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Texas Instruments LM3670MFX-1.2/NOPB
- Part No.:
- LM3670MFX-1.2/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3670MFX-1.2/NOPB.pdf
- Description:
- IC REG BUCK 1.2V 350MA SOT23-5
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM3670MFX-1.2/NOPB from Texas Instruments is a fixed-output 1.2 V, 350-mA synchronous step-down DC-DC converter in SOT-23-5 package, operating from 2.5 V to 5.5 V input, featuring 1-MHz PWM switching, 15-µA quiescent current, and automatic PFM/PWM mode transition. It powers core logic rails in battery-powered handheld devices requiring stable low-voltage supply with minimal external components.
For engineers reviewing the LM3670MFX-1.2/NOPB datasheet, LM3670MFX-1.2/NOPB pinout, LM3670MFX-1.2/NOPB application, or LM3670MFX-1.2/NOPB equivalent, key selection criteria include its fixed 1.2 V output tolerance (±4.5%), 100% duty-cycle low-dropout capability, internal synchronous rectification, shutdown current of 0.1 µA, and compatibility with single Li-Ion or triple NiMH/NiCd battery sources.
Technical Context
The LM3670MFX-1.2/NOPB implements voltage-mode control with input feed-forward for high line regulation and uses internal PFET/NFET synchronous rectification to achieve 90–95% efficiency at 1–100 mA loads. Its architecture supports three functional modes: fixed-frequency 1-MHz PWM (70–350 mA), hysteretic PFM (light-load, 15 µA IQ), and shutdown (0.1 µA).
It integrates soft-start (400 µs typical with 10 µF COUT), undervoltage lockout (2.4 V), cycle-by-cycle current limiting (620 mA typical peak), and thermal shutdown. The FB pin is internally tied to generate fixed 1.2 V output-no external resistor divider required-distinguishing it from adjustable variants.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.2 V ±4.5% over 0–150 mA load and −40°C to +125°C junction temperature. |
| Input Voltage Range | 2.5 V to 5.5 V - supports single Li-Ion (2.7–4.2 V) or three-cell NiMH/NiCd (3.6 V nominal) without pre-regulation. |
| Max Load Current | 350 mA - sustained output current with proper thermal layout and ≥800 mA saturation inductor. |
| Switching Frequency | 1 MHz typical (550–1300 kHz range) - enables use of tiny 4.7–10 µH inductors and low-ESR ceramic capacitors. |
| Quiescent Current | 15 µA typical in PFM mode - extends battery life during standby in portable systems. |
| Shutdown Current | 0.1 µA typical - minimizes leakage when EN is pulled low, critical for long-term storage or deep-sleep states. |
| Efficiency | 94% typical at 10 mA, 92% at 300 mA (VIN = 3.6 V, VOUT = 1.2 V) - enabled by internal synchronous rectification. |
| Duty Cycle Range | 0–100% - allows dropout operation down to VIN = VOUT + ILOAD × (RDSON_P + RINDUCTOR), e.g., ~2.5 V minimum for full 350 mA at 1.2 V. |
Pinout & Package
SOT-23-5 package (2.90 mm × 1.60 mm body size), thermally enhanced for PCB-mounted power dissipation in space-constrained portable designs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power Input | Connects to input filter capacitor (≥4.7 µF ceramic); must withstand 6 V absolute max and supply peak switch current up to 750 mA. |
| GND (Pin 2) | Ground Reference | Primary return path for PFET, NFET, bias, and feedback circuits; requires low-impedance PCB connection to minimize noise and thermal rise. |
| EN (Pin 3) | Digital Enable | Active-high logic input (VIH ≥1.3 V, VIL ≤0.4 V); pulling low disables regulator and reduces IQ to 0.1 µA - no floating allowed. |
| FB (Pin 4) | Feedback Node | Internally connected to 0.5 V reference for fixed 1.2 V output; not externally configurable - leave unconnected per datasheet. |
| SW (Pin 5) | Switching Node | Drives external inductor; carries high di/dt square wave (0–VIN); requires short, low-inductance trace to minimize EMI and voltage overshoot. |
Key Features
| Feature | Design Value |
|---|---|
| Internal Synchronous Rectification | Eliminates external Schottky diode, reducing conduction loss and enabling >90% efficiency at light loads without heat sink. |
| Automatic PFM/PWM Mode Switching | Seamlessly transitions between 1-MHz PWM (high load) and variable-frequency PFM (light load), maintaining >85% efficiency from 1 mA to 350 mA. |
| 100% Duty-Cycle Low-Dropout Operation | Enables regulation even when VIN approaches VOUT (e.g., 1.3 V input → 1.2 V output at light load), extending usable battery range. |
| Integrated Soft-Start | Controls inrush current during startup (typical 400 µs with 10 µF COUT), preventing input rail collapse and system brownout. |
| Thermal & Current Protection | Includes cycle-by-cycle current limit (750 mA peak) and thermal shutdown - ensures robustness under overload or poor PCB thermal design. |
Applications
| Mobile Phone Core Logic | PDA Application Processor Rail |
|---|---|
Use Scenario: Powering ARM-based application processors (e.g., OMAP, i.MX) requiring tightly regulated 1.2 V core voltage during burst-mode CPU activity and deep-sleep states. IC Role / Device Role / Timing Role: Primary step-down regulator delivering 350 mA peak current with <50 mV load transient deviation and automatic mode switching to preserve battery runtime. Use Value: Enables 1.2 V core rail stability across 2.5–5.5 V battery swing while maintaining <15 µA quiescent draw in idle - directly extending talk time by >12% vs. LDO solutions. | Use Scenario: Supplying memory interface and display controller logic in palm-sized PDAs with dual-battery backup and compact PCB layout. IC Role / Device Role / Timing Role: Fixed-output buck converter providing low-noise 1.2 V supply with integrated soft-start and PFM mode for rapid wake-up from suspend-to-RAM. Use Value: Reduces component count to only three passives (inductor + 2 ceramics), shrinking BOM cost and board area by 40% versus discrete DC-DC + LDO architectures. |
| Handheld Medical Instrument MCU | Portable Test Equipment Digital Core |
Use Scenario: Powering ultra-low-power microcontrollers (e.g., MSP430, nRF52) in FDA-cleared glucose meters and pulse oximeters operating from coin-cell or Li-Po batteries. IC Role / Device Role / Timing Role: Primary voltage regulator delivering precise 1.2 V to MCU core and ADC reference, with shutdown control synchronized to measurement cycles. Use Value: Achieves 0.1 µA shutdown current and <1% output voltage drift over temperature - meeting Class II medical device power integrity requirements. | Use Scenario: Generating clean 1.2 V supply for FPGA configuration logic and high-speed serial transceivers in field-deployable oscilloscope modules. IC Role / Device Role / Timing Role: High-efficiency buck converter supporting dynamic voltage scaling and fast load transient response (<10 µs recovery) during protocol handshaking. Use Value: Delivers 94% efficiency at 100 mA and maintains <20 mV output ripple under 200 mA step load - ensuring signal integrity in 100+ Mbps digital interfaces. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62231DRYR | Fixed 1.2 V output, 300 mA max, 2.05–6.0 V input, 3.6 MHz switching, 17 µA IQ, WSON-6 package. | Higher frequency enables smaller inductors but increases EMI sensitivity; lower max current limits use in high-pulse-load scenarios. | Prefer for space-constrained designs needing sub-1 mm² solution; verify thermal performance at 300 mA continuous. |
| AP63201SG-12 | Fixed 1.2 V output, 2 A max, 2.5–5.5 V input, 1.5 MHz switching, 25 µA IQ, TSOT23-6 package with exposed pad. | Higher current rating and thermal performance suit higher-power SoCs; larger package requires more PCB area and layout effort. | Choose when future-proofing for >350 mA loads or demanding thermal environments; validate EN pin logic thresholds against host MCU. |
Compared with TPS62231DRYR and AP63201SG-12, the LM3670MFX-1.2/NOPB offers optimal balance of ultra-low IQ (15 µA), proven 350 mA capability in minimal SOT-23-5 footprint, and seamless battery-voltage-range support - making it ideal for cost-sensitive, battery-life-critical handhelds where 300–350 mA peak is sufficient.
Availability
LM3670MFX-1.2/NOPB is available at Aetrix Electronics and suitable for mobile phones, PDAs, handheld medical instruments, and portable test equipment requiring stable component supply with consistent parametric performance and long-term manufacturability.
Supply support for LM3670MFX-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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management ICs for industrial, automotive, and consumer markets.
The LM3670 product line delivers miniature, high-efficiency step-down converters optimized for ultralow-voltage battery-powered systems - designed specifically to replace inefficient linear regulators in space- and energy-constrained portable electronics.
FAQ
What is the output voltage tolerance of the LM3670MFX-1.2/NOPB over full load and temperature?
The LM3670MFX-1.2/NOPB delivers a fixed 1.2 V output with ±4.5% tolerance across 0–150 mA load and −40°C to +125°C junction temperature, as specified in the Electrical Characteristics table. This tolerance includes line, load, and temperature effects - no external trimming is possible since the FB pin is internally configured for 1.2 V.
Can the LM3670MFX-1.2/NOPB operate from a single 2.5 V Li-ion cell throughout its discharge curve?
Yes, the LM3670MFX-1.2/NOPB supports input voltages down to 2.5 V and features 100% duty-cycle operation, allowing it to regulate 1.2 V output even as the cell discharges to 2.5 V (with light load). At 350 mA, minimum VIN is ~2.7 V due to RDSON and inductor losses - confirmed by Equation (3) in the datasheet.
What external components are required to implement the LM3670MFX-1.2/NOPB?
Only three external components are required: a 4.7 µF ceramic input capacitor (CIN), a 10 µH inductor rated ≥800 mA saturation current, and a 10 µF ceramic output capacitor (COUT). No feedback resistors are needed - the LM3670MFX-1.2/NOPB is factory-configured for fixed 1.2 V output.
How does the LM3670MFX-1.2/NOPB manage efficiency at very light loads (e.g., 100 µA)?
At light loads, the LM3670MFX-1.2/NOPB automatically enters PFM mode, reducing switching frequency and bias current to achieve 15 µA typical quiescent current. Output voltage is regulated within ±0.8% of nominal by pulsing the PFET, minimizing energy waste while maintaining tight regulation - unlike forced-PWM converters that suffer steep efficiency drop below 1 mA.
Is thermal derating required for the LM3670MFX-1.2/NOPB at 350 mA continuous load?
Yes - the LM3670MFX-1.2/NOPB has RθJA = 163.3°C/W. At 350 mA and 3.6 V input, power dissipation is ~0.42 W; ambient temperature must be limited to ≤65°C on a standard 2-layer PCB with recommended copper pour to keep junction temperature ≤125°C. Adding thermal vias under the GND pad reduces RθJB to 26.8°C/W, enabling full-rated current in most handheld layouts.
LM3670MFX-1.2/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- 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:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LM3670MFX-1.2/NOPB FAQ
1.How can I place an order for LM3670MFX-1.2/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3670MFX-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 LM3670MFX-1.2/NOPB reliable?
The price and inventory of LM3670MFX-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 LM3670MFX-1.2/NOPB is usually 5 days.
3.What payment methods are accepted for LM3670MFX-1.2/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3670MFX-1.2/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3670MFX-1.2/NOPB?
LM3670MFX-1.2/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3670MFX-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 LM3670MFX-1.2/NOPB?
For technical support, including LM3670MFX-1.2/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3670MFX-1.2/NOPB requirements.
6.How does Aetrix verify that LM3670MFX-1.2/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3670MFX-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 LM3670MFX-1.2/NOPB meets industry standards.
7.What is the process for return or replacement of LM3670MFX-1.2/NOPB?
All LM3670MFX-1.2/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3670MFX-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 LM3670MFX-1.2/NOPB part is unused and in its original packaging.
Return procedure for LM3670MFX-1.2/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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