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Texas Instruments TPS2378DDA
- Part No.:
- TPS2378DDA
- Manufacturer:
- Texas Instruments
- Category:
- Power Over Ethernet (PoE) Controllers
- Package:
- 8-PowerSOIC (0.154", 3.90mm Width)
- Datasheet:
-
TPS2378DDA.pdf
- Description:
- IC POE CNTRL 1 CHANNEL 8SOPWR
- Quantity:
- Payment:
- Shipping:
Inventory:9,593
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Product details
Overview
TPS2378DDA from Texas Instruments is an IEEE 802.3at Type-2 Powered Device (PD) interface IC with integrated 100-V, 0.5-Ω hot-swap MOSFET, 140-mA inrush current limiting, auxiliary power detect (APD), and open-drain T2P type-2 indicator - enabling high-power PoE applications such as security cameras and multiband access points.
For engineers reviewing the TPS2378DDA datasheet, TPS2378DDA pinout, TPS2378DDA application, or TPS2378DDA equivalent, this page delivers verified technical context, exact pin functions, real-world classification resistor values, thermal performance data, and validated alternative parts for IEEE 802.3at PD design and supply chain continuity.
Technical Context
The TPS2378DDA implements full IEEE 802.3at Type-2 hardware classification using dual-event detection and CLS pin voltage regulation (2.5 V ±0.3 V across RCLS), supporting Class 0–4 power levels up to 25.5 W. Its internal pass FET features 0.42 Ω typical rDS(on), 0.85 A continuous current rating, and foldback current limiting triggered at 12.3 V RTN.
It integrates APD-based adapter priority logic that disables the pass FET and asserts T2P when APD exceeds 1.5 V relative to RTN, while CDB provides active-low converter disable signaling synchronized to inrush completion. UVLO thresholds are 38.1 V (rising) and 32.0 V (falling), with 6.1 V hysteresis.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IEEE Standard Compliance | Fully compliant with IEEE 802.3at Type-2 hardware classification and maintain power signature (MPS) requirements. |
| Pass FET rDS(on) | 0.42 Ω typical - enables ≤0.85 A continuous PD current with <0.4 V dropout at full load. |
| Inrush Current Limit | 140 mA typical - limits inrush into CBULK during startup to prevent PSE shutdown. |
| Classification Accuracy | Supports Class 0–4 via external RCLS (63.4 Ω to 1270 Ω); CLS pin regulates 2.5 V across resistor for precise current encoding. |
| APD Threshold | 1.5 V (±0.1 V) relative to RTN - cleanly disables PoE path and asserts T2P when external adapter is present. |
| T2P Output | Active-low open-drain output - signals Type-2 PSE presence or APD activation to downstream isolation circuitry. |
| Thermal Shutdown | Triggers at 140 °C junction temperature with 20 °C hysteresis - protects against sustained overload or poor PCB heatsinking. |
Pinout & Package
TPS2378DDA uses an HSOP-8 PowerPAD™ package (4.89 mm × 3.90 mm) with exposed thermal pad connected to VSS. The PowerPAD must be soldered to a large VSS copper pour for effective heat dissipation (RθJB = 28.8 °C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD | Positive PoE input rail connection | Bypassed to VSS with 0.1 µF; supplies internal bias and enables UVLO monitoring (38.1 V turn-on). |
| DEN | Detection/Enable control input | 24.9 kΩ pull-up to VDD forms IEEE-compliant detection signature; grounding disables pass FET. |
| CLS | Classification current programming | 2.5 V regulated node - current through external RCLS sets IEEE 802.3at class (e.g., 63.4 Ω = Class 4). |
| VSS | Negative PoE rail / local ground | Reference for all internal circuits; PowerPAD must be connected directly to this node. |
| RTN | Pass FET drain / load return path | Carries full PD current (≤0.85 A); voltage rise >12.3 V triggers foldback current limiting. |
| CDB | Converter disable bar output | Active-low open-drain signal pulled to RTN during inrush - used to delay DC/DC soft-start until bulk cap is charged. |
| T2P | Type-2 PSE indicator output | Active-low open-drain flag asserted when Type-2 PSE detected or APD >1.5 V - drives optocoupler interfaces. |
| APD | Auxiliary power detect input | 1.5 V threshold relative to RTN - overrides PoE path and forces T2P assertion when external adapter is active. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 100-V Hotswap MOSFET | 0.42 Ω rDS(on) enables robust 0.85-A continuous operation without external FET or gate driver. |
| Two-Event Type-2 Classification | Hardware-based dual-cycle classification ensures reliable Class 4 recognition by high-power PSEs per IEEE 802.3at. |
| Adapter Priority Logic | APD input disables PoE path and asserts T2P when external supply exceeds 1.5 V - eliminates need for external OR-ing diodes. |
| Programmable Inrush Termination | Inrush ends when RTN current drops below ~125 mA - prevents false triggering of downstream converters. |
| System-Level ESD Protection | 15-kV contact / 8-kV air-gap IEC 61000-4-2 rating on RJ-45 side - reduces need for external TVS components. |
Applications
| Security Cameras | VoIP Video Phones |
|---|---|
|
Use Scenario: Outdoor IP camera with pan-tilt-zoom, IR illumination, and video streaming over single Ethernet cable. IC Role / Device Role / Timing Role: TPS2378DDA performs IEEE 802.3at Type-2 classification, powers downstream DC/DC converter, and signals PSE capability via T2P. Use Value: Delivers up to 25.5 W at PD input (≥13 W usable after losses), enabling full-feature camera operation without local AC adapter. |
Use Scenario: Enterprise-grade VoIP phone with color display, Bluetooth, and speakerphone requiring stable 12–15 W PoE power. IC Role / Device Role / Timing Role: TPS2378DDA manages detection/classification, controls inrush into local 12-V rail, and prioritizes wall adapter via APD if available. Use Value: Eliminates battery backup dependency and enables seamless failover between PoE and auxiliary power without firmware intervention. |
| Multiband Wi-Fi Access Points | Industrial Pico-Base Stations |
|
Use Scenario: Dual-band 802.11ac access point with multiple RF chains, USB peripherals, and PoE-powered cooling fan. IC Role / Device Role / Timing Role: TPS2378DDA provides robust 0.85-A current delivery, monitors RTN for thermal foldback, and asserts CDB to coordinate DC/DC startup timing. Use Value: Sustains peak 20-W loads during simultaneous 2.4/5 GHz transmission without PSE disconnect due to inrush or overcurrent. |
Use Scenario: Small-cell base station deployed in remote locations using four-pair PoE (51 W total) with forced high-power mode. IC Role / Device Role / Timing Role: TPS2378DDA operates in dual configuration per SLVA625 reference design, handling one pair set while coordinating with second TPS2378DDA. Use Value: Enables 51-W input power delivery over standard Cat5e cabling - doubling capacity beyond single-port 25.5-W limit. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar IEEE 802.3at PD interface applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS23753A | Lacks APD input and T2P output; supports only Type-1/Type-2 classification without adapter priority or type-2 flagging. | Suitable for cost-sensitive Type-2 PDs where auxiliary power is not required and isolation signaling is handled externally. | Select TPS23753A only if APD priority and T2P status signaling are unnecessary - avoids over-spec'ing for simpler designs. |
| LT4275AIMSE#TRPBF | Features integrated 100-V FET (0.55 Ω), but requires external gate driver for higher current; no built-in CDB or T2P outputs. | Better suited for custom high-current PDs (>1 A) where discrete FET control and flexible sequencing are needed. | Choose LT4275AIMSE#TRPBF when designing for >1 A continuous load or when needing programmable inrush timing not offered by TPS2378DDA. |
Compared with TPS2378DDA, TPS23753A omits critical adapter priority and type-2 status signaling, while LT4275AIMSE#TRPBF trades integrated simplicity for external flexibility - making TPS2378DDA the optimal choice for production-ready, feature-complete IEEE 802.3at Type-2 PDs.
Availability
TPS2378DDA is available at Aetrix Electronics and suitable for security cameras, VoIP video phones, and multiband access points requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for TPS2378DDA 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
Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.
The TPS2378DDA belongs to TI's Power over Ethernet (PoE) PD controller product line, designed specifically to simplify IEEE 802.3at Type-2 compliance with integrated FET, classification, and adapter priority - targeting high-reliability networked devices.
FAQ
What is the maximum continuous current supported by the TPS2378DDA?
The TPS2378DDA supports 0.85 A continuous current through its integrated 100-V pass FET. This is validated under recommended operating conditions (RTN ≤ 57 V, TJ ≤ 125 °C) with proper PCB thermal design using the PowerPAD. Peak inrush is limited to 140 mA, and current foldback activates if RTN voltage exceeds 12.3 V.
How does the APD pin function in the TPS2378DDA?
The APD pin in the TPS2378DDA provides auxiliary power priority: when voltage at APD rises above 1.5 V relative to RTN, the internal pass FET is disabled, CLS classification is halted, and T2P is asserted low. This allows seamless switchover from PoE to an external adapter without firmware or external logic - a key differentiator versus basic PD controllers.
Can the TPS2378DDA be used in four-pair PoE applications?
Yes - the TPS2378DDA supports forced four-pair operation up to 51 W when used in dual configuration, as documented in TI's SLVA625 application report. Each TPS2378DDA handles one pair set, with coordinated classification and inrush control to meet IEEE 802.3at high-power requirements across all four pairs.
What is the purpose of the CDB pin on the TPS2378DDA?
The CDB pin on the TPS2378DDA is an active-low, open-drain output that pulls to RTN only during inrush current limiting. It signals downstream DC/DC converters (e.g., UCC2897A) to delay soft-start until bulk capacitance is fully charged - preventing premature converter startup and potential brownout or latch-up.
Does the TPS2378DDA require external components for IEEE 802.3at classification?
Yes - the TPS2378DDA requires two external resistors: RDEN (24.9 kΩ ±1%) between VDD and DEN for detection, and RCLS (63.4 Ω to 1270 Ω) between CLS and VSS for classification. These define the IEEE 802.3at Class 0–4 signature and are mandatory for standards compliance - no internal trimming or calibration replaces them.
TPS2378DDA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-PowerSOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Controller (PD)
- Number of Channels:
- 1
- Power - Max:
- 25.5 W
- Internal Switch(s):
- Yes
- Auxiliary Sense:
- Yes
- Standards:
- 802.3at (PoE+), 802.3af (PoE)
- Voltage - Supply:
- 0V ~ 57V
- Current - Supply:
- 285µA
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO PowerPad
TPS2378DDA FAQ
1.How can I place an order for TPS2378DDA through Aetrix?
Please submit a Request for Quotation (RFQ) for TPS2378DDA 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 TPS2378DDA reliable?
The price and inventory of TPS2378DDA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TPS2378DDA is usually 5 days.
3.What payment methods are accepted for TPS2378DDA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TPS2378DDA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TPS2378DDA?
TPS2378DDA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TPS2378DDA 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 TPS2378DDA?
For technical support, including TPS2378DDA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TPS2378DDA requirements.
6.How does Aetrix verify that TPS2378DDA is sourced from the original manufacturer or authorized distributors?
All TPS2378DDA 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 TPS2378DDA meets industry standards.
7.What is the process for return or replacement of TPS2378DDA?
All TPS2378DDA units undergo pre-shipment inspection (PSI). If there is an issue with TPS2378DDA, 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 TPS2378DDA part is unused and in its original packaging.
Return procedure for TPS2378DDA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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