Analog Devices Inc. LTC3225EDDB#TRPBF

Overview

LTC3225EDDB#TRPBF from Analog Devices (formerly Linear Technology) is a programmable supercapacitor charger IC designed to charge two series-connected supercapacitors to 4.8V or 5.3V from 2.8V–5.5V input. It delivers up to 150mA output current, features automatic cell balancing without external resistors, and operates in a compact 10-lead 2mm × 3mm DFN package. It is used in backup power systems for real-time clocks, SRAM, and low-power IoT sensors.

For engineers reviewing the LTC3225EDDB#TRPBF datasheet, LTC3225EDDB#TRPBF pinout, LTC3225EDDB#TRPBF application, or LTC3225EDDB#TRPBF equivalent, key selection criteria include its dual-cell balancing architecture, VSEL-programmable output voltage (4.8V/5.3V), PROG-resistor-set charge current, PGOOD status flag, and sub-1μA discharge current when input is removed.

Technical Context

The LTC3225EDDB#TRPBF implements a constant-frequency switched-capacitor charge pump (f_OSC = 0.6–1.5 MHz) to double VIN and regulate COUT with ±100mV hysteresis. Its internal balancing loop continuously monitors CX (midpoint voltage) and dynamically adjusts per-cell charge current-up to ±50% deviation-to maintain ≤2.75V across each supercapacitor.

It integrates UVLO (2.65V/2.75V thresholds), thermal shutdown (~150°C), overcurrent protection, and a high-impedance PGOOD open-drain output that asserts low when VOUT falls >7.2% below regulation. Shutdown current is <1μA with input removed, and no-inductor operation eliminates EMI concerns in space-constrained designs.

Key Specifications

Pinout & Package

Package: 10-lead 2mm × 3mm plastic DFN (DDB) with exposed thermal pad (Pin 11) requiring soldering to PCB ground plane for thermal performance (θ_JA = 76°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar supercapacitor charging applications.

Compared with LTC3225EDDB-1#TRPBF, the LTC3225EDDB#TRPBF supports higher supercapacitor voltage ratings and enables longer backup runtime; compared with LTC3204EDD#TRPBF, it eliminates balancing resistor losses and improves safety margin against cell overvoltage during mismatched aging.

Availability

LTC3225EDDB#TRPBF is available at Aetrix Electronics and suitable for real-time clock backup, SRAM data retention, and low-power wireless transceiver applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LTC3225EDDB#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 acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for all Linear IC products, including precision power management solutions.

The LTC3225EDDB#TRPBF belongs to Linear's supercapacitor charger product line, engineered specifically for high-reliability, no-inductor backup power systems where cell balancing, ultra-low quiescent current, and compact packaging are essential.

FAQ

What is the maximum supercapacitor stack voltage supported by the LTC3225EDDB#TRPBF?

The LTC3225EDDB#TRPBF supports a maximum COUT voltage of 5.3V (when VSEL = high). This corresponds to 2.65V per supercapacitor in a two-series configuration, ensuring safe operation within standard 2.7V-rated supercapacitor limits. Exceeding this voltage risks overvoltage damage to individual cells, even with automatic balancing active.

How does the LTC3225EDDB#TRPBF achieve automatic cell balancing without external resistors?

The LTC3225EDDB#TRPBF continuously monitors the CX pin-the midpoint voltage between two series supercapacitors-and dynamically adjusts the charge current delivered to each cell. If one cell's voltage lags, its current increases (up to +50%); if it leads, current decreases (down to −50%). This closed-loop control enforces equal voltage distribution without dissipative balancing resistors.

Can the LTC3225EDDB#TRPBF be used to charge a single supercapacitor?

Yes-the LTC3225EDDB#TRPBF can charge a single supercapacitor by connecting two matched ≥100μF ceramic capacitors in series across the supercapacitor terminals, then routing CX to their junction. This creates an artificial voltage divider enabling the internal balancing loop to regulate total voltage while protecting the single cell from overvoltage.

What is the minimum flying capacitor value required for the LTC3225EDDB#TRPBF?

The LTC3225EDDB#TRPBF requires a minimum 0.6μF flying capacitor (CFLY) to deliver rated output current. A 1μF X5R or X7R ceramic capacitor is recommended for stable performance across temperature and bias voltage; polarized types (tantalum/aluminum) are prohibited due to voltage reversal during startup.

Does the LTC3225EDDB#TRPBF remain powered when the input supply is disconnected?

When the input supply is removed and SHDN is tied to VIN, the LTC3225EDDB#TRPBF draws less than 1μA from the supercapacitors-effectively entering ultra-low-power retention mode. This preserves stored energy for extended backup duration without requiring additional external disconnect circuitry.