Texas Instruments LM2698MM-ADJ/NOPB

Overview

LM2698MM-ADJ/NOPB from Texas Instruments is a current-mode PWM boost regulator IC with integrated 1.9-A/0.2-Ω MOSFET switch, supporting adjustable output voltages up to 17 V from inputs as low as 2.2 V. It delivers 12 V at 400 mA from a 5-V source and operates at selectable 600 kHz or 1.25 MHz switching frequencies. Used in DSL modems and diagnostic medical instrumentation for efficient step-up conversion.

For engineers reviewing the LM2698MM-ADJ/NOPB datasheet, LM2698MM-ADJ/NOPB pinout, LM2698MM-ADJ/NOPB application, or LM2698MM-ADJ/NOPB equivalent, key selection criteria include its internal switch R_DS(ON), feedback voltage accuracy (1.26 V ±3%), shutdown quiescent current (5 µA), frequency select pin logic, and VC compensation network design requirements.

Technical Context

The LM2698MM-ADJ/NOPB implements current-mode control with cycle-by-cycle peak-current limiting and 85% maximum duty cycle clamping. Its error amplifier features 135 µmho transconductance and 120 V/V gain, with external compensation via the VC pin enabling stable loop response using ceramic output capacitors.

Switching frequency is selected by the FSLCT pin: grounded for 600 kHz (±20%), tied to VIN for 1.25 MHz (±20%). The device includes under-voltage lockout (UVP on-threshold 2.05 V), thermal shutdown, and over-voltage protection, operating across –40°C to +125°C junction temperature.

Key Specifications

Pinout & Package

LM2698MM-ADJ/NOPB is housed in an 8-pin VSSOP (DGK) package measuring 3.00 mm × 3.00 mm with 0.65 mm pitch, optimized for high-density PCB layouts and thermal performance (θ_JA = 142.5°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar boost regulator applications.

Compared with LM2698MM-ADJ/NOPB, TPS61088RHLR provides higher current capability and better efficiency above 300 mA, while LT3467EDD#TRPBF reduces bill-of-materials with integrated diode but sacrifices frequency flexibility and output voltage range.

Availability

LM2698MM-ADJ/NOPB is available at Aetrix Electronics and suitable for DSL modems, diagnostic medical instrumentation, set-top boxes, and distributed power architectures requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM2698MM-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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management ICs for industrial, automotive, and communications markets.

The LM2698MM-ADJ/NOPB belongs to TI's SIMPLE SWITCHER® family of integrated DC/DC regulators, designed specifically for ease of use in cost-sensitive, space-constrained power conversion applications without requiring expert power design knowledge.

FAQ

What is the minimum input voltage required for stable operation of the LM2698MM-ADJ/NOPB?

The LM2698MM-ADJ/NOPB operates stably down to 2.2 V input voltage across its full temperature range (–40°C to +125°C). Below this threshold, under-voltage lockout activates and disables switching. At 2.2 V input, the device maintains regulation for outputs ≥2.2 V, though maximum achievable output current decreases due to reduced duty cycle headroom and higher R_DS(ON).

How does the FSLCT pin affect the switching frequency of the LM2698MM-ADJ/NOPB?

The FSLCT pin on the LM2698MM-ADJ/NOPB selects between two factory-trimmed switching frequencies: grounding the pin configures 600 kHz operation (±20%), while connecting it to VIN selects 1.25 MHz (±20%). No external resistor or voltage divider is needed - the pin senses logic level directly. This selection impacts inductor size, capacitor ESR requirements, and EMI profile.

Can the LM2698MM-ADJ/NOPB be used in SEPIC topology, and what design considerations apply?

Yes, the LM2698MM-ADJ/NOPB datasheet explicitly supports SEPIC converter implementation. Key considerations include using coupled inductors or two separate inductors with matched values, ensuring the coupling coefficient meets stability requirements, and recalculating compensation network values due to altered power stage transfer function. The VC pin remains active for loop stabilization.

What is the purpose of the NC pin (Pin 8) on the LM2698MM-ADJ/NOPB, and how should it be handled?

Pin 8 of the LM2698MM-ADJ/NOPB is designated NC (No Connect) and must be connected to ground per the official datasheet. Though not internally bonded, grounding Pin 8 prevents floating node effects, reduces EMI susceptibility, and ensures mechanical stability in the VSSOP package. Leaving it unconnected violates recommended layout practices and may cause erratic behavior.

How does the LM2698MM-ADJ/NOPB achieve output voltage accuracy, and what limits its precision?

The LM2698MM-ADJ/NOPB achieves output voltage accuracy via a precision 1.26 V ±0.03 V internal bandgap reference feeding the FB comparator. Accuracy is limited by resistor divider tolerance (R_FB1/R_FB2), temperature drift of external resistors, PCB leakage currents near FB, and line regulation (≤0.1% over 2.2–12 V input). Using 0.5% metal-film resistors and guarding the FB trace yields ±1% total output tolerance.