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Texas Instruments LM3668SD-4550/NOPB
- Part No.:
- LM3668SD-4550/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LM3668SD-4550/NOPB.pdf
- Description:
- IC REG BUCK BOOST PROG 1A 12WSON
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM3668SD-4550/NOPB from Texas Instruments is a synchronous dual-mode buck-boost DC-DC converter delivering regulated 4.5 V or 5.0 V output from 2.5 V–5.5 V input, supporting up to 1-A load at VIN ≥ 3.9 V, featuring 2.2-MHz fixed-frequency PWM operation, 45-µA quiescent current in PFM mode, and internal synchronous rectification for high efficiency in portable Li-Ion-powered systems.
For engineers reviewing the LM3668SD-4550/NOPB datasheet, LM3668SD-4550/NOPB pinout, LM3668SD-4550/NOPB application, or LM3668SD-4550/NOPB equivalent, this device is selected for compact, battery-efficient power conversion where input voltage may fall below or rise above the required output - especially in WiMax modems, portable HDDs, and handheld peripherals requiring stable dual-voltage rail generation with minimal external components.
Technical Context
The LM3668SD-4550/NOPB implements a single-inductor buck-boost topology with four internal MOSFETs (two P-channel, two N-channel) enabling seamless mode transition between buck and boost based on real-time VIN-to-VOUT comparison. Its voltage-mode control loop uses an internal error amplifier and 2.2-MHz oscillator to regulate output with ±3% feedback accuracy.
Operation includes three functional states: forced PWM (fixed 2.2 MHz), automatic PFM-PWM (45 µA IQ at light load), and shutdown (0.01 µA). The MODE/SYNC pin supports either intelligent mode selection or external clock synchronization (1.6–2.7 MHz), while VSEL sets output to 4.5 V (low) or 5.0 V (high) - precisely matching the LM3668SD-4550/NOPB variant specification.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Configurable 4.5 V (VSEL = low) or 5.0 V (VSEL = high); enables dual-rail support without external resistors |
| Input Voltage Range | 2.5 V to 5.5 V; compatible with single-cell Li-Ion (2.7–4.2 V) and 3-cell NiMH (3.0–4.5 V) batteries |
| Max Output Current | 1 A at VIN ≥ 3.9 V; ensures full-load capability across typical battery discharge curve for 5-V peripherals |
| Switching Frequency | 2.2 MHz (typical, PWM mode); allows use of small 2.2-µH inductor and 10-µF/22-µF ceramic capacitors |
| Quiescent Current | 45 µA (typical, PFM mode); extends standby time in always-on portable devices like WiMax modems |
| Shutdown Current | 0.01 µA (typical); minimizes battery drain during system sleep or power-off states |
| Feedback Accuracy | ±3% over −40°C to +85°C; maintains tight regulation across temperature without calibration |
Pinout & Package
LM3668SD-4550/NOPB is housed in a thermally enhanced 12-pin WSON (DQB) package, 3.00 mm × 3.00 mm, with exposed die attach pad (DAP) connected to SGND for improved thermal performance. Pin count, layout, and thermal metrics (RθJA = 47.3°C/W) are validated per JEDEC JESD51-7 on 4-layer FR-4 board.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT | Regulated output node | Connects directly to output capacitor; delivers stable 4.5 V or 5.0 V to load |
| SW2 | Switching node (P2/N2) | Internal connection to PFET P2 and NFET N2; critical for boost-mode energy transfer |
| PGND | Power ground return | Low-impedance path for high-current switch return; separate from analog ground |
| SW1 | Switching node (P1/N1) | Internal connection to PFET P1 and NFET N1; critical for buck-mode energy transfer |
| PVIN | Main power input | Supplies power switches; connect to 10-µF input capacitor near pin for low-ESR filtering |
| EN | Digital enable input | Active-high logic control; pulling low disables converter and reduces IQ to 0.01 µA |
| VDD | Signal supply | Bias supply for control circuitry; recommended 1-µF ceramic decoupling capacitor |
| NC | No-connect terminal | Must be tied to SGND on PCB; no internal connection |
| SGND | Analog/control ground | Reference for FB, MODE/SYNC, VSEL; must be star-connected to DAP and PGND |
| MODE/SYNC | Mode select / clock sync | Low = auto PFM-PWM; high = forced PWM; also accepts 1.6–2.7 MHz external clock |
| VSEL | Output voltage select | Logic low → 4.5 V; logic high → 5.0 V; defines LM3668SD-4550/NOPB's dual-output capability |
| FB | Feedback input | Monitors VOUT via resistor divider; internal reference is 0.6 V; accuracy ±3% over temp |
Key Features
| Feature | Design Value |
|---|---|
| Single-inductor buck-boost architecture | Eliminates need for separate buck + boost ICs or dual inductors; reduces BOM count and board area by >30% |
| Automatic buck/boost mode transition | Seamless crossover at VIN ≈ VOUT without output glitch or control-loop instability |
| Internal synchronous rectification | Uses integrated N-channel MOSFETs (N1/N2) instead of diodes; improves efficiency by 8–12% at 500-mA load |
| Thermal and overload protection | Integrated thermal shutdown (150°C trip) and cycle-by-cycle current limiting (1.85-A peak) prevent damage under fault |
| Internal soft-start | 600-µs max startup time with controlled ramp; prevents inrush current and output overshoot at power-on |
Applications
| Handset Peripherals | WiMax Modems |
|---|---|
Use Scenario: Powering RF front-end modules, audio codecs, and display drivers in smartphones with dynamically varying battery voltage. IC Role / Device Role / Timing Role: Primary buck-boost regulator generating stable 4.5 V or 5.0 V from collapsing Li-Ion cell (2.8–4.2 V). Use Value: Maintains full functionality during deep discharge; eliminates brownouts when VBAT drops below 3.3 V while preserving 5-V interface compliance. |
Use Scenario: Supplying 5-V PA bias and baseband ICs in portable WiMax CPE units operating from USB or battery sources. IC Role / Device Role / Timing Role: Efficient step-up/down converter enabling single-rail design across 3.3–5.5 V input range. Use Value: Delivers 1-A peak current at >90% efficiency in both buck and boost modes, reducing thermal load and extending field-deployed runtime. |
| Portable Hard Disk Drives | MP3 Players |
Use Scenario: Providing regulated 5-V motor drive and 4.5-V logic supply for 2.5-inch HDDs powered by single-cell Li-Ion. IC Role / Device Role / Timing Role: Dual-output-capable DC-DC converter supporting simultaneous 4.5 V and 5.0 V rails via VSEL toggling. Use Value: Enables direct replacement of discrete buck + LDO solutions; reduces solution size by 40% and improves transient response to spin-up loads. |
Use Scenario: Powering DSP, DAC, and OLED display in ultra-thin MP3 players where board space and battery life are critical. IC Role / Device Role / Timing Role: Low-quiescent-current buck-boost regulator maintaining 4.5 V output during playback and standby. Use Value: 45-µA PFM IQ extends playback time by >15% vs. conventional PWM-only converters; 2.2-MHz switching avoids audible noise. |
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 2.5-A output capability; 2.5-MHz switching; requires external VSEL resistor network for 4.5/5.0 V | Targeted at higher-power applications (e.g., tablets); lacks integrated VSEL logic for direct 4.5/5.0 V selection | Choose TPS63020DSJR only if >1-A load or tighter output tolerance (<±2%) is required; adds routing complexity |
| MAX8815AETE+T | Fixed 4.5-V output only; no VSEL pin; 1.5-MHz switching; 50-µA PFM IQ | Suitable for cost-sensitive 4.5-V-only designs; cannot support 5.0-V mode without redesign | Select MAX8815AETE+T only for fixed 4.5-V applications where VSEL flexibility is unnecessary and footprint is secondary |
Compared with TPS63020DSJR and MAX8815AETE+T, the LM3668SD-4550/NOPB uniquely integrates hardware-selectable 4.5/5.0 V outputs, 2.2-MHz operation for ultra-compact filtering, and 45-µA PFM IQ - making it optimal for space-constrained, dual-voltage portable systems requiring zero-resistor configuration and minimal bill-of-materials.
Availability
LM3668SD-4550/NOPB is available at Aetrix Electronics and suitable for WiMax modems, portable hard disk drives, and handset peripherals requiring stable component supply with guaranteed long-term manufacturability and consistent electrical performance.
Supply support for LM3668SD-4550/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 decades of expertise in power management ICs for portable and industrial applications.
The LM3668 product line was designed specifically for high-efficiency, single-inductor buck-boost conversion in space- and battery-constrained portable electronics - targeting applications where input voltage crosses the output setpoint and seamless mode transition is essential.
FAQ
What output voltages does the LM3668SD-4550/NOPB support?
The LM3668SD-4550/NOPB supports two factory-configured output voltages: 4.5 V when VSEL is pulled low (to SGND), and 5.0 V when VSEL is pulled high (to VIN or logic high). This dual-output capability is hardwired into the LM3668SD-4550/NOPB variant and requires no external feedback resistors.
How does the LM3668SD-4550/NOPB handle input voltage crossing the output voltage?
The LM3668SD-4550/NOPB automatically transitions between buck and boost modes using internal voltage-mode control and real-time VIN/VOUT comparison. During crossover (e.g., VIN dropping from 4.8 V to 4.2 V while regulating 4.5 V), the device maintains regulation without dropout or glitch - confirmed in Figure 20 of the SNVS449O datasheet.
What is the maximum load current the LM3668SD-4550/NOPB can deliver at 4.5 V output?
At 4.5 V output, the LM3668SD-4550/NOPB delivers up to 1 A when input voltage is 3.9 V or higher, 800 mA at VIN = 3.4–3.8 V, and 700 mA at VIN = 3.0–3.3 V - all specified in the "For 4.5 V–5 V" section of the official datasheet (SNVS449O, p.1).
Does the LM3668SD-4550/NOPB require external compensation components?
No, the LM3668SD-4550/NOPB features fully internal compensation. Its voltage-mode control loop is factory-tuned for stability with standard 2.2-µH inductors and 22-µF ceramic output capacitors - eliminating the need for external RC networks or loop compensation adjustments.
Can the LM3668SD-4550/NOPB synchronize to an external clock?
Yes - when the MODE/SYNC pin is driven high, the LM3668SD-4550/NOPB enters forced PWM mode and accepts an external clock signal from 1.6 MHz to 2.7 MHz applied to the same pin, enabling EMI reduction through frequency dithering or system-level clock alignment.
LM3668SD-4550/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 12-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Not For New Designs
- 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):
- 4.5V, 5V
- 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)
LM3668SD-4550/NOPB FAQ
1.How can I place an order for LM3668SD-4550/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3668SD-4550/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 LM3668SD-4550/NOPB reliable?
The price and inventory of LM3668SD-4550/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3668SD-4550/NOPB is usually 5 days.
3.What payment methods are accepted for LM3668SD-4550/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3668SD-4550/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3668SD-4550/NOPB?
LM3668SD-4550/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3668SD-4550/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 LM3668SD-4550/NOPB?
For technical support, including LM3668SD-4550/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3668SD-4550/NOPB requirements.
6.How does Aetrix verify that LM3668SD-4550/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3668SD-4550/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 LM3668SD-4550/NOPB meets industry standards.
7.What is the process for return or replacement of LM3668SD-4550/NOPB?
All LM3668SD-4550/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3668SD-4550/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 LM3668SD-4550/NOPB part is unused and in its original packaging.
Return procedure for LM3668SD-4550/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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