REF3220AMDBVREP Datasheet, PDF (10/25 Pages) Texas Instruments – 4 ppm100 A SOT23-6 SERIES VOLTAGE REFERENCES

REF3212-EP, REF3220-EP, REF3225-EP
REF3230-EP, REF3233-EP, REF3240-EP
SBVS078B – OCTOBER 2006 – REVISED AUGUST 2011
THEORY OF OPERATION
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The REF32xx is a family of CMOS, precision bandgap voltage references. Figure 3 shows the basic bandgap
topology. Transistors Q₁ and Q₂ are biased so that the current density of Q₁ is greater than that of Q₂. The
difference of the two base-emitter voltages (Vbe₁ – Vbe₂) has a positive temperature coefficient and is forced
across resistor R₁. This voltage is amplified and added to the base-emitter voltage of Q₂, which has a negative
temperature coefficient. The resulting output voltage is virtually independent of temperature.
+
Vbe₁
Q₁ I ^-
R1
+
Vbe₂
- _{N Q2}
V_BANDGAP
Figure 3. Simplified Schematic of Bandgap Reference
10
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