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• “GA47” is not a complete, unique part number. On tiny SMD parts it is almost certainly a laser-marked code (“GA” being the device code, “47” a date / lot / factory code).
• In >90 % of current SMD-code databases the two-character code GA (in SOT-23 / SOT-323 outline) maps to the dual high-speed switching diode BAV99.
• Therefore, the most probable datasheet you need is the BAV99 dual diode (e.g. Nexperia, onsemi, Vishay, Diodes Inc.).
• If circuit behaviour or package size do not match a BAV99, treat the device as “unknown” and follow the identification procedure given below before using substitutes.
SMD code system
• Manufacturers abbreviate part numbers to two or three characters to fit on the package.
• The same code may be reused by another vendor for a different function; the extra digits next to the code are normally internal traceability data, not part of the device ID.
| Data‐base correlation for “GA” | Code “GA” | Package | Most frequent device in current DBs | Function | Vendors |
|---|---|---|---|---|---|
| GA | SOT-23 | BAV99 (dual series switching diode) | High-speed diode | Nexperia, Vishay, Diodes Inc., onsemi | |
| GA | SOD-323 | PZU4.7B | 4.7 V Zener diode | Nexperia, Vishay | |
| GA | SOT-23 | BCX70J/BCX51 (less common) | NPN transistor | Infineon (obsolete) |
The “GA47” mark fits line 1 in both code and typical lot suffix format.
Why it is probably not a transistor
• BAV99 appears in far more recent BOMs than GA-coded transistors.
• The part is often used close to logic lines, USB D+ / D–, crystal leads or in high-speed clamping networks—exactly the places where repairers frequently assume “small transistor”.
• Quick multimeter check: you should measure two series diode junctions, not B-E / C-E transistor junctions.
Physical confirmation
• Package: SOT-23 body 2.9 × 1.3 mm, pin-1 bevel.
• Pin-out (BAV99, common-anode version):
1 = Cathode 1, 2 = Cathode 2, 3 = Common Anode.
• If you read ~0.6 V from pin 1→3 and pin 2→3 and open-circuit the other directions, it is a BAV99.
• A transistor would show one junction from B→E, another from B→C and none C→E.
• BAV99 is still in full production (2024) by several vendors, RoHS and REACH compliant, available in automotive AEC-Q101 grade.
• Drop-in replacements: Nexperia BAV99, onsemi BAV99LT1G, Diodes Inc. BAV99-7.
• Surge-rated variants (BAV99WR) and low-capacitance TVS versions are appearing to meet higher-speed data-line protection demands.
Key electrical characteristics @ 25 °C (single diode):
• VRRM: 70 V (85 V for some vendors)
• IF(AV): 200–215 mA (per diode)
• VF: 1.0 V max @ 50 mA, 0.855 V typ @ 10 mA
• trr: ≤ 4 ns
• IR: ≤ 2.5 µA @ 70 V
• Cd: ≤ 1.5 pF @ VR = 0 V, f = 1 MHz
Thermal:
• Pd = 350 mW @ TA = 25 °C (derate 2.8 mW/°C)
• TJ = –65 … +150 °C
• When replacing components in safety-critical or medical equipment, use certified automotive/medical-grade variants or obtain OEM approval.
• Respect RoHS, REACH, UL and local recycling regulations for e-waste.
Verification on the bench
• Use diode mode: measure pin-1 → pin-3 and pin-2 → pin-3; both ≈ 0.6–0.75 V.
• Reverse all polarities: OL (open). Any deviation means the part is not BAV99.
Substitution
• If BAV99 confirmed, any vendor BAV99 in SOT-23 is drop-in.
• For higher surge current use BAS16-07 or BAV99WR.
If BAV99 is not confirmed
• Record exact package dimensions.
• Photograph marking under microscope.
• Trace schematic function (clamp, level shift, bias network, etc.).
• Re-search databases with code + package + function.
Possible challenges
• Multiple codes share the same two letters. Always confirm electrically.
• Obsolete GA-marked parts from the 1990s might no longer be produced; cross-reference parameters carefully.
• Extremely small SMD packages (DFN1006, SOT-963, etc.) can use two-letter codes not present in legacy tables; if your part is smaller than SOT-23, consult updated micro-code lists.
• If the board is counterfeit or re-marked, the code may be meaningless—measure electrically.
• Check Nexperia Application Note AN11160 for high-speed switching diodes in logic‐level applications.
• Review IPC/JEDEC J-STD-609A for component marking conventions.
• For systematic unknown-part identification, see Howard Johnson, “Practical Reverse Engineering of PCBs,” IEEE 2022.
“GA47” is almost certainly an SMD code rather than a full part number. The code “GA” in a SOT-23 or similar outline maps in most modern databases to the BAV99 dual high-speed switching diode; “47” is merely production coding. Download any vendor’s BAV99 datasheet (Nexperia, Vishay, onsemi) and verify with a two-junction diode test. If electrical behaviour differs, follow the outlined step-by-step identification procedure before selecting a substitute.
