AMC2244/AMC2344/AMC2444
APPLICATION INFORMATION
Product Description
The AMC2244/AMC2344/AMC2444 are low-power wideband monolithic operational amplifiers implemented with a
classical voltage-feedback topology. This allows them to be used in a variety of applications where current-feedback
amplifiers are not appropriate. For example, a capacitor to be placed in the feedback path, making it an excellent
choice for applications such as active filters, sample-and-holds, or integrators. Similarly, because of the ability to use
diodes in the feedback network, the AMC2244/AMC2344/AMC2444 are an excellent choice for applications such as
fast log amplifiers.
Power Dissipation
In order to prevent the junction temperature to exceed 150°C , it is important to calculate the maximum junction
temperature (TJmax) for all applications to determine if power-supply voltages, load conditions, or package type need
to be modified such that the AMC2244/AMC2344/AMC2444 remain in the safe operating area. These parameters are
related as follows:
TJmax = Tmax + (θJA× PDmaxtotal)
Where PDmaxtotal is the sum of the maximum power dissipation of each amplifier in the package (PDmax).
PDmax for each amplifier can be calculated as follows :
PDmax= ( 2 × VS × ISmax + (VS - Voutmax) × ( Voutmax /RL))
where:
Tmax =Maximum Ambient Temperature
θJA = Thermal Resistance of the Package
PDmax = Maximum Power Dissipation of 1 Amplifier
VS = Supply Voltage
I
Smax = Maximum Supply Current of 1 Amplifier
outmax = Maximum Output Voltage Swing of the Application
V
RL = Load Resistance
To serve as a guide for the user, we can calculate maximum allowable supply voltages for the example of the video
cable-driver below since we know that TJmax = 150°C, Tmax = 75°C, ISmax = 8.2 mA, and the package θJAs are shown in
Table 1. If we assume (for this example ) that we are driving a back-terminated video cable, then the maximum
average value (over duty-cycle) of Voutmax is 1.4V, and RL = 150Ω, giving the results seen in Table 1.
Table 1
Device
Package
8P DIP
PDmax @ Tmax
0.789W @ 75°C
0.600W @ 75°C
1.071W @ 75°C
0.682W @ 75°C
Max VS
±16.6V
±12.1V
±11.5V
±7.5V
θJA
AMC2244M
AMC2244DM
95°C /W
125°C /W
70°C /W
110°C /W
8P SOIC
AMC2344N/AMC2444N 14P DIP
AMC2344D/AMC2444D 14P SOIC
Copyright © 2006 2006 ADDtek Corp.
7
DD006_E -- JUNE 2006
ADDTEK [ ADDTEK CORP ]
