ISL28236_14 Datasheet, PDF (12/15 Pages) Intersil Corporation – 5MHz, Dual Precision Rail-to-Rail Input-Output (RRIO) Op Amps

ISL28236
Using Only One Channel
If the application only requires one channel, the user must
configure the unused channel to prevent it from oscillating. The
unused channel will oscillate if the input and output pins are
floating. This will result in higher than expected supply currents
and possible noise injection into the channel being used. The
proper way to prevent this oscillation is to short the output to the
negative input and ground the positive input (as shown in
Figure 37).
-
+
FIGURE 37. PREVENTING OSCILLATIONS IN UNUSED CHANNELS
Power Dissipation
It is possible to exceed the +125°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 1:
T_JMAX = T_MAX + _JAxPD_MAXTOTAL
(EQ. 1)
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 using Equation 2:
PD_MAX
=
V_S  I_SMAX + V_S
-
V_OUTMAX


V_{-----O----U----T----M-----A----X--}
R_L
(EQ. 2)
where:
• T_MAX = Maximum ambient temperature
• _JA = Thermal resistance of the package
• PD_MAX = Maximum power dissipation of 1 amplifier
• V_S = Total supply voltage
• I_SMAX = Maximum supply current of 1 amplifier
• V_OUTMAX = Maximum output voltage swing of the application
• R_L = Load resistance
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FN6921.2
July 24, 2014