Texas Instruments TLVH431QDCKT

Overview

TLVH431QDCKT from Texas Instruments is a low-voltage adjustable precision shunt regulator in SC-70 package, featuring 1.24 V reference voltage (±1.5% at 25°C), 100 μA to 70 mA cathode current range, and operation from –40°C to +125°C. It replaces Zener diodes in secondary-side regulation of isolated flyback SMPSs and serves as an integrated-reference comparator for power-rail monitoring.

For engineers reviewing the TLVH431QDCKT datasheet, TLVH431QDCKT pinout, TLVH431QDCKT application, or TLVH431QDCKT equivalent, key selection criteria include reference tolerance grade (Q-grade = ±1.5% at 25°C, ±31 mV over full temperature), ultra-low minimum cathode current (100 μA), dynamic impedance (0.25 Ω), and SC-70 footprint compatibility with space-constrained industrial and automotive power designs.

Technical Context

The TLVH431QDCKT implements a three-terminal shunt-regulator architecture with internal 1.24 V bandgap reference and high-gain NPN-based error amplifier. Its Darlington output stage enables sharp turn-on and stable regulation down to 1.24 V, supporting closed-loop voltage feedback via external resistor dividers or open-loop comparator operation with integrated reference.

Unlike the TL431, it operates at lower headroom (≥1.24 V cathode-to-anode) and lower minimum cathode current (100 μA vs. 1 mA), making it suitable for 3.3 V and lower isolated supplies. It is internally compensated and does not require an output capacitor for stability, though capacitive load effects on phase margin are characterized per Figure 5-15–5-17.

Key Specifications

Pinout & Package

TLVH431QDCKT is packaged in SC-70 (DCK), a 6-pin surface-mount package measuring 2.00 mm × 1.25 mm with 0.65 mm pitch. Pin 2 is substrate-connected and must be tied to ANODE or left floating; pins 4 and 5 are no-connect (NC).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar shunt-regulator applications.

Compared with TLVH431QDCKT, TLVH431CDCKT trades extended temperature capability for lower cost in benign environments, while TLVH431AQDBVR improves reference accuracy by 33% but increases board area and requires pinout adaptation - neither is pin-compatible, and both demand validation of thermal derating and layout impact.

Availability

TLVH431QDCKT is available at Aetrix Electronics and suitable for automotive power management, industrial isolated converters, and battery-backed voltage monitoring systems requiring stable component supply across extended temperature ranges.

Supply support for TLVH431QDCKT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company specializing in analog, embedded processing, and power management technologies, with leadership in precision analog ICs for industrial and automotive markets.

The TLVH431 family was designed specifically for low-voltage, high-accuracy shunt regulation in isolated power supplies and voltage-monitoring systems where space, thermal constraints, and extended temperature operation are critical.

FAQ

What is the reference voltage tolerance of TLVH431QDCKT over its full operating temperature range?

The TLVH431QDCKT has a reference voltage tolerance of ±1.5% at 25°C, and its full-temperature-range deviation is ±31 mV (–40°C to +125°C). This corresponds to a V_REF range of 1.194 V to 1.286 V across temperature, as specified in Section 5.5 of the SLVS555N datasheet. The Q-grade designation confirms this extended-temperature characterization for TLVH431QDCKT.

Can TLVH431QDCKT replace a standard Zener diode in a 3.3 V power rail clamp?

Yes, TLVH431QDCKT can directly replace a Zener diode in a 3.3 V rail clamp with superior performance: it offers ±1.5% initial tolerance (vs. ±5% typical for Zeners), 0.25 Ω dynamic impedance (vs. 10–100 Ω for Zeners), and <0.1 μA off-state cathode current (vs. >1 μA for most Zeners). Its SC-70 package also provides 40% smaller footprint than SOT-23-3, making TLVH431QDCKT ideal for compact, low-leakage clamping.

What is the minimum cathode current required for regulation in TLVH431QDCKT?

The minimum cathode current required for regulation in TLVH431QDCKT is 100 μA, as specified in Section 5.5 (I_K(min)) of the datasheet. Below this level, the device may not enter proper linear regulation due to insufficient bias for the internal Darlington output stage. This value is confirmed across the full –40°C to +125°C temperature range and is a key differentiator from the TL431 (1 mA minimum).

Does TLVH431QDCKT require an output capacitor for stability in shunt regulator mode?

No, TLVH431QDCKT is internally compensated and does not require an output capacitor between CATHODE and ANODE for basic stability in shunt regulator mode. However, if a capacitive load is added (e.g., for filtering), Figures 5-15 through 5-17 in the datasheet provide phase-margin guidance versus load capacitance and cathode voltage. TLVH431QDCKT's stability is maintained up to ~10 nF at V_KA = 1.25 V, depending on operating conditions.

How does the SC-70 package of TLVH431QDCKT affect thermal performance compared to SOT-23 variants?

The SC-70 (DCK) package of TLVH431QDCKT has a junction-to-ambient thermal resistance (R_θJA) of 259 °C/W, significantly higher than SOT-23-3 (206 °C/W) or SOT-89 (52 °C/W). This means TLVH431QDCKT dissipates less power before reaching thermal limits - for example, at 25°C ambient, max continuous power is ~0.39 W before hitting 125°C junction. Layout with thermal vias and copper pour is strongly recommended to mitigate this limitation in TLVH431QDCKT designs.