V
max 0 I
min 0 I
(
⋅
DD
(
V
V
V
dV
---------------- -
V
=
DD
DD
SS
DD
(
(
dt
–
Diagram for Capacitive Load
V
OUT
,
,
V
–
© 2011 Microchip Technology Inc.
I
I
DC
DD
–
SS
OUT
V
OUT
OUT
V
SS
+
=
SS
) I
I
V
)
)
)
) I
⎛
⎝
OUT
V
+
(
AC
AC
Q
Q
I
SS
sin
+
ω
+
(
C
4V
----------------------- -
V
(
2V
ω
L
PK
SS
AC
cos
t
AC
C
)
π
)
–
L
fC
L
V
(
fC
), which is
ω
OUT
V
L
t
L
⎞
⎠
)
OUT
)
)
OUT
,