TLV431ACDBZR

Part: TLV431ACDBZR — Texas Instruments (TLV431A, DBZ SOT-23-3 package)

Type: Adjustable Precision Shunt Regulator (Voltage Reference)

Description: 1.24 V low-voltage adjustable shunt regulator with 1% initial tolerance (TLV431A), output adjustable from VREF to 6 V, 80 μA typical operating cathode current and 0.25 Ω typical dynamic impedance.

Operating Conditions:

• Cathode voltage VKA: VREF (1.24 V) to 6 V
• Cathode current IK: 0.1 to 15 mA
• Operating temperature: 0 to 70 °C for the C grade (grade-dependent: I grade -40 to 85 °C, Q grade -40 to 125 °C)

Absolute Maximum Ratings:

• Cathode voltage VKA: 7 V
• Continuous cathode current IK: -20 to 20 mA
• Reference current Iref: -0.05 to 3 mA
• Operating virtual junction temperature: 150 °C
• Storage temperature: -65 to 150 °C

Key Specs:

• VREF (TLV431A, TA = 25 °C, VKA = VREF, IK = 10 mA): 1.228 / 1.24 / 1.252 V (min/typ/max)
• VREF over full temperature range (TLV431A): 1.221–1.259 V (C), 1.215–1.265 V (I), 1.209–1.271 V (Q)
• VREF deviation over temperature (typ/max): 4/12 mV (C), 6/20 mV (I), 11/31 mV (Q)
• Ratio of VREF change to VKA change (VKA = VREF to 6 V, IK = 10 mA): -1.5 typ, -2.7 max mV/V
• Reference terminal current Iref (IK = 10 mA, R1 = 10 kΩ, R2 open): 0.15 μA typ, 0.5 μA max
• Minimum cathode current for regulation IK(min): 55 μA typ, 80 μA max (C/I); 100 μA max (Q)
• Off-state cathode current (VREF = 0, VKA = 6 V): 0.001 μA typ, 0.1 μA max
• Dynamic impedance |zKA| (f ≤ 1 kHz, IK = 0.1 to 15 mA): 0.25 Ω typ, 0.4 Ω max
• Thermal resistance RθJA (DBZ): 206 °C/W

Features:

• Low-voltage operation, VREF = 1.24 V
• Adjustable output voltage from VREF to 6 V
• Reference tolerance at 25 °C: 0.5% (TLV431B), 1% (TLV431A), 1.5% (TLV431)
• Typical temperature drift: 4 mV (0 to 70 °C), 6 mV (-40 to 85 °C), 11 mV (-40 to 125 °C)
• Low operating cathode current, 80 μA typical
• Sharp turn-on characteristic, suitable as a low-voltage Zener replacement
• ESD: HBM ±2000 V, CDM ±1000 V

Applications:

• Adjustable voltage and current referencing
• Secondary-side regulation in flyback SMPSs
• Zener replacement
• Voltage monitoring
• Comparator with integrated reference

Package:

• DBZ (SOT-23, 3 pins), 2.92 mm × 2.37 mm
• Other TLV431A packages: DBV (SOT-23, 5), PK (SOT-89, 3), LP (TO-92, 3), D (SOIC, 8)

• Low-voltage operation, VREF = 1.24V
• Adjustable output voltage, V O = VREF to 6V
• Reference voltage tolerances at 25°C
• -0.5% for TLV431B
• -1% for TLV431A
• -1.5% for TLV431
• Typical temperature drift
• -4mV (0°C to 70°C)
• -6mV (-40°C to 85°C)
• -11mV (-40°C to 125°C)
• Low operational cathode current, 80μA typical
• 0.25Ω typical output impedance
• Ultra-small SC-70 package offers 40% smaller footprint than SOT-23-3
• See TLVH431 and TLVH432 for:
• -Wider VKA (1.24V to 18 V) and IK (80mA)
• -Additional SOT-89 package
• -Multiple pinouts for SOT-23-3 and SOT-89 packages
• On products compliant to MIL-PRF-38535, all parameters are tested unless otherwise noted. on all other products, production processing does not necessarily include testing of all parameters.

• Adjustable voltage and current referencing
• Secondary side regulation in flyback SMPSs
• Zener replacement
• Voltage monitoring
• Comparator with integrated reference

Simplified Schematic

TLV431, TLV431A, TLV431B

SLVS139Z - JULY 1996 - REVISED JUNE 2024

Figure 4-3. DBZ (SOT-23-3) Package (Top View)

Figure 4-5. DCK (SC-70) Package (Top View)

NC - No internal connection

• Pin 2 is attached to Substrate and must be connected to ANODE or left open.
• • Must be connected to ANODE or left open

Figure 4-2. DBV (SOT-23-5) Package (Top View)

Figure 4-6. LP (TO-92/TO-226) Package (Top View)

Table 4-1. Pin Functions

at 25°C free-air temperature (unless otherwise noted)

$$\left|\alpha V_{REF}\right|\left(\frac{\text{ppm}}{^{\circ}\text{C}}\right)=\frac{\left(\frac{V_{REF(dev)}}{V_{REF}\left(T_A=25^{\circ}\text{C}\right)}\right)\times 10^{6}}{\Delta T_A}$$

where ΔTA is the rated operating free-air temperature range of the device. αV REF can be positive or negative, depending on whether minimum VREF or maximum VREF, respectively, occurs at the lower temperature.

over operating free-air temperature range (unless otherwise noted) (1)

over operating free-air temperature range (unless otherwise noted)

Figure 8-1 shows the TLV431, TLV431A, or TLV431B used in a 3.3V isolated flyback supply. Output voltage VO can be as low as reference voltage VREF (1.24V ± 1%). The output of the regulator, plus the forward voltage drop of the optocoupler LED (1.24 + 1.4 = 2.64V), determine the minimum voltage that can be regulated in an isolated supply configuration. Regulated voltage as low as 2.7 Vdc is possible in the topology shown in Figure 8-1.

The 431 family of devices are prevalent in these applications, being designers go to choice for secondary side regulation. Due to this prevalence, this section will further go on to explain operation and design in both states of TLV431 that this application will see, open loop (Comparator + Vref) and closed loop (Shunt Regulator).

Further information about system stability and using a TLV431 device for compensation can be found in the application note Compensation Design With TL431 for UCC28600 (SLUA671).

Figure 8-1. Flyback with Isolation Using TLV431, TLV431A, or TLV431B as Voltage Reference and Error Amplifier

• (1) For all available packages, see the orderable addendum at the end of the data sheet.

(2) The package size (length × width) is a nominal value and includes pins, where applicable