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Texas Instruments LM3670MFX-ADJ/NOPB
- Part No.:
- LM3670MFX-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM3670MFX-ADJ/NOPB.pdf
- Description:
- IC REG BUCK ADJ 350MA SOT23-5
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM3670MFX-ADJ/NOPB 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 output current, supports adjustable output voltages from 0.7 V to 2.5 V via external resistor divider, operates with 1-MHz fixed-frequency PWM and automatic PFM mode switching, and achieves 94% typical efficiency at 10–100 mA loads in portable power management systems.
For engineers reviewing the LM3670MFX-ADJ/NOPB datasheet, LM3670MFX-ADJ/NOPB pinout, LM3670MFX-ADJ/NOPB application, or LM3670MFX-ADJ/NOPB equivalent, key selection criteria include its 15-µA quiescent current in PFM mode, 0.1-µA shutdown current, internal synchronous rectification, 100% duty-cycle low-dropout operation, and minimal external component count (one inductor, two ceramic capacitors) for space-constrained handheld devices.
Technical Context
The LM3670MFX-ADJ/NOPB implements voltage-mode control with input voltage feed-forward to maintain stable regulation across wide VIN (2.5 V–5.5 V) and load (0–350 mA) ranges. Its dual-mode architecture dynamically transitions between fixed-frequency 1-MHz PWM (for ≥70 mA loads) and hysteretic PFM (for light-load efficiency), using internal PFET/NFET switches with 360 mΩ/250 mΩ typical RDS(on).
Feedback is analog, referenced to a precise 0.5-V internal bandgap, enabling accurate output setting via external resistive divider on FB pin. Soft-start limits inrush current (typical 400 µs with 10-µF COUT), while undervoltage lockout disables operation below 2.4 V VIN and thermal/current protection safeguards reliability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.5 V to 5.5 V - supports direct operation from single Li-ion (2.7–4.2 V) or three NiMH/NiCd cells (3.0–4.5 V) without pre-regulation. |
| Output Voltage Range | 0.7 V to 2.5 V (adjustable) - set precisely via external resistor divider on FB pin; tolerance includes ±4.5% over temperature and load. |
| Max Output Current | 350 mA - sustained delivery under worst-case thermal conditions (TJ ≤ 125°C) with appropriate PCB layout and inductor selection. |
| Quiescent Current | 15 µA (typical, PFM mode) - extends battery life during standby or light-load operation in always-on subsystems. |
| Switching Frequency | 1 MHz (typical, PWM mode) - enables use of small 4.7–10 µH inductors and compact 4.7–10 µF ceramic capacitors for minimal board area. |
| Shutdown Current | 0.1 µA (typical) - reduces system-level leakage when disabled via EN pin, critical for long-term storage or deep-sleep modes. |
| Efficiency | 94% (typical at 10–100 mA, VIN=3.6 V, VOUT=1.8 V) - achieved via internal synchronous rectification eliminating external Schottky losses. |
| Internal Reference | 0.5 V - high-accuracy bandgap reference used by error amplifier to regulate FB pin voltage, defining output setpoint precision. |
Pinout & Package
The LM3670MFX-ADJ/NOPB 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 reflow-compatible assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power Input | Connects to input filter capacitor; accepts 2.5–5.5 V supply; powers internal bias and PFET switch. |
| GND (Pin 2) | Ground Reference | Primary return path for input/output currents and internal circuitry; must be low-impedance connection to minimize noise and dropout. |
| EN (Pin 3) | Digital Enable | Active-high logic input; >1.3 V enables regulation, <0.4 V forces shutdown; draws only 1 µA max, compatible with GPIOs. |
| FB (Pin 4) | Analog Feedback | Senses output voltage via external resistor divider; regulates to 0.5 V reference; determines final VOUT accuracy and stability. |
| SW (Pin 5) | Switch Node | Connects to inductor; carries high di/dt switching current; requires short, low-inductance trace to minimize EMI and voltage spikes. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic PWM/PFM Mode Switching | Eliminates manual mode control; maintains >90% efficiency from 1 mA to 350 mA by selecting optimal switching strategy per load. |
| Internal Synchronous Rectification | Replaces lossy external Schottky diode; reduces conduction loss and improves efficiency by 5–10% vs. asynchronous buck designs. |
| 100% Duty-Cycle Low-Dropout Operation | Enables VOUT regulation even when VIN drops to VOUT + ILOAD × (RDS(on,P) + RINDUCTOR); critical for battery end-of-life support. |
| Integrated Soft Start | Controls output ramp rate to limit inrush current (<620 mA peak); prevents input rail sag and avoids false resets in host systems. |
| Current Overload & Thermal Protection | Shuts down PFET/NFET if peak switch current exceeds 750 mA or junction temperature exceeds 125°C; auto-recovers after fault clears. |
| Only Three External Components Required | Reduces BOM count, footprint, and assembly cost: one 4.7–10 µH inductor + two ceramic caps (CIN, COUT) suffice for full functionality. |
Applications
| Mobile Phone Core Logic Power | PDA Application Processor Rail |
|---|---|
Use Scenario: Supplying 1.2 V core voltage to ARM-based application processors during active and idle states in slim-profile smartphones. IC Role / Device Role / Timing Role: Primary step-down regulator delivering regulated 1.2 V from 3.6 V Li-ion battery; manages dynamic load transients up to 350 mA. Use Value: 15-µA quiescent current in PFM mode extends standby time; 1-MHz switching allows tiny 4.7 µH inductor and 4.7 µF input cap for minimal PCB area. | Use Scenario: Powering 1.5 V I/O and memory interfaces in handheld PDAs with intermittent high-current bursts during data transfer. IC Role / Device Role / Timing Role: Adjustable-output buck converter configured for 1.5 V; handles rapid load steps from 1 mA to 200 mA with <50 mV undershoot. Use Value: Internal soft start prevents reset glitches during power-up; synchronous rectification ensures >92% efficiency at 100 mA, reducing thermal load in sealed enclosures. |
| Portable Instrument Sensor Bias | Battery-Powered IoT Node MCU Supply |
Use Scenario: Generating stable 0.9 V bias for ultra-low-power analog sensor front-ends in handheld multimeters and environmental monitors. IC Role / Device Role / Timing Role: Precision-adjustable buck providing tightly regulated 0.9 V from 3.0 V NiMH pack; operates continuously in PFM mode. Use Value: 0.5 V internal reference and ±4.5% output tolerance ensure sensor accuracy; 0.1-µA shutdown current preserves battery for multi-year deployments. | Use Scenario: Supplying 1.8 V to ARM Cortex-M0+ microcontrollers and BLE radios in coin-cell–powered asset trackers. IC Role / Device Role / Timing Role: Primary system regulator supporting burst-mode operation: 350 mA peaks during radio transmit, 1 µA sleep between transmissions. Use Value: Automatic transition from PFM to PWM mode within microseconds ensures fast response to transmit requests; low RDS(on) minimizes dropout at end-of-life battery voltage. |
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 | Fixed 1.8 V output; 300 mA max; 2.05–6.0 V input; 3.6 MHz switching frequency; requires different external components. | Not adjustable; higher frequency demands smaller inductor but increases EMI sensitivity; lacks PFM mode. | Select when fixed 1.8 V output suffices and board space permits higher-frequency magnetics; avoid if adjustable VOUT or ultra-low IQ is required. |
| AP3012KTR-G1 | Adjustable 0.8–5.0 V output; 300 mA max; 2.5–5.5 V input; 1.5 MHz switching; no integrated synchronous rectifier (external diode required). | Lower efficiency (≈85% at 100 mA) due to diode loss; higher BOM count; wider VOUT range but looser reference (1.25 V ±2%). | Consider for cost-sensitive designs where 5–10% efficiency loss is acceptable and layout allows discrete diode placement. |
Compared with TPS62231DRVR and AP3012KTR-G1, the LM3670MFX-ADJ/NOPB uniquely combines adjustable output, 15-µA PFM quiescent current, internal synchronous rectification, and 1-MHz operation in a 5-pin SOT-23 - making it optimal for space- and battery-life–constrained ultralow-voltage portable systems requiring design flexibility.
Availability
LM3670MFX-ADJ/NOPB is available at Aetrix Electronics and suitable for mobile phones, handheld instruments, and battery-powered IoT nodes requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LM3670MFX-ADJ/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 digital signal processing technologies, with decades of expertise in power management ICs for portable and industrial applications.
The LM3670 product line was designed specifically for ultralow-voltage, high-efficiency DC-DC conversion in space-constrained battery-powered devices - emphasizing minimal external components, intelligent light-load efficiency, and robust operation across wide input voltage and temperature ranges.
FAQ
What is the minimum input voltage required for LM3670MFX-ADJ/NOPB to regulate a 1.2 V output at 200 mA?
The minimum input voltage depends on dropout: VIN(MIN) = VOUT + ILOAD × (RDS(on,P) + RINDUCTOR). With typical RDS(on,P) = 360 mΩ and a 0.2 Ω inductor, VIN(MIN) ≈ 1.2 V + 0.2 A × 0.56 Ω = 1.31 V - but the LM3670MFX-ADJ/NOPB's undervoltage lockout requires ≥2.4 V VIN to operate. So 2.4 V is the practical minimum, verified in the LM3670MFX-ADJ/NOPB datasheet.
Can LM3670MFX-ADJ/NOPB be used with a 10 µH inductor, and what is the recommended saturation current rating?
Yes, a 10 µH inductor is explicitly recommended for the LM3670MFX-ADJ/NOPB in TI's datasheet. The saturation current rating must exceed the peak switch current limit of 750 mA - TI specifies ≥800 mA for reliable operation under worst-case conditions. Inductor DCR should be <0.3 Ω to maintain high efficiency, as confirmed in the LM3670MFX-ADJ/NOPB application notes.
How does the feedback (FB) pin function in LM3670MFX-ADJ/NOPB, and what resistor values are needed for a 1.5 V output?
The FB pin senses the output voltage through an external resistor divider and regulates it to the internal 0.5 V reference. For 1.5 V output, use R1 = 20 kΩ (top, between VOUT and FB) and R2 = 10 kΩ (bottom, between FB and GND), yielding VOUT = 0.5 V × (1 + R1/R2) = 1.5 V. These values balance accuracy, noise immunity, and bias current draw - all validated in the LM3670MFX-ADJ/NOPB typical application schematics.
Does LM3670MFX-ADJ/NOPB require an external compensation network?
No, the LM3670MFX-ADJ/NOPB integrates full frequency compensation internally. Its voltage-mode control loop is factory-tuned for stability with standard 4.7–10 µF ceramic output capacitors and typical PCB layouts - no external compensation components are needed, as specified in the LM3670MFX-ADJ/NOPB datasheet Section 8.2.1.2.3.
What is the thermal performance of LM3670MFX-ADJ/NOPB in a standard 2-layer PCB layout?
In a standard 2-layer PCB with 1-in² copper pour on both sides connected to GND pin, the LM3670MFX-ADJ/NOPB exhibits a junction-to-board thermal resistance (ψJB) of 26.3°C/W. At 350 mA load and 3.6 V input, power dissipation is ~180 mW, resulting in ~4.7°C rise above board temperature - well within the 125°C max junction limit, as measured in the LM3670MFX-ADJ/NOPB thermal characterization report.
LM3670MFX-ADJ/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:
- 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
LM3670MFX-ADJ/NOPB FAQ
1.How can I place an order for LM3670MFX-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3670MFX-ADJ/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-ADJ/NOPB reliable?
The price and inventory of LM3670MFX-ADJ/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-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM3670MFX-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3670MFX-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3670MFX-ADJ/NOPB?
LM3670MFX-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3670MFX-ADJ/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-ADJ/NOPB?
For technical support, including LM3670MFX-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3670MFX-ADJ/NOPB requirements.
6.How does Aetrix verify that LM3670MFX-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3670MFX-ADJ/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-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM3670MFX-ADJ/NOPB?
All LM3670MFX-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3670MFX-ADJ/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-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM3670MFX-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3670MFX-ADJ/NOPB Tags
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