STS232240B151 - 24V TVS ESD Array, SOT-23 | Eaton
MPN: STS232240B151 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.67 | $0.67 |
| 10 | $0.6 | $6.00 |
| 100 | $0.52 | $52.00 |
| 500 | $0.45 | $225.00 |
| 1,000 | $0.39 | $390.00 |
STS232240B151 Overview
A TVS (Transient Voltage Suppressor) diode array is a discrete semiconductor protection device that clamps transient over-voltages to a safe level by avalanching through a reverse-biased PN junction. TVS arrays belong to the broader hierarchy of discrete semiconductors, sitting below circuit-protection components like varistors and PTC fuses but above signal-level Zener clamps in peak-current handling, made for sub-nanosecond response and tens-of-amperes pulse ratings.
Key features of the STS232240B151 include: bidirectional single-channel protection (one protected line), 24V reverse working voltage (VRWM), 60V maximum clamping voltage (VC) at the 8/20 us test waveform, 15 pF typical capacitance to preserve signal edges on RS-485 / RS-232 buses, and a compact SOT-23-3 footprint that drops onto generic TSMC/IEC 61340-3-1 ESD layouts. The 8/20 us waveform is the industry-standard short-pulse test defined by the IEC 61000-4-5 surge immunity standard, with peak current 6A ensuring robust surge handling on industrial signal lines.
Typical applications include RS-485 transceiver protection on factory-floor nodes, set-top box and notebook data-line protection, portable electronics with exposed I/O, and control/monitoring systems. The 24V working voltage and 60V clamp voltage bracket the 24 V industrial bus common-mode range, protecting downstream transceivers without disturbing normal signal swing.
Designers should place the STS232240B151 within 5 mm of the connector pin to minimize parasitic inductance to the protected IC, and route the ground return directly to the chassis or system ground. The bidirectional construction means it protects against both positive and negative transients without polarity orientation during placement.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the Eaton datasheet alone, including the parametric comparison vs competing SOT-23-3 TVS diodes and the recommended layout rules for IEC 61000-4-2 air-discharge compliance.
Drop-in alternatives for STS232240B151 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
SMAJ24CA
✅ Drop-In📋 Reference alternative (not in catalog)
PESD24VS1UB
✅ Drop-In📋 Reference alternative (not in catalog)
SMBJ24CA
✅ Drop-In📋 Reference alternative (not in catalog)
ESD5V0S1B-N
✅ Drop-In📋 Reference alternative (not in catalog)
SP3010-04UTG
✅ Drop-In📋 Reference alternative (not in catalog)
STS232240B151 Specifications
| Manufacturer | Eaton - Electronics Division |
| Product Type | TVS Diode Array / ESD Suppressor |
| Package | SOT-23-3 (3-pin, gull-wing) |
| Mounting Type | Surface Mount |
| Working Voltage (VRWM) | 24 V |
| Clamping Voltage (VC) | 60 V at 8/20 us, 6 A |
| Peak Pulse Current (IPP) | 6 A (8/20 us waveform) |
| Channel Capacitance | 15 pF (typical) |
| Polarity | Bidirectional (single channel) |
| Number of Protected Lines | 1 |
| Operating Temperature Range | -40C to +125C |
| RoHS Status | Compliant |
| Lead-Free | Yes |
| MSL Level | 1 |
STS232240B151 Pin Configuration
| Pin 1 | Signal 1 — Protected line 1 (bidirectional) |
| Pin 2 | GND — Ground return for clamping |
| Pin 3 | Signal 2 — Protected line 2 (bidirectional) |
Typical Applications
STS232240B151 is suitable for 6 applications: RS-485 / RS-422 Industrial Bus Protection, Set-Top Box and Notebook Data Line Protection, Cellular Handset and Accessory ESD Protection, Industrial Control and Monitoring Systems, Portable Electronics I/O Protection, Wireless Bus Protection.
RS-485 / RS-422 Industrial Bus Protection
The Eaton STS232240B151 is well-suited for protecting RS-485 and RS-422 transceiver lines on industrial fieldbus nodes because its 24 V working voltage covers the 24 V common-mode rail common on factory floors, while its 60 V clamping voltage at 6 A (8/20us) sits well below the absolute-maximum ratings of popular transceivers such as the MAX3485, SN65HVD72, and ISL3179. Engineers typically place one STS232240B151 between each signal pair and ground within 5 mm of the connector, routing the ground return directly to chassis ground. The 15 pF capacitance preserves 10 Mbps RS-485 signal integrity without measurable edge degradation.
Recommended
Set-Top Box and Notebook Data Line Protection
The Eaton STS232240B151 protects exposed I/O lines on set-top boxes and notebooks, where external connectors routinely encounter ESD events during user handling. Its bidirectional single-channel construction means a single SOT-23 part clamps both positive and negative ESD discharges per IEC 61000-4-2 without orientation-sensitive placement, simplifying high-volume assembly. With 60 V clamping and 6 A peak pulse, it absorbs direct contact-discharge transients on HDMI auxiliary, USB-OTG VBUS, and RJ-45 magnetics without disturbing the downstream signal chain.
Recommended
Cellular Handset and Accessory ESD Protection
The STS232240B151 serves as a single-line ESD suppressor on cellular handsets and accessories where 24 V-rated signal lines such as headset microphone bias or accessory ID pins are exposed to user-contact ESD. Eaton specifies the part for -40C to +125C operation, matching the thermal envelope of consumer handset designs. Its 15 pF capacitance is acceptable for audio-band signals and low-speed serial, while the 60 V clamp protects downstream codec and charger ICs from direct air-discharge strikes.
Recommended
Industrial Control and Monitoring Systems
For industrial control and monitoring systems with 24 V PLC I/O and HMI panels, the Eaton STS232240B151 clamps induced surge transients from switching solenoids, motor starters, and inductive loads. The 6 A (8/20us) peak pulse rating covers the secondary surge level of IEC 61000-4-5 industrial immunity tests, and the SOT-23-3 footprint fits inside the limited PCB area of compact PLC modules. The 24 V working voltage exactly matches 24 V PLC digital I/O rails, ensuring the suppressor never conducts during normal operation.
Recommended
Portable Electronics I/O Protection
The STS232240B151 protects exposed I/O ports on portable electronics such as handheld test instruments, portable medical devices, and battery-powered industrial readers where connectors may be exposed to ESD during field use. Its 15 pF capacitance preserves signal edges on USB, RS-232, and SPI lines below 50 MHz, while the 60 V clamp keeps sensitive microcontrollers and ADC inputs within their absolute-maximum ratings. The SOT-23-3 footprint minimizes PCB area, which is at a premium in portable designs.
Recommended
Wireless Bus Protection
Wireless infrastructure equipment such as small-cell backhaul, fixed wireless CPE, and antenna-mounted RF modules often require ESD protection on control and telemetry lines that share the same chassis as the RF chain. The STS232240B151 protects these low-speed control lines while its 15 pF capacitance is too high to place directly on RF paths above 100 MHz - so engineers typically use it on UART, GPIO, or I2C control paths adjacent to, but not in series with, the RF chain. The 24 V working voltage tolerates industrial PoE bias rails found in outdoor wireless deployments.
Recommended
Recommended Products Summary
Engineering reference data for STS232240B151 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SMAJ24CA | PESD24VS1UB | SMBJ24CA | ESD5V0S1B-N |
|---|---|---|---|---|---|
| Package | SOT-23-3 | SMA (DO-214AC) | SOT-23-3 (same) | SMB (DO-214AA) | SOT-23-3 (same) |
| Brand | Eaton | Littelfuse | Nexperia | Littelfuse | onsemi |
| Working Voltage (VRWM) | 24 V | 24 V | 24 V | 24 V | 5 V |
| Clamping Voltage (VC) | 60 V at 8/20us, 6A | 38.9 V at 8/20us, 17.7A | 14 V at 8/20us | 38.9 V at 8/20us, 17A | 20 V at 8/20us |
| Peak Pulse Current (IPP) | 6 A | 17.7 A | 3 A | 17 A | 12 A |
| Polarity | Bidirectional | Bidirectional | Unidirectional | Bidirectional | Bidirectional |
| Operating Temperature | -40C to +125C | -65C to +150C | -40C to +125C | -65C to +150C | -40C to +125C |
| Approx. 1pc Price (USD) | $0.67 | $0.35 | $0.42 | $0.40 | $0.18 |
Key Differentiators
- Higher working voltage (24 V) than typical 5V TVS arrays (vs ESD5V0S1B-N)
- Bidirectional single-channel in compact SOT-23-3 (vs PESD24VS1UB)
- Compact SOT-23-3 footprint vs larger SMA/SMB packages (vs SMAJ24CA)
Design Notes
Place the Eaton STS232240B151 within 5 mm of the protected connector pin to minimize the parasitic inductance of the trace between the connector and the TVS diode. Long traces add series impedance that lets the connector-side voltage overshoot during the sub-nanosecond ESD edge, potentially exceeding the protected IC's absolute-maximum rating even though the TVS itself is correctly clamping.
Route the STS232240B151 ground pin (pin 2) directly to chassis ground or the system ground plane using a short, wide trace or via. Avoid routing the ground through shared signal-ground traces that carry return currents, which can lift the ground reference during a surge and shift the protected line voltage above the IC's tolerance. Best practice: dedicated ground via placed next to pin 2, stitched directly to the chassis ground pour.
Do not stack two STS232240B151 parts in series to achieve higher peak pulse current - the internal Zener mismatch can cause one device to carry the entire pulse and fail. If higher peak current is required, use a single higher-rated SMAJ24CA or SMBJ24CA (17.7 A and 17 A respectively) instead, accepting the larger package. The SOT-23-3 STS232240B151 is rated for 6 A and should not be paralleled for surge applications.
Compliance Information
RoHS and lead-free confirmed per Eaton product page; AEC-Q100 not applicable (discrete TVS, not automotive-qualified per datasheet); REACH and halogen-free status not explicitly listed.
