Analog Devices Inc. LTC3246IMSE#PBF

Overview

LTC3246IMSE#PBF from Analog Devices is a switched-capacitor buck-boost DC/DC converter with integrated watchdog timer and reset controller. It delivers regulated 3.3V, 5V, or adjustable (2.5V–5V) output from 2.7V–38V input, supports up to 500mA load, operates with 20µA quiescent current, and features automatic multimode (2:1/1:1/1:2) charge pump switching-enabling reliable power for automotive ECU and industrial housekeeping supplies.

For engineers reviewing the LTC3246IMSE#PBF datasheet, LTC3246IMSE#PBF pinout, LTC3246IMSE#PBF application, or LTC3246IMSE#PBF equivalent, key selection criteria include wide-input-voltage operation (2.7V–38V), integrated windowed watchdog timing, pushbutton reset capability via RSTI, ultralow EMI without inductors, and ISO 26262 diagnostic coverage suitability.

Technical Context

The LTC3246IMSE#PBF implements fractional switched-capacitor conversion using a single external flying capacitor to achieve 2:1 step-down, 1:1 pass-through, or 1:2 step-up modes-automatically selected based on real-time VIN–VOUT relationship and load conditions. Its internal mode control logic includes hysteresis to prevent oscillation at transition boundaries.

It integrates dual independent timing circuits: an RT-controlled reset timer (150–270ms internal, adjustable with CRT) and a WT-controlled windowed watchdog (37.5ms–2.2s internal, adjustable with CWT), both referenced to a stable internal BIAS voltage. The RST open-drain output asserts low during reset timeout or VOUT undervoltage/overvoltage events (93–99% UV, 106–111.5% OV thresholds).

Key Specifications

Pinout & Package

Package: 16-lead plastic MSOP with exposed thermal pad (Pin 17 = GND), requiring soldering to PCB ground plane for thermal performance (θ_JA = 40°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck-boost charge pump regulator applications.

Compared with MAX17521GTE+ and LTC3265EMSE#PBF, the LTC3246IMSE#PBF uniquely combines ultra-wide 2.7V–38V operation, integrated windowed watchdog, and 500mA output in a no-inductor package-making it the only choice for space-constrained, safety-aware automotive and industrial regulators.

Availability

LTC3246IMSE#PBF is available at Aetrix Electronics and suitable for automotive ECU power supplies, industrial housekeeping rails, and low-power 12V-to-5V conversion requiring stable component supply across extended temperature and long production lifecycles.

Supply support for LTC3246IMSE#PBF 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 (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving automotive, industrial, communications, and healthcare markets.

The LTC3246IMSE#PBF belongs to ADI's Power by Linear™ family of highly integrated DC/DC converters engineered for reliability-critical applications-including automotive ECUs, industrial controllers, and systems requiring ISO 26262 diagnostic coverage.

FAQ

What output voltage options does the LTC3246IMSE#PBF support?

The LTC3246IMSE#PBF supports three output configurations: fixed 5V (SEL2=HIGH, SEL1=LOW), fixed 3.3V (SEL2=HIGH, SEL1=HIGH), or adjustable 2.5V–5V (SEL2=LOW, SEL1=HIGH) via external resistor divider on the OUTS/ADJ pin. In all cases, the device maintains regulation across its full 2.7V–38V input range using automatic mode switching between 2:1, 1:1, and 1:2 charge pump ratios. The LTC3246IMSE#PBF achieves this without external inductors or complex control circuitry.

How does the watchdog timer in the LTC3246IMSE#PBF differ from a standard timeout watchdog?

The LTC3246IMSE#PBF implements a windowed watchdog timer-requiring WDI falling edges to occur within a defined time window (e.g., 37.5ms–2.2s), not just before a single timeout. This prevents false resets caused by overly frequent or stalled pulses, a critical requirement for ISO 26262 ASIL-B/C systems. The window is set via WT pin capacitance or internal bias, and the LTC3246IMSE#PBF asserts RST if WDI remains static or toggles too rapidly-ensuring detection of both software lockup and runaway execution.

Can the LTC3246IMSE#PBF operate from a 2.7V input while delivering 500mA at 5V output?

Yes-the LTC3246IMSE#PBF enters 1:2 step-up mode at low input voltages and can sustain 500mA at 5V output down to approximately 3.0V input (based on 8Ω max 1:2 output impedance). At 2.7V input, output current is limited to ~150mA to maintain regulation. For full 500mA capability across the entire 2.7V–38V range, use the LTC3246IMSE#PBF with appropriate input capacitance and thermal management; its 150°C max junction temperature rating allows operation in high-ambient environments when properly heatsinked via the exposed pad.

What protection features are built into the LTC3246IMSE#PBF?

The LTC3246IMSE#PBF includes overtemperature shutdown (trip at ~175°C, restart at ~165°C), short-circuit foldback limiting (250mA typical), and VOUT overvoltage/undervoltage reset (93–99% UV, 106–111.5% OV thresholds). It also features input undervoltage lockout (2.35V typical) and internal current limiting on both VOUT and BIAS outputs. These protections operate autonomously without external components-ensuring robust operation in automotive and industrial environments where supply transients and fault conditions are common. The LTC3246IMSE#PBF integrates all these functions in a single 16-lead MSOP package.

Is the LTC3246IMSE#PBF pin-compatible with other members of the LTC3246 family?

Yes-the LTC3246IMSE#PBF shares identical pinout, package (16-lead MSOP), and electrical interface with all grade variants (E, H, MP), including LTC3246EMSE#PBF and LTC3246HMSE#PBF. Differences are limited to guaranteed operating temperature ranges (–40°C to 125°C for I-grade) and screening/test rigor-not functionality or layout. This allows seamless drop-in replacement across temperature grades during design-in or production ramp, provided thermal and reliability requirements align with the I-grade specification. The LTC3246IMSE#PBF requires no PCB changes when substituting for other LTC3246 MSOP variants.