ADPA1106 datasheet(17/19 Pages) AD

17 / 19 page

Data Sheet

ADPA1106

APPLICATIONS INFORMATION

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Rev. 0 | 17 of 19

Figure 53. Recommended Detector Subtraction Circuit

THERMAL MANAGEMENT

Proper thermal management is critical to achieve the specified

performance and rated operating life. Pulsed biasing is required

to limit the average power dissipated and maintain a safe channel

temperature. The channel (or die) temperature correlates closely

with the mean time to failure.

Consider a continuous bias case (see Figure 54). When bias is ap-

plied, the channel temperature (TCHAN) of the device rises through

a turn on transient interval and eventually settles to a steady state

value. Calculate the θJC thermal resistance of the device as the rise

in TCHAN above the starting TBASE divided by the total device PDISS

with the following equation:

θJC = tRISE/PDISS

where:

tRISE is the peak rise in the TCHAN of the device above the TBASE

(°C).

PDISS is the power dissipation (W) of the device.

Figure 54. Continuous Bias

Next, consider a pulsed bias case at a fixed pulse width and duty

cycle (see Figure 55). When bias is applied, the TCHAN of the

device can be described as a series of exponentially rising and

decaying pulses. The peak channel temperature reached during

consecutive pulses increases during the turn on transient interval,

and eventually settles to a steady state condition where peak

channel temperatures from pulse to pulse stabilize.

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