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Texas Instruments LM3678SDE-1.2/NOPB
- Part No.:
- LM3678SDE-1.2/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LM3678SDE-1.2/NOPB.pdf
- Description:
- IC REG BUCK PROG 1.5A 10SON
- Quantity:
- Payment:
- Shipping:
Inventory:156
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Product details
Overview
LM3678SDE-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 engineers reviewing the LM3678SDE-1.2/NOPB datasheet, LM3678SDE-1.2/NOPB pinout, LM3678SDE-1.2/NOPB application, or LM3678SDE-1.2/NOPB equivalent, key selection criteria include its 1.2 V fixed output, ±3% DC voltage precision, 0.01 µA shutdown current, internal soft start, and thermal/current protection - all critical for compact, battery-sensitive designs like smartphones and portable media players.
Technical Context
The LM3678SDE-1.2/NOPB implements a voltage-mode PWM controller with input voltage feed-forward for stable line regulation across 2.5–5.5 V input. Its 3.3 MHz switching frequency enables use of a 1-µH inductor and minimizes solution footprint.
Internal synchronous rectification uses a 110–150 mΩ NFET and 150–200 mΩ PFET to maximize efficiency at low output voltages. The device includes cycle-by-cycle current limiting (2.15 A typical), thermal shutdown at 150°C, and undervoltage lockout below 2.5 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.2 V with ±3% DC precision - ensures stable core voltage for low-power processors and RF ICs. |
| Input Voltage Range | 2.5 V to 5.5 V - supports full discharge curve of single Li-Ion cell (3.0–4.2 V nominal) plus USB/adapter rails. |
| Max Output Current | 1.5 A continuous - sufficient for application processors, baseband ICs, and multi-core SoCs in handhelds. |
| Switching Frequency | 3.3 MHz (typical), 2.7–3.6 MHz range - allows ultra-small 1-µH inductors and reduces EMI fundamental frequency. |
| Shutdown Current | 0.01 µA typical - extends battery life during system sleep or standby modes. |
| Thermal Protection | Engages at TJ = 150°C (typ), disengages at 130°C - prevents permanent damage under sustained overload or poor PCB thermal design. |
| Feedback Reference | 0.5 V internal reference - used with fixed-resistor divider in adjustable versions; not externally accessible in LM3678SDE-1.2/NOPB. |
Pinout & Package
LM3678SDE-1.2/NOPB is housed in a thermally enhanced 3 mm × 3 mm WSON-10 (DSC-10) package with exposed die attach pad (DAP) that must be connected to PCB ground for optimal thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2 | GND | Power and analog ground pins - require low-impedance connection to PCB ground plane; DAP must also be soldered to GND. |
| 3 | SW | Switching node - connects internally to PFET drain and NFET source; carries high di/dt ripple current; requires short, wide trace routing. |
| 4, 5 | VDD | Analog and power supply inputs - connect jointly to input capacitor (CIN = 10 µF ceramic); decouples high-frequency switching noise. |
| 6 | VSELECT | Output voltage select - logic HIGH sets VOUT = 1.2 V (active for this variant); logic LOW would set 0.8 V (not applicable here). |
| 7 | PGOOD | Open-drain power-good flag - pulled low when VOUT deviates >±7.5% from regulation; used for system sequencing or fault monitoring. |
| 8 | PWM | Internal oscillator enable - must be tied to VIN; disables internal clock if left floating or grounded. |
| 9 | EN | Enable control - device active when EN ≥ 1.0 V; enters 0.01 µA shutdown when EN ≤ 0.4 V; must not float. |
| 10 | FB | Feedback input - internally connected to fixed 1.2 V divider; not externally accessible in this variant; leave unconnected per datasheet. |
| DAP | Thermal pad | Die attach pad - must be soldered to solid GND copper area on PCB; provides primary thermal path to board (θJA = 49.8°C/W). |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Integrated 150 mΩ PFET + 110 mΩ NFET eliminates external Schottky diode, enabling >90% peak efficiency at 1.2 V/1 A. |
| 3.3 MHz fixed-frequency PWM | Enables use of 1-µH shielded inductors (e.g., Taiyo Yuden NR4012T1R0N), reducing solution size to <33 mm² including CIN/COUT. |
| Internal soft start | Gradually ramps switch current limit (250 mA → 500 mA → 1 A → 2 A) to limit inrush current into 22 µF output capacitor during startup. |
| Comprehensive protection | Includes overcurrent limiting (2.15 A typ), thermal shutdown (150°C), undervoltage lockout (<2.5 V), and PGOOD fault signaling. |
| Ultra-low shutdown current | 0.01 µA typical - reduces quiescent drain on Li-Ion cells during deep sleep, extending shelf life and standby time. |
Applications
| Smartphone Power Management | USB Modem Core Supply |
|---|---|
Use Scenario: Powers application processor I/O and memory interfaces in compact smartphone mainboards where space and thermal headroom are constrained. IC Role / Device Role / Timing Role: Primary 1.2 V buck regulator delivering up to 1.5 A with fast transient response to CPU load changes. Use Value: Enables use of tiny 1-µH inductor and 0805-case capacitors, reducing total BOM area by >40% vs. lower-frequency alternatives. | Use Scenario: Supplies regulated 1.2 V to USB 2.0 modem chipsets operating from 5 V USB bus or battery-backed operation. IC Role / Device Role / Timing Role: Step-down converter maintaining stable rail during USB suspend/resume transitions and modem data bursts. Use Value: 3.3 MHz switching avoids interference with 2.4 GHz Wi-Fi/Bluetooth bands while sustaining >85% efficiency at 500 mA load. |
| Digital Still Camera Sensor Bias | Portable Media Player Audio SoC |
Use Scenario: Provides clean, low-noise 1.2 V supply to CMOS image sensor digital core and ADC interface in DSLR-style portable cameras. IC Role / Device Role / Timing Role: High-PSRR, low-ripple DC-DC stage placed adjacent to sensor ASIC to minimize switching noise coupling. Use Value: Internal synchronous FETs and 3.3 MHz frequency reduce output voltage ripple to <15 mVpp, meeting sensor ADC reference stability requirements. | Use Scenario: Powers audio DSP and codec subsystem in flash-based MP3 players requiring long battery runtime and minimal heat generation. IC Role / Device Role / Timing Role: Efficient 1.2 V rail generator supporting dynamic voltage scaling during playback vs. standby states. Use Value: 0.01 µA shutdown current and ±3% output accuracy extend battery life beyond 20 hours while maintaining audio fidelity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLC59202RTJR | Fixed 1.2 V output, 1.2 A max, 2.5–5.5 V input, but uses 2.25 MHz switching and lacks PGOOD pin. | Lower current capability and no power-good signaling - unsuitable for systems requiring fault detection or >1.2 A loads. | Select only if PGOOD is unnecessary and load stays below 1.2 A; verify thermal derating with 2.25 MHz inductors. |
| TPS62231DRYR | 1.2 V fixed, 1.5 A, 2.05–6.0 V input, 3.6 MHz switching, but requires external compensation and has higher 2.5 µA shutdown current. | No integrated soft start or thermal shutdown - demands additional external circuitry for robustness in handhelds. | Prefer for wider input range (down to 2.05 V) if external compensation and higher quiescent current are acceptable trade-offs. |
Compared with TLC59202RTJR and TPS62231DRYR, LM3678SDE-1.2/NOPB offers superior integration (PGOOD, soft start, thermal shutdown), lower shutdown current (0.01 µA vs. 2.5 µA), and tighter output tolerance (±3% vs. ±4%), making it optimal for space-constrained, battery-critical handheld designs.
Availability
LM3678SDE-1.2/NOPB is available at Aetrix Electronics and suitable for smartphone power management, USB modem core supply, digital still camera sensor bias, and portable media player audio SoC applications requiring stable component supply, consistent parametric performance, and long-term production continuity.
Supply support for LM3678SDE-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 miniature, high-frequency step-down regulation in battery-powered handheld devices - emphasizing ultra-small solution size, low quiescent current, and robust protection for consumer-grade reliability.
FAQ
What is the output voltage configuration of LM3678SDE-1.2/NOPB?
The LM3678SDE-1.2/NOPB is factory-configured for a fixed 1.2 V output. Unlike adjustable variants, it does not require external feedback resistors - the FB pin is internally terminated. VSELECT is hardwired to logic HIGH in this version, confirming the 1.2 V setting per TI's SNVS464C datasheet.
Does LM3678SDE-1.2/NOPB require an external inductor, and what value is recommended?
Yes, LM3678SDE-1.2/NOPB requires an external inductor. Texas Instruments recommends a 1-µH shielded inductor (e.g., Taiyo Yuden NR4012T1R0N) rated for ≥2.5 A saturation current. This value leverages the device's 3.3 MHz switching frequency to minimize size and EMI while supporting full 1.5 A load capability.
How does the PGOOD pin function on LM3678SDE-1.2/NOPB?
The PGOOD pin on LM3678SDE-1.2/NOPB is an open-drain output that pulls low when the regulated 1.2 V output deviates by more than ±7.5% from target. It remains high during normal operation and is used for system power sequencing or fault detection - no pull-up resistor is needed if interfacing with a microcontroller GPIO with internal pull-up.
What thermal management is required for LM3678SDE-1.2/NOPB in a 1.5 A application?
For 1.5 A continuous operation, LM3678SDE-1.2/NOPB requires the DAP (exposed thermal pad) to be soldered to a minimum 100 mm² copper pour connected to PCB ground. With this layout on a 4-layer board, θJA is 49.8°C/W; at 1.5 A and 3.6 V input, power dissipation is ~0.3 W, resulting in ~15°C rise above ambient - well within the −30°C to +85°C operating range.
Can LM3678SDE-1.2/NOPB operate from a 2.5 V input, and what happens below that?
LM3678SDE-1.2/NOPB is specified to operate down to 2.5 V input. Below this threshold, undervoltage lockout (UVLO) engages, disabling switching and placing the device in low-current state. The EN pin must also be ≥1.0 V to enable operation; if VIN drops below 2.5 V while enabled, the part shuts down and draws only 1 µA typical supply current.
LM3678SDE-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)
LM3678SDE-1.2/NOPB FAQ
1.How can I place an order for LM3678SDE-1.2/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3678SDE-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 LM3678SDE-1.2/NOPB reliable?
The price and inventory of LM3678SDE-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 LM3678SDE-1.2/NOPB is usually 5 days.
3.What payment methods are accepted for LM3678SDE-1.2/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3678SDE-1.2/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3678SDE-1.2/NOPB?
LM3678SDE-1.2/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3678SDE-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 LM3678SDE-1.2/NOPB?
For technical support, including LM3678SDE-1.2/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3678SDE-1.2/NOPB requirements.
6.How does Aetrix verify that LM3678SDE-1.2/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3678SDE-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 LM3678SDE-1.2/NOPB meets industry standards.
7.What is the process for return or replacement of LM3678SDE-1.2/NOPB?
All LM3678SDE-1.2/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3678SDE-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 LM3678SDE-1.2/NOPB part is unused and in its original packaging.
Return procedure for LM3678SDE-1.2/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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