ISL28270_0708 Datasheet, PDF (17/18 Pages) Intersil Corporation – Dual and Quad Channel Micropower, Single Supply, Rail-to-Rail Input and Output (RRIO) Instrumentation Amplifiers

ISL28270, ISL28273, ISL28470
Power Dissipation
It is possible to exceed the +150°C maximum junction
temperatures under certain load and power-supply
conditions. It is therefore important to calculate the
maximum junction temperature (T_JMAX) for all applications
to determine if power supply voltages, load conditions, or
package type need to be modified to remain in the safe
operating area. These parameters are related in Equation 7:
T_JMAX = T_MAX + (θ_JAxPD_MAXTOTAL)
(EQ. 7)
where:
• P_DMAXTOTAL is the sum of the maximum power
dissipation of each amplifier in the package (PD_MAX)
• PD_MAX for each amplifier can be calculated as shown in
Equation 8:
PD_MAX
=
2*V_S × I_SMAX + (V_S
-
V_OUTMAX
)
×
V_{-----O----U----T----M-----A----X--}
R_{L (EQ.}
8)
where:
• T_MAX = Maximum ambient temperature
• θ_JA = Thermal resistance of the package
• PD_MAX = Maximum power dissipation of 1 amplifier
• V_S = Supply voltage (Magnitude of V₊ and V_-)
• I_MAX = Maximum supply current of 1 amplifier
• V_OUTMAX = Maximum output voltage swing of the
application
• R_L = Load resistance
17
FN6260.4
August 3, 2007