I am looking into replacing the main voltage regulator (LT1086) on the DIY WB-O2 kit with a Linear Technology LT1764. There are a few differences. Using the LT1764 would allow for less input voltage from the battery (approx. 1 volts less than the LT1086). This would make the min. input voltage 12.7 - 1.0 = 11.7 volts.

The main differences are:

LT1086 LT1764
curr. limit 1.5 A 3.0 A
v_ref 1.25 V 1.21 V
v_drop_out 1.5 V 0.7 V

Can the NTK WB-O2 handle the 3.0 A current upon start-up?
I also need to check what resistors may need to be replace for the v_ref change from 1.25 volts to 1.21 volts.

It seems to me that the LT1764 would be a good replacement for the existing LT1086.

J

 

The LT1963 seems like a better choice.
Only need to check the 1.21V reference. LT1086 has a 1.25V reference.

 

The max current is the max that it can supply, it won't force 3A through the circuit.

 

Correct.

WB cold = approx. 3 ohms
WB voltage = approx. 10.5

current cold (not limited) = 3 amps

LT1086 current limits it to approx. 1.5 A

 

I looked at at the DIY WBO2 circuit and figured out the answers.

1) The regulator output resistor does the current regulation so either of the regulators I was asking about would work

2) The v_ref change would make the warm-up time longer. This could be resolved by adding more parallel resistance with the output resistor.

*** Neither device would work because the ADJ pin is clamped to +/- 7 volts *** It would take a circuit redesign in order to use the different regulators. Oh well, it was a thought.

J