[time-nuts] LT3042, etc. Re: HP E1938A schematics.

[jimlux]

On 7/8/19 4:53 PM, Richard (Rick) Karlquist wrote:
> 
> 
> On 7/8/2019 11:09 AM, jimlux wrote:
> 
>>
>> Not only are they low noise, but they have spectacularly good HF 
>> rejection across the regulator up to 10s of MHz.
>>
> 
> In the 5071A, I wanted high bandwidth PSRR and stumbled across
> a designer's manual (HP internal document) for the MMS Modular
> Measurement System.  They described a regulator with a common base
> pass transistor and an op amp, with a bandwidth approaching 1 MHz.
> Quite state of the art for the time.  I copied the design in several
> 5071A modules.  We used it to regulate +5V from the Vicor modules down 
> to +4.5V working voltage for 100 series ECL or analog.  It worked quite
> well.  Now I could replace it with an LT3065.
> 
> Rick N6RK

Barely<grin> - I've got bit in the past by coming too close to the LDO 
minimum voltage.  300mV for those parts, so as long as your +5 had 
decent regulation, and the ripple didn't drop below 4.8V, and you didn't 
draw more than 300 mA.