Volatge Drop of Paralleled AMC7135 chips?

[kosPap]

hi all!
I am kinda in a bind on this....w
e all have multiple 7135 chip drivers
each chip has/wants 0.15 of voltage drop under load
the drivers have the chips in parallel.
what will be the collective voltage drop?
are they added (I doupt) or is ti calculated in another way?
Assuming the chips act as smart resistors shouldn't they be calculated as parralleled resistors?

 

[CKOD]

The the drop out voltage (i.e. the voltage across the chip while out of regulation) would be the same no matter how many are in parallel.

 

[li_gangyi]

It should be the same, but the dropout does change with current passing through, so the more you have in parallel, the less of a drop out for the same given load. However it's not free lunch though, the quiescent current stacks up with each additional regulator (the amount of current the regulator sucks even when sitting pretty).

 

[kosPap]

hmmm guys I caanot follow you.

let's put it simplier.....

I am desining a battery/LED output combination....

in order to remain in regulation I need to ahve covered the LED Vf + the Chip voltage needs = battery working voltage under the designed current.
example 3.3 + 0.15*? = 3.5 (XML & Panasonic NCR @ 2.8A)

 

[CKOD]

It should be the same, but the dropout does change with current passing through, so the more you have in parallel, the less of a drop out for the same given load. However it's not free lunch though, the quiescent current stacks up with each additional regulator (the amount of current the regulator sucks even when sitting pretty).

Good point, but that affects them more after they are out of regulation. When they are just transitioning from in to out of regulation, each one should should be passing 350mA, and its voltage drop should be the same (barring manufacturing variance, temperature differences etc) So it should be pretty fixed at ~.15v

 

[li_gangyi]

hmmm guys I caanot follow you.

in order to remain in regulation I need to ahve covered the LED Vf + the Chip voltage needs = battery working voltage under the designed current.
example 3.3 + 0.15*? = 3.5 (XML & Panasonic NCR @ 2.8A)

It'll just stay at Vf+0.15 = xV. The dropout for parallel regulators stays the same.

 

[kosPap]

these clear things up...thank you.