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Texas Instruments LM3678SD-1.2/NOPB
- Part No.:
- LM3678SD-1.2/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LM3678SD-1.2/NOPB.pdf
- Description:
- IC REG BUCK PROG 1.5A 10SON
- Quantity:
- Payment:
- Shipping:
Inventory:1,140
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Product details
Overview
LM3678SD-1.2/NOPB from Texas Instruments is a high-efficiency, synchronous step-down DC-DC converter optimized for single-cell Li-Ion battery-powered handheld devices. It delivers up to 1.5 A at a fixed 1.2 V output, operates from 2.5 V to 5.5 V input, features 3.3 MHz fixed-frequency PWM control, and integrates both PFET and NFET switches in a 3 mm × 3 mm WSON-10 package for compact portable power rails.
For engineers reviewing the LM3678SD-1.2/NOPB datasheet, LM3678SD-1.2/NOPB pinout, LM3678SD-1.2/NOPB application, or LM3678SD-1.2/NOPB equivalent, key selection criteria include its ±3% output voltage precision, 0.01 µA shutdown current, internal soft-start, PGOOD flag, and VSELECT-controlled dual-output-voltage capability (0.8 V/1.2 V).
Technical Context
The LM3678SD-1.2/NOPB employs voltage-mode PWM control with input voltage feed-forward to maintain stable regulation across wide VIN and load transients. Its internal 0.5 V reference feeds an error amplifier that compares FB voltage against VREF, modulating PFET on-time to regulate output.
It integrates synchronous rectification using internal PFET (150–200 mΩ) and NFET (110–150 mΩ) switches, enabling high efficiency at low output voltages. Protection includes cycle-by-cycle current limiting (2.15 A typical), thermal shutdown (150°C), undervoltage lockout, and soft-start sequencing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.2 V ±3% - ensures stable core logic or memory rail without external feedback resistors. |
| Input Voltage Range | 2.5 V to 5.5 V - supports direct operation from single Li-Ion (2.7–4.2 V) or regulated 3.3 V/5 V rails. |
| Max Output Current | 1.5 A continuous - sufficient for application processors, RF transceivers, or display drivers in handhelds. |
| Switching Frequency | 3.3 MHz (typical), 2.7–3.6 MHz range - enables use of 1 µH inductors and minimizes solution footprint (<33 mm²). |
| Shutdown Current | 0.01 µA (typical) - preserves battery life during system sleep or standby modes. |
| PGOOD Flag | Open-drain output active when VOUT within ±7.5% - provides system-level power sequencing and fault monitoring. |
| VSELECT Logic | Logic-high selects 1.2 V; logic-low selects 0.8 V - allows dynamic voltage scaling or hardware-configurable output selection. |
Pinout & Package
LM3678SD-1.2/NOPB is housed in a thermally enhanced 3 mm × 3 mm WSON-10 package (DSC-10) with exposed die attach pad (DAP) for PCB ground connection to improve thermal performance. The DAP must be soldered to a dedicated GND copper area with multiple vias.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1,2 GND | Power and analog ground reference | Separate pins reduce noise coupling between power return paths and sensitive analog circuitry. |
| 3 SW | Switching node | Connects to internal PFET drain and NFET source; carries high di/dt switching current - requires short, low-inductance routing. |
| 4,5 VDD | Analog and power supply input | Both pins connect to input capacitor; dual VDD improves current sharing and reduces IR drop in high-current paths. |
| 6 VSELECT | Output voltage select control | Digital input determining fixed output: HIGH = 1.2 V, LOW = 0.8 V - compatible with GPIO or pull-up/down resistor. |
| 7 PGOOD | Power-good status flag | Open-drain output pulled low if VOUT deviates >±7.5%; requires external pull-up for system monitoring. |
| 8 PWM | PWM mode enable | Must be tied to VIN to activate fixed-frequency PWM operation - not used in PFM mode. |
| 9 EN | Enable control | Active-high logic: <0.4 V = shutdown (0.01 µA IQ), >1.0 V = enabled - prevents floating via pull-down resistor. |
| 10 FB | Feedback input | Internally connected to 0.5 V reference; unused in fixed-output versions but must be tied to VOUT per layout guidelines. |
| DAP | Thermal pad | Exposed copper pad under package - must be soldered to solid GND plane with ≥4 thermal vias for thermal dissipation (θJA = 49.8°C/W). |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Integrated PFET (150–200 mΩ) and NFET (110–150 mΩ) eliminate external Schottky loss - boosts efficiency by 8–12% vs. diode-based buck at 1.2 V/1 A. |
| 3.3-MHz fixed-frequency PWM | Enables 1-µH inductor use and ultra-compact BOM - reduces total solution size to <33 mm² with only three external components (L, CIN, COUT). |
| Internal soft-start | Gradually ramps switch current limit (250 mA → 500 mA → 1 A → 2 A) - limits inrush current and prevents output overshoot during startup. |
| Current-limit protection | 2.15 A (typ) peak switch current limit with timed recovery during overload - prevents thermal runaway during short-circuit or heavy transient events. |
| Thermal shutdown | Engages at TJ = 150°C (typ), releases at 130°C - protects silicon integrity under sustained high-power or poor PCB thermal conditions. |
Applications
| Smartphone Application Processor Core Rail | USB Modem Baseband Power |
|---|---|
Use Scenario: Powers ARM Cortex-A series CPU cores requiring tightly regulated 1.2 V at up to 1.5 A during burst processing. IC Role / Device Role / Timing Role: Primary synchronous buck regulator delivering clean, low-noise DC power with fast transient response to handle CPU DVFS transitions. Use Value: 3.3 MHz switching and internal FETs minimize voltage droop during 0→1 A load steps, maintaining core stability without external compensation. | Use Scenario: Supplies 1.2 V to USB 2.0 modem ICs (e.g., LTE baseband SoCs) operating from 3.6 V battery input in portable hotspots. IC Role / Device Role / Timing Role: Compact, high-efficiency point-of-load converter enabling full-speed USB data transfer without thermal throttling. Use Value: 0.01 µA shutdown current extends standby time; PGOOD flag synchronizes modem boot sequence with host enumeration. |
| Portable Media Player DSP Rail | Wi-Fi/BT Combo Module Power |
Use Scenario: Provides 1.2 V to audio DSPs and codec interfaces in personal media players with strict EMI and ripple requirements. IC Role / Device Role / Timing Role: Low-noise, high-PSRR buck regulator minimizing switching artifacts in analog audio signal paths. Use Value: Fixed 1.2 V output eliminates FB resistor network errors; 3.3 MHz frequency shifts noise spectrum above sensitive audio band (20 Hz–20 kHz). | Use Scenario: Powers dual-band Wi-Fi + Bluetooth combo modules (e.g., TI WL1837MOD) in smartphones and tablets. IC Role / Device Role / Timing Role: High-current, thermally robust DC-DC stage supporting burst transmit currents up to 1.2 A while maintaining RF isolation. Use Value: Exposed DAP and low RDS(on) FETs sustain 1.2 A at TA = 85°C without derating; VSELECT allows firmware-controlled voltage scaling for different radio modes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down DC-DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62231DRVR | Fixed 1.2 V, 3 MHz, 0.65 µA IQ, 6-pin WSON - lacks PGOOD, VSELECT, and thermal shutdown. | No power-good signaling or dual-voltage flexibility; suited for simpler, lower-power systems. | Choose when minimal BOM count and ultra-low quiescent current outweigh need for fault reporting or voltage scaling. |
| TPS62130ARGTR | Adjustable 0.9–3.6 V, 2.5 A, 2.25 MHz, 16-pin QFN - requires external feedback resistors and has larger footprint. | Supports wider output range and higher current but increases design complexity and board area. | Choose when system requires programmable output or >1.5 A load capability, accepting added layout and component overhead. |
Compared with TPS62231DRVR, LM3678SD-1.2/NOPB adds PGOOD monitoring and VSELECT flexibility at slightly higher IQ; versus TPS62130ARGTR, it trades adjustability and current headroom for smaller size, lower cost, and simplified fixed-voltage implementation.
Availability
LM3678SD-1.2/NOPB is available at Aetrix Electronics and suitable for smartphone power management, USB modem subsystems, portable media player DSP supplies, and Wi-Fi/BT module rails requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM3678SD-1.2/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 technologies, with decades of expertise in high-efficiency DC-DC conversion for portable electronics.
The LM3678 product line was designed specifically for space-constrained, battery-powered handheld applications - delivering high current density, low quiescent power, and integrated protection in miniature WSON packages.
FAQ
What is the output voltage tolerance of the LM3678SD-1.2/NOPB?
The LM3678SD-1.2/NOPB provides a fixed 1.2 V output with ±3% DC accuracy over temperature and line/load conditions. This specification is guaranteed across the full operating ambient temperature range (−30°C to +85°C) and input voltage range (2.5 V to 5.5 V), ensuring reliable operation for core logic rails without external trimming.
Does the LM3678SD-1.2/NOPB require external feedback resistors?
No, the LM3678SD-1.2/NOPB does not require external feedback resistors. It is a fixed-output variant with internal resistor divider setting 1.2 V; the FB pin is internally connected to the 0.5 V reference and must be tied directly to the output capacitor per TI layout recommendations to ensure stability and noise immunity.
How does the VSELECT pin function on the LM3678SD-1.2/NOPB?
On the LM3678SD-1.2/NOPB, the VSELECT pin configures the output voltage: logic HIGH (≥1.2 V) selects 1.2 V, and logic LOW (≤0.4 V) selects 0.8 V. Though the part is marked "-1.2", VSELECT remains functional - enabling hardware-selectable dual-rail operation without changing the bill of materials.
What is the recommended inductor value for the LM3678SD-1.2/NOPB?
Texas Instruments recommends a 1 µH shielded inductor with ≥2.5 A saturation current rating (e.g., Taiyo Yuden NR4012T1R0N) for the LM3678SD-1.2/NOPB. This value leverages the 3.3 MHz switching frequency to minimize size and ripple while maintaining stability across the full 0–1.5 A load range and input voltage span.
Can the LM3678SD-1.2/NOPB operate from a 2.5 V input?
Yes, the LM3678SD-1.2/NOPB is fully specified to operate from 2.5 V input, delivering 1.2 V at up to 1.5 A. However, TI recommends enabling the device only after VIN reaches 2.5 V or higher - and holding EN low during initial power-up below this threshold to prevent unstable regulation or excessive current draw.
LM3678SD-1.2/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Programmable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.8V, 1.2V
- Voltage - Output (Max):
- -
- Current - Output:
- 1.5A
- Frequency - Switching:
- 3.3MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -30°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-SON (3x3)
LM3678SD-1.2/NOPB FAQ
1.How can I place an order for LM3678SD-1.2/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3678SD-1.2/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 LM3678SD-1.2/NOPB reliable?
The price and inventory of LM3678SD-1.2/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3678SD-1.2/NOPB is usually 5 days.
3.What payment methods are accepted for LM3678SD-1.2/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3678SD-1.2/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3678SD-1.2/NOPB?
LM3678SD-1.2/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3678SD-1.2/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 LM3678SD-1.2/NOPB?
For technical support, including LM3678SD-1.2/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3678SD-1.2/NOPB requirements.
6.How does Aetrix verify that LM3678SD-1.2/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3678SD-1.2/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 LM3678SD-1.2/NOPB meets industry standards.
7.What is the process for return or replacement of LM3678SD-1.2/NOPB?
All LM3678SD-1.2/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3678SD-1.2/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 LM3678SD-1.2/NOPB part is unused and in its original packaging.
Return procedure for LM3678SD-1.2/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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