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Texas Instruments LM2698MMX-ADJ
- Part No.:
- LM2698MMX-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM2698MMX-ADJ.pdf
- Description:
- IC REG BST SEPIC ADJ 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,412
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Product details
Overview
LM2698MMX-ADJ from Texas Instruments is a current-mode PWM boost regulator IC with an integrated 1.9A/0.2Ω MOSFET switch, operating from 2.2V to 12V input and delivering adjustable output up to 17V. It supports dual switching frequencies (600kHz or 1.25MHz via FSLCT pin), features external compensation (VC pin), shutdown control (SHDN), and delivers 12V at 400mA from a 5V source in typical boost configuration.
For engineers reviewing the LM2698MMX-ADJ datasheet, LM2698MMX-ADJ pinout, LM2698MMX-ADJ application, or LM2698MMX-ADJ equivalent, key selection considerations include its adjustable feedback topology (RFB1/RFB2), thermal performance in VSSOP-8 (θJA = 195–235°C/W), internal current limit (1.35A min), and compatibility with ceramic output capacitors due to external VC-loop compensation.
Technical Context
The LM2698MMX-ADJ implements peak-current-mode control with a transconductance error amplifier (gm = 40–290 µmho) and programmable oscillator (600kHz/1.25MHz). Its internal 18V-rated switch enables operation across wide VIN–VOUT differentials, while the VC pin allows full loop compensation tuning for stability with low-ESR ceramic outputs.
It integrates undervoltage lockout (UVP thresholds: 1.85–2.2V), thermal shutdown, and 85% maximum duty cycle limiting. The FB pin senses a precise 1.2285–1.2915V reference, enabling accurate output regulation via external resistor divider - critical for adjustable-output designs like 3.3V→12V or 5V→10V conversion.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.2V to 12V - supports single-cell Li-ion, USB, and industrial 5V/12V rails without pre-regulation. |
| Output Voltage Range | Adjustable from 2.2V to 17V - set by external RFB1/RFB2 divider; no fixed-output variants. |
| Switch Current Limit | 1.35A (min) - defines maximum sustainable load current under worst-case VIN/VOUT conditions. |
| Feedback Reference Voltage | 1.26V ±2.5% - determines output accuracy; e.g., 12V output requires RFB1/RFB2 ≈ 8.5. |
| Switching Frequency | 600kHz (FSLCT = GND) or 1.25MHz (FSLCT = VIN) - selects trade-off between inductor size and efficiency. |
| Quiescent Current | 2.0mA (active), 5µA (shutdown) - enables low-power standby in battery-backed systems. |
| RDS(ON) | 0.2Ω (typical at VIN = 2.7V, ISW = 1A) - directly impacts conduction loss and thermal rise at high load. |
Pinout & Package
LM2698MMX-ADJ is housed in an 8-lead VSSOP (DGK) package - 3.0mm × 3.0mm, 0.65mm pitch, exposed thermal pad (not electrically connected). This thermally enhanced SOIC variant supports higher power density than standard MSOP.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VC | Compensation network node | Connects external RC network to stabilize voltage loop; sets pole/zero locations for phase margin ≥78°. |
| 2 - FB | Feedback input | Senses resistive divider output; regulates VOUT to 1.26V reference - determines final output accuracy. |
| 3 - SHDN | Active-low enable | Pull low to suspend switching; reduces IQ to 5µA - essential for system-level power sequencing. |
| 4 - GND | Analog + power ground | Common return for error amp, bias, and switch current; must be low-impedance plane beneath IC. |
| 5 - SW | Switch node | Drives external inductor/diode; swings from GND to ~VIN + VOUT - requires tight layout to minimize EMI. |
| 6 - VIN | Power input | Supplies internal circuitry and switch driver; requires local 0.1–1µF ceramic bypass near pin. |
| 7 - FSLCT | Frequency select | Ground = 600kHz; connect to VIN = 1.25MHz - enables optimization for size (high-f) or efficiency (low-f). |
| 8 - NC | No-connect | Must be tied to GND per datasheet - improves thermal conduction and reduces noise coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 1.9A/18V/0.2Ω MOSFET | Eliminates external switch; enables compact 12V@400mA boost from 5V with <15mm² solution size. |
| External VC compensation | Allows full loop tuning for any output capacitor ESR/ESL - supports ultra-low-ESR ceramics without instability. |
| Dual-frequency selection (600kHz/1.25MHz) | Enables inductor downsizing (e.g., 10µH @ 1.25MHz vs. 22µH @ 600kHz) while maintaining >85% efficiency. |
| Current-mode control architecture | Provides inherent line/load regulation and simplified Type-II compensation - no need for feedforward or slope compensation. |
| 8-pin VSSOP thermal package | 235°C/W θJA (minimal copper); 195°C/W with 0.2523 in² heat sinking - supports 1.35A continuous output at TA ≤ 60°C. |
Applications
| DSL Modem Power Supply | Diagnostic Medical Instrumentation |
|---|---|
Use Scenario: Generating isolated 12V rail from 3.3V logic supply to drive analog front-end ADCs and op-amps. IC Role / Device Role / Timing Role: Primary DC-DC boost converter providing regulated 12V output with low ripple (<20mVpp) and fast transient response. Use Value: Enables clean analog signal chain operation; 1.25MHz option minimizes inductor footprint in space-constrained PCB layouts. |
Use Scenario: Powering portable ultrasound transducer bias circuits requiring stable 10V from a 3.3V lithium battery. IC Role / Device Role / Timing Role: Adjustable-output boost regulator with shutdown control for battery conservation during idle periods. Use Value: 5µA shutdown current extends battery life; 1.26V FB reference ensures ±2% output accuracy over temperature and load. |
| Set-Top Box AV Rail | Industrial Sensor Node |
Use Scenario: Deriving 5V auxiliary rail from main 12V supply to power HDMI interface ICs and microcontrollers. IC Role / Device Role / Timing Role: Non-inverting boost converter operating in continuous conduction mode (CCM) with 600kHz switching. Use Value: Internal 0.2Ω RDS(ON) limits conduction loss to <120mW at 400mA, reducing thermal stress on VSSOP package. |
Use Scenario: Providing 8V for RF power amplifier bias in LPWAN gateways powered by 2.5–3.6V primary battery. IC Role / Device Role / Timing Role: Wide-input boost regulator supporting brownout-free operation down to 2.2V input. Use Value: UVP lockout (1.95V typ.) prevents erratic behavior during battery discharge; 125°C max junction rating suits enclosed enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS61088RHLR | Higher 8.5A switch, 2.7–12V input, fixed 5V/12V options only; no adjustable FB reference. | Requires redesign of feedback network; lacks VC pin for custom compensation. | Choose when >1A output or integrated soft-start is required; not drop-in for LM2698MMX-ADJ's adjustable topology. |
| MAX17062ETA+ | Lower 1.2A switch, 2.5–5.5V input, 1.2MHz fixed frequency, integrated MOSFETs but no VC pin. | Cannot support >5.5V input or >12V output; limited to mid-range boost ratios. | Select for cost-sensitive, lower-current apps where 5V input and 8–10V output suffice; no RFB1/RFB2 flexibility. |
Compared with TPS61088RHLR and MAX17062ETA+, the LM2698MMX-ADJ uniquely combines adjustable output (via FB divider), external VC compensation for ceramic-capacitor stability, and 2.2V minimum start-up - making it optimal for precision, wide-input, and thermally constrained boost designs.
Availability
LM2698MMX-ADJ is available at Aetrix Electronics and suitable for DSL modems, diagnostic medical instrumentation, set-top boxes, industrial sensor nodes, and portable test equipment requiring stable component supply and long-term manufacturability.
Supply support for LM2698MMX-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 specializing in analog, embedded processing, and power management ICs, with decades of expertise in DC-DC conversion and high-reliability power solutions.
The LM2698 product line delivers SIMPLE SWITCHER® boost regulators targeting space-constrained, high-efficiency applications where design simplicity, thermal robustness, and adjustable output voltage are critical - especially in telecom, medical, and industrial edge devices.
FAQ
What is the minimum input voltage required for LM2698MMX-ADJ to start switching?
The LM2698MMX-ADJ has an absolute minimum operating input voltage of 2.2V, verified across temperature (−40°C to +125°C). Startup occurs reliably at 2.2V with proper input capacitance and load; below this, undervoltage lockout (UVP) disables the switch. The LM2698MMX-ADJ datasheet specifies 2.2V as the guaranteed functional lower limit, not a typical value.
How do I calculate the feedback resistor values for a specific output voltage using LM2698MMX-ADJ?
Use the formula VOUT = 1.26V × (1 + RFB1/RFB2), where 1.26V is the nominal FB reference. For example, to set 12V output: RFB1/RFB2 = (12V / 1.26V) − 1 ≈ 8.5. Select standard E96 values - e.g., RFB2 = 3.48kΩ and RFB1 = 30.1kΩ as shown in TI's typical application. The LM2698MMX-ADJ tolerates ±2.5% FB reference variation, so final output accuracy depends on resistor tolerance.
Does LM2698MMX-ADJ support SEPIC or flyback topologies, or is it boost-only?
The LM2698MMX-ADJ supports boost, SEPIC, and flyback configurations per its official datasheet (SNVS153E, Sections 1.1 and Application Figures 21–22). Its current-mode controller and floating SW pin allow reconfiguration - e.g., in SEPIC, SW drives coupled inductors and CSEPIC; in flyback, SW connects to transformer primary. No hardware change is needed beyond external component selection.
What is the purpose of the NC pin (Pin 8) on LM2698MMX-ADJ, and how should it be connected?
Pin 8 is a no-connect terminal explicitly designated as NC in the LM2698MMX-ADJ datasheet. It must be tied to GND - not left floating - to improve thermal conduction from the package's exposed pad and reduce noise coupling into sensitive analog circuitry. TI's layout guidelines require grounding Pin 8 via short trace to the GND plane beneath the IC.
Can LM2698MMX-ADJ operate at 1.25MHz with full 400mA output current and maintain thermal safety?
Yes - at 1.25MHz, the LM2698MMX-ADJ delivers 400mA continuously when mounted on a PCB with ≥0.2523 in² copper pour (θJA = 195°C/W). At TA = 60°C, junction temperature reaches ~117°C (TJ = 60 + (1.35A × 0.2Ω × 195) ≈ 117°C), staying within the 125°C max rating. Derating is recommended above 60°C ambient or with minimal copper.
LM2698MMX-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Boost, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.2V
- Voltage - Input (Max):
- 12V
- Voltage - Output (Min/Fixed):
- 2.2V
- Voltage - Output (Max):
- 17.5V
- Current - Output:
- 1.35A (Switch)
- Frequency - Switching:
- 600kHz, 1.25MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-VSSOP
LM2698MMX-ADJ FAQ
1.How can I place an order for LM2698MMX-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2698MMX-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 LM2698MMX-ADJ reliable?
The price and inventory of LM2698MMX-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2698MMX-ADJ is usually 5 days.
3.What payment methods are accepted for LM2698MMX-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2698MMX-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2698MMX-ADJ?
LM2698MMX-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2698MMX-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 LM2698MMX-ADJ?
For technical support, including LM2698MMX-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2698MMX-ADJ requirements.
6.How does Aetrix verify that LM2698MMX-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2698MMX-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 LM2698MMX-ADJ meets industry standards.
7.What is the process for return or replacement of LM2698MMX-ADJ?
All LM2698MMX-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2698MMX-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 LM2698MMX-ADJ part is unused and in its original packaging.
Return procedure for LM2698MMX-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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