Other Parts Discussed in Thread: TL431
I'm doing a theoretical voltage accuracy analysis on TLV431 Low-Voltage Adjustable Precision Shunt Regulator with Vka > Vref and I found some specifications in the datasheet, which don't make sense to me. Basically I try to find a minimum reference current for the TLV431 to work fine.
My circuit looks similar to fig. 23 given in the datasheet:
The datasheet can be found at: www.ti.com/.../slvs139x.pdf
On page 4 under 6.1 (Absolute Maximum Ratings) it says that the reference current (Iref) has to be between -0.05mA and 3mA.
The following page (5) indicates ,under specified test conditions, at 6.5 (Electrical Characteristics for TLV431)
which is fine.
Then, on page 17 in section 8.3 (Feature Description) it is written, that the reference pin needs at least 0.5µA to work proper.
Now to my question: Does this mean, that the minimum working current is 0.5µA as stated in 8.3 and the values for the test conditions do not apply to my circuit (Vka > Vref)? Or can the device work with reference currents below 0.5 µA in my circuit as well?
Furthermore I'm getting confused with the negative minimum current as shown in 6.1. If there would be a negative current, my reference voltage would get falsified since the current generates an voltage over R2. Anyway a negative current out of an npn base doesn't make sense to me under this circumstances and would cause the device to not work as desired.
Any help on this would be appreciated.
PS: Throughout my investigations I noticed the same thing for the TL431 device, which works in a similar way with different reference voltage.