BBNG board questions

Being a noob in electronics and engineering etc., I've been having difficulties understanding the specificiations of the BBNG board for years:
http://theledguy.chainreactionweb.com/product_info.php?cPath=48_49_61&products_id=730

My questions are:

a. What does it mean by "safe mode?"

b. For NG750/1000 what does it mean by "critical starting voltage?" I understand that BBNG is for primary/NiMH cells only, so in the case of 2xAA config, which of these cells do achieve an initial VIn of ~3.4V?

c. Why can't the BBNG be used with Li-Ions?

d. Under what circumstances does the BBNG achieve better efficiency than the (invincible) GD when used with primaries/NiMHs?

e. Provided that the LE has adequete heatsinking, can an NG1000 drive an SSC P4 effectively in a 2xAA config without overheating (ie. achieving "angry blue" on emitter die)?

f. If NG is the improved BB, then why do the BB and BBNG boards still co-exist?

yazkaz said:

Being a noob in electronics and engineering etc., I've been having difficulties understanding the specificiations of the BBNG board for years:
http://theledguy.chainreactionweb.com/product_info.php?cPath=48_49_61&products_id=730

My questions are:

a. What does it mean by "safe mode?"

b. For NG750/1000 what does it mean by "critical starting voltage?" I understand that BBNG is for primary/NiMH cells only, so in the case of 2xAA config, which of these cells do achieve an initial VIn of ~3.4V?

c. Why can't the BBNG be used with Li-Ions?

d. Under what circumstances does the BBNG achieve better efficiency than the (invincible) GD when used with primaries/NiMHs?

e. Provided that the LE has adequete heatsinking, can an NG1000 drive an SSC P4 effectively in a 2xAA config without overheating (ie. achieving "angry blue" on emitter die)?

f. If NG is the improved BB, then why do the BB and BBNG boards still co-exist?

Click to expand...

I'll take a whack at some of your questions.

a. Google the TI TPS61030 regulator IC and read about the soft start feature.

b. See posts 10 and 12 in this thread.

c. The BBNG can run with 1xLi-ion according to Wayne. See posts 13 and 14 in this thread for example. I've also successfully tested a BBNG 1000/SSC P4 on 1xLi-ion for function (same tower as mentioned in (e) below).

e. I've built an AW/Arcmania Turbo Tower using a BBNG 1000 and an SSC P4 U2SW0H-bin LED. I hooked it up to 2xAA Eneloops to test for function and the tower worked. Can't say what the output was though since this was merely a function test of the bare tower (not in a TurboHead). Plus, my test leads were very skinny wires, which can add appreciable resistance to the system. Since 2xNiMH may already be close to just making it to full regulation (especially on re-start), any additional resistance in the system adds to the voltage drop and makes it even harder to reach full regulation. The same tower runs well using 2xAlkaline C cells. See this post.

"Angry blue" is a function of overheating the LED, not the driver board.

The answer to f is:

The BBNG can only boost and drive one LED since the input/output voltage rating is only 5V. The original Badboy can boost up to ~23V allowing it to drive a string of LEDs and run from a higher input voltage like 12V.

For most single die LEDs the Vf is in the 3V-4V range and for boost to work correctly the battery voltage must them be less than Vf to be in boost mode limiting your battery selection to those that are less or near equal to the Vf of the LED you want to drive.

A really good example is the set the sense resistor on the BB for 20mA and you can then drive 5-7 standard 5mm in series with two AA batteries. That is not possible with the BBNG.

Wayne