PTL432LIBQDBZR - 2.495V Adjustable Shunt Reference | Texas Instruments
MPN: PTL432LIBQDBZR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.2 | $0.20 |
| 10 | $0.18 | $1.80 |
| 100 | $0.15 | $15.00 |
| 500 | $0.13 | $65.00 |
| 1,000 | $0.11 | $110.00 |
| 3,000 | $0.09 | $270.00 |
PTL432LIBQDBZR Overview
A shunt voltage reference is a two-terminal (or three-terminal) IC that behaves like a programmable Zener diode. Internally it contains a precise bandgap reference, an error amplifier, and a pass transistor; when biased above its reference voltage, the device regulates the voltage across its cathode-anode terminals to the programmed value. The voltage reference category sits within voltage references -> power management ICs -> analog semiconductors, and forms the accuracy anchor in any closed-loop power-supply or data-acquisition system.
Key features include a low minimum cathode current of 400 nA typical, optimized reference input current that improves measurement accuracy over legacy TL431 designs, ±0.5% reference voltage tolerance, and operation across the full -40C to +125C automotive/industrial temperature range. The wide adjustable range from 2.495V to 36V enables use from sub-3.3V rails up to 24V industrial buses.
Architecturally, the PTL432LI family improves upon the classic TL431 by reducing the reference input current and minimizing reference voltage drift over temperature, while keeping the standard pinout (REF/ADJ, ANODE, CATHODE in SOT-23-3). The "LI" suffix designates the low-Ibias optimized variant that simplifies high-impedance feedback networks and reduces standby power in battery-powered designs.
Typical applications include adjustable voltage references for switching converter feedback networks, secondary-side voltage monitoring, isolated supply references, and precision comparator thresholds. Engineers value the SOT-23-3 footprint for compact designs where a TO-92 TL431 would dominate the PCB.
When designing with this part, choose a cathode bias resistor that supplies at least 400 nA at the lowest VIN minus VREF condition, while ensuring the maximum cathode current does not exceed 15 mA at high VIN or short-circuit events.
This page aggregates datasheet specifications, real distributor pricing tiers, drop-in same-brand alternatives, and design notes that complement the manufacturer datasheet.
Drop-in alternatives for PTL432LIBQDBZR — 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 PTL432LIBQDBZR (same form factor and footprint) — differing in Reference Type, Operating Temperature Range, Package, MSL Level, Typical Output Impedance.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
TL432LIBQDBZR
✅ Drop-In✓ In Stock
$0.15 / Unit
View Datasheet →TL431LIBQDBZR
✅ Drop-In📋 Reference alternative (not in catalog)
TL432LIBQDBZRQ1
✅ Drop-In✓ In Stock
$0.38 / Unit
View Datasheet →PTL432LIBQDBZRQ1
✅ Drop-In📋 Reference alternative (not in catalog)
TL431LIQDBZR
✅ Drop-In📋 Reference alternative (not in catalog)
PTL432LIBQDBZR Specifications
| Reference Type | Shunt, Adjustable |
| Reference Voltage | 2.495 V |
| Output Voltage Range | 2.495 V to 36 V |
| Reference Voltage Tolerance | ±0.5% |
| Cathode Current (Min) | 400 nA (typical) |
| Cathode Current (Max) | 15 mA |
| Operating Temperature Range | -40C to +125C |
| Temperature Grade | Industrial / Automotive (Q1 variant) |
| Package | SOT-23-3 (DBZ) |
| Number of Pins | 3 |
| Mounting Type | Surface Mount |
| MSL Level | 1 |
| Lead Free | Yes |
| RoHS Status | Compliant |
| Reference Input Current | Optimized (low-Ibias LI family) |
PTL432LIBQDBZR Pin Configuration
| Pin 1 | REF — Reference input (connect to external resistor divider from cathode) |
| Pin 2 | ANODE — Anode (ground reference) |
| Pin 3 | CATHODE — Cathode (regulated output / bias current input) |
Typical Applications
PTL432LIBQDBZR is suitable for 6 applications: Adjustable Switching Converter Feedback, Precision Voltage Monitor / Brown-Out Reset, Adjustable Zener Diode Replacement, Isolated Supply Reference Loop, Battery-Powered Precision Threshold Detector, Lab Bench Power Supply Reference.
Adjustable Switching Converter Feedback
The PTL432LIBQDBZR's 2.495V reference and 400 nA minimum cathode current make it ideal as the secondary-side feedback reference in isolated DC-DC converters such as flyback, forward, and LLC topologies. The wide 2.495V to 36V output range covers common secondary rails (3.3V, 5V, 12V, 15V, 24V) when paired with an external resistor divider at the TL431-style compensation network. Its low Ibias allows high-value feedback resistors that minimize standby current, while the SOT-23-3 footprint fits compact secondary-side layouts next to the optocoupler. Compared to fixed references, the shunt topology also absorbs transient overshoot without external protection.
Recommended
Precision Voltage Monitor / Brown-Out Reset
Engineers use the PTL432LIBQDBZR as the reference element in undervoltage lockout (UVLO), overvoltage protection, and battery-monitor comparator circuits. Its 2.495V bandgap reference drives a comparator to assert a system reset when the rail drops below a programmed threshold. The very low 400 nA minimum cathode current means the entire monitor circuit can be powered from a 100 kOhm bias resistor drawing negligible quiescent current, allowing always-on supervisory functions from a coin cell. The -40C to +125C operating range supports automotive battery monitoring (with Q1 variant) and industrial PLC supplies across the full industrial temperature envelope.
Recommended
Adjustable Zener Diode Replacement
The PTL432LIBQDBZR functionally replaces a discrete Zener diode with a tighter-tolerance, lower-noise programmable reference. Designers use it as a clamping reference in analog signal chains, amplifier offset nulling networks, or instrumentation input protection stages. Compared to a 1N4728-class Zener (which has ±5% tolerance and 5 mA knee current), the PTL432LI delivers ±0.5% initial tolerance, sub-microamp knee current, and dramatically lower broadband noise for audio and precision-sensor front-ends. The SOT-23-3 SMD package allows drop-in placement on dense multi-channel instrumentation boards.
Recommended
Isolated Supply Reference Loop
In isolated DC-DC modules (5V/3.3V from a 24V industrial bus), the PTL432LIBQDBZR provides the precision reference on the secondary side of the isolation barrier, driving the optocoupler LED through a TL431-style compensation network. The 2.495V reference and 36V cathode rating let one footprint support output voltages from 3.3V to 24V via divider scaling, simplifying BOM flexibility for multi-output modules. The 400 nA minimum cathode current enables deep light-load efficiency optimization required by Energy Star and EU Ecodesign standby requirements.
Recommended
Battery-Powered Precision Threshold Detector
IoT sensor nodes, wearable health monitors, and remote telemetry units use the PTL432LIBQDBZR to detect battery end-of-discharge thresholds without draining the battery itself. Because the shunt reference draws only 400 nA minimum cathode current, the entire detection circuit can run from the battery continuously for years on a single coin cell. The 2.495V reference sets predictable thresholds for 3V primary lithium or rechargeable Li-ion chemistries when paired with an external divider. The SOT-23-3 footprint enables compact wearable form factors.
Recommended
Lab Bench Power Supply Reference
Programmable laboratory power supplies use the PTL432LIBQDBZR as the precision reference element that determines the output voltage setpoint accuracy. Its ±0.5% initial tolerance, low drift, and 36V compliance allow wide-range programmable supplies (0-30V output) to maintain sub-1% setpoint accuracy across the entire adjustment range. The shunt topology is inherently short-circuit tolerant, surviving load faults without damage - a critical feature for bench supplies driving unknown DUTs. Drop-in SOT-23-3 packaging simplifies PCB repair and field replacement of legacy TO-92 TL431 references.
Recommended
Recommended Products Summary
Engineering reference data for PTL432LIBQDBZR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TL432LIBQDBZR | TL431LIBQDBZR | TL432LIBQDBZRQ1 | PTL432LIBQDBZRQ1 | TL431LIQDBZR |
|---|---|---|---|---|---|---|
| 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 |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Reference Voltage | 2.495 V | 2.495 V | 2.495 V | 2.495 V | 2.495 V | 2.495 V |
| 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 |
| Min Cathode Current | 400 nA | 400 nA | 400 nA | 400 nA | 400 nA | 400 nA |
| Max Cathode Current | 15 mA | 15 mA | 15 mA | 15 mA | 15 mA | 15 mA |
| Reference Voltage Tolerance | ±0.5% | ±0.5% | ±0.5% | ±0.5% | ±0.5% | ±0.5% |
| AEC-Q100 Qualified | No | No | No | Yes | Yes | No |
Key Differentiators
- Lowest cathode current in its SOT-23-3 class (vs TL432LIBQDBZR)
- Automotive-grade variant available in same package (vs TL431LIQDBZR)
- Compact SOT-23-3 saves PCB area versus TO-92 (vs TL431 in TO-92 package)
Design Notes
Select the cathode bias resistor RBias so that (VIN - VREF) / RBias delivers at least 400 nA (typical) of cathode current at the lowest VIN minus VREF condition, while staying below 15 mA at maximum VIN. Estimated: if VIN ranges from 5V to 36V and VREF (output) = 5V, then at VIN_min = 6V (worst case headroom 1V), RBias_max = (6V - 5V) / 400 nA = 2.5 MOhm - but in practice a 100 kOhm to 470 kOhm value is chosen for noise immunity, and minimum VIN must exceed the output voltage by at least the device's reference voltage (2.495V).
Place the PTL432LIBQDBZR close to the secondary-side optocoupler LED with short traces between cathode and the bias resistor, and between the REF pin and the divider network. Minimize leakage on the REF pin by routing it away from high-impedance noise sources; the optimized-low-Ibias LI architecture is sensitive to PCB leakage. Use a ground plane under the SOT-23-3 pad for thermal dissipation - though shunt references dissipate little power, a continuous ground plane improves reference stability by reducing thermal gradients.
Do not load the cathode beyond 15 mA - this is the absolute maximum rating and sustained overcurrent causes permanent reference drift. Ensure that the divider resistors have 1% tolerance or better; 5% resistors degrade total accuracy to roughly ±3% even with a ±0.5% reference. Avoid low-ESR ceramic bypass capacitors directly on the cathode when the cathode drives a switching converter feedback loop - they introduce noise; instead use a small RC filter (10 kOhm + 100 nF) at the REF pin if needed.
Compliance Information
RoHS and REACH compliant per TI TL431LI/TL432LI datasheet family. The PTL432LIBQDBZR is industrial grade; the PTL432LIBQDBZRQ1 variant is AEC-Q100 qualified for automotive.
