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Texas Instruments LM3676SDX-ADJ
- Part No.:
- LM3676SDX-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LM3676SDX-ADJ.pdf
- Description:
- IC REG BUCK ADJ 600MA 8WSON
- Quantity:
- Payment:
- Shipping:
Inventory:1,716
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Product details
Overview
LM3676SDX-ADJ from Texas Instruments is a 2-MHz, 600-mA synchronous step-down DC-DC converter optimized for single Li-Ion battery (2.9V–5.5V) power rails in portable electronics. It delivers adjustable output voltage (1.1V–3.3V), features automatic PFM/PWM mode switching, internal soft-start, and thermal/overcurrent protection. Used in mobile phones and digital cameras for efficient low-voltage core rail generation.
For engineers reviewing the LM3676SDX-ADJ datasheet, LM3676SDX-ADJ pinout, LM3676SDX-ADJ application, or LM3676SDX-ADJ equivalent, key selection criteria include its 8-lead WSON package, 0.5V internal reference, 16µA quiescent current in PFM mode, 1020mA typical current limit, and support for external feedback resistor networks to set VOUT.
Technical Context
The LM3676SDX-ADJ employs voltage-mode PWM control with input voltage feed-forward for stable line regulation. Its internal 2-MHz oscillator enables compact 2.2µH inductor and ceramic capacitor designs. The device integrates PFET and NFET synchronous rectifiers with 380mΩ/250mΩ typical RDS(ON), eliminating external diodes.
Mode control is implemented via a dedicated MODE pin (<0.4V for Auto PFM/PWM, >1.0V for forced PWM), while FB pin senses output through an external resistor divider. Shutdown is controlled by EN pin (<0.4V disables operation, drawing only 0.01µA).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.9V to 5.5V - supports full discharge curve of single Li-Ion cell without dropout. |
| Max Output Current | 600 mA - sustained load capability across full input range and temperature (−30°C to +125°C). |
| Switching Frequency | 2 MHz typical - enables use of tiny 2.2 µH inductor and 4.7 µF/10 µF ceramic capacitors. |
| Quiescent Current | 16 µA typical in PFM mode - extends battery life during light-load standby in portable devices. |
| Feedback Reference | 0.5 V - sets output via external R1/R2 divider; supports 1.1V–3.3V adjustable VOUT. |
| Current Limit | 1020 mA typical - protects internal switches and external components during overload or short-circuit. |
| Shutdown Current | 0.01 µA typical - ensures near-zero power draw when disabled via EN pin. |
Pinout & Package
LM3676SDX-ADJ is housed in an 8-lead non-pullback WSON package (Package Number NGQ0008A, 2.0 mm × 2.0 mm × 0.8 mm, exposed thermal pad). This RoHS-compliant, lead-free package provides low thermal resistance (θJA = 56°C/W on 4-layer board) and supports automated assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 PGND | Power Ground | High-current return path for internal PFET/NFET switches; must be connected to low-impedance ground plane. |
| 2 SW | Switch Node | Connection point between internal PFET drain and NFET source; ties to inductor and output filter. |
| 3 MODE | Mode Control Input | Digital input selecting Auto (PFM/PWM) or forced PWM; <0.4V = Auto, >1.0V = PWM, floating prohibited. |
| 4 FB | Feedback Input | Analog input sensing output voltage via external resistor divider; internal 0.5V reference sets VOUT = 0.5V × (1 + R1/R2). |
| 5 VIN | Input Supply | Main power input (2.9V–5.5V); requires local 4.7 µF ceramic capacitor placed adjacent to pin. |
| 6 NC | No Connect | Internally unconnected; must remain floating - no PCB trace or component connection. |
| 7 SGND | Signal Ground | Reference for FB, EN, MODE pins; should be routed separately from PGND and joined at single point. |
| 8 EN | Enable Input | Active-high digital enable; <0.4V = shutdown (0.01 µA ISHDN), >1.0V = operational. |
Key Features
| Feature | Design Value |
|---|---|
| Internal Synchronous Rectification | Integrated PFET/NFET pair replaces external Schottky diode, reducing conduction loss and improving efficiency at low VOUT. |
| Automatic PFM/PWM Mode Switching | Transitions seamlessly between high-efficiency PFM (16 µA IQ) at light loads and low-noise PWM (2 MHz fixed) above ~100 mA. |
| Internal Soft-Start | Gradually ramps switch current limit (70→140→280→1020 mA) to limit inrush current during startup with 10 µF COUT. |
| Thermal & Overcurrent Protection | Thermal shutdown engages at TJ ≈ 150°C; cycle-by-cycle current limiting prevents damage during sustained overload. |
| 100% Duty-Cycle LDO Mode | Operates linearly (PFET fully on) when VIN ≈ VOUT, supporting dropout down to ILOAD × RDS(ON) + VOUT with ~25 mV ripple. |
Applications
| Mobile Phone Power Management | Digital Still Camera Core Rail |
|---|---|
Use Scenario: Powers baseband processor core voltage (1.2V–1.8V) from a single Li-Ion battery in smartphones with dynamic load profiles. IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated, low-noise supply with fast transient response to CPU DVFS events. Use Value: 2-MHz switching enables compact 2.2 µH inductor and 10 µF ceramic output capacitor, reducing PCB area by >40% vs. 500-kHz alternatives. | Use Scenario: Supplies image sensor and ISP logic rails (1.1V–2.5V) in compact digital cameras requiring ultra-low quiescent current during standby. IC Role / Device Role / Timing Role: Adjustable-output DC-DC converter enabling precise voltage tuning per sensor vendor requirements. Use Value: 16 µA PFM quiescent current extends battery runtime during multi-hour idle periods without compromising wake-up speed. |
| MP3 Player Audio Codec Supply | WLAN Baseband Processor Rail |
Use Scenario: Generates clean 1.5V supply for audio DAC/ADC in portable music players with strict EMI limits. IC Role / Device Role / Timing Role: Low-noise synchronous buck converter operating in forced PWM mode to suppress switching frequency harmonics near audio band. Use Value: Fixed 2-MHz PWM eliminates variable-frequency PFM noise, simplifying EMI filtering and meeting Class D amplifier immunity specs. | Use Scenario: Provides 1.8V or 2.8V supply to WLAN SoC in handheld devices with bursty RF transmit/receive current demands. IC Role / Device Role / Timing Role: High-efficiency buck regulator with fast load transient response (<10 µs recovery) to maintain stable voltage during TX power ramp-up. Use Value: Automatic PFM→PWM transition at ~100 mA ensures minimal voltage droop during 802.11ac packet transmission bursts. |
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 | 3-MHz fixed-frequency, 600-mA sync buck; 0.6-V reference; 17-µA IQ in PFM; WSON-6 package (2.0×2.0 mm). | Smaller footprint (6-pin vs. 8-pin), but lacks MODE pin for explicit PWM forcing and has no NC pin. | Preferred where board space is critical and Auto mode suffices; not suitable if forced PWM control or signal/power ground separation (SGND/PGND) is required. |
| TPS62260DRVR | 2.25-MHz, 600-mA sync buck; 0.6-V reference; 19-µA IQ; includes I2C interface for dynamic voltage scaling; WSON-8 package. | Offers programmable output via I2C instead of resistor divider; higher IQ and no dedicated MODE pin. | Select when system-level DVFS is needed; avoid when analog feedback adjustment or pin-compatible replacement for LM3676SDX-ADJ layout is mandatory. |
Compared with TPS62231DRVR and TPS62260DRVR, the LM3676SDX-ADJ provides explicit MODE pin control, separate SGND/PGND terminals for noise-sensitive layouts, and a 0.5-V reference enabling tighter output tolerance with standard resistor values - making it optimal for cost-sensitive, fixed-function portable designs requiring design simplicity and proven reliability.
Availability
LM3676SDX-ADJ is available at Aetrix Electronics and suitable for mobile phone power management, digital still camera core rails, MP3 player audio codec supplies, and WLAN baseband processor rails requiring stable component supply across production lifecycles.
Supply support for LM3676SDX-ADJ 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 company headquartered in Dallas, Texas, designing and manufacturing analog ICs, embedded processors, and digital signal processors for industrial, automotive, and consumer markets.
The LM3676 product line targets ultra-compact, high-efficiency DC-DC conversion in battery-powered portable electronics, emphasizing low quiescent current, small external component count, and robust protection features for Li-Ion systems.
FAQ
What is the minimum input voltage required for LM3676SDX-ADJ to regulate a 1.2V output?
The LM3676SDX-ADJ can operate in 100% duty-cycle LDO mode when input voltage approaches the output level. Minimum VIN is calculated as VIN,MIN = ILOAD × (RDS(ON)(P) + RINDUCTOR) + VOUT. For 1.2V at 100 mA, with typical 380 mΩ PFET RDS(ON) and 0.1 Ω inductor DCR, VIN,MIN ≈ 1.2V + 0.118V = 1.318V - though functional regulation requires VIN ≥ 2.9V per datasheet operating rating. Below 2.9V, the device enters undervoltage lockout and ceases switching.
How do I configure LM3676SDX-ADJ for a 1.8V output?
To set LM3676SDX-ADJ to 1.8V, use the formula VOUT = 0.5V × (1 + R1/R2). With R2 = 200 kΩ (recommended for noise immunity and low divider current), R1 = 520 kΩ yields 1.8V. Table 1 in the SNVS426C datasheet confirms R1 = 464 kΩ and R2 = 178 kΩ for 1.8V; C1 = 8.2 pF is added for stability. Place R1 between VOUT and FB, R2 between FB and SGND, and connect C1 from FB to SGND.
Does LM3676SDX-ADJ require an external compensation network?
Yes - unlike fixed-output versions, the LM3676SDX-ADJ requires external compensation for stability when using the adjustable feedback configuration. For VOUT ≤ 2.5V, add C1 (e.g., 8.2 pF for 1.8V) from FB to SGND to introduce a zero near 45 kHz. For VOUT > 2.5V (e.g., 2.8V or 3.3V), add both C1 and C2 (e.g., 8.2 pF and 33 pF) to place a pole-zero pair. These values are specified in Table 1 of the SNVS426C datasheet and must be used to prevent oscillation.
Can LM3676SDX-ADJ be used with a 1 µH inductor?
No - the LM3676SDX-ADJ datasheet specifies a minimum inductance of 1.76 µH at rated current and temperature, and recommends 2.2 µH for reliable performance. A 1 µH inductor would increase peak inductor current beyond the 1020 mA typical limit, risk saturation, degrade efficiency, and potentially trigger overcurrent protection under full 600 mA load. TI's suggested inductors (e.g., Coilcraft DO3314-222MX) are all 2.2 µH with ≥1200 mA saturation rating.
What is the purpose of the NC pin on LM3676SDX-ADJ?
Pin 6 on the LM3676SDX-ADJ is designated NC (No Connect) and is internally unconnected. It must remain electrically floating - no PCB trace, pull-up, pull-down, or capacitor should be attached. Connecting this pin may cause unpredictable behavior or damage. The NC pin exists for package compatibility within the LM3676 family and does not serve any functional role in the LM3676SDX-ADJ device.
LM3676SDX-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.9V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.1V
- Voltage - Output (Max):
- 3.3V
- Current - Output:
- 600mA
- Frequency - Switching:
- 2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -30°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-WSON (3x3)
LM3676SDX-ADJ FAQ
1.How can I place an order for LM3676SDX-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3676SDX-ADJ 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 LM3676SDX-ADJ reliable?
The price and inventory of LM3676SDX-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3676SDX-ADJ is usually 5 days.
3.What payment methods are accepted for LM3676SDX-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3676SDX-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3676SDX-ADJ?
LM3676SDX-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3676SDX-ADJ 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 LM3676SDX-ADJ?
For technical support, including LM3676SDX-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3676SDX-ADJ requirements.
6.How does Aetrix verify that LM3676SDX-ADJ is sourced from the original manufacturer or authorized distributors?
All LM3676SDX-ADJ 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 LM3676SDX-ADJ meets industry standards.
7.What is the process for return or replacement of LM3676SDX-ADJ?
All LM3676SDX-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM3676SDX-ADJ, 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 LM3676SDX-ADJ part is unused and in its original packaging.
Return procedure for LM3676SDX-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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