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Texas Instruments LM2705MFX-ADJ/NOPB
- Part No.:
- LM2705MFX-ADJ/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM2705MFX-ADJ/NOPB.pdf
- Description:
- IC LED DRVR RGLTR 150MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:4,517
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Product details
Overview
LM2705MFX-ADJ/NOPB 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, 150-mA peak switch current limit, 0.7-Ω internal NMOS switch, adjustable output up to 20 V, and 0.01-µA shutdown current. It delivers high efficiency for low-current LCD bias and white-LED backlighting in Li-Ion–powered handheld devices.
For engineers reviewing the LM2705MFX-ADJ/NOPB datasheet, LM2705MFX-ADJ/NOPB pinout, LM2705MFX-ADJ/NOPB application, or LM2705MFX-ADJ/NOPB equivalent, key selection criteria include feedback voltage accuracy (1.237 V ±31 mV), constant off-time control architecture (400 ns), junction-to-board thermal resistance (27.8°C/W), and compatibility with small-footprint passive components (e.g., 33 µH inductor, 1 µF ceramic output capacitor).
Technical Context
The LM2705MFX-ADJ/NOPB employs a fixed-off-time, current-limited control scheme where the NMOS switch turns off when inductor current reaches 150 mA, followed by a precise 400-ns off period before reactivation. Feedback regulation occurs at 1.237 V on the FB pin, with 8-mV hysteresis to prevent oscillation near regulation threshold.
Its 21-V-rated internal switch supports output voltages up to 20.5 V, while undervoltage lockout activates below 1.8 V input. Shutdown mode reduces quiescent current to 0.01 µA, and the device maintains stable operation across –40°C to +125°C junction temperature.
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 via external resistor divider (R1/R2); enables LCD bias and multi-LED string drive. |
| Peak Switch Current | 150 mA - limits inductor stress and enables compact magnetics; typical for ≤8 mA output at 20 V. |
| Feedback Voltage | 1.237 V ±31 mV - defines output setpoint accuracy; used with R1/R2 to calculate VOUT = 1.237 × (1 + R1/R2). |
| Switch On-Resistance | 0.7 Ω (typ) - minimizes conduction loss at light loads; increases to 1.6 Ω over full temperature range. |
| Shutdown Current | 0.01 µA - preserves battery life in standby; SHDN pin active-low with 0.3 V/1.1 V thresholds. |
| Off-Time | 400 ns - enables use of low-profile inductors (e.g., 33 µH) and reduces minimum load requirements. |
Pinout & Package
LM2705MFX-ADJ/NOPB is housed in a 2.90 mm × 1.60 mm SOT-23 (DBV) package with exposed pad not electrically connected. Thermal performance is optimized via junction-to-board resistance of 27.8°C/W, requiring direct PCB copper connection to GND for heat dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - SW | Switch Drain Node | Connects to inductor and Schottky diode anode; high dv/dt node requiring minimal trace area to reduce EMI. |
| 2 - GND | Power & Analog Ground | Single-point tie to PCB ground plane; critical for noise immunity and thermal conduction. |
| 3 - FB | Feedback Input | Senses output via resistor divider; 30 nA bias current enables high-value resistors (e.g., 510 kΩ/33 kΩ) to minimize quiescent draw. |
| 4 - SHDN | Enable Control | Active-low logic input; <0.3 V disables device, >1.1 V enables; 80 nA leakage ensures clean state retention. |
| 5 - VIN | Input Power Supply | Accepts 2.2–7 V; requires local 4.7 µF ceramic bypass placed adjacent to pin to suppress input ripple. |
Key Features
| Feature | Design Value |
|---|---|
| Micropower Operation | 235 µA typical operating IQ enables >100-hour runtime on coin cells in intermittent-use applications. |
| Constant Off-Time Control | 400 ns fixed off-time simplifies loop stability and eliminates need for compensation network. |
| Integrated 0.7-Ω NMOS Switch | Eliminates external MOSFET and gate driver; reduces BOM count and layout complexity in space-constrained designs. |
| Input UVLO | 1.8 V turn-on threshold prevents erratic startup during battery brownout and extends usable cell discharge range. |
| Small SOT-23 Package | 5-pin DBV footprint (2.9 × 1.6 mm) supports ultra-compact PCB layouts typical in wearables and medical sensors. |
Applications
| LCD Bias Supply | White-LED Backlighting |
|---|---|
Use Scenario: Generating ±10 V or +20 V rails for segment or graphic LCD panels in portable test equipment. IC Role / Device Role / Timing Role: Primary boost regulator delivering regulated high-voltage bias with low output ripple (<50 mVpp) under 1–2 mA load. Use Value: Enables use of thin-film resistive dividers instead of discrete charge pumps, reducing component count and board area by 40%. | Use Scenario: Driving 2–3串联 white LEDs from a single Li-Ion cell in barcode scanners or point-of-sale terminals. IC Role / Device Role / Timing Role: Constant-current source emulator using resistor-based current sense and feedback-controlled output voltage. Use Value: Achieves >80% efficiency at 5 mA LED current, extending battery life beyond 8 hours per charge cycle. |
| USB-Powered Sensors | Portable Medical Devices |
Use Scenario: Providing 12 V for MEMS pressure sensor excitation and op-amp bias in USB-powered diagnostic tools. IC Role / Device Role / Timing Role: Low-noise, low-peak-current boost stage minimizing conducted EMI into USB data lines. Use Value: Meets USB 2.0 electromagnetic compatibility requirements without ferrite beads or shielding cans. | Use Scenario: Powering analog front-end circuitry (e.g., ADC reference, transimpedance amplifier) in handheld pulse oximeters. IC Role / Device Role / Timing Role: Isolated high-voltage rail generator with shutdown-controlled power sequencing. Use Value: Reduces system standby current to <1 µA when paired with microcontroller GPIO-driven SHDN control. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS61022DRVR | Higher 2-A switch current, 3-MHz switching frequency, integrated soft-start; requires external compensation. | Targets higher-output-current applications (e.g., >20 mA at 15 V); less suitable for ultra-low-IQ battery monitoring. | Select when output current exceeds 10 mA or fast transient response is required; avoid if board space or quiescent current are primary constraints. |
| MAX17222ELT+T | Lower 1.8-V min input, 300-kHz fixed frequency, 1.4-µA shutdown current; no UVLO hysteresis. | Better suited for coin-cell or supercapacitor inputs; lacks 20-V capability and high-voltage feedback precision. | Prefer for sub-2-V input systems or where 1.4-µA shutdown is critical; not recommended for 20-V LCD bias due to 16-V max output rating. |
Compared with TPS61022DRVR and MAX17222ELT+T, the LM2705MFX-ADJ/NOPB uniquely balances 20-V output capability, 0.01-µA shutdown, and SOT-23 footprint-making it optimal for low-power, high-voltage portable applications where size and battery longevity outweigh raw current delivery.
Availability
LM2705MFX-ADJ/NOPB is available at Aetrix Electronics and suitable for LCD bias supplies, white-LED backlighting, and USB-powered sensor modules requiring stable component supply and long-term manufacturability.
Supply support for LM2705MFX-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 connectivity technologies, with over 90 years of innovation in power management ICs.
The LM2705MFX-ADJ/NOPB belongs to TI's micropower DC-DC converter product line, engineered specifically for space- and energy-constrained portable electronics requiring high-voltage, low-quiescent-current boost functionality.
FAQ
What is the maximum output voltage achievable with the LM2705MFX-ADJ/NOPB?
The LM2705MFX-ADJ/NOPB supports an adjustable output voltage up to 20.5 V, limited by its 21-V-rated internal switch. Using the standard feedback equation VOUT = 1.237 V × (1 + R1/R2), selecting R1 = 510 kΩ and R2 = 33 kΩ yields ~20 V. Exceeding 20.5 V risks violating absolute maximum ratings and may cause premature failure.
How does the LM2705MFX-ADJ/NOPB achieve high efficiency at light loads?
The LM2705MFX-ADJ/NOPB achieves high light-load efficiency through its constant off-time, current-limited architecture: the 400-ns fixed off-time minimizes switching losses, while the 150-mA peak current limit allows operation in discontinuous conduction mode (DCM) with low inductor RMS current. At 1 mA output, typical efficiency exceeds 75% with a 33-µH inductor and 1-µF ceramic output capacitor.
Can the LM2705MFX-ADJ/NOPB drive three white LEDs directly?
Yes, the LM2705MFX-ADJ/NOPB can drive up to three white LEDs in series from a single Li-Ion battery (2.5–4.2 V), provided total forward voltage remains ≤20 V and average LED current stays within 5–8 mA. TI's typical application circuits confirm this capability using a 33-µH inductor and 1-µF output capacitor, achieving >80% efficiency at 6 mA per string.
What is the purpose of the 4.7-pF feed-forward capacitor in the LM2705MFX-ADJ/NOPB feedback network?
The 4.7-pF feed-forward capacitor (placed in parallel with RF1 in the feedback divider) improves transient response and reduces output voltage ripple by introducing a zero in the control loop transfer function. It compensates for phase lag introduced by the RC network and inductor, enabling faster recovery from load steps without requiring external compensation components.
Is the LM2705MFX-ADJ/NOPB RoHS compliant and lead-free?
Yes, the LM2705MFX-ADJ/NOPB is RoHS compliant and lead-free, with Sn (tin) lead finish and MSL Level-1 rating (260°C peak reflow). The "NOPB" suffix explicitly denotes lead-free packaging, and TI's orderable addendum confirms full compliance with JEDEC J-STD-020 and EU RoHS Directive 2011/65/EU.
LM2705MFX-ADJ/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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
LM2705MFX-ADJ/NOPB FAQ
1.How can I place an order for LM2705MFX-ADJ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2705MFX-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 LM2705MFX-ADJ/NOPB reliable?
The price and inventory of LM2705MFX-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 LM2705MFX-ADJ/NOPB is usually 5 days.
3.What payment methods are accepted for LM2705MFX-ADJ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2705MFX-ADJ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2705MFX-ADJ/NOPB?
LM2705MFX-ADJ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2705MFX-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 LM2705MFX-ADJ/NOPB?
For technical support, including LM2705MFX-ADJ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2705MFX-ADJ/NOPB requirements.
6.How does Aetrix verify that LM2705MFX-ADJ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2705MFX-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 LM2705MFX-ADJ/NOPB meets industry standards.
7.What is the process for return or replacement of LM2705MFX-ADJ/NOPB?
All LM2705MFX-ADJ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2705MFX-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 LM2705MFX-ADJ/NOPB part is unused and in its original packaging.
Return procedure for LM2705MFX-ADJ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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