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Texas Instruments LM2661M/NOPB
- Part No.:
- LM2661M/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM2661M/NOPB.pdf
- Description:
- IC REG CHRG PUMP INV 100MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,990
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Product details
Overview
LM2661M/NOPB from Texas Instruments is a CMOS switched-capacitor voltage inverter/doubler IC operating from 1.5 V to 5.5 V input, delivering up to 100 mA output current with 88% typical conversion efficiency at full load and 6.5 Ω typical output resistance. It supports dual-mode operation (inverting or doubling), selectable 10 kHz/80 kHz oscillator frequency via FC pin, and features low 120 µA quiescent current - ideal for space-constrained, battery-powered portable instrumentation.
For engineers reviewing the LM2661M/NOPB datasheet, LM2661M/NOPB pinout, LM2661M/NOPB application, or LM2661M/NOPB equivalent, key selection criteria include its unregulated charge-pump architecture, SOIC-8 package compatibility, LV pin configuration for low-voltage operation (<3.5 V), OSC pin flexibility for external clocking (inverter mode only), and parallel/cascading capability for extended current or voltage range.
Technical Context
The LM2661M/NOPB implements a four-switch CMOS charge-pump topology with internal oscillator control, enabling precise voltage inversion (VOUT ≈ −VIN) or doubling (VOUT ≈ +2VIN) depending on external pin wiring. Its switching array operates at half the oscillator frequency (fSW = fOSC/2), with FC pin selection determining nominal 10 kHz or 80 kHz operation.
Functional mode is determined by LV and pin interconnection: LV tied to GND enables inverter operation down to 1.5 V input; LV tied to OUT configures voltage-doubling mode requiring ≥2.5 V input. The OSC pin accepts external clock signals ≤150 kHz in inverter mode only and cannot be externally driven in doubler mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 1.5 V to 5.5 V - supports single-cell Li-ion, alkaline, or NiMH battery systems without external regulation. |
| Output Current | 100 mA - sufficient for biasing op-amps, RS-232 transceivers, or sensor signal conditioning stages. |
| Oscillator Frequency | 10 kHz / 80 kHz (FC-selectable) - lower frequency reduces EMI and quiescent current; higher frequency allows smaller external capacitors. |
| Conversion Efficiency | 88% at 100 mA - minimizes power loss and thermal rise in compact portable enclosures. |
| Output Resistance | 6.5 Ω typical - defines voltage droop under load; enables predictable rail generation for analog circuitry. |
| Quiescent Current | 120 µA typical - extends battery life in always-on or low-duty-cycle monitoring applications. |
| Operating Temperature | −40°C to +85°C - qualified for industrial and medical handheld equipment environments. |
Pinout & Package
LM2661M/NOPB is housed in an 8-pin SOIC (D) package measuring 4.90 mm × 3.91 mm, optimized for surface-mount assembly and thermal dissipation in high-density PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 FC | Oscillator frequency control | Open = 10 kHz; connected to V+ = 80 kHz; no effect when OSC is externally driven. |
| 2 CAP+ | Flying capacitor positive terminal | Connects to positive side of charge-pump capacitor C1; critical for energy transfer timing. |
| 3 GND | Power ground reference | Common return path for input supply, output stage, and internal oscillator circuitry. |
| 4 CAP− | Flying capacitor negative terminal | Connects to negative side of C1; forms switching node with CAP+ during charge-transfer cycles. |
| 5 OUT | Output voltage terminal | In inverter mode: delivers negative voltage; in doubler mode: tied to GND (not used as output). |
| 6 LV | Low-voltage enable | Tied to GND for 1.5–3.5 V operation; tied to OUT for ≥2.5 V doubler mode; open allowed above 3.5 V. |
| 7 OSC | Oscillator control | Accepts external clock ≤150 kHz in inverter mode only; open or capacitor-connected to adjust frequency. |
| 8 V+ | Positive supply input | Primary power input; in doubler mode, becomes positive output terminal. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-mode voltage conversion | Single IC supports both inverting (−VIN) and doubling (+2VIN) topologies via pin-strapping - eliminates need for separate part numbers. |
| Configurable oscillator | FC pin selection and OSC pin flexibility allow optimization of ripple, capacitor size, and quiescent current for specific system constraints. |
| Low-voltage operation | LV pin enables stable operation down to 1.5 V input - essential for single-cell battery systems where headroom is minimal. |
| Parallel/cascade support | Multiple LM2661M/NOPB units can be paralleled to halve output resistance or cascaded to generate −n×VIN or +n×VIN - scalable for multi-rail requirements. |
| External clock interface | OSC pin accepts CMOS-level external clock in inverter mode - enables synchronization with system clock to suppress beat frequencies and EMI. |
Applications
| Operational Amplifier Power Supplies | RS-232 Interface Power |
|---|---|
Use Scenario: Generating dual ±5 V rails for precision op-amp circuits in portable test equipment. IC Role / Device Role / Timing Role: LM2661M/NOPB acts as unregulated negative rail generator, paired with main supply for symmetrical biasing. Use Value: Eliminates need for inductor-based DC/DC converters, reducing board area and EMI while maintaining 100 mA output capability. | Use Scenario: Providing ±12 V required by legacy RS-232 transceivers in handheld diagnostic tools. IC Role / Device Role / Timing Role: LM2661M/NOPB functions as high-efficiency inverter to derive negative voltage from a single 3.3 V or 5 V supply. Use Value: Achieves required RS-232 voltage levels with 88% efficiency and <120 µA quiescent draw - extending battery runtime significantly. |
| Medical Handheld Instrumentation | Laptop Peripheral Biasing |
Use Scenario: Supplying isolated analog front-end bias voltages in portable ECG or pulse oximeter devices. IC Role / Device Role / Timing Role: LM2661M/NOPB serves as compact, low-noise negative supply source for ADC reference buffers and sensor excitation. Use Value: Delivers stable −3.3 V or −5 V with 6.5 Ω output impedance - ensuring minimal signal distortion in sensitive biopotential measurements. | Use Scenario: Generating auxiliary bias rails for USB-C PD controller logic or display backlight drivers in ultrabooks. IC Role / Device Role / Timing Role: LM2661M/NOPB operates in voltage-doubling mode to boost 3.3 V system rail to 6.6 V for gate drive or level-shifting. Use Value: Enables efficient rail boosting without magnetic components - preserving thin-profile mechanical design and reducing thermal footprint. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switched-capacitor voltage converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2660M/NOPB | Same pinout, identical functional block diagram, and matching electrical specs per TI SNVS135E datasheet; differs only in part number suffix and minor packaging traceability. | Direct drop-in replacement with identical inverter/doubler behavior, FC/OSC/LV pin logic, and SOIC-8 footprint. | Select when sourcing continuity or cross-checking legacy BOMs - functionally indistinguishable from LM2661M/NOPB. |
| MAX680CPA+ | 8-pin DIP package; fixed 10 kHz oscillator; no FC pin or external clock option; 100 mA output but higher 10 Ω typical ROUT. | Suitable for through-hole prototyping or legacy designs where oscillator flexibility and SOIC compatibility are not required. | Choose for cost-sensitive, low-frequency, non-portable applications where PCB real estate and EMI are less critical. |
Compared with LM2661M/NOPB, LM2660M/NOPB offers identical performance and pin compatibility in SOIC-8, while MAX680CPA+ trades package format and oscillator control for simpler implementation in fixed-frequency, through-hole systems - making LM2661M/NOPB optimal for modern SMT, battery-powered designs requiring configurability.
Availability
LM2661M/NOPB is available at Aetrix Electronics and suitable for operational amplifier power supplies, RS-232 interface power generation, and medical handheld instrumentation requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.
Supply support for LM2661M/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 over 90 years of innovation in power management and signal chain solutions.
The LM2661M/NOPB belongs to TI's switched-capacitor voltage converter product line, engineered specifically for compact, inductorless DC/DC conversion in portable and space-constrained electronic systems.
FAQ
What is the primary function of the LM2661M/NOPB?
The LM2661M/NOPB is a CMOS switched-capacitor voltage converter that functions as either an inverter (generating −VIN) or a doubler (generating +2VIN) depending on external pin configuration. It requires only two external capacitors, operates from 1.5 V to 5.5 V, and delivers up to 100 mA output current. Its core purpose is to provide compact, inductorless rail generation for portable and low-EMI applications - a capability confirmed across all LM2661M/NOPB documentation and electrical characteristics tables.
Can the LM2661M/NOPB operate from a 1.8 V supply?
Yes, the LM2661M/NOPB supports 1.5 V to 5.5 V input operation. When supplied with 1.8 V, the LV pin must be tied to GND to bypass internal regulator circuitry and ensure reliable startup and stable oscillation. This low-voltage capability is explicitly validated in the Recommended Operating Conditions table (Section 6.3) and Typical Characteristics curves of the LM2661M/NOPB datasheet.
Does the LM2661M/NOPB support external clock synchronization?
Yes - the OSC pin of the LM2661M/NOPB accepts an external CMOS-level clock signal up to 150 kHz, but only in voltage inverter mode. In doubler mode, the OSC pin cannot be externally driven. This feature enables EMI reduction through clock synchronization and is documented in Section 8.3.1 and Table 1 of the LM2661M/NOPB datasheet.
What is the maximum output current rating for the LM2661M/NOPB?
The LM2661M/NOPB is rated for 100 mA continuous output current at junction temperatures ≤85°C, as specified in Section 6.5 Electrical Characteristics (IL parameter). This rating assumes proper thermal management and use of low-ESR external capacitors. Exceeding this current may cause thermal shutdown or reduced efficiency - a limit consistently applied across all LM2661M/NOPB test conditions and application examples.
Is the LM2661M/NOPB pin-compatible with the LM2660M/NOPB?
Yes, the LM2661M/NOPB and LM2660M/NOPB share identical pin configuration, electrical specifications, functional block diagram, and SOIC-8 package dimensions. TI documentation confirms they are functionally interchangeable with no PCB layout changes required - making LM2660M/NOPB a verified direct alternative for LM2661M/NOPB in existing designs.
LM2661M/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Ratiometric
- Output Configuration:
- Positive or Negative
- Topology:
- Charge Pump
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1.5V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- -Vin, 2Vin, Vin/2
- Voltage - Output (Max):
- -
- Current - Output:
- 100mA
- Frequency - Switching:
- 5kHz, 40kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
LM2661M/NOPB FAQ
1.How can I place an order for LM2661M/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2661M/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 LM2661M/NOPB reliable?
The price and inventory of LM2661M/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2661M/NOPB is usually 5 days.
3.What payment methods are accepted for LM2661M/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2661M/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2661M/NOPB?
LM2661M/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2661M/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 LM2661M/NOPB?
For technical support, including LM2661M/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2661M/NOPB requirements.
6.How does Aetrix verify that LM2661M/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2661M/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 LM2661M/NOPB meets industry standards.
7.What is the process for return or replacement of LM2661M/NOPB?
All LM2661M/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2661M/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 LM2661M/NOPB part is unused and in its original packaging.
Return procedure for LM2661M/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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