CLC1001ISO8X View Datasheet(PDF) - Exar Corporation
Part Name
Description
MFG CO.
'CLC1001ISO8X' PDF : 17 Pages View PDF
Data Sheet
eo2 = en2
2
1+ Rf
Rg
+
in2Rs2
1+ Rf
Rg
op amp noise terms en, in and ii
2
+ ii2Rf2
The effective load resistor (Rloadeff) will need to include
the effect of the feedback network. For instance,
op amp noiseRtleoramdesffeinn, fiinguarned3ii would be calculated as:
RL || (Rf + Rg)
2
2
These measurements are basic and are relatively easy to
+ eR2s
1 + Rf
Rg
+
eR2g
Rf
Rg
+ eR2f
external resistor noisepteerrfmorsmfowr iRths,stRagndaanrddRlafb equipment. For design purposes
however, prior knowledge of actual signal levels and load
external resistor noise terms for RS, Rg and Rf
impedance is needed to determine the dissipated power.
Here, PD can be found from
High source impedances are sometimes unavoidable, but
they increase noise from the source impedance and also
PD = PQuiescent + PDynamic - PLoad
make the circuit more sensitive to the op amp current
noise. Analyze all noise sources in the circuit, not just the
op amp itself, to achieve low noise in your application.
Quiescent power can be derived from the specified IS
values along with known supply voltage, VSupply. Load
power can be calculated as above with the desired signal
Power Dissipation
amplitudes using:
Power dissipation should not be a factor when operating
(VLOAD)RMS = VPEAK / √2
under the stated 500Ω load condition. However,
( ILOAD)RMS = ( VLOAD)RMS / Rloadeff
applications with low impedance, DC coupled loads
should be analyzed to ensure that maximum allowed
junction temperature is not exceeded. Guidelines listed
below can be used to verify that the particular application
The dynamic power is focused primarily within the output
stage driving the load. This value can be calculated as:
will not cause the device to operate beyond it’s intended
operating range.
Maximum power levels are set by the absolute maximum
junction rating of 150°C. To calculate the junction
PDYNAMIC = (VS+ - VLOAD)RMS × ( ILOAD)RMS
Assuming the load is referenced in the middle of the
power rails or Vsupply/2.
temperature, the package thermal resistance value
ThetaJA (ӨJA) is used along with the total die power
dissipation.
Figure 4 shows the maximum safe power dissipation in the
package vs. the ambient temperature for the packages
TJunction = TAmbient + (ӨJA × PD)
available.
Where TAmbient is the temperature of the working environment.
2.5
In order to determine PD, the power dissipated in the load
needs to be subtracted from the total power delivered by
the supplies.
PD = Psupply - Pload
Supply power is calculated by the standard power
equation.
Psupply = Vsupply × IRMS supply
2
SOIC-8
1.5
SOT23-6
1
0.5
Vsupply = VS+ - VS-
Power delivered to a purely resistive load is:
0
-40 -20
0
20
40
60
80
Ambient Temperature (°C)
100 120
Pload = ((VLOAD)RMS2)/Rloadeff
©2007-2013 Exar Corporation
Figure 4. Maximum Power Derating
14/17
Rev 1G
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