MSK801_15 Datasheet, PDF (3/6 Pages) M.S. Kennedy Corporation – 10 MHz full power bandwidth min.

APPLICATION NOTES
Heat Sinking
To determine if a heat sink is necessary for your applica-
tion and if so, what type, refer to the thermal model and
governing equation below.
Thermal Model:
Stability and Layout Considerations
As with all wideband devices, proper decoupling of the
power lines is extremely important. The power supplies
should be bypassed as near to pins 10 and 12 as possible
with a parallel grouping of a 0.01µf ceramic disc and a 4.7µf
tantalum capacitor. Wideband devices are also sensitive
to printed circuit board layout. Be sure to keep all runs as
short as possible, especially those associated with the sum-
ming junction, power lines and compensation pins.
Governing Equation:
TJ=PD x (RθJC + RθCS + RθJC) + TA
Where
TJ=Junction Temperature
PD=Total Power Dissipation
RθJC=Junction to Case Thermal Resistance
RθCS=Case to Heat Sink Thermal Resistance
RθSA=Heat Sink to Ambient Thermal Resistance
TC=Case Temperature
TA=Ambient Temperature
TS=Sink Temperature
Example:
This example demonstrates a worst case analysis for
the op-amp output stage. This occurs when the output volt-
age is 1/2 the power supply voltage. Under this condition,
maximum power transfer occurs and the output is under
maximum stress.
Conditions:
VCC=±16VDC
VO=±8Vp Sine Wave, Freq.=1KHz
RL=100Ω
For a worst case analysis we will treat the +8Vp sine
wave as an 8VDC output voltage.
1.) Find Driver Power Dissapation
PD=(VCC-VO) (VO/RL)
=(16V-8V) (8V/100Ω)
=0.64W
2.) For conservative design, set TJ=+125°C
3.) For this example, worst case TA=+50°C
4.) RθJC=65°C/W from MSK 801 Data Sheet
5.) RθCS=0.15°C/W for most thermal greases
6.) Rearrange governing equation to solve for RθSA
RθSA=((TJ-TA)/PD) - (RθJC) - (RθCS)
=((125°C -50°C)/0.64W) - 65°C/W - 0.15°C/W
=117.2 - 65.15
=52.0°C/W
Recommended External Component Selection
Guide Using External Rf
APPROXIMATE
DESIRED GAIN
RI(+)
RI(-)
Rf
1
-1
500Ω 1KΩ 1KΩ
+1
1
-5
1KΩ
820Ω
0Ω
1KΩ
0Ω
4.99KΩ
+5
1 -10
0Ω
910Ω
910Ω
1KΩ
3.6KΩ
10KΩ
+10
0Ω
1KΩ 9.1KΩ
R1
C1
43Ω
43Ω
120Ω
120Ω
150Ω
150Ω
0.01µf
0.01µf
0.01µf
0.01µf
0.01µf
0.01µf
1 The positive input resistor is selected to minimize offset
currents. The positve input can be grounded without a
resistor if desired.
2 This feedback capacitor will help compensate for stray
input capacitance. The value of this capacitor can be
dependent on individual applications. A 2 to 9 pf capacitor
is usually optimum for most applications.
Load Considerations
When determining the load an amplifier will see, the
capacative portion must be taken into consideration. For
an amplifier that slews at 1000V/µS, each pf will require 1
mA of output current. To minimize ringing with highly
capacitive loads, reduce the load time constant by adding
shunt resistance.
Case Connection
The MSK 801 has pin 8 internally connected to the
case. The case is not electrically connected to the internal
circuit. Pin 8 should be tied to a ground plane for shielding.
For special applications, consult factory.
3
Rev. D 9/06