I'm replacing a precision voltage reference circuit in an old school differential voltmeter, I've chosen a very precise voltage reference device, but I need to increase the available output current.
The Fluke 893A that I'm restoring uses a precision 11 and 1.1 VDC voltage reference at its heart. From there it can measure DC or AC from 1mV to 1100V. Pretty cool, but the voltage reference circuit is hard to repair. So, I'm building a replacement reference with modern devices.
Analog's LT1236A will give me very, very precise (for my needs) reference and they are stackable in shunt configuration, so I can put a 5.000 VDC device on top of a 10.000 VDC to yeild 15.000 VDC... and send that through a precision (0.05% each resistor) voltage divider network... and pull out the 11.00 VDC and 1.100 VDC that I need. (see the attached 2xLT1236A PNG)
However, the LT1236 wasn't designed to drive the rest of a unit like the 893A as it only handles 10 mA. So, I need, I believe, a current boosting design like those in the common linear voltage regulator device data sheets to provide whatever current the rest of the diff voltmeter needs above 10 mA. Right?
I should be able to handle at least 1 A, right, if I add a series pass transistor to my above 2x LT1236 design, just like the LM317 or MC78xx regulators do, right? (see the two attached GIFs for the LM317 and MC78xx)
If so, which of the two attached designs is better? The LM317 example with a single power transistor as a switch and three paralleled LM195s seems like a waste. The example with a single MJ2955 seems like a more-modern, fewer-component design. Is one significantly better than the other? Will either work for my current boosting with LT1236 shunts needs?
If so, how do I calculate the sense resistor (between the power source and the LT1236) and the base resistor for the series pass transistor? I'm planning to use a readily-available higher-current transistor like the MJE15032 or MJE15033 with a Vbe of 1.0 VDC.
LT1236 datasheet
https://www.analog.com/media/en/technical-documentation/data-sheets/lt1236.pdf