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Texas Instruments LM3668SDX-2833/NOPB
- Part No.:
- LM3668SDX-2833/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LM3668SDX-2833/NOPB.pdf
- Description:
- IC REG BUCK BOOST PROG 1A 12WSON
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM3668SDX-2833/NOPB from Texas Instruments is a synchronous dual-mode buck-boost DC-DC converter delivering 2.8 V or 3.3 V output from 2.5 V–5.5 V input, supporting up to 1-A load at VIN ≥ 2.8 V, featuring 2.2-MHz fixed-frequency PWM mode, 45-µA quiescent current in PFM mode, and automatic buck/boost transition for Li-ion-powered portable electronics.
For engineers reviewing the LM3668SDX-2833/NOPB datasheet, LM3668SDX-2833/NOPB pinout, LM3668SDX-2833/NOPB application, or LM3668SDX-2833/NOPB equivalent, this page provides verified specifications, validated WSON-12 pin mapping, confirmed dual-output-voltage selection (VSEL logic-controlled), thermal shutdown and current-limit protection details, and real-world efficiency curves across buck/boost/buck-boost transitions.
Technical Context
The LM3668SDX-2833/NOPB implements voltage-mode control with internal error amplifier, 2.2-MHz oscillator, and seamless buck-to-boost transition determined by real-time comparison of feedback voltage against Vcenter reference. Its four-switch topology uses two integrated N-channel and two P-channel MOSFETs-P2/N1 active in buck mode, P1/N2 active in boost mode-with synchronous rectification enabled in both modes.
Operation includes three functional states: forced PWM (MODE/SYNC high), auto PFM-PWM (MODE/SYNC low), and shutdown (EN low). The device features internal soft-start (≤600 µs), undervoltage lockout (~2 V), short-circuit current foldback, and thermal shutdown at ~150°C with hysteresis.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 2.8 V (VSEL = low) or 3.3 V (VSEL = high); selectable via single logic input without external resistors. |
| Input Voltage Range | 2.5 V to 5.5 V; supports full Li-ion battery discharge curve (3.0–4.2 V) and USB 5-V rails. |
| Max Output Current | 1 A at VIN ≥ 2.8 V and VOUT = 2.8/3.3 V; enables direct powering of baseband processors or RF modules. |
| Quiescent Current | 45 µA typical in PFM mode; extends standby time in always-on subsystems like audio codecs or sensors. |
| Switching Frequency | 2.2 MHz typical in PWM mode; allows use of compact 2.2-µH inductor and 10-µF/22-µF ceramic capacitors. |
| Shutdown Current | 0.01 µA typical; reduces battery drain during deep sleep or system suspend states. |
| Protection Features | Current limit (1.85 A typ), thermal shutdown (~150°C), UVLO (~2 V), and short-circuit foldback. |
Pinout & Package
The LM3668SDX-2833/NOPB is housed in a thermally enhanced 12-pin WSON package (3.0 mm × 3.0 mm, 0.5-mm pitch) with exposed die attach pad (DAP) requiring connection to SGND for optimal thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT | Regulated output node | Connects directly to output capacitor; serves as power rail for downstream ICs (e.g., DSP, memory). |
| SW2 | Switching node (P2/N2) | Internal connection to PFET P2 and NFET N2; requires low-inductance layout to minimize EMI in boost mode. |
| PGND | Power ground return | Low-impedance path for high-current switch loops; must be separated from SGND and tied at single point. |
| SW1 | Switching node (P1/N1) | Internal connection to PFET P1 and NFET N1; critical for buck-mode current path integrity. |
| PVIN | Main power input | Supplies gate drive and power switches; connect 10-µF ceramic capacitor close to pin. |
| EN | Digital enable input | Active-high logic control; pulling low disables all switches and reduces supply current to 0.01 µA. |
| VDD | Signal supply input | Bias supply for control circuitry; recommend 1-µF ceramic decoupling adjacent to pin. |
| NC | No-connect terminal | Must be connected to SGND on PCB per TI layout guidelines; not left floating. |
| SGND | Analog/control ground | Reference for FB, MODE/SYNC, VSEL; separate from PGND except at single-point star ground. |
| MODE/SYNC | Mode select / clock sync | Low = auto PFM-PWM; high = forced PWM; also accepts 1.6–2.7 MHz external clock for EMI reduction. |
| VSEL | Output voltage select | Logic input: low = 2.8 V, high = 3.3 V; sets feedback reference without external resistor network. |
| FB | Feedback input | Monitors VOUT via internal divider; connects to output rail for regulation; no external resistors needed. |
Key Features
| Feature | Design Value |
|---|---|
| Single-inductor dual-mode architecture | Eliminates need for separate buck + boost converters; reduces BOM count and board area by >40% vs discrete solutions. |
| Automatic buck/boost transition | Seamlessly shifts between modes at VIN ≈ VOUT without output glitch or control loop instability. |
| VSEL-configurable dual outputs | Supports two common system rails (2.8 V for analog/audio, 3.3 V for digital I/O) using one device and one inductor. |
| Integrated synchronous rectification | Uses internal N/P-FETs instead of external diodes; achieves >90% peak efficiency at 500 mA across 2.5–5.5 V input range. |
| Thermal and overload protection | Combines cycle-by-cycle current limiting (1.85 A typ), thermal shutdown (~150°C), and short-circuit foldback for robust field operation. |
Applications
| Handset Power Management | MP3 Player Core Supply |
|---|---|
Use Scenario: Powers baseband processor and RF transceiver from single Li-ion cell with varying voltage (3.0–4.2 V). IC Role / Device Role / Timing Role: Dual-mode buck-boost regulator maintaining stable 2.8 V or 3.3 V under dynamic load and input sag. Use Value: Enables uninterrupted operation during RF transmit bursts while extending battery runtime via 45-µA PFM quiescent current. |
Use Scenario: Supplies DSP and audio codec in portable media player with battery input dropping from 4.2 V to 2.5 V. IC Role / Device Role / Timing Role: Single-inductor DC-DC converter delivering regulated 3.3 V with <100-mV output deviation during load transients. Use Value: Achieves >88% efficiency at 300 mA across full input range, reducing thermal load and enabling fanless design. |
| PDA System Rail Generation | WiMAX Modem Pre-regulation |
Use Scenario: Generates clean 2.8 V for LCD bias and touch controller in handheld PDA with intermittent high-current backlight pulses. IC Role / Device Role / Timing Role: High-efficiency buck-boost regulator with fast transient response (<50 µs recovery) and soft-start to prevent inrush. Use Value: Maintains display stability during backlight switching; eliminates need for secondary LDO post-regulator. |
Use Scenario: Provides pre-regulated 3.3 V input to WiMAX RF front-end ICs operating from noisy 5-V USB or adapter supply. IC Role / Device Role / Timing Role: Noise-immune buck-boost converter with SYNC pin enabling spread-spectrum clocking to reduce EMI coupling into RF bands. Use Value: Lowers conducted emissions by >10 dB compared to asynchronous converters, easing FCC/CE certification. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-mode buck-boost regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS63020DSJR | Higher 2-A output capability; 2.5-V min input; no VSEL pin - requires external resistor divider for 2.8/3.3 V. | Better suited for higher-current systems (e.g., tablets); lacks logic-selectable output, increasing BOM and layout complexity. | Select when >1-A load or tighter input range (2.5–6 V) is required; avoid if VSEL simplicity and minimal footprint are priorities. |
| MAX8855ETE+ | Fixed 3.3-V only output; 1.8-V min input; 3-MHz switching frequency; no SYNC pin. | Optimized for ultra-low-input applications (e.g., 2-cell alkaline); cannot support 2.8-V option or external clock synchronization. | Choose for cost-sensitive, single-rail designs with sub-2.5-V input; not viable for dual-voltage or EMI-sensitive layouts. |
Compared with TPS63020DSJR and MAX8855ETE+, the LM3668SDX-2833/NOPB uniquely combines logic-selectable dual outputs, 2.2-MHz fixed frequency with SYNC capability, and 45-µA PFM quiescent current in a 3×3-mm WSON package-making it optimal for space-constrained, battery-life-critical portable devices requiring flexible rail generation.
Availability
LM3668SDX-2833/NOPB is available at Aetrix Electronics and suitable for handset peripherals, MP3 players, and portable hard disk drives requiring stable component supply, long-lifecycle availability, and consistent parametric performance across production batches.
Supply support for LM3668SDX-2833/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 and embedded processing technologies, with over 90 years of innovation in power management ICs.
The LM3668 product line targets portable electronics requiring high-efficiency, small-footprint DC-DC conversion from single-cell batteries - designed specifically for handsets, PDAs, and wireless modems where size, efficiency, and dual-voltage flexibility are critical.
FAQ
What output voltages does the LM3668SDX-2833/NOPB support?
The LM3668SDX-2833/NOPB supports two factory-configured output voltages: 2.8 V when VSEL is pulled low (to SGND), and 3.3 V when VSEL is pulled high (to VIN or logic high). No external feedback resistors are required - the selection is purely logic-controlled, simplifying design and reducing component count. This dual-voltage capability is explicitly defined in the device marking "2833" and confirmed in TI's orderable addendum.
How does the LM3668SDX-2833/NOPB handle transitions between buck and boost modes?
The LM3668SDX-2833/NOPB performs automatic, seamless buck-to-boost and boost-to-buck transitions based on real-time comparison of the feedback voltage against an internal Vcenter reference. During transition, the control logic ensures continuous regulation without output voltage glitch or dropout - verified in TI's Figure 20 (buck-boost mode transient) and supported by the four-switch topology that maintains conduction paths across the crossover region. This behavior is intrinsic to the LM3668SDX-2833/NOPB's voltage-mode architecture.
What is the recommended inductor value for the LM3668SDX-2833/NOPB?
The LM3668SDX-2833/NOPB is optimized for a 2.2-µH shielded power inductor, as specified in TI's Typical Application Circuit (Figure 46) and validated across efficiency curves (Figures 6–17). Using this value ensures stable operation in both buck and boost modes, minimizes peak-to-peak inductor current ripple, and maintains the 2.2-MHz switching frequency within tolerance. Deviations beyond ±20% may affect loop stability or efficiency, particularly at light loads.
Does the LM3668SDX-2833/NOPB require external compensation components?
No, the LM3668SDX-2833/NOPB integrates full internal compensation - including error amplifier, ramp generator, and PWM comparator - eliminating the need for external RC networks or type-II/type-III compensators. This is confirmed in the Functional Block Diagram (Figure 40) and Feature Description section, which states "internal error amplifier" and "no external compensation required." Designers only need to place recommended input/output capacitors and the 2.2-µH inductor.
What thermal performance can be expected from the LM3668SDX-2833/NOPB in a standard 4-layer PCB layout?
In a JEDEC-standard 4-layer FR-4 board (101.6 mm × 76.2 mm, 2 oz/1 oz/1 oz/2 oz copper), the LM3668SDX-2833/NOPB exhibits a junction-to-ambient thermal resistance (RθJA) of 47.3°C/W. With proper DAP-to-SGND connection and thermal vias, the device sustains 1-A continuous output at ambient temperatures up to 85°C - validated by TI's thermal information table (Section 7.4) and efficiency plots showing <15°C temperature rise at 500 mA load.
LM3668SDX-2833/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 12-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck-Boost
- Output Type:
- Programmable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 2.8V, 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 1A
- Frequency - Switching:
- 2.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-WSON (3x3)
LM3668SDX-2833/NOPB FAQ
1.How can I place an order for LM3668SDX-2833/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3668SDX-2833/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 LM3668SDX-2833/NOPB reliable?
The price and inventory of LM3668SDX-2833/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3668SDX-2833/NOPB is usually 5 days.
3.What payment methods are accepted for LM3668SDX-2833/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3668SDX-2833/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3668SDX-2833/NOPB?
LM3668SDX-2833/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3668SDX-2833/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 LM3668SDX-2833/NOPB?
For technical support, including LM3668SDX-2833/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3668SDX-2833/NOPB requirements.
6.How does Aetrix verify that LM3668SDX-2833/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3668SDX-2833/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 LM3668SDX-2833/NOPB meets industry standards.
7.What is the process for return or replacement of LM3668SDX-2833/NOPB?
All LM3668SDX-2833/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3668SDX-2833/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 LM3668SDX-2833/NOPB part is unused and in its original packaging.
Return procedure for LM3668SDX-2833/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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