Analog Devices Inc. LTC3251EMSE-1.2#TRPBF

Overview

LTC3251EMSE-1.2#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-output, 2-phase spread spectrum charge pump DC/DC converter delivering up to 500mA at 1.2V from a 2.7V–5.5V input. It replaces inductor-based buck regulators in space-constrained battery-powered systems, achieving twice the efficiency of LDOs with no magnetic components. Its Super Burst mode draws only 10µA quiescent current and supports handheld devices requiring low-noise, high-efficiency 1.2V core or I/O rail generation.

For engineers reviewing the LTC3251EMSE-1.2#TRPBF datasheet, LTC3251EMSE-1.2#TRPBF pinout, LTC3251EMSE-1.2#TRPBF application, or LTC3251EMSE-1.2#TRPBF equivalent, key selection criteria include its 1.2V ±4.2% output regulation over 0–500mA load, 10µA Super Burst operating current, 2-phase spread spectrum architecture for <20dBm peak EMI reduction, and thermally enhanced 10-pin MSOP package with exposed GND pad.

Technical Context

The LTC3251EMSE-1.2#TRPBF implements dual-phase switched-capacitor fractional conversion using two interleaved flying capacitors (C1, C2), enabling continuous charge transfer that halves input current draw versus single-phase pumps and doubles efficiency over LDOs. Regulation is achieved via internal feedback sensing referenced to a 0.8V FB threshold, with output voltage fixed at 1.2V by internal resistor divider.

Its operating modes-Continuous Spread Spectrum (1.0–1.6MHz random frequency), Burst Mode (35µA I_IN, 50mA burst threshold), and Super Burst Mode (10µA I_IN, 40mA max output)-are selected via CMOS-compatible MD0/MD1 pins. Spread spectrum is disabled on LTC3251-1.2 variants via MODE pin tied low, locking switching to 1.6MHz for deterministic noise control.

Key Specifications

Pinout & Package

Package: 10-lead plastic MSOP with exposed thermal pad (Pin 11), θ_JA = 40°C/W, θ_JC = 10°C/W. Exposed pad must be soldered to PCB ground plane for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar charge pump DC/DC converter applications.

Compared with MAX8814EETE+T and TLC59284RGER, the LTC3251EMSE-1.2#TRPBF uniquely combines 500mA capability, 10µA Super Burst current, and 2-phase spread spectrum in a 10-pin MSOP - making it the sole option for high-efficiency, ultra-low-noise, long-life 1.2V conversion where board space and EMI are critical.

Availability

LTC3251EMSE-1.2#TRPBF is available at Aetrix Electronics and suitable for handheld devices, cellular phones, and portable medical sensors requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LTC3251EMSE-1.2#TRPBF 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

Analog Devices, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LTC3251 family was designed by ADI's former Linear Technology division specifically for ultra-compact, low-EMI, battery-powered applications needing inductorless step-down conversion with programmable efficiency/noise trade-offs.

FAQ

What is the output voltage tolerance of the LTC3251EMSE-1.2#TRPBF across full load and temperature?

The LTC3251EMSE-1.2#TRPBF delivers a nominal 1.2V output with guaranteed regulation of 1.15V to 1.25V (±4.2%) over 0–500mA load current, 2.7–5.5V input, and –40°C to +85°C ambient temperature. This specification is verified across all operating modes including Continuous, Burst, and Super Burst - ensuring consistent rail accuracy in both active and low-power states.

Does the LTC3251EMSE-1.2#TRPBF require external resistors to set the output voltage?

No. The LTC3251EMSE-1.2#TRPBF is a fixed-output variant with internal resistor divider setting VOUT to 1.2V. Unlike the adjustable LTC3251, it does not use the FB pin for voltage programming. The MODE pin controls spread spectrum enable/disable but does not affect output voltage setting - the 1.2V output is factory-trimmed and requires no external components for regulation.

How does the LTC3251EMSE-1.2#TRPBF achieve lower EMI than conventional buck converters?

The LTC3251EMSE-1.2#TRPBF uses 2-phase interleaved spread spectrum switching (1.0–1.6MHz random frequency) to distribute energy across a wide band, reducing peak spectral emissions by >20dBm. Its dual-phase architecture also cancels input ripple current, allowing 1µF input capacitance versus 10µF in buck converters - further suppressing conducted EMI without inductors or ferrites.

What is the minimum input voltage required for the LTC3251EMSE-1.2#TRPBF to maintain regulation at 500mA?

The LTC3251EMSE-1.2#TRPBF requires VIN ≥ 2 × (VOUT + R_OL × IOUT) for regulation. With R_OL = 0.7Ω max and VOUT = 1.2V, minimum VIN at 500mA is 3.0V. Below this, dropout occurs. The datasheet confirms stable 1.2V output down to 3.0V input at full 500mA load - validating operation across the full 3.0–5.5V range specified for high-current conditions.

Can the LTC3251EMSE-1.2#TRPBF be used with tantalum or aluminum electrolytic capacitors for flying caps?

No. The LTC3251EMSE-1.2#TRPBF flying capacitor terminals (C1+, C1−, C2+, C2−) experience voltage polarity reversal during startup and switching cycles. Tantalum and aluminum electrolytics are polarized and will fail catastrophically under reverse bias. Only X5R/X7R ceramic capacitors rated for ≥2V bias and ≥1µF (with ≥0.4µF effective capacitance over temperature/voltage) are permitted - per Absolute Maximum Ratings and Layout Guidelines.