Analog Devices Inc. LTC3221EDC-3.3#TRPBF

Overview

LTC3221EDC-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a micropower regulated charge pump DC/DC converter delivering a stable 3.3V ±4% output from 1.8V–4.4V input, supporting up to 60mA load current with only 8µA no-load quiescent current and no inductors required. It operates in Burst Mode® for ultralow power consumption and features short-circuit protection, shutdown disconnect, and a 2mm × 2mm 6-pin DFN package - ideal for compact battery-powered medical sensors and memory backup supplies.

For engineers reviewing the LTC3221EDC-3.3#TRPBF datasheet, LTC3221EDC-3.3#TRPBF pinout, LTC3221EDC-3.3#TRPBF application, or LTC3221EDC-3.3#TRPBF equivalent, key selection criteria include input voltage range (1.8V–4.4V), regulated 3.3V output tolerance, 60mA max load capability, 8µA quiescent current, and shutdown current <1µA - all critical for low-power wearable and IoT edge node designs.

Technical Context

The LTC3221EDC-3.3#TRPBF uses a switched-capacitor voltage doubler architecture with controlled-current switching (ISW) and hysteresis-based regulation via an internal comparator. It achieves regulation without inductors by dynamically charging and discharging a flying capacitor (CFLY) to maintain VOUT within ±4% across load and input variations.

Burst Mode® operation disables most internal circuitry when VOUT remains above the lower comparator threshold, reducing average supply current to 8µA at no load. The SHDN pin (active-low) fully disconnects VOUT from VIN during shutdown, drawing <1µA, and the exposed thermal pad (Pin 7) must be soldered to PCB ground for thermal and electrical integrity.

Key Specifications

Pinout & Package

Package: 2mm × 2mm, 0.75mm height, 6-pin DFN with exposed thermal pad (Pin 7 = GND). Requires soldering of exposed pad to PCB ground plane for thermal performance and electrical reference.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar regulated charge pump applications.

Compared with LTC3221EDC-3.3#TRPBF, LTC3204EDC-3.3#TRPBF offers 2.5× more output current at the cost of 3× higher quiescent current and incompatible pinout, while LTC1754ES5-3.3#TRMPBF trades 17% lower current and no shutdown for SOT-23 simplicity - making LTC3221EDC-3.3#TRPBF optimal for balanced ultra-low-power, moderate-current, and feature-complete designs.

Availability

LTC3221EDC-3.3#TRPBF is available at Aetrix Electronics and suitable for low-power medical sensors, memory backup supplies, tire pressure monitoring systems, and RF transmitter bias supplies requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LTC3221EDC-3.3#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LTC3221 product line was designed specifically for micropower, inductorless DC/DC conversion in space- and energy-constrained battery-operated systems - emphasizing ultralow quiescent current, robust short-circuit behavior, and minimal external component count.

FAQ

What is the minimum input voltage required for LTC3221EDC-3.3#TRPBF to regulate 3.3V output?

The LTC3221EDC-3.3#TRPBF requires a minimum input voltage of 1.8V to initiate regulation and sustain 3.3V output at zero load. For full 60mA output capability, VIN must be ≥2.0V per the datasheet's "IOUT = 0mA TO 60mA; VIN >2V" specification. Below 2.0V, maximum load current decreases progressively - e.g., at 1.9V input, usable output current is limited to ~30mA before regulation degrades beyond ±4%.

Can LTC3221EDC-3.3#TRPBF drive a 100mA load if VIN is increased to 4.4V?

No. The LTC3221EDC-3.3#TRPBF is rated for a maximum continuous output current of 60mA regardless of input voltage - this limit is enforced by internal current control (ISW) and thermal design. Attempting 100mA will cause VOUT to droop below 3.168V (–4% limit), trigger repeated burst cycles, and risk thermal shutdown. For >60mA, consider LTC3204EDC-3.3#TRPBF or LTC3240-3.3#TRPBF instead.

Is an external feedback resistor divider required for LTC3221EDC-3.3#TRPBF?

No. The LTC3221EDC-3.3#TRPBF is the fixed-output variant with internal resistive divider set for 3.3V ±4%; it does not expose an FB pin. Only the base part number LTC3221 (without -3.3 or -5 suffix) includes FB functionality for adjustable output. Using LTC3221EDC-3.3#TRPBF eliminates need for external resistors, simplifying layout and reducing BOM count.

What is the recommended flying capacitor value and type for LTC3221EDC-3.3#TRPBF?

The datasheet specifies a minimum 0.6µF flying capacitor, and recommends a 1µF X5R or X7R ceramic capacitor in 0603 or 0805 case size. Polarized capacitors (tantalum, aluminum) are strictly prohibited due to voltage reversal during startup. A 1µF, 6.3V, 0603 X5R ceramic capacitor (e.g., Murata GRM188R60J105KAAL) meets all requirements and ensures full 60mA output capability across temperature.

Does LTC3221EDC-3.3#TRPBF require the exposed thermal pad to be connected to ground?

Yes. The exposed pad (Pin 7) is electrically and thermally connected to GND internally and must be soldered to a PCB ground plane. Failure to do so increases thermal resistance (θJA) beyond 80°C/W, causing junction temperature to exceed 125°C at 60mA load - potentially triggering thermal shutdown or reducing reliability. The datasheet explicitly states "EXPOSED PAD IS GND (PIN 7) MUST BE SOLDERED TO PCB".