LTC4020 buck/boost charger conversion to Boost only ?

[JuhaH]

Hi,

I'm on my way of choosing the charger for 48V Li-Ion pack. First, do you know any alternative to LTC4020 to charge the 48V pack with 2Amps? So far I think LTC4020 is the most suitable, BUT... it is a buck boost charger and at the end I only need Boost section of the charger. So is there app notes of how to modify the circuit to drop off the Buck part ? I do not wish to populate the board with these unused components for buck or is the circuit designed such way that you carry always them both ?
Thanks :thumbsup:
Juhah

 

[KlausST]

Hi,

A pure buck topology has a minimum output voltage of V_in minus some voltage drop.
So if the input voltage is - let's say - 24V, then the output voltage is always above 23V.

This usually is no problem as long as the battery is healthy ... and connected the correct direction.
Therefore a pure buck needs an additional switch ... just for safety reasons.
With this additional switch it is not much effort to build a buck boost topology, maybe this is why they built it.

Klaus

 

[smijesh]

LTC3862 is boost converter it will fulfill your requirements...

 

[JuhaH]

LTC3862 is boost converter it will fulfill your requirements...
View attachment 139869

Thanks for the output but LTC3862 is just a boost switcher regulator. Perhaps you could convert it to CV/CC charger with an external controller but I'm now looking for a stand alone unit. There isn't too many available as far as I have found, all of them end at 36V lacking my requirements of 48Volts. The picture you posted isn't from Linear.com ?

 

[JuhaH]

LTC3862 is boost converter it will fulfill your requirements...
View attachment 139869

Thanks for the reply, LTC3862 isn't a charger but a boost converter without CV/CC. Perhaps you could build one with additional controller but I'm more looking for stand alone unit here for 12S Li-Ion.