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Texas Instruments LM3679UR-1.2/NOPB
- Part No.:
- LM3679UR-1.2/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 5-XFBGA, DSBGA
- Datasheet:
-
LM3679UR-1.2/NOPB.pdf
- Description:
- IC REG BUCK 1.2V 350MA 5DSBGA
- Quantity:
- Payment:
- Shipping:
Inventory:2,500
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Product details
Overview
LM3679UR-1.2/NOPB from Texas Instruments is a 3 MHz, 350 mA synchronous step-down DC-DC converter optimized for ultra-low-profile mobile power rails. It delivers a fixed 1.2 V output from a single Li-Ion cell (2.5 V to 5.5 V input), features automatic PFM/PWM mode switching, 16 µA typical quiescent current, and internal soft-start - enabling use in space-constrained applications such as digital still cameras and MP3 players.
For engineers reviewing the LM3679UR-1.2/NOPB datasheet, LM3679UR-1.2/NOPB pinout, LM3679UR-1.2/NOPB application, or LM3679UR-1.2/NOPB equivalent, key selection criteria include its 5-bump DSBGA YPD package (0.3 mm height), 0.55 mm max solution height with external components, ±2.5% output voltage accuracy in PWM mode, and integrated synchronous rectification for >90% efficiency at 300 mA load.
Technical Context
The LM3679UR-1.2/NOPB implements voltage-mode control with input voltage feed-forward to maintain stable regulation across 2.5 V–5.5 V input range. Its internal 0.5 V reference and feedback loop regulate output via external resistor divider - though for the -1.2/NOPB variant, the divider is internal, fixing VOUT = 1.2 V.
It integrates complementary PFET and NFET switches (RDSON(P) = 450 mΩ typ, RDSON(N) = 250 mΩ typ), a 3 MHz oscillator, thermal shutdown (150°C trip), current limit (950 mA typ), and undervoltage lockout. Mode transitions occur automatically: PWM (>80 mA), PFM (1–80 mA), and shutdown (<0.4 V on EN).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.2 V ±2.5% (PWM mode); enables direct powering of low-voltage core logic without external resistors. |
| Max Output Current | 350 mA continuous; supports high-efficiency operation up to full load across full input range (2.7 V–5.5 V). |
| Switching Frequency | 3 MHz (2.5–3.5 MHz range); permits use of sub-1 µH inductors and 0603-size ceramic capacitors for minimal PCB footprint. |
| Quiescent Current | 16 µA typical in PFM mode; extends battery life in standby/low-load states (e.g., display-off in portable instruments). |
| Shutdown Current | 0.01 µA typical; reduces system leakage during deep sleep or power-off sequences. |
| Input Voltage Range | 2.5 V to 5.5 V; compatible with single-cell Li-Ion (fully charged to depleted) and regulated 3.3 V/5 V rails. |
| Feedback Reference | Internal 0.5 V bandgap; eliminates external resistor network for fixed-output variants like LM3679UR-1.2/NOPB. |
Pinout & Package
LM3679UR-1.2/NOPB uses a lead-free 5-bump DSBGA YPD package (0.3 mm height, 1.0 mm × 1.0 mm footprint), optimized for ultra-thin mobile designs. The package supports 0.55 mm max solution height when paired with specified low-profile external components (e.g., LQM21PN1R0MC0 inductor and dual JMK107BJ475K capacitors).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (A1) | Power input | Accepts 2.5–5.5 V; must be decoupled with ≥4.7 µF ceramic capacitor placed adjacent to pin to suppress high-frequency switching noise. |
| GND (A3) | Ground reference | Primary return path for PFET/NFET switches and control circuitry; requires low-inductance connection to power plane. |
| EN (C1) | Enable control | Active-high logic input; device enabled at >1.0 V, disabled at <0.4 V; must not float - tie to GND or host GPIO for sequencing. |
| FB (C3) | Feedback sense | Internally connected to 1.2 V divider; no external resistors required - simplifies layout and improves stability vs. adjustable variants. |
| SW (B2) | Switching node | Drives external inductor; carries high di/dt pulses; requires short, wide trace and tight coupling to GND to minimize EMI and voltage spikes. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic PFM/PWM mode switching | Eliminates manual mode control; maintains >85% efficiency from 1 mA to 350 mA by dynamically selecting optimal regulation strategy. |
| Internal synchronous rectification | Replaces lossy Schottky diode with integrated NFET (250 mΩ RDSON), improving efficiency by ~8% at 100 mA vs. asynchronous alternatives. |
| Soft-start circuit | Staged current-limit ramp (200→400→600→920 mA) prevents inrush into large output caps; ensures controlled 200–300 µs startup even at full 350 mA load. |
| Thermal & current protection | Integrated shutdown triggers at 150°C junction temp and 950 mA peak switch current - protects IC and external inductor under fault conditions. |
| Ultra-low profile packaging | YPD DSBGA (0.3 mm height) enables total solution height ≤0.55 mm - meets mechanical constraints of slim digital cameras and ultraportable audio devices. |
Applications
| Digital Still Cameras | MP3 Players |
|---|---|
Use Scenario: Powering image sensor core and ISP logic during burst capture mode with rapid on/off cycling. IC Role / Device Role / Timing Role: Primary 1.2 V buck regulator delivering stable rail with fast transient response to handle sensor pixel readout surges. Use Value: 3 MHz switching and internal soft-start ensure <300 µs voltage stabilization after wake-up, minimizing frame drop during startup. | Use Scenario: Supplying DSP and audio codec during playback with intermittent high-current decode bursts. IC Role / Device Role / Timing Role: Efficient 1.2 V power source that transitions seamlessly between PFM (standby) and PWM (active decode) modes. Use Value: 16 µA quiescent current extends battery runtime in pause mode; 90%+ efficiency at 200 mA sustains >10-hour playback. |
| Portable Hard Disk Drives | Mobile Phones (Baseband Core) |
Use Scenario: Providing regulated 1.2 V to HDD controller ASIC during spin-up and data transfer phases. IC Role / Device Role / Timing Role: High-current (350 mA) synchronous buck converter with thermal foldback to prevent overheating in sealed enclosures. Use Value: Integrated current limit (950 mA) and thermal shutdown protect against motor stall-induced overloads without external sensing. | Use Scenario: Powering application processor core voltage domain in LTE smartphones with aggressive power gating. IC Role / Device Role / Timing Role: Always-on 1.2 V supply enabling fast wake-from-sleep transitions while maintaining low system leakage. Use Value: 0.01 µA shutdown current minimizes battery drain during extended idle periods; EN pin allows precise SoC-controlled sequencing. |
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 |
|---|---|---|---|
| TPS62231DRYR | Fixed 1.2 V output, 3 MHz switching, but uses 6-pin WSON (2 mm × 2 mm, 0.8 mm height); higher IQ (25 µA PFM) and lower max current (300 mA). | Less suitable for ultra-low-profile designs due to larger footprint and height; better for cost-sensitive mid-volume production. | Select TPS62231DRYR if board space allows larger package and 300 mA suffices; avoid when 0.55 mm solution height is mandatory. |
| AP63202WU-12 | 1.2 V fixed output, 2.5 MHz switching, SOT-563 package (1.6 mm × 1.6 mm, 0.6 mm height); no PFM mode - operates PWM-only with 40 µA IQ. | Higher quiescent current limits battery life in always-on sensors; SOT-563 eases assembly but increases solution height beyond 0.55 mm. | Choose AP63202WU-12 only for non-battery applications or where reflow simplicity outweighs profile and efficiency requirements. |
Compared with LM3679UR-1.2/NOPB, TPS62231DRYR trades ultra-thinness for wider availability and simpler layout, while AP63202WU-12 sacrifices PFM efficiency and profile for robust SMT manufacturability - making LM3679UR-1.2/NOPB the sole choice for <0.55 mm height + battery longevity-critical designs.
Availability
LM3679UR-1.2/NOPB is available at Aetrix Electronics and suitable for digital still cameras, portable hard disk drives, MP3 players, and mobile phone baseband power rails requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.
Supply support for LM3679UR-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 LM3679 product line was designed specifically for ultra-thin battery-powered devices demanding minimal solution height, automatic light-load efficiency optimization, and seamless integration with Li-Ion power sources - targeting mobile imaging, audio, and communications subsystems.
FAQ
What is the maximum recommended output current for LM3679UR-1.2/NOPB in a 0.55 mm low-profile solution?
The LM3679UR-1.2/NOPB supports up to 300 mA continuous output current when implemented with the recommended low-profile external components (e.g., LQM21PN1R0MC0 inductor and dual JMK107BJ475K capacitors). At 350 mA, thermal derating applies - maximum ambient temperature drops to 60°C on a 4-layer JEDEC board per the dissipation rating table. For full 350 mA capability, standard-height external components and enhanced thermal layout are required.
Does LM3679UR-1.2/NOPB require external feedback resistors to set the 1.2 V output?
No, LM3679UR-1.2/NOPB does not require external feedback resistors. It integrates an internal resistor divider referenced to the 0.5 V internal bandgap, fixing the output at 1.2 V. This eliminates layout complexity, improves regulation accuracy by removing resistor tolerance errors, and enhances stability - distinguishing it from adjustable variants like LM3679TL.
How does the automatic PFM/PWM mode switching in LM3679UR-1.2/NOPB improve battery life?
LM3679UR-1.2/NOPB reduces quiescent current from 35 µA (PWM) to 16 µA (PFM) under light loads (<80 mA), extending battery runtime in standby or low-activity states. During PFM mode, it also lowers switching frequency and disables non-essential bias circuits - demonstrated by >85% efficiency at 1 mA load, versus <60% for fixed-frequency alternatives. This behavior is fully automatic and requires no external control signals.
What is the minimum input voltage required to enable LM3679UR-1.2/NOPB safely?
The LM3679UR-1.2/NOPB should not be enabled until VIN reaches at least 2.5 V. Although the EN pin activates at >1.0 V, the device's undervoltage lockout (UVLO) prevents proper regulation below 2.5 V input. Enabling prematurely risks unstable output, excessive current draw, or failure to start. TI recommends holding EN low until VIN stabilizes above 2.5 V - especially critical during Li-Ion battery cold-start conditions.
Can LM3679UR-1.2/NOPB be used with ceramic capacitors smaller than 0603 size?
No, LM3679UR-1.2/NOPB is not characterized or recommended for use with capacitors smaller than 0603 (1608 metric). The 3 MHz switching frequency demands low-ESR, high-SRF ceramics; 0402 parts exhibit degraded capacitance under DC bias and insufficient ripple current handling. TI's Bill of Materials specifies JMK107BJ475K (0603, 4.7 µF) for CIN and dual units for COUT - using smaller case sizes risks output instability, increased ripple, and thermal stress on the IC.
LM3679UR-1.2/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 5-XFBGA, DSBGA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.2V
- Voltage - Output (Max):
- -
- Current - Output:
- 350mA
- Frequency - Switching:
- 3MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -30°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 5-DSBGA (1.47x1.02)
LM3679UR-1.2/NOPB FAQ
1.How can I place an order for LM3679UR-1.2/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3679UR-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 LM3679UR-1.2/NOPB reliable?
The price and inventory of LM3679UR-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 LM3679UR-1.2/NOPB is usually 5 days.
3.What payment methods are accepted for LM3679UR-1.2/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3679UR-1.2/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3679UR-1.2/NOPB?
LM3679UR-1.2/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3679UR-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 LM3679UR-1.2/NOPB?
For technical support, including LM3679UR-1.2/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3679UR-1.2/NOPB requirements.
6.How does Aetrix verify that LM3679UR-1.2/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3679UR-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 LM3679UR-1.2/NOPB meets industry standards.
7.What is the process for return or replacement of LM3679UR-1.2/NOPB?
All LM3679UR-1.2/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3679UR-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 LM3679UR-1.2/NOPB part is unused and in its original packaging.
Return procedure for LM3679UR-1.2/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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