Texas Instruments LM2681M6X

Overview

LM2681M6X from Texas Instruments is a CMOS switched-capacitor voltage converter operating as either a voltage doubler (2.5V–5.5V input → up to 11V output) or voltage splitter (1.8V–11V input → half-voltage output), delivering up to 20 mA with 15 Ω typical output impedance, 90% conversion efficiency at full load, and 160 kHz oscillator frequency in a SOT-23-6 package. It serves battery-powered portable electronics requiring compact, low-quiescent-power DC-DC conversion without inductors.

For engineers reviewing the LM2681M6X datasheet, LM2681M6X pinout, LM2681M6X application, or LM2681M6X equivalent, key selection criteria include its dual-mode operation (doubling/splitting), SOT-23-6 footprint compatibility, 550 µA no-load supply current, and need for only two external capacitors plus one Schottky diode for startup - critical for space-constrained, low-power designs.

Technical Context

The LM2681M6X implements a four-switch CMOS charge-pump topology with internal MOSFETs having 8–16 Ω combined R_DS(on), switching at 40–80 kHz (half the 80–160 kHz oscillator frequency). Its oscillator uses OUT–GND voltage for self-starting, requiring ≥1.8V across those pins - satisfied via external Schottky diode D1 during initial power-up.

In voltage-doubler mode, it transfers energy through C1 (pumping cap) and regulates output via C2 (output cap); in split mode, it reconfigures internal switch sequencing to divide V_IN by two, eliminating the need for D1 and supporting higher input voltages up to 11V due to reduced per-switch voltage stress.

Key Specifications

Pinout & Package

SOT-23-6 package (TI package code DBV), 2.9 mm × 1.6 mm × 1.15 mm body, gull-wing leads, RoHS-compliant matte tin (Cu-Sn) finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar switched-capacitor voltage converter applications.

Compared with MAX680ESA+ and TPS60403DBVR, the LM2681M6X uniquely supports both doubling and splitting in the same SOT-23-6 footprint, offers best-in-class 90% efficiency at 20 mA, and maintains lowest no-load current (550 µA), making it optimal for flexible, ultra-low-power dual-mode applications where board space and battery life are critical.

Availability

LM2681M6X is available at Aetrix Electronics and suitable for cellular phones, handheld instruments, PDAs, operational amplifier power supplies, and interface power supplies requiring stable component supply with long-term manufacturability.

Supply support for LM2681M6X 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 designing analog, embedded processing, and logic products for industrial, automotive, and consumer markets.

The LM2681 product line delivers compact, inductorless DC-DC conversion for portable electronics, emphasizing low quiescent current, dual-mode flexibility, and SOT-23 integration to simplify power architecture in space-constrained devices.

FAQ

What is the primary function of the LM2681M6X?

The LM2681M6X is a CMOS switched-capacitor voltage converter that operates in two modes: as a voltage doubler (2.5V–5.5V input → up to 11V output) or as a voltage splitter (1.8V–11V input → half-voltage output). It delivers up to 20 mA with 15 Ω typical output impedance and requires only two external capacitors - and optionally one Schottky diode for startup in doubler mode. The LM2681M6X is designed for compact, low-noise, inductor-free power conversion in portable electronics.

Does the LM2681M6X require an external Schottky diode in all configurations?

No - the external Schottky diode (e.g., 1N5817) is required only in voltage-doubler mode to ensure reliable oscillator startup by charging the OUT pin above 1.8V. In voltage-split mode, the LM2681M6X uses OUT and GND as its internal oscillator power rails, so no startup diode is needed. This simplifies the BOM and layout when implementing split-rail generation from higher input voltages up to 11V.

What are the key capacitor requirements for stable operation of the LM2681M6X?

The LM2681M6X requires two external capacitors: C1 (charge-pump capacitor) and C2 (output filter capacitor). TI specifies 3.3 µF, ≤0.3 Ω ESR ceramic or tantalum types for optimal performance. Higher ESR increases output resistance and ripple; insufficient capacitance causes excessive voltage drop under load. For 20 mA operation, low-ESR ceramics (e.g., X7R 0805) are strongly recommended to maintain 90% efficiency and <15 Ω output impedance - both critical parameters verified for the LM2681M6X in production testing.

Can multiple LM2681M6X devices be paralleled to increase output current?

Yes - any number of LM2681M6X units can be paralleled to reduce composite output resistance and increase available output current beyond 20 mA. Each LM2681M6X must use its own dedicated C1 pumping capacitor, while a single shared C2 output capacitor suffices. The resulting output resistance is approximately R_OUT/N, where N is the number of paralleled devices. This technique is documented in the LM2681M6X datasheet Figure 13 and validated for stable operation across the full −40°C to +85°C range.

Is the LM2681M6X RoHS compliant and what is its moisture sensitivity level?

Yes - the LM2681M6X/NOPB is RoHS compliant and classified as "Green (RoHS & no Sb/Br)" per TI's packaging addendum. Its moisture sensitivity level is MSL Level-1 (unlimited floor life at ≤30°C/60% RH), with peak reflow temperature rated at 260°C. The device uses matte tin (Cu-Sn) lead finish and ships in tape-and-reel format (3000 units per reel), fully qualified for automated SMT assembly per J-STD-020.