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onsemi BZX84C20LT3
- Part No.:
- BZX84C20LT3
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
BZX84C20LT3.pdf
- Description:
- DIODE ZENER 20V 225MW SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:3,866
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Product details
Overview
BZX84C20LT3 from onsemi is a 20 V, ±5% tolerance Zener diode in SOT-23 package, rated for 225 mW power dissipation on FR-5 board at 25°C, with 55 Ω dynamic impedance at 5 mA test current and 14 mV/°C temperature coefficient - used for voltage reference and overvoltage protection in portable power rails.
For engineers reviewing the BZX84C20LT3 datasheet, pinout, applications, or equivalent options, key selection criteria include nominal Zener voltage (20 V), tolerance (±5%), Zener impedance (55 Ω @ 5 mA), thermal resistance (556 °C/W), and ESD rating (>16 kV HBM).
Technical Context
This device operates as a two-terminal voltage reference, conducting in reverse breakdown when cathode voltage exceeds anode by ≥20 V. Its 225 mW power rating is defined on FR-5 board at 25°C, derating linearly above that temperature at 1.8 mW/°C.
The SOT-23 package features three terminals: Pin 1 (anode), Pin 2 (no connection), Pin 3 (cathode), with polarity indicated by a band on the cathode end. It achieves Class 3 ESD robustness (>16 kV HBM) and UL 94 V-0 flammability rating.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage | 20 V nominal, 18.8–21.2 V min/max at 5 mA - sets precise clamping threshold for 3.3 V/5 V rail monitoring |
| Power Dissipation | 225 mW on FR-5 board at 25°C - limits continuous current to ~11.25 mA at 20 V without heatsinking |
| Zener Impedance | 55 Ω at IZT = 5 mA - determines regulation stability under load transients |
| Temp. Coefficient | +14 mV/°C - causes +140 mV drift over 10°C ambient change, requiring thermal layout consideration |
| Reverse Leakage | 50 nA max at VR = 15 V - ensures minimal quiescent current in standby mode |
| Capacitance | 85 pF at VR = 0 V, f = 1 MHz - impacts high-frequency noise filtering capability |
| ESD Rating | Class 3 (>16 kV HBM) - supports direct interface with exposed I/O in handheld devices |
Pinout & Package
SOT-23 surface-mount plastic package (Case 318, Style 8), void-free thermosetting epoxy, UL 94 V-0 rated, with cathode identified by polarity band. Maximum soldering temperature: 260°C for 10 seconds.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Anode | Connected to lower-potential node; reverse-biased operation requires this terminal at lower voltage than cathode |
| 2 | No Connection | Internally unconnected; must remain floating - no PCB trace or pad required |
| 3 | Cathode | Connected to higher-potential node; polarity band on package marks this terminal |
Key Features
| Feature | Design Value |
|---|---|
| 225 mW Power Rating | Enables compact voltage clamping in space-constrained portable designs without external heat sinking |
| ±5% Zener Tolerance | Provides predictable 18.8–21.2 V regulation window for mid-precision reference applications |
| SOT-23 Package | Supports automated pick-and-place assembly and achieves <1 mm² board footprint on high-density PCBs |
| ESD >16 kV HBM | Eliminates need for external ESD protection in battery-powered handheld interfaces |
| UL 94 V-0 Flammability | Meets safety requirements for consumer electronics enclosures without additional flame-retardant coating |
Applications
| Battery Voltage Monitoring | USB Port Overvoltage Protection |
|---|---|
Use Scenario: Monitoring Li-ion battery pack voltage during charging/discharging cycles in Bluetooth headsets. IC Role / Device Role / Timing Role: Zener reference element providing stable 20 V clamp point for comparator input. Use Value: Prevents false low-battery alerts by maintaining reference accuracy across −20°C to +70°C operating range. | Use Scenario: Protecting USB data lines from transient surges caused by hot-plug events in portable media players. IC Role / Device Role / Timing Role: Shunt clamping device diverting ESD energy away from USB transceiver IC inputs. Use Value: Leverages >16 kV HBM rating to absorb IEC 61000-4-2 Level 4 surges without degradation. |
| 3.3 V LDO Feedback Divider | Industrial Sensor Signal Conditioning |
Use Scenario: Setting output voltage of adjustable LDO regulators in programmable logic controllers. IC Role / Device Role / Timing Role: Precision voltage reference in resistor divider network feeding LDO feedback pin. Use Value: ±5% tolerance ensures regulated output stays within ±2% of target 3.3 V despite supply ripple. | Use Scenario: Providing stable bias voltage for analog front-end amplifiers in wireless temperature sensors. IC Role / Device Role / Timing Role: Low-noise DC reference source for op-amp biasing and ADC reference scaling. Use Value: 85 pF capacitance minimizes high-frequency coupling into sensitive analog signal paths. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MMBZ5255BLT1 | 20 V nominal, ±5%, 225 mW, but 30 Ω Zener impedance @ 20 mA - lower dynamic impedance at higher current | Optimized for higher-current regulation (e.g., 15–20 mA), less suitable for low-quiescent microcontroller monitoring | Select MMBZ5255BLT1 only if design operates near 20 mA Zener current and requires tighter regulation under load |
| BZX84C20LT1G | Identical electrical specs and SOT-23 package, but Pb-free (RoHS-compliant) construction | Required for EU/China RoHS-regulated products; same thermal and electrical behavior as BZX84C20LT3 | Choose BZX84C20LT1G for new designs targeting environmental compliance; BZX84C20LT3 remains valid for legacy non-RoHS production |
Compared with BZX84C20LT3, MMBZ5255BLT1 offers lower impedance at higher currents but lacks identical 5 mA test-point specification, while BZX84C20LT1G provides identical performance in a Pb-free package - making it a drop-in replacement where RoHS compliance is mandatory.
Availability
BZX84C20LT3 is available at Aetrix Electronics and suitable for battery management systems, USB interface protection, and industrial sensor signal conditioning requiring stable component supply and long-term obsolescence support.
Supply support for BZX84C20LT3 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.
The BZX84C20LT3 belongs to the BZX84CxxxLT1 Zener regulator family, designed specifically for space-constrained, low-power voltage reference and transient suppression in portable and high-density electronics.
FAQ
What is the maximum power dissipation of BZX84C20LT3 on FR-5 board?
The BZX84C20LT3 has a maximum power dissipation of 225 mW on FR-5 board at 25°C ambient temperature. This rating decreases linearly at 1.8 mW/°C above 25°C, resulting in approximately 207 mW at 35°C. Derating must be applied in thermally constrained layouts to avoid junction temperature exceedance.
Does BZX84C20LT3 have a functional connection on pin 2?
No, BZX84C20LT3 pin 2 is internally unconnected (NC). The device uses only pins 1 (anode) and 3 (cathode) for operation. PCB layout must leave pin 2 floating - no trace, pad, or solder mask opening is required for this terminal.
What is the Zener impedance of BZX84C20LT3 and why does it matter?
The BZX84C20LT3 has a maximum Zener impedance (ZZT) of 55 Ω measured at 5 mA test current. This value reflects how tightly the device maintains its 20 V breakdown voltage under varying load conditions - lower impedance improves regulation accuracy during current transients in power supply feedback or reference circuits.
Can BZX84C20LT3 be used as a substitute for BZX84C20LT1?
Yes, BZX84C20LT3 is functionally identical to BZX84C20LT1 except for tape-and-reel packaging: BZX84C20LT1 ships in 3,000-unit reels, while BZX84C20LT3 ships in 10,000-unit reels. Electrical, thermal, and mechanical specifications are fully interchangeable - no design or layout changes are needed when switching between them.
What is the temperature coefficient of BZX84C20LT3 and how does it affect circuit performance?
The BZX84C20LT3 has a temperature coefficient of +14 mV/°C at 5 mA test current. This means its Zener voltage increases by approximately 14 mV for every 1°C rise in junction temperature. In a 50°C ambient-to-junction swing, this results in ~700 mV total drift - requiring thermal isolation or compensation in precision reference applications.
BZX84C20LT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- BZX84CxxxLT1
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Voltage - Zener (Nom) (Vz):
- 20 V
- Tolerance:
- ±6%
- Power - Max:
- 225 mW
- Impedance (Max) (Zzt):
- 55 Ohms
- Current - Reverse Leakage @ Vr:
- 50 nA @ 14 V
- Voltage - Forward (Vf) (Max) @ If:
- 900 mV @ 10 mA
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3 (TO-236)
BZX84C20LT3 FAQ
1.How can I place an order for BZX84C20LT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX84C20LT3 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for BZX84C20LT3 reliable?
The price and inventory of BZX84C20LT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX84C20LT3 is usually 5 days.
3.What payment methods are accepted for BZX84C20LT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX84C20LT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX84C20LT3?
BZX84C20LT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX84C20LT3 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for BZX84C20LT3?
For technical support, including BZX84C20LT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX84C20LT3 requirements.
6.How does Aetrix verify that BZX84C20LT3 is sourced from the original manufacturer or authorized distributors?
All BZX84C20LT3 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BZX84C20LT3 meets industry standards.
7.What is the process for return or replacement of BZX84C20LT3?
All BZX84C20LT3 units undergo pre-shipment inspection (PSI). If there is an issue with BZX84C20LT3, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The BZX84C20LT3 part is unused and in its original packaging.
Return procedure for BZX84C20LT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX84C20LT3 Tags
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