Data Sheet

ADPA1107

Rev. 0 | Page 19 of 20

THERMAL MANAGEMENT

Proper thermal management is critical to achieve the specified

performance and rated operating life. Pulsed biasing limits

the average power dissipated and maintains a safe channel

temperature. The channel (or die) temperature correlates

closely with the mean time to failure (MTTF).

Consider a continuous bias condition (see Figure 52). When

rises through a turn on transient interval and eventually settles

calculated by

(1)

where:

TIME

Figure 52. Channel Temperature Rise for Continuous Bias Condition

Next, consider a pulsed bias condition at a low duty cycle (see

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.

POWER DISSIPATED

DURING THE PULSE

TIME

Figure 53. Pulsed Bias Condition at a Low Duty Cycle

Table 7 shows the thermal resistance values for various pulse

conditions.

Table 7. Pulse Settings and Thermal Resistance Values

Pulse Settings

Pulse Width (µs)

Duty Cycle (%)

100

10

1.72

100

20

1.76

500

10

2.10

Narrower pulse widths and/or lower duty cycles can result in

greater reliability.