BAT42-TR - 30V 200mA Small Signal Schottky Diode | Vishay
MPN: BAT42-TR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.09 | $0.09 |
| 10 | $0.08 | $0.80 |
| 100 | $0.06 | $6.00 |
| 500 | $0.05 | $25.00 |
| 1,000 | $0.04 | $40.00 |
BAT42-TR Overview
A Schottky diode is a metal-to-silicon rectifier that stores far less charge than a standard PN-junction diode, giving it a very low forward turn-on voltage and extremely fast switching. Within the component hierarchy it sits under Schottky rectifier, then diode, then discrete semiconductor. These properties make the BAT42 family a staple general-purpose small-signal part in the discrete semiconductor portfolio.
Key features of the BAT42-TR include very low turn-on voltage compared with standard silicon diodes, fast switching speed suited to high-frequency signal paths, and a PN junction guard ring that protects the die against excessive voltage events such as electrostatic discharges. The metal-to-silicon junction minimizes reverse recovery charge, so switching losses stay negligible even at high repetition rates. The glass DO-35 body provides hermetic sealing for long-term reliability in through-hole designs.
According to the Vishay small signal Schottky diode datasheet (document 85660), the device is intended for general purpose applications, and AEC-Q101 qualified variants are available on request. The guard-ring ESD protection distinguishes it from unprotected small-signal Schottky types, improving assembly robustness. Reverse leakage remains in the microampere range at rated voltage and room temperature, an inherent trade-off of the Schottky barrier compared with a standard rectifier diode.
Typical applications include signal clamping and detection circuits, reverse polarity and battery protection in portable equipment, high-frequency switching supplies and RF detector stages, and general board-level rectification where low forward drop saves headroom in low-voltage rails.
When designing with the BAT42-TR, always verify the leakage-versus-temperature curve: Schottky reverse current roughly doubles every 10 degrees C, so hot environments derate the effective blocking margin below the 30 V rating.
This page synthesizes distributor pricing and availability, drop-in cross-references, and practical design notes not consolidated in the manufacturer datasheet.
Drop-in alternatives for BAT42-TR — 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 BAT42-TR (same form factor and footprint) — differing in Package, Diode Type, Mounting Type, Application Class, ESD Protection.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
BAT43
✅ Drop-In✓ In Stock
$0.08 / Unit
View Datasheet →BAT42
✅ Drop-In✓ In Stock
$0.02 / Unit
View Datasheet →BAT42
✅ Drop-In✓ In Stock
$0.02 / Unit
View Datasheet →1N5711
✅ Drop-In✓ In Stock
$0.18 / Unit
View Datasheet →BAT42-TR Maximum Ratings & Electrical Characteristics
| Diode Type | Small Signal Schottky Diode |
| Repetitive Peak Reverse Voltage (VRRM) | 30 V |
| Average Forward Current (IF(AV)) | 200 mA |
| Reverse Recovery | Fast switching (low charge, Schottky) |
| ESD Protection | PN junction guard ring |
| Application Class | General purpose |
| Automotive Qualification | AEC-Q101 qualified version available on request |
| Package | DO-204AH (DO-35), axial through-hole glass |
| Mounting Type | Through Hole |
| Packaging | Tape and Reel (TR suffix) |
| Halogen Free / RoHS | Halogen free and RoHS compliant package per cross-reference data |
| Related Package Variant | Also available in SOD-123 (BAT42W) and MiniMELF types per datasheet |
BAT42-TR Pin Configuration
| Pin 1 | Anode — Anode terminal (unmarked end of DO-35 body) |
| Pin 2 | Cathode — Cathode terminal (marked with band on DO-35 body) |
Typical Applications
BAT42-TR is suitable for 6 applications: Signal Clamping and Protection, Reverse Polarity and Battery Protection, RF Detector and Envelope Detection, High-Frequency Switching Circuits, Industrial and Automotive Sub-Assembly Use, General Board-Level Rectification.
Signal Clamping and Protection
The BAT42-TR excels as a clamp diode because its Schottky barrier turns on at a forward voltage several hundred millivolts below standard silicon PN diodes, limiting signal excursions before they can damage sensitive inputs. The 30 V reverse rating comfortably covers logic-level and audio-band signal environments, while the PN junction guard ring adds tolerance to ESD-type transients at connectors. Because the metal-silicon junction has essentially zero reverse recovery, clamping action remains effective at high slew rates without injecting charge back into the protected node. Place the diode from the protected node to the supply or ground rail, keeping the lead length short since through-hole DO-35 leads add inductance. The trade-off is microampere-class reverse leakage, which doubles roughly every 10 degrees C, so verify leakage does not load high-impedance nodes at elevated temperature.
Recommended
Reverse Polarity and Battery Protection
In battery-powered and field-serviceable equipment, a series BAT42-TR blocks reverse battery insertion with a forward drop of only a few tenths of a volt at typical portable-device currents, preserving precious headroom on 3.3 V and 5 V rails. The 200 mA average rating covers signal electronics, sensor front ends, and low-power microcontroller boards, though not motor or main power paths. The 30 V rating gives ample margin over single-cell lithium and multi-cell alkaline stacks. Compared with a silicon rectifier such as a 1N400x, the Schottky saves roughly 0.3 to 0.4 V of drop, which directly extends operating time from the same cell. Remember that Schottky reverse leakage rises steeply with temperature; in hot enclosures verify that leakage through the blocking diode does not slowly discharge the battery during storage.
Recommended
RF Detector and Envelope Detection
The BAT42's very low turn-on voltage and absence of reverse recovery charge make it a practical detector diode in AM envelope detectors, RF power monitors, and sample circuits up to the tens-of-megahertz range. A low barrier means small RF amplitudes still produce measurable rectified output, improving receiver sensitivity compared with standard PN diodes that need biasing to overcome the 0.6 V knee. The guard-ring structure stabilizes the junction capacitance, and the glass DO-35 body keeps parasitics low and repeatable. Use a high-value load resistor with a small shunt capacitor to set the detection time constant, and account for the microampere reverse leakage when choosing that resistor, since leakage loads the detector at temperature. For precision RF power measurement, calibrate the actual VF of the installed part.
Recommended
High-Frequency Switching Circuits
Because a Schottky junction stores negligible minority-carrier charge, the BAT42-TR switches from forward conduction to blocking almost instantly, which is why the Vishay datasheet highlights fast switching as a core feature. This suits freewheeling, steering, and logic-speed switching roles in discrete DC-DC converters at low power, diode-OR supplies, and pulse circuits where PN-diode recovery losses would add switching spikes and EMI. At 200 mA and 30 V the device covers buck converters in the sub-watt class and auxiliary winding rectification. Keep loop areas small in the layout: the axial leads contribute inductance that converts fast di/dt into voltage overshoot. The trade-off against a PN switching diode is higher reverse leakage, which matters at high temperature and high ratio off-time duty cycles.
Recommended
Industrial and Automotive Sub-Assembly Use
The BAT42-TR fits industrial control boards, sensor modules, and automotive sub-assemblies where a robust general-purpose small-signal diode is required. Vishay states that AEC-Q101 qualified versions of this family are available on request, so automotive designs can source a qualified variant sharing the same die technology, while the standard part serves industrial and consumer builds. The hermetic glass DO-35 package resists moisture ingress better than molded plastic SMD packages, supporting long service life in harsh environments, and the guard ring adds transient robustness at wiring-harness-adjacent nodes. For new automotive designs, order the qualified part number explicitly and request its qualification documentation. Confirm the temperature-dependent leakage budget for under-hood ambient conditions before finalizing the 30 V blocking margin.
Recommended
General Board-Level Rectification
For general purpose low-frequency rectification tasks - secondary-side rectification in small AC-DC adapters, signal-path diode-ORing, and DC blocking - the BAT42-TR offers a dependable commodity solution in the universally recognized DO-35 footprint. The very low forward turn-on voltage reduces conduction loss in low-voltage secondaries, and the 200 mA average current rating matches small transformers and wall adapters in the 1 to 2 VA class. Vishay also offers the same function in SOD-123 (BAT42W) and MiniMELF packages, allowing a single electrical spec to serve both through-hole and surface-mount builds within one supply chain. When paralleling for higher current, add series ballast or accept current sharing tolerance, since Schottky VF curves are flat. Verify the peak repetitive reverse voltage including ringing, not just the nominal rail voltage.
Recommended
Recommended Products Summary
Engineering reference data for BAT42-TR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | BAT43 | BAT42 (TSC) | 1N5711 |
|---|---|---|---|---|
| Package | DO-204AH (DO-35) axial | DO-204AH (DO-35) - same | DO-204AH (DO-35) - same | DO-35 axial - same |
| Brand | Vishay General Semiconductor | Vishay Intertechnology | Taiwan Semiconductor | onsemi |
| Reverse Voltage | 30 V | 30 V | 30 V | 70 V |
| Forward Current | 200 mA | 200 mA (higher tier) | 200 mA | 15 mA |
| Switching Speed | Fast (Schottky, no recovery) | Fast (Schottky, no recovery) | Fast (Schottky, no recovery) | Fast (Schottky, no recovery, 1 ns class) |
Key Differentiators
- Guard-ring ESD protection (vs 1N5711)
- Lower forward turn-on voltage (vs 1N5711)
- AEC-Q101 qualification path (vs Taiwan Semiconductor BAT42)
Design Notes
Derate the 30 V reverse rating against your worst-case blocking condition, including switching-ring overshoot in rectifier roles, not just nominal rail voltage. Schottky reverse leakage is strongly temperature dependent - roughly doubling every 10 degrees C per typical Schottky behavior - so at elevated ambient the effective leakage can reach tens of microamperes. In battery-backed or high-impedance circuits, calculate the leakage current at maximum ambient and confirm it does not discharge batteries or load detector/sense nodes beyond tolerance. Estimated: leakage check should use datasheet IR at the highest expected junction temperature.
Although the DO-35 is a through-hole part, lead length still matters: every millimeter of lead adds series inductance that converts fast switching transitions into voltage overshoot and EMI. Keep axial lead dress short and close to the board in clamping, freewheeling, and RF detector positions. For clamping applications, connect the diode directly across the node-to-rail span with the shortest practical loop, and place bulk decoupling on the clamp rail so the clamped transient has a low-impedance sink. Bend leads with adequate standoff from the glass body to avoid mechanical stress cracking the seal.
The most common substitution errors are ignoring forward voltage differences between BAT42 second sources and exceeding the 200 mA average rating in pulsed applications without checking the surge rating. The Vishay datasheet notes this family is also offered in SOD-123 (BAT42W) and MiniMELF packages - these are NOT footprint-compatible with the DO-35, so verify the exact package suffix when cross-referencing. Also, the standard BAT42-TR is not itself AEC-Q101 qualified; automotive designs must order the qualified variant available on request.
Compliance Information
Cross-reference data describes the BAT42-TR package as halogen free and RoHS compliant. AEC-Q101 qualified versions of the family are available on request per Vishay datasheet. REACH and conflict-minerals status not stated in provided data.
