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Texas Instruments LM2705MF-ADJ
- Part No.:
- LM2705MF-ADJ
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM2705MF-ADJ.pdf
- Description:
- IC LED DRVR RGLTR 150MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,597
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Product details
Overview
LM2705MF-ADJ from Texas Instruments is a micropower step-up DC-DC converter in a 5-pin SOT-23 package, featuring 2.2–7 V input range, adjustable output up to 20 V, 150-mA peak switch current limit, 0.7-Ω internal NMOS switch, and 400-ns fixed off-time control. It delivers high efficiency in space-constrained portable applications such as white-LED backlighting for Li-Ion–powered handheld devices.
For engineers reviewing the LM2705MF-ADJ datasheet, LM2705MF-ADJ pinout, LM2705MF-ADJ application, or LM2705MF-ADJ equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed application use cases, and two rigorously cross-checked alternative parts with documented functional and application differences.
Technical Context
The LM2705MF-ADJ employs a constant off-time (COT) control architecture with internal current-limited switching, enabling high light-load efficiency and stable regulation across wide input and load variations. Its 400-ns fixed off-time and 1.237-V feedback reference allow precise output voltage setting via external resistor dividers while minimizing inductor size and output ripple.
It integrates an undervoltage lockout (UVP) at 1.8 V, 0.01-µA shutdown current, and thermal protection with 125°C max junction temperature. The 21-V-rated internal switch supports outputs up to 20.5 V, and its low 0.7-Ω RDS(ON) reduces conduction loss under peak 150-mA switch current.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.2 V to 7 V - supports single-cell Li-Ion (2.5–4.2 V) and 2–4 alkaline batteries without external regulation. |
| Output Voltage | Adjustable up to 20 V - set by external R1/R2 divider; enables LCD bias and multi-LED string driving from low-voltage sources. |
| Peak Switch Current | 150 mA - limits inductor stress and enables compact 33–68 µH inductors for portable footprint constraints. |
| Switch RDS(ON) | 0.7 Ω (typ) - reduces conduction loss and improves efficiency at medium loads; rises to 1.6 Ω over full temp range. |
| Feedback Reference | 1.237 V ±31 mV - defines output accuracy; hysteresis of 8 mV prevents oscillation near regulation threshold. |
| Shutdown Current | 0.01 µA - enables ultra-low-power battery preservation during system sleep modes. |
| Switch Off-Time | 400 ns - enables use of small-profile inductors and fast transient response; fixed timing simplifies loop stability. |
Pinout & Package
LM2705MF-ADJ is housed in a 5-pin SOT-23 (DBV) package measuring 2.90 mm × 1.60 mm, optimized for high-density portable PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - SW | Switch node | Drain of internal NMOS power switch; connects to inductor and Schottky diode anode; requires minimal trace area to suppress EMI. |
| 2 - GND | Ground reference | Analog and power ground; must tie directly to PCB ground plane to ensure stable feedback and minimize noise coupling. |
| 3 - FB | Feedback input | Senses output voltage via external resistor divider; trip point at 1.237 V sets VOUT = 1.237 × (1 + R1/R2); bias current ≤120 nA minimizes divider error. |
| 4 - SHDN | Enable control | Active-low logic input; <0.3 V disables device (0.01 µA IQ), >1.1 V enables operation; compatible with standard GPIOs. |
| 5 - VIN | Power input | Supplies analog and power circuits; accepts 2.2–7 V; requires local 4.7-µF ceramic bypass capacitor placed adjacent to pin. |
Key Features
| Feature | Design Value |
|---|---|
| Micropower operation | 235 µA typical quiescent current when enabled - extends battery life in always-on sensor or display bias rails. |
| Fixed off-time control | 400-ns non-overlapping off period - eliminates need for external compensation and ensures stable operation with ceramic output caps. |
| Integrated 150-mA switch | 0.7-Ω RDS(ON) NMOS - removes external MOSFET, reduces BOM count, and maintains >85% efficiency at 5–10 mA loads. |
| Input UVLO | 1.8-V turn-on threshold - prevents erratic startup and protects battery from deep discharge in Li-Ion systems. |
| Small SOT-23 footprint | 2.90 mm × 1.60 mm body - enables placement in tight spaces behind displays or within compact camera modules. |
Applications
| White-LED Backlighting | LCD Bias Supply |
|---|---|
|
Use Scenario: Powering 2–3 white LEDs from a single Li-Ion cell (2.5–4.2 V) in smartphones or portable media players. IC Role / Device Role / Timing Role: Step-up regulator providing regulated 12–20 V output with current-mode control to drive LED strings in constant-voltage mode. Use Value: Enables uniform brightness across LED strings using only one IC and minimal external components; 150-mA peak current supports up to three 20-mA LEDs. |
Use Scenario: Generating high-voltage bias (e.g., +15 V and –10 V) for TFT-LCD panel gate drivers and source drivers. IC Role / Device Role / Timing Role: Primary positive rail generator; paired with charge-pump or inverting converter for negative rail; operates in discontinuous conduction mode for low-noise bias. Use Value: Delivers stable, low-ripple 20-V output with <1% line/load regulation; 400-ns off-time minimizes inductor size and EMI in sensitive display timing paths. |
| Handheld Device Power Rails | Digital Camera Flash Support |
|
Use Scenario: Providing auxiliary 5–12 V rails for sensors, audio codecs, or RF front-ends in Bluetooth headsets and wearables. IC Role / Device Role / Timing Role: Standby-capable boost converter activated on demand; shutdown current of 0.01 µA preserves battery during idle periods. Use Value: Eliminates need for separate LDOs or larger buck-boost ICs; 2.2-V minimum input allows operation down to nearly depleted battery states. |
Use Scenario: Charging a 100-µF flash capacitor to 300 V in compact digital cameras using a cascaded boost topology. IC Role / Device Role / Timing Role: First-stage boost controller feeding into a flyback or charge-pump multiplier; handles initial 3–5 V to 12–20 V conversion with high reliability. Use Value: 21-V switch rating and robust 150-mA current limit enable reliable energy transfer without external current sensing; thermal shutdown prevents damage during repeated flash cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS61040DRVR | Higher 28-V switch rating, 0.5-Ω RDS(ON), but fixed 28-V OVP and no adjustable UVLO. | Supports higher-output designs (e.g., 24-V LCD bias), but less optimal for sub-20-V LED strings due to tighter OVP margin. | Preferred when >20-V output or lower RDS(ON) is critical; requires revalidation of feedback network and layout for higher-frequency operation (1.2 MHz vs 1 MHz effective). |
| MAX17062ETA+ | Integrated soft-start, 1.2-MHz switching, but 1.8-V min input and 120-mA peak current limit. | Better suited for noise-sensitive audio rails; limited to ≤15-V output and lower current than LM2705MF-ADJ's 150 mA. | Choose when fast transient response and low EMI are prioritized over maximum output voltage or peak current capability. |
Compared with TPS61040DRVR and MAX17062ETA+, the LM2705MF-ADJ offers superior trade-off between 20-V output headroom, 150-mA peak current, and ultra-low 0.01-µA shutdown current-making it uniquely suitable for long-duration Li-Ion–powered LED and LCD bias where efficiency at microamp loads is decisive.
Availability
LM2705MF-ADJ is available at Aetrix Electronics and suitable for white-LED backlighting, LCD bias supplies, and handheld device auxiliary rails requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM2705MF-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 leader delivering analog, embedded processing, and connectivity solutions with emphasis on power management innovation and industrial reliability.
The LM2705MF-ADJ belongs to TI's micropower DC-DC converter product line, engineered specifically for ultra-low-quiescent-current, high-efficiency boost conversion in battery-powered portable electronics.
FAQ
What is the maximum output voltage achievable with the LM2705MF-ADJ?
The LM2705MF-ADJ supports an adjustable output voltage up to 20 V, limited by its 21-V-rated internal switch and absolute maximum SW pin voltage rating. This is achieved using external resistors R1 and R2 per the formula VOUT = 1.237 V × (1 + R1/R2). The LM2705MF-ADJ datasheet confirms 20 V as the validated maximum under recommended operating conditions with proper layout and component selection.
Does the LM2705MF-ADJ require an external Schottky diode?
Yes, the LM2705MF-ADJ requires an external Schottky diode connected between the SW pin and output capacitor. The IC integrates only the NMOS power switch; the diode completes the boost converter path. TI recommends diodes with low forward voltage (<0.4 V) and reverse breakdown >20 V - such as the RB050M-30 - to maintain efficiency and reliability in the LM2705MF-ADJ circuit.
How does the LM2705MF-ADJ achieve low quiescent current in shutdown mode?
The LM2705MF-ADJ achieves 0.01 µA shutdown current by fully disabling its internal oscillator, reference, and gate driver circuits when the SHDN pin is pulled below 0.3 V. This deep disable state isolates all internal power domains except minimal leakage paths. Measured data in the LM2705MF-ADJ datasheet (Section 6.5, ISD parameter) confirms this value across –40°C to 125°C ambient.
Can the LM2705MF-ADJ drive three white LEDs directly?
Yes, the LM2705MF-ADJ is explicitly rated to drive up to three white LEDs from a single Li-Ion battery, as stated in its official description and typical application schematics. With a 150-mA peak switch current limit and efficient 20-V output capability, the LM2705MF-ADJ sustains ~20 mA per LED in series configuration while maintaining >85% efficiency at light loads - a key design target validated in TI's Application Report SNVA222.
What is the recommended inductor value for a 20-V output from a 3.7-V Li-Ion input using the LM2705MF-ADJ?
For a 20-V output from a nominal 3.7-V Li-Ion input, TI recommends a 68-µH inductor (e.g., Coilcraft DT1608C-680X) to balance ripple current, light-load efficiency, and physical size. This value appears in the "Typical 20-V Application" schematic (Figure 12) and is validated in Section 8.2.1 of the LM2705MF-ADJ datasheet. Lower values like 33 µH increase ripple and reduce efficiency at low loads, while higher values risk saturation under peak 150-mA current.
LM2705MF-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 2.2V
- Voltage - Supply (Max):
- 7V
- Voltage - Output:
- 20V
- Current - Output / Channel:
- 150mA
- Frequency:
- -
- Dimming:
- -
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LM2705MF-ADJ FAQ
1.How can I place an order for LM2705MF-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2705MF-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 LM2705MF-ADJ reliable?
The price and inventory of LM2705MF-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2705MF-ADJ is usually 5 days.
3.What payment methods are accepted for LM2705MF-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2705MF-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2705MF-ADJ?
LM2705MF-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2705MF-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 LM2705MF-ADJ?
For technical support, including LM2705MF-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2705MF-ADJ requirements.
6.How does Aetrix verify that LM2705MF-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2705MF-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 LM2705MF-ADJ meets industry standards.
7.What is the process for return or replacement of LM2705MF-ADJ?
All LM2705MF-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2705MF-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 LM2705MF-ADJ part is unused and in its original packaging.
Return procedure for LM2705MF-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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