STMicroelectronics

BAT48 - 40V 350mA Small-Signal Schottky Diode | STMicroelectronics

MPN: BAT48 ✓ Active

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40 V Vdss 350 mA Id DO-35 (axial, through-hole, glass) Package Fast switching Speed

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Price updated: 2026-09-14

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BAT48 Overview

The STMicroelectronics BAT48 is a 40 V, 350 mA small-signal Schottky barrier diode with very low turn-on voltage and fast switching, housed in an axial-leaded DO-35 glass package (the BAT48 series is also available in SOD-123 and SOD-323 surface-mount variants).

A Schottky diode is a metal-to-silicon rectifier that forms a junction between a metal and a doped semiconductor, producing a lower forward voltage drop and dramatically faster switching than conventional PN-junction diodes. Within the power-management component hierarchy, the BAT48 belongs to the small-signal Schottky diode family, under discrete semiconductors, diodes, rectifiers.

Key differentiating features include the 40 V reverse voltage rating, 350 mA average forward current capability, very low forward turn-on voltage, and fast reverse recovery - web source data indicates Trr of approximately 5 ns, roughly an order of magnitude better than general-purpose PN diodes (>100 ns). Each die integrates a PN junction guard ring providing protection against excessive voltages such as electrostatic discharges (ESD), improving assembly robustness.

Architecturally, the metal-semiconductor junction conducts via majority carriers, eliminating minority-carrier storage charge and enabling the fast switching behavior. The DO-35 glass body offers hermetic sealing, stable leakage characteristics across temperature, and convenient hand-solderability on through-hole boards and perfboards.

Typical applications include hard/soft clipping stages in guitar pedals and audio circuits, low-voltage rectification and reverse-polarity protection in battery-powered devices, RF detection, and general-purpose switching in PWM circuits where switching loss matters.

Design consideration: Schottky leakage current rises significantly with temperature; derate the 350 mA rating when ambient temperature exceeds 75C and verify forward-voltage drop at your actual operating current when substituting.

This page synthesizes distributor listings, cross-reference data, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone. Pricing references are as of 2026-09-14.

Drop-in alternatives for BAT48 — 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 BAT48 (same form factor and footprint) — differing in Package, ESD Protection, Mounting Type, Repetitive Peak Reverse Voltage (VRRM), Average Forward Current (IF(AV)).

BAT43

STMicroelectronics

Package: DO-35 (glass axial, through-hole)

ESD Protection: Integrated guard ring against excessive voltage

Repetitive Peak Reverse Voltage (VRRM): 30 V

Compare with BAT48 →

BAT43-R0

Taiwan Semiconductor

Package: DO-35 axial glass (through hole)

ESD Protection: Fast guard ring against excessive voltage (ESD)

Repetitive Peak Reverse Voltage (VRRM): 30 V

Compare with BAT48 →

✅ Drop-In

📦 SOD-323

same die family, SMD SOD-323 instead of DO-35 axial - electrically equivalent, different footprint for reflow assembly

📋 Reference alternative (not in catalog)

BAT48 Maximum Ratings & Electrical Characteristics

Diode Type	Small-signal Schottky barrier diode
Reverse Voltage (VRRM)	40 V
Average Forward Current (IF(AV))	350 mA
Reverse Recovery Time (Trr)	approx. 5 ns (per web source data)
Turn-On Voltage Feature	Very low turn-on voltage
Switching Speed	Fast switching
ESD Protection	Integrated PN junction guard ring
Package	DO-35 (axial, through-hole, glass)
Series Packages	SOD-123, SOD-323, DO-35
Mounting Type	Through Hole
Application	General purpose, low turn-on, fast switching
Polarity Marking	Cathode band (per DO-35 convention)

BAT48 Pin Configuration

Pin 1	Anode — Positive terminal; current flows into the Schottky junction
Pin 2	Cathode — Marked by the band on the DO-35 glass body; current exits

Typical Applications

BAT48 is suitable for 6 applications: Guitar Pedal Clipping / Audio Signal Shaping, Reverse Polarity Protection in Battery Devices, Low-Voltage Signal Rectification and Detection, Freewheeling / Flyback Clamp in PWM Circuits, OR-ing / Diode-OR Power Supply Combiners, Prototyping, Repair and Educational Through-Hole Boards.

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Guitar Pedal Clipping / Audio Signal Shaping

The BAT48 is a favorite clipping diode in guitar effect pedals because its very low Schottky turn-on voltage produces a softer, warmer compression onset than standard silicon PN diodes, preserving sustain and harmonic content. Community references (PedalPCB forums) show BAT48 used for hard clipping, often asymmetrically paired with a 1N4148 for asymmetric transfer curves. In this role it handles only signal-level currents far below its 350 mA rating, so lifetime is effectively unlimited. The DO-35 glass package is ideal for hand soldering on perfboards and eyelet boards used in boutique pedal assembly, and its fast switching adds no audible phase distortion at audio frequencies.

Recommended

1N4148 (PN diode for asymmetric clipping pair) 1N34A (Germanium alternative for softer clipping)

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Reverse Polarity Protection in Battery Devices

Placed in series with a 9 V or 12 V battery rail, the BAT48 blocks reverse installation while dropping very little voltage in normal operation thanks to its low forward turn-on voltage - a direct benefit for battery life and headroom in analog circuits. The 40 V reverse rating provides comfortable margin above 12 V systems, surviving negative transients during connection bounce. At the typical 50-350 mA loads of portable and pedal circuits, dissipation stays in the tens of milliwatts, avoiding thermal design work. Compared with a standard silicon diode, the Schottky saves roughly 0.2-0.3 V of drop, which matters in low-voltage analog rails.

Recommended

1N5819 (Higher-current Schottky for main rails) BAT46 · STMicroelectronics

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Low-Voltage Signal Rectification and Detection

The BAT48's metal-silicon junction conducts at low forward voltages, making it effective for rectifying and detecting small AC or RF signals that would not turn on a conventional silicon PN diode. Its fast switching (Trr approximately 5 ns per web source data) supports detection well into RF ranges where recovery-limited PN diodes fail. Envelope-detector and AM-detector stages in test fixtures and simple receivers benefit from the low conduction threshold and the guard-ring ESD robustness during handling. Note that junction capacitance, not recovery, becomes the limiting factor at high frequency, so verify capacitance against the ST datasheet for the specific band of interest.

Recommended

1N5711 · STMicroelectronics BAT43 · STMicroelectronics

⚙️

Freewheeling / Flyback Clamp in PWM Circuits

In low-power PWM drivers for relays, small motors, and LEDs, the BAT48 can serve as a freewheeling diode where switching loss matters: its fast recovery avoids the long conduction tails of PN diodes, reducing turn-on stress on the switching transistor. Web source data highlights Trr of approximately 5 ns versus >100 ns for general-purpose diodes as the critical advantage in PWM applications. The 40 V rating suits 12 V and 24 V rails with clamping margin; the 350 mA current limit restricts use to small solenoids and signal-class loads. For inductive loads above a few hundred milliamps, step up to a power Schottky such as the 1N5819 family.

Recommended

1N5819 (1 A freewheeling Schottky for larger loads) IRLZ34N (Logic-level MOSFET switch companion)

🔌

OR-ing / Diode-OR Power Supply Combiners

The BAT48 suits low-current diode-OR combining of two supply sources - for example, battery plus adapter feeding a pedal or sensor node - because the low forward voltage minimizes the differential needed before one source takes over. At sub-350 mA loads, dissipation stays negligible, and the guard-ring ESD structure adds robustness during connector mating. The 40 V rating tolerates adapter transients that cheaper 20 V-class Schottkys cannot. Designers should verify the reverse leakage of the blocking diode at maximum ambient, since Schottky leakage rises with temperature and can slowly discharge a battery when the adapter path is blocked.

Recommended

BAT46 · STMicroelectronics TLS205B0LDV50 (LDO post-regulator for combined rail)

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Prototyping, Repair and Educational Through-Hole Boards

The axial DO-35 glass package makes the BAT48 exceptionally convenient for breadboards, perfboards, and through-hole repair work - leads accept hand soldering and repeated rework without the handling constraints of SMD parts. Its glass body is hermetic, resisting moisture ingress that affects plastic-packaged diodes in storage. In education and repair contexts, the clearly banded cathode, forgiving 40 V / 350 mA envelope, and low turn-on voltage make it a versatile default small-signal rectifier for demonstrating Schottky versus PN diode behavior on a scope: students can directly observe the reduced forward drop and the absence of reverse-recovery artifacts.

Recommended

1N4148 (PN diode for comparison experiments) 1N4007 (Mains-class rectifier for contrast demos)

Recommended Products Summary

1N4148 PN diode for asymmetric clipping pair Used in: Guitar Pedal Clipping / Audio Signal Shaping, Prototyping, Repair and Educational Through-Hole Boards 1N34A Germanium alternative for softer clipping Used in: Guitar Pedal Clipping / Audio Signal Shaping 1N5819 Higher-current Schottky for main rails Used in: Reverse Polarity Protection in Battery Devices, Freewheeling / Flyback Clamp in PWM Circuits BAT46 STMicroelectronics Used in: Reverse Polarity Protection in Battery Devices, OR-ing / Diode-OR Power Supply Combiners 1N5711 STMicroelectronics Used in: Low-Voltage Signal Rectification and Detection BAT43 STMicroelectronics Used in: Low-Voltage Signal Rectification and Detection IRLZ34N Logic-level MOSFET switch companion Used in: Freewheeling / Flyback Clamp in PWM Circuits TLS205B0LDV50 LDO post-regulator for combined rail Used in: OR-ing / Diode-OR Power Supply Combiners 1N4007 Mains-class rectifier for contrast demos Used in: Prototyping, Repair and Educational Through-Hole Boards

What is the BAT48 diode and its key specifications?

The BAT48 is a small-signal Schottky barrier diode from STMicroelectronics rated 40 V reverse voltage and 350 mA average forward current, in an axial DO-35 glass package (series also offered in SOD-123 and SOD-323). It features very low turn-on voltage, fast switching (web data indicates Trr around 5 ns), and an integrated PN junction guard ring for ESD protection. According to the ST datasheet, the series targets general-purpose applications requiring low forward drop and high speed.

What is the reverse voltage rating of the BAT48?

The BAT48 is rated for 40 V of repetitive peak reverse voltage. According to the STMicroelectronics product page and datasheet, the entire BAT48 series uses 40 V Schottky barrier dies, so this rating applies to the DO-35, SOD-123, and SOD-323 package variants alike. For circuits with inductive kickback or transients above 40 V, add a clamp or select a higher-voltage Schottky; exceeding VRRM risks avalanche breakdown and leakage-driven thermal runaway.

How much current can the BAT48 handle?

The BAT48 handles up to 350 mA average forward current. According to the DigiKey listing for the STMicroelectronics part ('Diode 40 V 350mA'), this rating applies to the DO-35 through-hole package under specified conditions. For designs needing more current in the same DO-35 footprint, the BAT46 (45 V class) is a family-adjacent option; for surface-mount designs, use the BAT48 SOD-123 or SOD-323 variants with appropriate copper thermal relief.

What is the difference between BAT48 and BAT43?

The main difference is reverse voltage: the BAT43 is a 20 V-class Schottky while the BAT48 is rated 40 V, with both in DO-35 glass packages and similar 350 mA-class current capability. Both are STMicroelectronics small-signal Schottky diodes with very low turn-on voltage and fast switching. If your circuit reverse bias never exceeds 20 V with margin, BAT43 is a suitable pin-compatible substitute; otherwise use BAT48. Guitar-pedal builders frequently interchange them for clipping duties, noting slightly different clipping thresholds from forward-voltage differences.

Can the BAT48 be used as a clipping diode in guitar pedals?

Yes, the BAT48 is widely used for hard clipping in guitar pedals. Community forum discussions (PedalPCB) reference the BAT48 for hard clipping stages, often paired asymmetrically with a 1N4148. What matters in this application is forward voltage drop at the small signal currents involved: the BAT48's very low turn-on voltage produces softer, warmer clipping than silicon PN diodes. Its DO-35 glass package is also convenient for hand soldering on perfboards.

What is the best drop-in replacement for BAT48?

The best drop-in replacement for BAT48 in the same DO-35 axial package is the BAT43 (STMicroelectronics) when only 20 V reverse voltage is required, or the BAT46 for a 45 V-class rating. Cross-reference data from Hotenda also confirms compatible equivalents from Vishay and Infineon under the BAT48 number in matching packages. Always verify forward voltage at your operating current and leakage behavior at your maximum ambient temperature before approving the substitution.

What is the difference between BAT48 and BAT46?

The BAT46 offers a higher reverse voltage class (45 V versus 40 V for the BAT48) in the same DO-35 axial package with comparable 350 mA-class current handling. Both are small-signal Schottky diodes with very low turn-on voltage and fast switching. In practice, a BAT46 can replace a BAT48 drop-in with extra voltage margin; the reverse substitution is acceptable only if circuit reverse bias stays well below 40 V. Verify the exact manufacturer datasheet since ratings vary slightly by brand.

Where can I download the BAT48 datasheet PDF?

The official BAT48 datasheet PDF is available directly from STMicroelectronics at st.com/resource/en/datasheet/bat48.pdf. This document covers the full BAT48 series (SOD-123, SOD-323, and DO-35 packages) including maximum ratings, electrical characteristics, forward-voltage curves, leakage versus temperature, and package mechanical drawings. Avoid third-party mirrors such as alldatasheet or datasheet4u when possible, as official manufacturer documents are always the most current revision.

What is the reverse recovery time of the BAT48?

Web source data for the BAT48 indicates a reverse recovery time of approximately 5 ns, roughly an order of magnitude faster than general-purpose PN junction diodes which typically exceed 100 ns. As with most Schottky diodes, recovery is dominated by junction capacitance rather than minority-carrier storage, so the BAT48 suits PWM switching and RF detection circuits where switching loss matters. Always confirm against the ST datasheet curve for your exact test conditions.

Is the BAT48 through-hole or surface mount?

The BAT48 (as listed by DigiKey under the STMicroelectronics part number) is a through-hole diode in a DO-35 axial glass package. However, the STMicroelectronics BAT48 series also includes surface-mount versions in SOD-123 and SOD-323 packages - these are separate orderable part numbers, not drop-in equivalents for the axial DO-35, since the footprints differ. Choose the SMD variants when reflow assembly is used; the DO-35 suits hand assembly, prototyping, and repair work.

Does the BAT48 have ESD protection?

Yes, according to the STMicroelectronics product description, BAT48 devices have integrated protection against excessive voltage such as electrostatic discharges, implemented via a PN junction guard ring around the Schottky junction. This guard-ring structure absorbs ESD events during handling and assembly that would otherwise puncture an unprotected metal-semiconductor junction. It also stabilizes reverse leakage behavior, improving yield and field reliability in through-hole and SMD assembly environments.

Is the BAT48 in stock and where can I buy it?

According to the DigiKey listing retrieved as of 2026-09-14, the BAT48 from STMicroelectronics is available with ships-today availability, and Mouser also lists the part with inventory and pricing. XAIPART offers quotation-based sourcing for the BAT48. For volume purchases, request a quote; for prototyping quantities, distributor stock is the fastest route. Always confirm real-time stock on the distributor page since small-signal diode inventory moves quickly.

What is the price of the BAT48?

Pricing for the BAT48 was not confirmed in the verified data used for this page, so exact unit pricing is marked as pending. As of 2026-09-14, DigiKey and Mouser list the STMicroelectronics BAT48 (40 V, 350 mA, DO-35) as an active, in-stock part; small-signal Schottky diodes of this class typically price in the low tens of cents at single-unit quantity, dropping significantly at 1000-piece volumes. Request a quote from XAIPART for current volume pricing.

What is the Vishay equivalent for BAT48?

Cross-reference data from Hotenda confirms Vishay as a compatible-equivalent manufacturer for the BAT48 number, meaning Vishay supplies a BAT48-branded 40 V Schottky in pin-compatible packages. Because the same industry-standard part number is used, substitution is straightforward: verify the package suffix (DO-35 axial versus SOD-123/SOD-323 SMD) and check the specific manufacturer's datasheet for forward-voltage and leakage values, which can differ slightly between silicon processes. Infineon is likewise listed as a cross-reference source.

Hey Google, what can replace a BAT48 diode?

You can replace a BAT48 with a BAT43 (same DO-35 package, but only 20 V reverse rating - fine below ~15 V bias), a BAT46 (DO-35, 45 V class, higher voltage margin), or a BAT48 from Vishay or Infineon under the same part number per cross-reference data. For SMD layouts, the BAT48 series' own SOD-123 and SOD-323 variants match electrically. Match forward voltage at your operating current for clipping applications to preserve tone.

What are the key specifications of BAT48 that engineers should know?

Engineers should know: BAT48 is a 40 V, 350 mA small-signal Schottky diode from STMicroelectronics in a DO-35 glass axial package (series also in SOD-123/SOD-323); it has very low turn-on voltage and fast switching with Trr around 5 ns per web data; a PN junction guard ring provides ESD protection; it suits general-purpose rectification, clipping, RF detection, and polarity protection. According to the ST datasheet and DigiKey listing, it is an active, through-hole, RoHS-era part.

Is the BAT48 suitable for reverse polarity protection?

Yes, the BAT48 works well for reverse-polarity protection in low-voltage battery circuits. Its 40 V reverse rating gives generous headroom for 5 V, 9 V, and 12 V systems, and the low forward voltage drop minimizes power loss when placed in series with the supply rail - important for battery life. At 350 mA maximum current, it protects portable devices and pedal circuits. For higher-current rails, use a power Schottky or a P-MOSFET ideal-diode arrangement instead.

Can BAT48 replace 1N34A germanium diodes?

Partially - pedal-building community threads mention 1N34A as a BAT48 substitute, but they are not identical. The BAT48 is a silicon Schottky with a higher forward voltage than a germanium 1N34A (roughly 0.2-0.3 V versus 0.45-0.55 V class at low currents, though exact values depend on current). In clipping circuits the BAT48 clips slightly harder than germanium but softer than standard silicon PN diodes, and it offers far better thermal stability and availability. Audible differences exist; verify by ear.

Engineering reference data for BAT48 — comparison, design guidance, and compliance information.

Selection Guide

Choose the STMicroelectronics BAT48 when you need a 40 V, 350 mA-class Schottky in a hand-solderable through-hole DO-35 package: guitar-pedal clipping, battery reverse-polarity protection, low-voltage OR-ing, RF detection, and small PWM freewheeling duty. Choose BAT43 instead if your reverse bias is guaranteed below roughly 15 V and you want the family's lowest-cost option. Choose BAT46 when you need extra voltage margin (45 V class) in the same footprint. Choose Vishay or Infineon BAT48 second sources when ST lead times stretch - cross-reference data confirms compatibility, but compare VF and leakage curves before mass production. For surface-mount boards, the BAT48 series' own SOD-123/SOD-323 variants match electrically but require a new footprint; they are not drop-in for the axial DO-35.

Comparison with Alternatives

Parameter	This Product	BAT43	BAT46	BAT48 (Vishay)	BAT48 (Infineon)
Package	DO-35 (axial glass)	DO-35 - same	DO-35 - same	DO-35 - same	DO-35 - same
Brand	STMicroelectronics	STMicroelectronics	STMicroelectronics	Vishay Intertechnology	Infineon
Reverse Voltage (VRRM)	40 V	20 V	45 V	40 V	40 V
Forward Current	350 mA	350 mA class	350 mA class	350 mA class	350 mA class
Mounting	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole

Key Differentiators

40 V rating with very low turn-on voltage (vs BAT43)
Integrated ESD guard ring (vs Generic unguarded Schottky diodes)
Higher voltage margin than BAT46 substitution in the other direction (vs BAT46)
Fast switching vs PN diodes (vs 1N4148)

Design Notes

Estimated: at 350 mA full load with a typical Schottky VF around 0.3-0.4 V (verify exact VF from the ST datasheet curve), the BAT48 dissipates roughly 105-140 mW - trivial for the DO-35 glass package, which dissipates 500 mW class. Derating becomes relevant only above about 75C ambient where reverse leakage doubles roughly every 10C; in battery-powered reverse-protection roles, check leakage-driven battery drain at maximum storage temperature.

Do not substitute the 20 V BAT43 for the 40 V BAT48 in circuits with inductive kickback (relay or solenoid coils) or unregulated adapter inputs - the voltage rating difference is the primary risk, not forward characteristics. Conversely, in pedal clipping stages the two are freely interchangeable by ear. When second-sourcing to Vishay or Infineon BAT48 parts, compare the VF-at-current and IR-at-voltage curves rather than assuming identical silicon.

For the axial DO-35, maintain the standard lead-bend spacing (about 0.4 inch on 0.1 inch grid with stress-relief bends) and keep the glass body at least 2 mm from the solder joint during hand soldering to avoid thermal shock cracking. In high-speed or RF detector layouts, keep anode/cathode leads short (under 10 mm) since lead inductance, not the 5 ns Trr, dominates switching behavior above tens of MHz.

Compliance Information

RoHS

Unknown

REACH

Unknown

AEC-Q100

Not Applicable

Lead Free

Unknown

Halogen Free

Unknown

Conflict Minerals

Unknown

Compliance data was not present in the verified web data for this part. Confirm RoHS/REACH status on the ST product page before BOM approval.

Data verified on: 2026-09-14 — data verified and curated by XAIPART's component engineering team

Sources: Manufacturer_Datasheet, Manufacturer_Product_Page, Distributor, Distributor, Octopart, Distributor, Distributor

Related Components & Terms

STMicroelectronics BAT48 BAT43 BAT46 1N4148 1N34A 1N5711 Vishay Intertechnology Infineon Schottky barrier diode small-signal diode rectifier diode DO-35 SOD-123 SOD-323 through-hole axial-leaded package PN junction guard ring ESD protection reverse recovery time forward voltage drop guitar pedal clipping reverse polarity protection RF detection PWM freewheeling