TLV431BIDBZR

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1. Describe

The TLV431BIDBZR device is a low voltage 3-terminal Adjustable reference voltage with specified heat More stable than applicable industrial and commercial temperature range. The output voltage can be set arbitrarily Value between VREF (1.24 V) and 6 V, two External resistance. These devices from one Voltage (1.24 V) is lower than the widely used TL431 And TL1431 shunt regulator reference.When used with optocoupler, TLV431 device Ideal voltage reference in isolated feedback 3V to 3.3V switching power supply circuit Supplies. These devices have a typical output The impedance is 0.25 Ω. Active output circuit provides A very sharp opening feature that makes them Great alternative to low voltage Zener diodes In many applications, including in-vehicle regulation And adjustable power supply.

2. Feature

    1. Low voltage operation, VREF = 1.24 V

    2. Adjustable output voltage, VO = VREF to 6 V

    3. Reference voltage tolerance at 25°C

        – 0.5% for TLV431B

        – 1% for TLV431A

        – 1.5% for TLV431

    4. Typical temperature drift

        – 4 mV (0°C to 70°C)

        – 6 mV (–40°C to 85°C)

        – 11 mV (–40°C to 125°C)

    5. Low operating cathode current, typically 80 µA

    6. 0.25Ω typical output impedance

    7. Ultra-small SC-70 package size reduced by 40% Floor area ratio SOT-23-3

    8. Please refer to TLVH431 and TLVH432 for:

        – Wider VKA (1.24 V to 18 V) and IK (80 mA)

        – Additional SOT-89 package

        – Multiple pin assignments for SOT-23-3 and SOT-89 combination

    9. On products that comply with MIL-PRF-38535, Unless otherwise stated, all parameters are tested famous. On all other products, the production Processing does not necessarily include testing All parameters.

3. Application

    1. Adjustable voltage and current reference

    2. Secondary side regulation in flyback SMPS

    3. Zener replacement

    4. Voltage monitoring

    5. Comparator with integrated reference

4. Pin configuration

5. Pin function

6. Function Description

TLV431BIDBZR is composed of internal reference and amplifier. The amplifier outputs a current sink reference pin and a virtual internal pin based on the difference between the two. The absorption current is generated by the internal Darlington pair. When running with sufficient voltage margin (≥ 1.24 V) and cathode current (Ika), TLV431 will force the reference pin voltage to 1.24 V. However, the reference pin cannot be left floating because it requires Iref ≥ 0.5 µA. This is because the reference pin is driven to npn, which requires base current to work properly. When feedback is applied from the cathode and the reference pin, the TLV431 acts as a Zener diode, and the regulation depends on the constant voltage of the current supplied to the cathode. This is due to the internal amplifier and reference entering the correct working area. The amount of current required for the above feedback is the same This situation must be applied to the device in an open loop, servo, or error amplification implementation so that it can be in the proper linear region and provide sufficient gain for the TLV431. Unlike many linear regulators, TLV431 performs internal compensation without output capacitors to maintain stability Between the cathode and the anode.

7. Application information

TLV431, TLV431A or TLV431BIDBZR for 3.3V isolated flyback power supply. The output voltage VO can be as low as the reference voltage VREF (1.24 V ± 1%). The output of the regulator plus the forward voltage drop of the optocoupler LED (1.24 + 1.4 = 2.64 V) determines the minimum voltage that can be adjusted in an isolated power supply configuration. In the topology shown, a regulated voltage as low as 2.7 Vdc is possible. The 431 series devices are common in these applications and are the designer's first choice for secondary-side voltage regulation. Due to this universality, this section will further explain the operation and design of the TLV431 in two states that this application will see, namely, open loop (comparator + Vref) and closed loop (shunt regulator).