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Texas Instruments LM3670MF-ADJ
- Part No.:
- LM3670MF-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3670MF-ADJ.pdf
- Description:
- IC REG BUCK ADJ 350MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,446
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Product details
Overview
LM3670MF-ADJ from Texas Instruments is a miniature synchronous step-down DC-DC converter optimized for ultralow-voltage circuits powered by single Li-Ion or three-cell NiMH/NiCd batteries. It delivers up to 350 mA load current, supports adjustable output voltages from 0.7 V to 2.5 V via external resistor divider, operates from 2.5 V to 5.5 V input, and features 1-MHz fixed-frequency PWM with automatic PFM mode switching - used in mobile phone core logic and RF power supply rails.
For engineers reviewing the LM3670MF-ADJ datasheet, LM3670MF-ADJ pinout, LM3670MF-ADJ application, or LM3670MF-ADJ equivalent, key selection criteria include its 15-µA quiescent current in PFM mode, internal synchronous rectification, 100% duty-cycle low-dropout operation, soft-start timing, and SOT-23-5 package compatibility with space-constrained portable designs.
Technical Context
The LM3670MF-ADJ employs voltage-mode control with input voltage feed-forward to maintain stable regulation across line and load variations. Its dual-mode operation - fixed-frequency 1-MHz PWM above ~70 mA and hysteretic PFM below - dynamically balances noise performance and efficiency.
Internal synchronous rectification uses integrated PFET and NFET switches (RDSON(P) = 360–690 mΩ, RDSON(N) = 250–660 mΩ at VIN = 3.6 V), enabling 90–95% typical efficiency at 1–100 mA loads. Feedback is sensed at the FB pin referencing a 0.5-V internal bandgap, supporting precise output adjustment via external R1/R2 divider.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5 V to 5.5 V - supports direct connection to single Li-ion (2.7–4.2 V) or 3×NiMH (3.0–4.5 V) without pre-regulation. |
| Output Voltage Range | 0.7 V to 2.5 V (adjustable) - set via external resistor divider on FB pin; enables custom rail generation for low-voltage ASICs or memory cores. |
| Max Load Current | 350 mA - sufficient for powering baseband processors, camera modules, or display drivers in handheld devices. |
| Quiescent Current | 15 µA (typical, PFM mode) - extends battery life during standby or light-load states in always-on subsystems. |
| Switching Frequency | 1 MHz (typical, PWM mode) - allows use of small 4.7–10 µH inductors and compact 4.7–10 µF ceramic capacitors. |
| Shutdown Current | 0.1 µA (typical) - minimizes leakage when system is fully powered down; EN pin logic threshold: VIH = 1.3 V, VIL = 0.4 V. |
| Efficiency | 94% (typical at 10–100 mA, VIN = 3.6 V, VOUT = 1.8 V) - enabled by internal synchronous rectification and low-RDSON FETs. |
| Feedback Reference | 0.5 V - stable internal reference used with external resistive divider to set output; tolerance ±2.5% over temperature and load. |
Pinout & Package
The LM3670MF-ADJ is housed in a 5-pin SOT-23 package (2.90 mm × 1.60 mm body size), optimized for high-density portable PCB layouts and compatible with standard reflow processes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power Input | Connects to input filter capacitor (≥4.7 µF ceramic); accepts 2.5–5.5 V; must withstand 6 V absolute max. |
| GND (Pin 2) | Ground Reference | Primary return path for input, output, and internal bias currents; requires low-impedance PCB connection to minimize noise. |
| EN (Pin 3) | Digital Enable | Active-high logic control; >1.3 V enables regulation, <0.4 V forces shutdown (0.1 µA IQ); must not be left floating. |
| FB (Pin 4) | Analog Feedback | Senses output voltage via external R1/R2 divider; internal 0.5-V reference sets VOUT = 0.5 × (1 + R1/R2). |
| SW (Pin 5) | Switching Node | Connects to inductor; carries high di/dt PWM current; requires short, low-inductance trace to minimize EMI and voltage spikes. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic PWM/PFM Mode Switching | Transitions seamlessly between 1-MHz PWM (≥70 mA) and low-noise PFM (≤70 mA), optimizing efficiency across full load range without external control. |
| 100% Duty-Cycle Low-Dropout Operation | Enables VOUT regulation even when VIN approaches VOUT + ILOAD × (RDSON(P) + RINDUCTOR), critical for battery end-of-life support. |
| Internal Soft Start | Limit in-rush current during startup; typical 400 µs rise time with 10-µF COUT and 350-mA load - prevents input rail collapse. |
| Current Overload Protection | Cycle-by-cycle peak-current limiting trips at 620 mA (typical), safeguarding internal FETs and external inductor under short-circuit or overload. |
| Thermal & UVLO Protection | Undervoltage lockout disables operation below VIN = 2.4 V; thermal shutdown activates above TJ = 125°C - ensures robustness in unregulated battery systems. |
Applications
| Mobile Phone Core Logic Supply | Handheld Device RF Power Rail |
|---|---|
Use Scenario: Powers ARM-based application processor core (e.g., Cortex-A series) requiring tightly regulated 1.0–1.2 V at up to 300 mA with dynamic voltage scaling. IC Role / Device Role / Timing Role: Primary buck regulator delivering dynamically adjusted low-voltage rail; FB pin monitors output and adjusts duty cycle in real time. Use Value: 15-µA PFM quiescent current extends standby time; 1-MHz switching avoids AM radio band interference; SOT-23-5 footprint saves board area. | Use Scenario: Supplies 1.8 V to cellular transceiver ICs (e.g., LTE front-end modules) where low noise and fast transient response are critical. IC Role / Device Role / Timing Role: High-efficiency, low-ripple DC-DC source with fast load-step recovery (<10 µs) due to voltage-mode control and internal compensation. Use Value: Internal synchronous rectification achieves >92% efficiency at 100 mA; PFM-to-PWM transition ensures stable output during burst transmission. |
| Portable Instrument Sensor Bias | Wearable Device MCU Core Rail |
Use Scenario: Generates precision 0.9 V bias for low-power analog sensor signal chains (e.g., MEMS accelerometers, gas sensors) in battery-operated test equipment. IC Role / Device Role / Timing Role: Adjustable-output buck converter with 0.5-V reference and ±2.5% FB tolerance - enables accurate, stable low-voltage bias generation. Use Value: 0.1-µA shutdown current eliminates drain during instrument sleep mode; soft-start prevents sensor offset shift at power-on. | Use Scenario: Powers ultra-low-power microcontroller (e.g., MSP430, nRF52) core at 0.8–1.1 V in fitness trackers and smartwatches operating from coin-cell or thin Li-Poly batteries. IC Role / Device Role / Timing Role: Primary system regulator managing deep-sleep wake-up transitions; EN pin synchronized with MCU GPIO for controlled power sequencing. Use Value: 100% duty-cycle operation sustains regulation down to VIN = 2.5 V - maximizes usable battery capacity; tiny 5-pin SOT-23 eases routing in constrained wearables. |
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 |
|---|---|---|---|
| TPS62231DRYR | Fixed 1.8 V output only; 2.05–6.5 V input; 400 mA max; 3-MHz switching; 17 µA IQ (PFM) | Lacks adjustable output - unsuitable where multiple rail voltages required from one BOM variant. | Select when fixed 1.8 V is sufficient and higher switching frequency enables smaller magnetics. |
| AP3012KTR-G1 | Adjustable 1.25–5.0 V output; 2.5–5.5 V input; 300 mA max; 1.5-MHz switching; 40 µA IQ (standby) | Higher quiescent current reduces battery life in always-on applications; no PFM/PWM auto-switching. | Choose for cost-sensitive designs where 300 mA load ceiling and moderate IQ are acceptable trade-offs. |
Compared with TPS62231DRYR and AP3012KTR-G1, the LM3670MF-ADJ uniquely combines adjustable output (0.7–2.5 V), ultra-low 15-µA PFM IQ, and seamless dual-mode operation - making it optimal for multi-rail, battery-limited portable systems requiring both flexibility and longevity.
Availability
LM3670MF-ADJ is available at Aetrix Electronics and suitable for mobile phones, handheld instrumentation, and wearable electronics requiring stable component supply, long-term manufacturability, and consistent parametric performance across production lots.
Supply support for LM3670MF-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, specializing in analog, embedded processing, and power management technologies for industrial, automotive, and consumer markets.
The LM3670 product line was designed specifically for ultralow-voltage, battery-powered portable electronics - emphasizing minimal external component count, nanoscale packaging, and intelligent power-state management to extend runtime in space-constrained devices.
FAQ
What is the minimum input voltage required for LM3670MF-ADJ to regulate a 0.9-V output at 200 mA?
The minimum input voltage depends on dropout: VIN(MIN) = VOUT + ILOAD × (RDSON(P) + RINDUCTOR). With RDSON(P) = 360 mΩ (typ) and a 30-mΩ inductor, VIN(MIN) ≈ 0.9 V + 0.2 A × 0.39 Ω = 0.978 V - but per spec, LM3670MF-ADJ requires ≥2.5 V input. So 2.5 V is the practical lower limit, enabling 100% duty-cycle operation down to that rail.
How does the LM3670MF-ADJ achieve automatic transition between PWM and PFM modes?
The LM3670MF-ADJ monitors inductor current and output voltage via internal comparators. When load drops below ~70 mA and inductor current becomes discontinuous for ≥32 clock cycles, it enters PFM mode - reducing switching frequency and quiescent current to 15 µA. LM3670MF-ADJ exits PFM automatically when output falls below the low2 PFM threshold (~0.8% below nominal), restoring 1-MHz PWM.
Can the LM3670MF-ADJ be used with ceramic output capacitors less than 10 µF?
Yes - the LM3670MF-ADJ is stable with ≥4.7 µF ceramic output capacitance. The datasheet specifies 10 µF for typical applications, but 4.7 µF is validated for most loads. Lower values increase output ripple; ensure ESR remains <10 mΩ and capacitance tolerance accounts for DC bias derating to maintain regulation stability.
What is the purpose of the SW pin on the LM3670MF-ADJ, and what layout guidance applies?
The SW pin is the switching node connecting the internal PFET drain and NFET source to the external inductor. It carries high di/dt current and generates EMI. For reliable operation, route SW with a short, wide, low-inductance trace; place the inductor adjacent to the SW pin; avoid routing sensitive analog traces nearby; and use a solid ground plane beneath the SW path to minimize loop area and radiated emissions.
Does the LM3670MF-ADJ require an external compensation network?
No - the LM3670MF-ADJ integrates full internal compensation. Its voltage-mode architecture with feed-forward and fixed 1-MHz oscillator eliminates the need for external RC networks or type-II/type-III compensators. Stability is guaranteed with the recommended 4.7 µF input and 10 µF output ceramic capacitors, simplifying design and reducing BOM count.
LM3670MF-ADJ 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:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.7V
- Voltage - Output (Max):
- 5.5V
- 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
LM3670MF-ADJ FAQ
1.How can I place an order for LM3670MF-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3670MF-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 LM3670MF-ADJ reliable?
The price and inventory of LM3670MF-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3670MF-ADJ is usually 5 days.
3.What payment methods are accepted for LM3670MF-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3670MF-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3670MF-ADJ?
LM3670MF-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3670MF-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 LM3670MF-ADJ?
For technical support, including LM3670MF-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3670MF-ADJ requirements.
6.How does Aetrix verify that LM3670MF-ADJ is sourced from the original manufacturer or authorized distributors?
All LM3670MF-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 LM3670MF-ADJ meets industry standards.
7.What is the process for return or replacement of LM3670MF-ADJ?
All LM3670MF-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM3670MF-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 LM3670MF-ADJ part is unused and in its original packaging.
Return procedure for LM3670MF-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3670MF-ADJ Tags
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