TCU Operating Voltage & Total Instantaneous Power delivered to Heaters

TCU can be operated in 28-75 V. But operating voltage & heaters ohm affects heaters instantaneous power. The limiting factor here is the maximum current capability per individual pin which is 3A continues and 5A peak for < 5 seconds, and the key point is the difference between the per-line limit and the total TCU intake limit.

For an individual heater line, with a 12 Ω heater:

• Heater voltage: 28V, Current: 3 A, Instantaneous Power: 65.3 W
• Heater voltage: 36V, Current: 3 A, Instantaneous Power: 108 W

So for example in 36V operating voltage, 108 W instantaneous power on one 12 Ω heater line is correct at 36 V, because that corresponds exactly to 3 A. However, the system must also respect the total input capability of the TCU, not only the single channel limit.
The relevant limits are main power input: 15 A continuous total, 25 A peak for less than 5 seconds

This gives the following total intake power figures:

• Input voltage: 28V, Total Continuous Input Power: 420 W, Total Peak Input Power (<5 s): 700 W
• Input voltage: 36V, Total Continuous Input Power: 540 W, Total Peak Input Power (<5 s): 900 W

So from a single-channel point of view, 108W on one 12 Ω heater is feasible.
From a system point of view, that power must still be shared with the other active heater lines so that the total TCU input current remains within the continuous and peak limits.