Answer: The TL431ACDBZR is TI’s 1 % (A-grade, commercial) TL431 in SOT-23 (DBZ), on 3000-piece reels. Vref is 2470 / 2495 / 2520 mV at 25 °C, Imin is 0.6 mA max, the cathode may go to 36 V, and it is rated for 0–70 °C. Pinout matches the plain TL431: 1 = cathode, 2 = REF, 3 = anode. Marking: TAC3, TACG, TACS or TACU. (TI SLVS543S pp.4–5, §6.8 p.9, Addendum p.34.)
Key specifications
| Parameter | Value | Condition | Source |
|---|---|---|---|
| Reference voltage Vref (min / typ / max) | 2470 / 2495 / 2520 mV (±1 %) | VKA = Vref, IKA = 10 mA, TA = 25 °C | §6.8 p.9 |
| Vref deviation over 0–70 °C, VI(dev) | 6 typ / 16 max mV | SOT-23-3 and TL432 devices; max − min over the rated range | §6.8 p.9, note 1 |
| ΔVref / ΔVKA | −1.4 typ / −2.7 max mV/V (ΔVKA = 10 V − Vref); −1 / −2 mV/V (36 V − 10 V) | IKA = 10 mA | §6.8 p.9 |
| Reference input current Iref | 2 typ / 4 max µA | IKA = 10 mA, R1 = 10 kΩ, R2 = ∞ | §6.8 p.9 |
| Iref deviation over temperature, II(dev) | 0.8 typ / 1.2 max µA | IKA = 10 mA, R1 = 10 kΩ, R2 = ∞ | §6.8 p.9 |
| Minimum cathode current for regulation Imin | 0.4 typ / 0.6 max mA | VKA = Vref | §6.8 p.9 |
| Off-state cathode current Ioff | 0.1 typ / 0.5 max µA | VKA = 36 V, Vref = 0 | §6.8 p.9 |
| Dynamic impedance | ZKA | 0.2 typ / 0.5 max Ω | |
| Cathode voltage VKA (recommended) | Vref to 36 V | Absolute maximum 37 V | §6.4 p.5; §6.1 p.5 |
| Cathode current IKA (recommended) | 1 – 100 mA | Absolute maximum −100 to 150 mA | §6.4 p.5; §6.1 p.5 |
| Operating free-air temperature (C grade) | 0 – 70 °C | TL43xxC; junction absolute maximum 150 °C | §6.4 p.5; §6.1 p.5 |
| RθJA / RθJC(top), DBZ (SOT-23-3) | 206 / 76 °C/W | JEDEC metrics, SPRA953 | §6.3 p.5 |
| Orderable / packing | TL431ACDBZR: Active, SOT-23 (DBZ) 3-pin, 3000 / large T&R, MSL 1 260 °C | Device marking TAC3, TACG, TACS, TACU | Package Option Addendum, PDF p.34 |
Pinout (SOT-23-3, DBZ)
| Pin (DBZ, SOT-23-3) | TL431 | TL432 (for comparison) |
|---|---|---|
| 1 | CATHODE | REF |
| 2 | REF | CATHODE |
| 3 | ANODE | ANODE |
Source: Table 5-1 and the DBZ top views, p.4. Anode is the common pin, normally tied to ground.
Other makers sell “TL431” in SOT-23 with either pin order, K/R/A or R/K/A, so check the pinout against the exact ordering code before you copy a footprint. The 1 % part with swapped pins 1 and 2 is the TL432ACDBZR; both use the same §6.8 electrical table.
What changes from the 2 % TL431CDBZR
| Parameter | TL431ACDBZR (§6.8 p.9) | TL431CDBZR (§6.5 p.6) |
|---|---|---|
| Vref min / max at 25 °C | 2470 / 2520 mV | 2440 / 2550 mV |
| Imin max | 0.6 mA | 1 mA |
| Ioff max (36 V) | 0.5 µA | 1 µA |
| II(dev) typ | 0.8 µA | 0.4 µA |
| VI(dev), ΔVref/ΔVKA, Iref, |ZKA| | same | same |
| Marking | TAC_ | T3C_ |
So the A grade buys initial accuracy and a lower current floor. It does not improve drift over temperature or line sensitivity.
Design notes
Setting the voltage. With a divider R1 (cathode to REF) and R2 (REF to anode), VKA = Vref × (1 + R1/R2) + Iref × R1 (Figure 7-2, p.19). The equation holds only while the cathode current is above Imin, so the part has enough loop gain (§9.2.2.2.1 p.26). Use the TL431 calculator to pick E24/E96 pairs and the series resistor.
Worked shunt example (12 V ±10 % in, 5 V out, 0–10 mA load). R1 = R2 = 10 kΩ gives 2.495 V × 2 + 2 µA × 10 kΩ = 5.010 V typical, and the divider draws 0.25 mA. The series resistor must still deliver 0.6 mA (A-grade Imin max) into the cathode at 10.8 V and full load. Using TI’s “>1 mA (Imin(max))” figure (§8.1 p.21): Rs ≤ (10.8 − 5.01) / (10 + 1 + 0.25 mA) = 515 Ω, so choose 510 Ω. At 13.2 V and no load, Rs passes 16.1 mA, of which 15.8 mA flows into the TL431ACDBZR: P = 5.01 V × 15.8 mA ≈ 79 mW, a rise of about 16 °C with RθJA = 206 °C/W. Rs itself dissipates about 0.13 W, so size its power rating for that, not for the 79 mW in the TL431. With the A grade’s 0.6 mA Imin you could size Rs a little higher, but TI’s general design rule is still “>1 mA” (§8.1 p.21), so the example keeps it.
What the grade does not cover. The tolerance printed on the grade is Vref at 25 °C with VKA = Vref. TI lists the other error terms separately (§9.2.2.2.2 p.27): resistor tolerance, VI(dev) over temperature, ΔVref/ΔVKA, and |ZKA| × ΔIKA. At a 5 V output each term is scaled by (1 + R1/R2) = 2:
- VI(dev) of 16 mV max becomes up to 32 mV at the output over 0–70 °C (0.64 %).
- Raising VKA from 2.495 V to 5.01 V (ΔVKA = 2.5 V) moves Vref by −1.4 mV/V typ to −2.7 mV/V max, i.e. −3.5 to −6.8 mV, or −7 to −13.5 mV at the output.
- A 10 mA swing in cathode current through |ZKA| = 0.5 Ω max adds 5 mV at VKA = Vref.
Add the initial tolerance (±25 mV on Vref, ±50 mV at 5 V) and the drift term (up to 32 mV) is now comparable to it. To hold a 5 V rail to 1 % overall you need 0.1 % resistors, a narrow temperature range, or a trim; otherwise the 0.5 % B grade (§6.11 p.12) helps only the initial term.
Capacitors on the cathode. TI states the TL43xx is internally compensated and stable with no capacitor between cathode and anode (§8.3 p.22). If you add one, or if the load itself is capacitive, check the value against the stability boundary charts, Figure 6-16 (p.17) and Figure 6-18 (p.18). Some combinations of capacitance and cathode current fall outside the stable region, so “adding a bigger cap” is not automatically safer.
Beyond the shunt. TI’s system examples use the same part as the reference in a high-current series regulator with a pass transistor (Figure 9-5, p.28), to raise the output of a fixed three-terminal regulator (Figure 9-6, p.28), as a crowbar (Figure 9-8, p.28), a voltage monitor (Figure 9-12, p.30) and a constant-current sink (Figure 9-15, p.30). In each one the cathode current still has to stay above Imin at the lightest load.
Pitfalls specific to TL431ACDBZR
- Expecting 1 % at the rail. 1 % is Vref at 25 °C with VKA = Vref. Over 0–70 °C at 5 V, drift and line terms can add about 45 mV more (see above).
- Assuming TL431A pinout = TL432A pinout. Same electrical table, different pins (p.4). Check the pinout against the ordering code; other makers also ship both orders.
- Ordering the A grade for −40 °C. TL431ACDBZR is the commercial (C) version, 0–70 °C (Addendum p.34). The A-grade industrial and automotive tables are §6.9 and §6.10.
- Huge divider values to save current. Iref up to 4 µA × R1 still applies; at 1 % accuracy a 47 kΩ R1 already uses 0.19 V of error budget at worst case.
- Confusing TAC with T3C. TAC_ is the 1 % TL431A; T3C_ is the 2 % TL431 (Addendum pp.34, 41). See the TL431 SOT-23 marking codes.
Part numbers (information only)
| Ordering code | Status | Packing | Marking | Source |
|---|---|---|---|---|
| TL431ACDBZR | Active | 3000, large T&R | TAC3, TACG, TACS, TACU | Addendum p.34 |
| TL431ACDBZT | Active | 250, small T&R | TAC3, TACG, TACS, TACU | Addendum p.34 |
G4 and ”.A” variants are also listed. The suffix letter after “TAC” varies by assembly site.
FAQ
- What is the TL431ACDBZR marking? TAC3, TACG, TACS or TACU (TI Package Option Addendum p.34).
- Is the TL431ACDBZR pinout the same as the TL431CDBZR? Yes. Both are pin 1 cathode, pin 2 REF, pin 3 anode in SOT-23 (p.4). Only the TL432 versions swap pins 1 and 2.
- What is the TL431ACDBZR reference voltage range? 2470 mV min, 2495 mV typ, 2520 mV max at 25 °C, VKA = Vref, IKA = 10 mA.
- What is the minimum cathode current of the TL431ACDBZR? 0.4 mA typical, 0.6 mA maximum (§6.8 p.9). TI’s general design guidance is still to supply more than 1 mA.
- Is the TL431ACDBZR rated for −40 °C? No. It is the commercial A grade, 0–70 °C. TI covers −40 °C with its I and Q grades.
Related (internal links)
- TL431 calculator
- TL431 SOT-23 marking codes
- TI TL431CDBZR (2 % grade)
- TI TL432ACDBZR (R/K/A pinout)
- TL431 alternatives
Sources (retrieved 2026-10-26)
- Texas Instruments, TL431, TL432 Precision Programmable Reference, SLVS543S (revised May 2024), including the Package Option Addendum: https://www.ti.com/lit/ds/symlink/tl431.pdf
Disclaimer
Values are copied from TI SLVS543S (revised May 2024) and its Package Option Addendum, read on 26 Oct 2026. Ordering data and markings can change; check the current TI addendum before you release a BOM, and validate the circuit on your own hardware.
Reviewed by: Jasper · Updated: 2026-10-26