Other Parts Discussed in Thread: LM5069, LM76005, TPS1663, TPS1653
Hello,
As referenced in this related post, we need precise inrush / continuous power limiting of an LM76005-based buck converter with a large amount of bulk output capacitance. At startup, we need to limit power to ~13W, and afterward this power limit will be increased in defined steps up to ~70W max using an MCU-controlled resistor ladder. For this purpose, the FAE in the other thread recommended the LM5069, and it appears that the TPS2490 is equally suitable for this purpose. We're on a tight timeline, and since the LM76005 does not appear to be effectively able to limit current using its soft-start function, we'd appreciate urgent design assistance from TI.
The biggest challenge in this design is that we require 6mF of output capacitance on the LM76005. It sounds like the topology that the other FAE was proposing was placing a hot-swap controller in front of the buck converter, with some amount of bulk input capacitance (we calculate ~14uF minimum). It would be helpful if you could provide a PSPICE simulation validating this approach. We were also planning to use a TPS259470x eFuse downstream of the buck to control inrush to a downstream module supplied by the buck.
Here are the overall parameters:
| V_in | 42-59V |
| V_out | 21V |
| V_out(p-p) | 100mV |
| I_out(max) | 3.4A |
| P_lim(inrush) | 13W |
| P_lim(max) | 70W |
| C_out | 6mF |
| C_in (upstream of HS controller) | 160uF |
