My Inquiry
My Account
Texas Instruments LM2678T-3.3/NOPB
- Part No.:
- LM2678T-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-220-7 Formed Leads
- Datasheet:
-
LM2678T-3.3/NOPB.pdf
- Description:
- IC REG BUCK 3.3V 5A TO220-7
- Quantity:
- Payment:
- Shipping:
Inventory:223
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM2678T-3.3/NOPB from Texas Instruments is a monolithic step-down (buck) switching voltage regulator delivering up to 5A output at fixed 3.3V, with 8–40V input range, 260kHz fixed-frequency operation, ±2% output tolerance, and 120mΩ internal DMOS switch. It serves as a high-efficiency primary DC/DC converter in industrial power supplies and embedded system rails.
For engineers reviewing the LM2678T-3.3/NOPB datasheet, LM2678T-3.3/NOPB pinout, LM2678T-3.3/NOPB application, or LM2678T-3.3/NOPB equivalent, key selection criteria include its 3.3V fixed output, thermal shutdown protection, ON/OFF control interface, 50μA standby current, and TO-263-7 (KTW) package compatibility with high-current PCB layouts.
Technical Context
The LM2678T-3.3/NOPB integrates a high-side DMOS power switch, fixed 260kHz PWM controller, internal feedback reference, and thermal/current protection circuitry. Its architecture uses bootstrap gate drive (CB pin) for full enhancement of the 120mΩ switch, enabling >90% efficiency at 5A load with minimal external components.
It operates in continuous conduction mode by default, supports shutdown via TTL-compatible ON/OFF pin (1.4V threshold), and maintains regulation across –40°C to 125°C junction temperature. The FB pin is internally tied to the 3.3V output divider, eliminating external resistors-unlike adjustable versions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±2% over full line/load/temperature (–40°C to 125°C) |
| Max Output Current | 5A continuous; current limit 6.1–8.3A (temperature-dependent) |
| Input Voltage Range | 8V to 40V DC - supports wide-input industrial and battery-derived supplies |
| Switching Frequency | 260kHz ±11% - enables use of compact, off-the-shelf inductors & capacitors |
| Efficiency | Up to 92% (at 12VIN/5A for 12V version); 82% typical at 12VIN/5A for 3.3V version |
| Quiescent Current | 6mA active; 50μA standby when ON/OFF pin = 0V - critical for low-power sleep modes |
| RDS(ON) | 0.12Ω typical at 25°C - minimizes conduction loss in high-current paths |
Pinout & Package
LM2678T-3.3/NOPB is supplied in the KTW (TO-263-7) thermally enhanced surface-mount package (10.1mm × 15.24mm), featuring an exposed thermal pad (DAP) that must be soldered to a PCB ground plane for optimal thermal performance (RθJA = 35°C/W with 0.4896 in² copper).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switch output | Drain node of internal high-side DMOS FET; connects to inductor and Schottky diode cathode - high dv/dt node requiring tight layout |
| 2 (VIN) | Input supply | Main power input (8–40V); requires low-ESR bypass capacitor placed <1cm from pin to minimize ringing |
| 3 (CB) | Bootstrap capacitor | Connects 100nF ceramic capacitor to SW pin to generate gate drive voltage >VIN for full FET enhancement |
| 4 (GND) | Power ground | Primary return path for input/output capacitors and thermal pad - must tie directly to large ground plane |
| 5 (NC) | No connect | Internally unconnected; leave floating or grounded per layout best practice (no functional impact) |
| 6 (FB) | Feedback sense | Internally connected to 3.3V output divider - short directly to VOUT for fixed-version regulation; no external resistors needed |
| 7 (ON/OFF) | Enable control | TTL-compatible digital input: >1.4V = ON, <0.8V = OFF; draws only 20μA when sourcing; internal 7V clamp protects against overvoltage |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 120mΩ DMOS switch | Eliminates need for external MOSFET and driver; reduces BOM count and layout complexity for 5A buck designs |
| Fixed 3.3V output with ±2% tolerance | Guarantees precise rail generation without trimming or external feedback resistors - simplifies qualification and production test |
| 260kHz fixed-frequency oscillator | Enables predictable EMI filtering and consistent inductor sizing; avoids frequency jitter seen in variable-frequency controllers |
| Thermal shutdown + current limiting | Self-protects under overload or poor heatsinking - prevents catastrophic failure during transient faults or startup surges |
| 50μA standby quiescent current | Supports ultra-low-power system sleep states while retaining fast wake-up capability via ON/OFF pin |
Applications
| Industrial PLC Power Rail | Automotive Infotainment Core Supply |
|---|---|
Use Scenario: Providing stable 3.3V main logic rail for programmable logic controllers operating from 24V bus with wide ambient temperature swings. IC Role / Device Role / Timing Role: Primary step-down regulator converting unregulated 24V to clean 3.3V for microcontroller, FPGA, and I/O peripherals. Use Value: Delivers 5A continuous current with ±2% output accuracy and thermal shutdown - ensuring reliable operation in sealed enclosures up to 70°C ambient. | Use Scenario: Generating 3.3V core voltage for infotainment SoC in vehicles where input voltage varies from 9V (cranking) to 16V (charging). IC Role / Device Role / Timing Role: High-efficiency preregulator feeding low-dropout linear regulators for noise-sensitive audio and display subsystems. Use Value: Maintains regulation down to 8V input and withstands 40V load-dump transients; 82%+ efficiency at 5A reduces thermal load in confined dash modules. |
| Medical Portable Device Battery Converter | Networking Equipment PoE Midspan Supply |
Use Scenario: Converting dual-cell Li-ion (6–8.4V) to regulated 3.3V for wireless telemetry and sensor processing in handheld diagnostics tools. IC Role / Device Role / Timing Role: Main DC/DC converter enabling long battery life via high efficiency and ultra-low 50μA shutdown current. Use Value: Achieves >85% efficiency across 6–8.4V input range; ON/OFF pin allows firmware-controlled power gating between measurements. | Use Scenario: Generating 3.3V auxiliary rail in Power over Ethernet (PoE) midspan injectors powering remote switches and access points. IC Role / Device Role / Timing Role: Secondary regulator deriving isolated 3.3V from intermediate 12V or 24V bus generated from PoE input. Use Value: TO-263-7 package provides robust thermal performance on dense PoE board layouts; 260kHz switching avoids interference with Ethernet signal bands. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2678-3.3 | Same silicon, identical electrical specs; differs only in RoHS/non-RoHS marking and packaging (bulk vs tape-and-reel) | No functional difference; LM2678-3.3 lacks /NOPB suffix but shares same KTW package and 3.3V fixed output | Select LM2678T-3.3/NOPB for lead-free compliance and automated assembly; LM2678-3.3 may be used if legacy RoHS waiver applies |
| TPS54560QDGQRQ1 | 42V input, 5A sync-buck with 3.5V–42V range, 100kHz–2.5MHz adjustable freq, integrated high/low-side FETs | Requires external compensation; supports wider VIN and higher efficiency (>94%) but adds design complexity | Choose TPS54560QDGQRQ1 for automotive AEC-Q100 qualification and flexible frequency tuning; LM2678T-3.3/NOPB preferred for cost-sensitive, fixed-frequency simplicity |
Compared with LM2678-3.3, the LM2678T-3.3/NOPB guarantees lead-free compliance and optimized tape-and-reel handling, while versus TPS54560QDGQRQ1 it trades programmability and AEC-Q100 for lower BOM cost, zero-compensation design, and proven field reliability in industrial systems.
Availability
LM2678T-3.3/NOPB is available at Aetrix Electronics and suitable for industrial PLCs, automotive infotainment systems, portable medical devices, and PoE-powered networking equipment requiring stable component supply and long-term manufacturability.
Supply support for LM2678T-3.3/NOPB 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 leader specializing in analog, embedded processing, and power management ICs, with decades of expertise in high-reliability power conversion solutions.
The LM2678 series belongs to TI's SIMPLE SWITCHER® family - designed specifically to simplify high-current DC/DC buck regulator implementation using minimal external components and industry-standard magnetics.
FAQ
What is the maximum input voltage rating for LM2678T-3.3/NOPB?
The absolute maximum input voltage for LM2678T-3.3/NOPB is 45V, but the recommended operating range is 8V to 40V DC. Exceeding 40V continuously risks violating thermal limits or triggering internal protection circuits. The device is commonly used with 24V industrial buses and 12V/28V automotive systems, and can survive brief 40V load-dump transients per specification.
Does LM2678T-3.3/NOPB require external feedback resistors?
No, LM2678T-3.3/NOPB does not require external feedback resistors. As a fixed-output variant, its internal resistor divider is factory-trimmed to set 3.3V output; the FB pin is internally connected to this network. Users simply connect FB directly to the output capacitor - unlike the adjustable LM2678 versions which require two external resistors to program VOUT.
What package type is used for LM2678T-3.3/NOPB?
LM2678T-3.3/NOPB is packaged in the KTW (TO-263-7) thermally enhanced surface-mount package, measuring 10.1mm × 15.24mm with an exposed thermal pad (DAP). This package provides superior heat dissipation compared to TO-220 alternatives and is optimized for high-current PCB layouts with direct DAP-to-ground-plane soldering.
How does the ON/OFF pin function on LM2678T-3.3/NOPB?
The ON/OFF pin (Pin 7) on LM2678T-3.3/NOPB is a TTL-compatible enable input: driving it below 0.8V disables the regulator, reducing quiescent current to 50μA; pulling it above 1.4V enables normal operation. It features an internal 20μA pull-up and 7V Zener clamp, allowing direct connection to microcontroller GPIO without level-shifting or external biasing.
Can LM2678T-3.3/NOPB be used in continuous conduction mode at full 5A load?
Yes, LM2678T-3.3/NOPB is rated for continuous 5A output in continuous conduction mode (CCM) when properly heatsinked. With the KTW package mounted on ≥0.4896 in² copper area, it sustains 5A at 12VIN with junction temperature ≤125°C. Efficiency remains ≥82% under these conditions, and internal current limiting (6.1–8.3A) provides fault protection during transients.
LM2678T-3.3/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- TO-220-7 Formed Leads
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 8V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 5A
- Frequency - Switching:
- 260kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-7
LM2678T-3.3/NOPB FAQ
1.How can I place an order for LM2678T-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2678T-3.3/NOPB 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 LM2678T-3.3/NOPB reliable?
The price and inventory of LM2678T-3.3/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2678T-3.3/NOPB is usually 5 days.
3.What payment methods are accepted for LM2678T-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2678T-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2678T-3.3/NOPB?
LM2678T-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2678T-3.3/NOPB 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 LM2678T-3.3/NOPB?
For technical support, including LM2678T-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2678T-3.3/NOPB requirements.
6.How does Aetrix verify that LM2678T-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2678T-3.3/NOPB 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 LM2678T-3.3/NOPB meets industry standards.
7.What is the process for return or replacement of LM2678T-3.3/NOPB?
All LM2678T-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2678T-3.3/NOPB, 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 LM2678T-3.3/NOPB part is unused and in its original packaging.
Return procedure for LM2678T-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM2678T-3.3/NOPB Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
