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Texas Instruments LM2611BMF
- Part No.:
- LM2611BMF
- Manufacturer:
- Texas Instruments
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM2611BMF.pdf
- Description:
- IC REG CUK ADJ 900MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:4,768
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Product details
Overview
LM2611BMF from Texas Instruments is a current-mode PWM Cuk converter IC with integrated DMOS FET, designed for high-efficiency negative voltage generation. It operates from 2.7 V to 14 V input, delivers −5 V at 300 mA from 5-V input, features 1.4-MHz fixed switching frequency, 0.7-Ω RDS(ON), and 1-mVp-p output ripple-enabling compact bias supplies in portable imaging and display systems.
For engineers reviewing the LM2611BMF datasheet, LM2611BMF pinout, LM2611BMF application, or LM2611BMF equivalent, this page provides verified technical context, validated pin functions, confirmed Cuk topology implementation constraints, real-world load capability curves, and cross-referenced alternatives for negative rail generation in MR head, CCD, LCD, and GaAs FET bias circuits.
Technical Context
The LM2611BMF implements a fixed-frequency (1.4 MHz) current-mode Cuk topology with internal slope compensation and cycle-by-cycle overcurrent protection. Its integrated 0.7-Ω DMOS switch and −1.23-V NFB reference enable precise output regulation via external resistor divider without external compensation components.
It supports hysteretic pulse-skipping at light loads and thermal shutdown at 163°C junction temperature. The device requires separate input and output inductors (L1/L2), a Cuk capacitor (CCUK), and low-ESR ceramic output capacitors to maintain stability and achieve <1-mVp-p ripple under full load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Cuk inverting DC/DC converter with integrated switch and current-mode control |
| Input Voltage Range | 2.7 V to 14 V - supports single-cell Li-ion, USB, and industrial 5–12-V rails |
| Output Voltage | Adjustable down to −36×VIN via NFB resistor divider; typical −5 V at 300 mA from 5-V input |
| Switch RDS(ON) | 0.7 Ω (Grade B) - enables >85% efficiency at 300 mA with minimal conduction loss |
| Switching Frequency | 1.4 MHz (±0.4 MHz over temp) - allows use of sub-3-mm inductors and 10–22 µH L1/L2 |
| NFB Reference | −1.23 V (±25 mV) - sets output voltage as VOUT = −1.23 × (1 + RFB1/RFB2) |
| Shutdown Current | <1 µA - preserves battery life in always-on bias applications like MR heads |
Pinout & Package
LM2611BMF is housed in a 5-pin SOT-23 package (1.60 mm × 2.90 mm body size) with exposed pad not electrically connected. Thermal resistance is RθJA = 163.5°C/W on standard 2-layer JEDEC board.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - SW | Switch drain node | Connects to input inductor (L1) and Cuk capacitor (CCUK); carries peak current up to 0.9 A |
| 2 - GND | Analog & power ground | Common return for feedback, shutdown, and power paths; must be low-impedance star point |
| 3 - NFB | Negative feedback input | Accepts resistor divider from VOUT; bias current ≤6.7 µA; reference = −1.23 V |
| 4 - SHDN | Logic-level shutdown control | High (>1.5 V) = active; low (<0.5 V) = shutdown with IQ <1 µA |
| 5 - VIN | Power input | Supplies internal circuitry and switch; requires local 0.1-µF ceramic bypass within 5 mm |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Cuk controller + DMOS switch | Eliminates need for external MOSFET driver and gate logic; reduces BOM count by ≥4 components |
| 1.4-MHz fixed-frequency operation | Enables use of 10–22 µH unshielded inductors (e.g., SUMIDA CR32 series) and 22 µF ceramic output caps |
| Low-RMS-current Cuk topology | Reduces input/output capacitor RMS stress vs buck-boost; supports 10–22 µH L1/L2 with <0.3-A ripple |
| Internal type-II/III compensation | Removes need for external compensation network; stable with recommended L1 = L2 = 10–22 µH |
| Hysteretic pulse-skipping mode | Maintains regulation at light loads while reducing switching losses; increases output ripple slightly |
Applications
| MR Head Bias | Digital Camera CCD Bias |
|---|---|
|
Use Scenario: Providing stable negative bias voltage to magnetoresistive read heads in HDD preamplifiers. IC Role / Device Role / Timing Role: Inverting DC/DC regulator generating −5 V from 3.3–5-V system rail with ultra-low ripple. Use Value: 1-mVp-p output ripple prevents signal corruption in high-sensitivity analog front-end circuits. |
Use Scenario: Supplying programmable negative bias to CCD image sensor vertical/horizontal drivers. IC Role / Device Role / Timing Role: Compact Cuk converter delivering −5 V at 300 mA with fast transient response for pixel clock synchronization. Use Value: 1.4-MHz switching enables small 15 µH/47 µH inductors and fits within tight camera module PCB area. |
| LCD Panel Bias | GaAs FET Bias |
|
Use Scenario: Generating negative gate drive voltage for active-matrix LCD source driver ICs. IC Role / Device Role / Timing Role: Efficient inverting regulator supporting wide input range (2.7–14 V) across multiple panel supply configurations. Use Value: Wide VIN range accommodates varying battery states and adapter inputs without redesign. |
Use Scenario: Delivering precise negative gate bias to GaAs FETs in RF front-end modules. IC Role / Device Role / Timing Role: Low-noise Cuk converter with internal compensation and feed-forward capacitor support (CFF). Use Value: Feed-forward capacitor (e.g., 330 pF) improves phase margin and load-step response for RF stability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar inverting DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2611AMF | Grade A variant: 1.2-A switch current limit, 0.5-Ω RDS(ON), same pinout and footprint | Supports higher output current (up to 375 mA at −5 V from 12-V input) with lower conduction loss | Select LM2611AMF when >300 mA load or lower dropout at high ambient temperature is required. |
| MAX764CSA+ | Fixed −5 V output, no adjustable NFB; 1.3-MHz frequency; 0.35-Ω RDS(ON); SO-8 package | Requires no feedback resistors but lacks output voltage flexibility; larger PCB footprint | Choose MAX764CSA+ only for fixed −5 V designs where layout space permits SO-8 and adjustability is unnecessary. |
Compared with LM2611AMF, the LM2611BMF trades 0.3-A peak current headroom and 0.2-Ω higher RDS(ON) for tighter Grade B production binning and lower cost in moderate-load applications. Against MAX764CSA+, LM2611BMF offers adjustable output, smaller SOT-23 footprint, and Cuk topology advantages-but requires external feedback resistors and inductor selection.
Availability
LM2611BMF is available at Aetrix Electronics and suitable for MR head bias, CCD imaging, LCD panel bias, and GaAs FET gate drive applications requiring stable component supply, long-term manufacturability, and consistent electrical performance across temperature.
Supply support for LM2611BMF 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 power management ICs, with decades of expertise in precision DC/DC conversion and high-reliability power solutions.
The LM2611 product line delivers compact, integrated Cuk converters for negative rail generation in portable and space-constrained systems-designed specifically for biasing sensitive analog components like MR sensors, CCDs, and RF FETs.
FAQ
What is the maximum output current capability of the LM2611BMF at −5 V from a 5-V input?
The LM2611BMF delivers up to 300 mA at −5 V when supplied from a 5-V input, as confirmed in the TI SNOS965J datasheet Figure 23 and Typical Application section. This rating assumes L1 = L2 = 22 µH, ambient temperature ≤85°C, and proper PCB thermal design per the recommended layout guidelines. Exceeding this current risks thermal shutdown or reduced regulation accuracy.
Does the LM2611BMF require external compensation components?
No, the LM2611BMF includes internal type-II/III compensation optimized for L1 and L2 values between 10 µH and 22 µH. External compensation is not needed for stable operation with recommended inductors. However, a feed-forward capacitor (CFF) may be added across RFB1 to improve transient response-TI recommends 330 pF for 5-V-to−5-V designs.
Can the LM2611BMF generate output voltages other than −5 V?
Yes, the LM2611BMF supports adjustable negative outputs using an external resistor divider on the NFB pin. With a −1.23-V internal reference, VOUT = −1.23 × (1 + RFB1/RFB2). For example, RFB1 = 29.4 kΩ and RFB2 = 10 kΩ set VOUT = −5 V. Resistor values ≤50 kΩ are recommended to minimize NFB pin leakage error.
What is the purpose of the Cuk capacitor (CCUK) in the LM2611BMF application circuit?
The Cuk capacitor (CCUK) is essential to the Cuk topology's operation-it transfers energy between input and output inductors during switching cycles. In the LM2611BMF, CCUK connects between SW and GND, enabling continuous input/output current waveforms and low RMS ripple. Typical values range from 1 µF to 2.2 µF (X5R ceramic), selected based on input voltage and desired ripple suppression.
How does the LM2611BMF behave under very light load conditions?
Under light loads, the LM2611BMF enters hysteretic pulse-skipping mode to maintain regulation while minimizing quiescent current. In this mode, switching pulses occur only as needed to sustain output voltage, increasing output ripple slightly compared to full PWM operation. The device remains fully regulated, and no external circuit changes are required to enable this behavior.
LM2611BMF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Negative
- Topology:
- Cuk
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 14V
- Voltage - Output (Min/Fixed):
- -1.23V
- Voltage - Output (Max):
- -32V
- Current - Output:
- 900mA
- Frequency - Switching:
- 1.4MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LM2611BMF FAQ
1.How can I place an order for LM2611BMF through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2611BMF 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 LM2611BMF reliable?
The price and inventory of LM2611BMF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2611BMF is usually 5 days.
3.What payment methods are accepted for LM2611BMF?
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4.How is shipping managed for LM2611BMF?
LM2611BMF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2611BMF 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 LM2611BMF?
For technical support, including LM2611BMF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2611BMF requirements.
6.How does Aetrix verify that LM2611BMF is sourced from the original manufacturer or authorized distributors?
All LM2611BMF 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 LM2611BMF meets industry standards.
7.What is the process for return or replacement of LM2611BMF?
All LM2611BMF units undergo pre-shipment inspection (PSI). If there is an issue with LM2611BMF, 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 LM2611BMF part is unused and in its original packaging.
Return procedure for LM2611BMF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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