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Texas Instruments LM3670MFX-3.3/NOPB
- Part No.:
- LM3670MFX-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3670MFX-3.3/NOPB.pdf
- Description:
- IC REG BUCK 3.3V 350MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:1,474
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Product details
Overview
LM3670MFX-3.3/NOPB from Texas Instruments is a fixed-output 3.3 V synchronous step-down DC-DC converter optimized for ultralow-voltage portable systems. It operates from 2.5 V to 5.5 V input, delivers up to 350 mA load current, features 1-MHz PWM switching, automatic PFM/PWM mode transition, and requires only three external components: one inductor and two ceramic capacitors. It powers core logic rails in battery-powered handheld devices.
For engineers reviewing the LM3670MFX-3.3/NOPB datasheet, LM3670MFX-3.3/NOPB pinout, LM3670MFX-3.3/NOPB application, or LM3670MFX-3.3/NOPB equivalent, key selection criteria include its 3.3 V fixed output, 15 µA quiescent current in PFM mode, 0.1 µA shutdown current, SOT-23-5 package footprint, and compatibility with single Li-Ion or triple NiMH/NiCd battery inputs.
Technical Context
The LM3670MFX-3.3/NOPB implements voltage-mode control with internal 0.5 V reference and feed-forward compensation to maintain tight line regulation (0.26 %/V typical). Its dual-mode operation-fixed-frequency 1-MHz PWM above ~70 mA and hysteretic PFM below-enables high efficiency across wide load ranges (90–95% at 1–100 mA; 90% at 350 mA).
Synchronous rectification uses integrated PFET and NFET switches (RDSON(P) = 360–690 mΩ, RDSON(N) = 250–660 mΩ) to eliminate external diode losses. The device supports 100% duty-cycle LDO-like operation for minimum dropout, with undervoltage lockout (2.4 V) and thermal/overcurrent protection built-in.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±6% over 0–350 mA load and 3.6–5.5 V input; enables direct replacement of LDOs in 3.3 V logic rails. |
| Input Voltage Range | 2.5 V to 5.5 V; supports single-cell Li-Ion (2.7–4.2 V) and three-cell NiMH/NiCd (3.0–4.5 V) without external regulators. |
| Max Load Current | 350 mA continuous; sufficient for powering microcontrollers, sensors, and interface ICs in compact portable designs. |
| Quiescent Current | 15 µA typical in PFM mode; extends battery life during standby or light-load operation in always-on subsystems. |
| Shutdown Current | 0.1 µA typical; reduces system leakage when disabled via EN pin, critical for long-term storage or deep-sleep modes. |
| Switching Frequency | 550–1300 kHz (typical 1 MHz); allows use of small 4.7–10 µH inductors and 4.7–10 µF ceramic capacitors for minimal board area. |
| Efficiency | 90% at 350 mA / 3.6 VIN → 3.3 VOUT; >94% at 10–100 mA, enabling thermally constrained PCB layouts. |
Pinout & Package
The LM3670MFX-3.3/NOPB is housed in a 5-pin SOT-23 package (2.90 mm × 1.60 mm body size), optimized for space-constrained portable PCBs and compatible with standard reflow processes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power input | Accepts 2.5–5.5 V supply; must be decoupled with ≥4.7 µF ceramic capacitor close to pin to suppress switching noise. |
| GND (Pin 2) | Ground reference | Primary return path for input/output currents and internal control circuitry; requires low-impedance connection to power plane. |
| EN (Pin 3) | Digital enable | Active-high logic input (VIH ≥1.3 V, VIL ≤0.4 V); pulls low (<0.4 V) to enter 0.1 µA shutdown state. |
| FB (Pin 4) | Feedback node | Internally tied to 3.3 V reference; not user-adjustable-connect directly to VOUT for fixed-output configuration. |
| SW (Pin 5) | Switching node | Drives external inductor; carries high di/dt current pulses; requires short, low-inductance trace to minimize EMI and voltage spikes. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated synchronous rectification | Eliminates external Schottky diode, reducing conduction loss and improving efficiency by 5–10% vs. asynchronous buck converters. |
| Automatic PFM/PWM mode switching | Transitions seamlessly between high-efficiency light-load PFM (15 µA IQ) and low-noise full-power PWM (1 MHz) without external control. |
| Internal soft-start | 400 µs typical startup time with 10 µF output capacitor; limits inrush current to protect input source and stabilize VOUT ramp. |
| 100% duty-cycle LDO-like operation | Maintains regulated 3.3 V output down to VIN ≈ 3.3 V + ILOAD×(RDS(ON)P + RINDUCTOR), extending usable battery range. |
| Thermal and overload protection | Shuts down on junction temperature >125°C or switch peak current >750 mA, preventing damage during fault conditions. |
Applications
| Mobile Phone Baseband Power | Wearable Sensor Hub Supply |
|---|---|
|
Use Scenario: Powers ARM Cortex-M based baseband processor and RF transceiver ICs in slim smartphone designs using single Li-Ion battery. IC Role / Device Role / Timing Role: Primary 3.3 V step-down regulator delivering stable rail for digital logic, memory interfaces, and analog peripherals. Use Value: 90% efficiency at 350 mA enables thermal compliance in sealed enclosures; 0.1 µA shutdown current preserves battery charge during overnight idle. |
Use Scenario: Supplies 3.3 V to ultra-low-power environmental sensor cluster (accelerometer, humidity, temperature) in fitness tracker. IC Role / Device Role / Timing Role: Always-on power source operating in PFM mode during sensor sleep cycles, switching to PWM only during data acquisition bursts. Use Value: 15 µA quiescent current extends 200 mAh coin-cell battery life to >6 months; SOT-23-5 footprint fits sub-10 mm² PCB area budgets. |
| Industrial Handheld Terminal | Portable Medical Monitor Front-End |
|
Use Scenario: Provides clean 3.3 V rail for barcode scanner ASIC, LCD controller, and Bluetooth LE module in ruggedized inventory scanner. IC Role / Device Role / Timing Role: Main DC-DC converter supporting wide-input battery voltage swing (3.0–4.5 V) while maintaining <±3% output regulation. Use Value: Input range down to 2.5 V ensures reliable operation until battery depletion; 1-MHz switching avoids audible noise in audio-sensitive environments. |
Use Scenario: Powers analog front-end (AFE) and microcontroller in battery-operated ECG/SpO₂ monitor requiring clinical-grade stability. IC Role / Device Role / Timing Role: Low-noise, high-PSRR power stage feeding precision ADCs and op-amps; operates in PWM mode during signal acquisition. Use Value: Internal synchronous rectification minimizes thermal drift in analog sections; soft-start prevents transient-induced measurement errors at power-on. |
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 |
|---|---|---|---|
| TSP53033 | 3.3 V fixed output, 500 mA max, 2.7–5.5 V input, 25 µA IQ, SOT-23-5 package | Higher current capability but higher quiescent current; no PFM mode | Select when >350 mA load or tighter input UVLO (2.7 V) is required; avoid if battery life is primary concern. |
| TPS622313DRYR | 3.3 V fixed output, 300 mA max, 2.05–6.0 V input, 17 µA IQ, 2.5 MHz switching, WSON-6 package | Wider input range and higher frequency allow smaller passives; different package and pinout | Choose for space-critical designs needing <1 mm height; requires PCB redesign due to non-pin-compatible WSON-6 footprint. |
Compared with TSP53033 and TPS622313DRYR, the LM3670MFX-3.3/NOPB offers the lowest shutdown current (0.1 µA), proven PFM/PWM auto-transition for mixed-load systems, and optimal balance of size, efficiency, and cost in SOT-23-5 for mid-power portable applications.
Availability
LM3670MFX-3.3/NOPB is available at Aetrix Electronics and suitable for mobile phones, wearable electronics, and industrial handheld terminals requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.
Supply support for LM3670MFX-3.3/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 and industrial markets.
The LM3670 series was designed specifically for ultralow-voltage battery-powered applications-delivering high efficiency, minimal external components, and robust protection in miniature SOT-23 packages for space- and power-constrained portable electronics.
FAQ
What is the recommended input capacitor for LM3670MFX-3.3/NOPB?
A 4.7 µF X5R/X7R ceramic capacitor placed within 2 mm of the VIN and GND pins is recommended for LM3670MFX-3.3/NOPB. This value provides adequate high-frequency filtering of switching noise and handles the input ripple current without excessive voltage droop. Larger values (e.g., 10 µF) may improve transient response but are not required for basic operation.
Can LM3670MFX-3.3/NOPB operate from a single 3.7 V Li-Ion cell throughout its discharge curve?
Yes, LM3670MFX-3.3/NOPB supports input voltages from 2.5 V to 5.5 V, covering the full discharge range of a single Li-Ion cell (≈4.2 V down to ≈2.7 V). Its 100% duty-cycle capability maintains regulation until VIN drops near 3.3 V plus dropout losses, enabling extended runtime compared to non-synchronous or non-LDO-mode buck converters.
Does LM3670MFX-3.3/NOPB require an external feedback resistor divider?
No, LM3670MFX-3.3/NOPB is a fixed-output variant with internal feedback network set to 3.3 V. Pin FB is internally connected to the reference and must be tied directly to VOUT-no external resistors are used or permitted. Attempting to add external dividers will disrupt regulation and is not supported.
What is the maximum achievable efficiency of LM3670MFX-3.3/NOPB and under what conditions?
The LM3670MFX-3.3/NOPB achieves up to 94% efficiency at 10–100 mA load with 3.6 V input and 3.3 V output in PWM mode. Peak efficiency occurs in this mid-load range due to optimal balance of switching and conduction losses. At 350 mA, efficiency remains at 90%, verified per TI's SNVS250F datasheet Figure 5.
How does the enable (EN) pin function on LM3670MFX-3.3/NOPB?
The EN pin on LM3670MFX-3.3/NOPB is an active-high digital control input. Driving it to ≥1.3 V enables normal operation; pulling it to ≤0.4 V places the device in shutdown mode with 0.1 µA typical supply current. The pin has negligible input current (≤1 µA), allowing direct connection to GPIO or open-drain logic without pull-up resistors.
LM3670MFX-3.3/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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):
- 3.3V
- Voltage - Output (Max):
- -
- Current - Output:
- 350mA
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LM3670MFX-3.3/NOPB FAQ
1.How can I place an order for LM3670MFX-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3670MFX-3.3/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 LM3670MFX-3.3/NOPB reliable?
The price and inventory of LM3670MFX-3.3/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3670MFX-3.3/NOPB is usually 5 days.
3.What payment methods are accepted for LM3670MFX-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3670MFX-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3670MFX-3.3/NOPB?
LM3670MFX-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3670MFX-3.3/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 LM3670MFX-3.3/NOPB?
For technical support, including LM3670MFX-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3670MFX-3.3/NOPB requirements.
6.How does Aetrix verify that LM3670MFX-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3670MFX-3.3/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 LM3670MFX-3.3/NOPB meets industry standards.
7.What is the process for return or replacement of LM3670MFX-3.3/NOPB?
All LM3670MFX-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3670MFX-3.3/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 LM3670MFX-3.3/NOPB part is unused and in its original packaging.
Return procedure for LM3670MFX-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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