TL431_10 Datasheet, PDF (6/12 Pages) Texas Instruments – PRECISION PROGRAMMABLE REFERENCE

PROGRAMMABLE PRECISION SHUNT REGULATOR TL431/A/C
The deviation parameters ΔV_REF/ΔT and ΔI_REF/ΔT are defined as the differences between the maximum and
minimum values obtained over the recommended temperature range. The average full-range temperature
coefficient of the reference voltage, αV_REF, is defined as :
(
V_I(dev)
) × 10⁶
αV_REF (ppm/℃) =
V_REF at 25℃
ΔT_A
Where :
ΔT_A is the recommended operating free-air temperature range of the device.
αV_REF can be positive or negative, depending on whether minimum V_REF or maximum V_REF, respectively, occurs at
the lower temperature.
Example : Maximum V_REF=2496mV at 30℃, maximum V_REF=2492mV at 0℃, V_REF=2495mV at 25℃,
ΔT_A=70℃ for TL431C.
( ^4mV )×10⁶
αV_REF =
2495mV
70℃
≈23ppm/℃
Because minimum V_REF occurs at the lower temperature, the coefficient is positive.
Calculating Dynamic Impedance
The dynamic impedance is defined as :
Z _KA
= ^ΔVKA
ΔI_KA
When the device is operating with two external resistors, the total dynamic impedance of the circuit is given by:
Z^'
ΔV
= _ΔI
≈
Z _KA
(1 + R1/R2 )
Dec. 2010 – Rev.1.5
-6-
HTC