TL432LIBQDBZRQ1 - Adjustable Shunt Reference, 0.5% | TI
MPN: TL432LIBQDBZRQ1 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.92 | $0.92 |
| 10 | $0.83 | $8.30 |
| 100 | $0.71 | $71.00 |
| 500 | $0.58 | $290.00 |
| 1,000 | $0.46 | $460.00 |
| 3,000 | $0.38 | $1,140.00 |
TL432LIBQDBZRQ1 Overview
A shunt voltage reference (also called a programmable zener reference) is a two-terminal or three-terminal device that maintains a fixed voltage at its cathode when biased with sufficient current. The three-terminal form adds a reference pin, allowing the cathode voltage to be programmed above the internal reference using an external resistor divider. The TL432 sits within the broader hierarchy of voltage references -> shunt regulators -> analog ICs -> power management semiconductors, and is commonly used in closed-loop feedback for switching power supplies, where it sets the output voltage set point. Compared to two-terminal zener diodes, three-terminal shunt references offer tighter initial tolerance, lower dynamic impedance, and programmability.
Key features include an adjustable output voltage range from 2.495 V (VREF) to 36 V set by two external resistors, a typical output impedance of 0.2 Ω that minimizes set-point shift with cathode current, and an optimized reference current designed for low minimum cathode current (I_min) operation. The device is specified across the automotive temperature range, qualified to AEC-Q100 standards, and supports solder reflow up to 260 °C per JEDEC J-STD-020.
Internally, the TL432 uses a bandgap reference core with on-chip op-amp drive to a pass transistor, providing stable VREF across temperature, supply, and load variations. The TL432 pinout is the reverse-polarity variant of the TL431: in the DBZ (SOT-23-3) package, the TL432 places the reference (REF) on pin 1, anode on pin 2, and cathode on pin 3, while the TL431 has anode on pin 1, cathode on pin 2, and reference on pin 3. Always verify pinout before substituting between TL431 and TL432.
Typical applications include isolated flyback converter secondary-side regulation, primary-side regulation with optocoupler feedback, automotive battery monitoring, precision current limiting, and adjustable zener replacement. The TL432LI-Q1 variants (LI suffix) provide optimized reference current for lower I_min and tighter TI operation versus the standard TL431/TL432 parts.
When designing with this device, ensure cathode current stays within the datasheet limits (typically 1 mA minimum, 15 mA continuous) across all load and temperature conditions. Add a 0.1 µF bypass capacitor at the reference pin if the divider impedance is high to prevent oscillation.
This page synthesizes distributor pricing, AEC-Q100-qualified drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for TL432LIBQDBZRQ1 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with TL432LIBQDBZRQ1 (same form factor and footprint) — differing in MSL Level, Operating Temperature Range, Reference Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
TL432BQDBZRQ1
✅ Drop-In📋 Reference alternative (not in catalog)
TL432AQDBZRQ1
✅ Drop-In📋 Reference alternative (not in catalog)
PTL432LIBQDBZR
✅ Drop-In✓ In Stock
$0.09 / Unit
View Datasheet →TL432BQDBZR
✅ Drop-In📋 Reference alternative (not in catalog)
TL432LIBCDBZR
✅ Drop-In📋 Reference alternative (not in catalog)
TL432LIBQDBZT
✅ Drop-In📋 Reference alternative (not in catalog)
TL432LIBQDBZRQ1 Specifications
| Reference Type | Shunt Voltage Reference, Adjustable |
| Nominal Reference Voltage (VREF) | 2.495 V |
| Output Voltage Range | 2.495 V to 36 V |
| Initial Tolerance (B grade) | ±0.5% |
| Maximum Cathode Current | 15 mA |
| Typical Output Impedance | 0.2 Ω |
| Operating Temperature Range | -40 °C to +125 °C (automotive) |
| Package | SOT-23-3 (DBZ) |
| Mounting Type | Surface Mount |
| Pin Count | 3 |
| Automotive Qualification | AEC-Q100 qualified (Q1 suffix) |
| MSL Level | 1 (per JEDEC J-STD-020) |
| RoHS Status | Compliant |
| Lead-Free | Yes |
| Product Family | TL431LI-Q1 / TL432LI-Q1 (optimized reference current) |
TL432LIBQDBZRQ1 Pin Configuration
| Pin 1 | REF — Reference input - external resistor divider programs cathode voltage above 2.495 V VREF |
| Pin 2 | ANODE — Anode - connect to ground or reference return |
| Pin 3 | CATHODE — Cathode - regulated output, sinks 1-15 mA to maintain VREF at REF pin |
Typical Applications
TL432LIBQDBZRQ1 is suitable for 7 applications: Isolated Flyback Secondary-Side Regulation, Primary-Side Regulation with Optocoupler Feedback, Automotive Battery Monitoring, Precision Current Limiting Circuit, Adjustable Zener Replacement, Switching Power Supply Feedback, Precision Comparator Threshold Generator.
Isolated Flyback Secondary-Side Regulation
The TL432LIBQDBZRQ1's 2.495 V VREF and 36 V cathode rating make it ideal as the secondary-side reference in isolated flyback converters. Connected between the output rail and an optocoupler LED, it sets the output voltage via a resistor divider, while its AEC-Q100 grade withstands automotive transients on 12 V/24 V battery rails. Optimized reference current reduces I_min, enabling operation at light loads without loss of regulation. Compared to discrete zener references, the 0.2 Ω typical output impedance minimizes set-point shift across load steps, improving cross-regulation in multi-output flyback designs.
Recommended
Primary-Side Regulation with Optocoupler Feedback
In primary-side regulation (PSR) topologies, the TL432LIBQDBZRQ1 still serves as the precision reference on the auxiliary winding or output rail, providing the error signal to the optocoupler that biases the primary-side controller. The 0.5% initial tolerance improves output voltage set-point precision versus standard 2% parts, critical for USB-PD and 5 V/2 A adapters. The 15 mA cathode current capacity supports optocoupler CTR variation over temperature, maintaining loop gain across -40 °C to +125 °C automotive range.
Recommended
Automotive Battery Monitoring
The TL432LIBQDBZRQ1's AEC-Q100 qualification and -40 °C to +125 °C operating range suit 12 V/24 V automotive battery monitoring modules, including over-voltage and under-voltage comparators. With a resistor divider scaling 12 V battery voltage to VREF, the TL432 cathode transitions sharply at the threshold, driving an N-channel MOSFET or comparator logic. The 36 V cathode rating easily tolerates 24 V jump-start transients per ISO 7637-2, while the 0.5% tolerance reduces calibration effort in production.
Recommended
Precision Current Limiting Circuit
The TL432LIBQDBZRQ1 forms a precision current limiter by sensing voltage across a low-side shunt resistor and comparing to VREF, with the cathode driving a pass transistor gate. The 0.2 Ω output impedance ensures the current limit set-point remains stable across load and temperature variations, unlike discrete BJT references. AEC-Q100 grade makes it suitable for automotive LED drivers, battery chargers, and motor control where constant-current accuracy matters. The 15 mA cathode current allows direct gate drive of small MOSFETs.
Recommended
Adjustable Zener Replacement
The TL432LIBQDBZRQ1 replaces discrete zener diodes from 2.5 V to 36 V in precision applications, offering tighter initial tolerance (±0.5% vs typical zener ±5%), lower dynamic impedance (0.2 Ω vs several ohms), and adjustable set-point via resistor divider. Engineers upgrading from 1N4731-type zeners benefit from reduced board space and improved temperature coefficient. The SOT-23-3 package fits standard zener footprints with minor layout adjustment for the REF pin bypass capacitor.
Recommended
Switching Power Supply Feedback
In non-isolated buck, boost, and SEPIC converters, the TL432LIBQDBZRQ1 directly senses the output rail and drives the PWM controller's feedback pin via an optocoupler or direct connection. The optimized-reference-current 'LI' variant maintains regulation at lower minimum load (I_min typically 0.4 mA) than standard TL432, improving light-load efficiency and meeting Energy Star no-load requirements. AEC-Q100 grade supports industrial and automotive 24 V input DC-DC modules used in body electronics and infotainment.
Recommended
Precision Comparator Threshold Generator
The TL432LIBQDBZRQ1 provides a precision threshold reference for window comparators in battery management systems, over-voltage protection circuits, and sensor signal conditioning. Combined with an op-amp comparator, the TL432 sets precise voltage thresholds (e.g., 3.3 V, 5.0 V) with 0.5% accuracy, far tighter than resistor-divider + zener combinations. The 36 V cathode rating supports direct connection to 12 V/24 V rails without pre-regulation.
Recommended
Recommended Products Summary
Engineering reference data for TL432LIBQDBZRQ1 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TL432BQDBZRQ1 | TL432AQDBZRQ1 | TL432LIBQDBZR | TL432BQDBZR | TL432LIBCDBZR | TL432LIBQDBZT |
|---|---|---|---|---|---|---|---|
| Package | SOT-23-3 (DBZ) | SOT-23-3 (DBZ) - same | SOT-23-3 (DBZ) - same | SOT-23-3 (DBZ) - same | SOT-23-3 (DBZ) - same | SOT-23-3 (DBZ) - same | SOT-23-3 (DBZ) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Reference Voltage (VREF) | 2.495 V | 2.495 V | 2.495 V | 2.495 V | 2.495 V | 2.495 V | 2.495 V |
| Initial Tolerance | ±0.5% (B grade) | ±0.5% (B grade) | ±1% (A grade) | ±0.5% (B grade) | ±0.5% (B grade) | ±0.5% (B grade) | ±0.5% (B grade) |
| AEC-Q100 Automotive | Yes (Q1) | Yes (Q1) | Yes (Q1) | No (commercial) | No (commercial) | No (commercial) | Yes (Q1) |
| Optimized Reference Current (LI) | Yes (LI) | No (standard) | No (standard) | Yes (LI) | No (standard) | Yes (LI) | Yes (LI) |
| Max Cathode Current | 15 mA | 15 mA | 15 mA | 15 mA | 15 mA | 15 mA | 15 mA |
| Output Voltage Range | 2.495 V to 36 V | 2.495 V to 36 V | 2.495 V to 36 V | 2.495 V to 36 V | 2.495 V to 36 V | 2.495 V to 36 V | 2.495 V to 36 V |
| Operating Temperature | -40 °C to +125 °C | -40 °C to +125 °C | -40 °C to +125 °C | -40 °C to +125 °C | -40 °C to +125 °C | -40 °C to +125 °C | -40 °C to +125 °C |
Key Differentiators
- Optimized reference current for lower minimum cathode current (vs TL432BQDBZRQ1)
- Tighter initial tolerance for precision applications (vs TL432AQDBZRQ1)
- Automotive AEC-Q100 qualification (vs TL432LIBQDBZR)
Design Notes
Always verify pinout before substituting between TL431 and TL432 - they have REVERSED pin assignments in the DBZ (SOT-23-3) package. The TL432 places REF on pin 1, ANODE on pin 2, CATHODE on pin 3. The TL431 places ANODE on pin 1, CATHODE on pin 2, REF on pin 3. Swapping them will short the reference input to ground and destroy the device through excessive cathode current.
Ensure cathode current stays within datasheet limits (typically 1 mA minimum, 15 mA maximum continuous) across all load and temperature conditions. Add a 0.1 µF bypass capacitor at the REF pin if the divider impedance is high (above 10 kΩ) to prevent oscillation. For optocoupler feedback, include a 1 kΩ resistor in series with the optocoupler LED to limit cathode current during transient events.
Keep the external resistor divider traces short and away from switching nodes to minimize noise injection into the REF pin. Place the 0.1 µF REF bypass capacitor directly between pin 1 (REF) and pin 2 (ANODE) with minimal trace length. The cathode pin should connect to the output rail via a short, wide trace to maintain regulation accuracy under load steps.
The TL432LIBQDBZRQ1 SOT-23-3 package has a thermal resistance of approximately 296 °C/W (JEDEC EIA/JESD51 standard board), so at 15 mA cathode current and 36 V cathode voltage, maximum power dissipation is 540 mW raising junction temperature by 160 °C above ambient. For continuous operation at high cathode voltage, derate cathode current to keep junction below 150 °C using TI's thermal derating curves.
When used as a comparator threshold reference, the TL432 cathode transition is sharp (typical dynamic impedance 0.2 Ω) but not as fast as a dedicated comparator. For high-speed comparator applications above 100 kHz, consider adding a discrete comparator (such as TL331 or LM393) downstream of the TL432 reference. The TL432 is optimized for slow DC reference applications, not high-speed switching.
Compliance Information
AEC-Q100 qualified per Q1 suffix in part number. RoHS compliant per TI product page. Lead-free (Pb-free) reflow-compatible per JEDEC J-STD-020 MSL1. Halogen-free per TI specifications. Conflict minerals compliant per TI supply chain disclosures.
