Analog Devices Inc. LTC3220IPF-1#PBF

Overview

LTC3220IPF-1#PBF from Analog Devices (formerly Linear Technology) is a 18-channel universal LED driver IC with integrated multi-mode charge pump, I²C-controlled 6-bit linear DACs, and independent blink/gradation per channel. It delivers up to 20mA per channel (360mA total), operates from 2.9V–5.5V VIN, and supports automatic 1x/1.5x/2x mode switching for optimal efficiency in QVGA+ display backlighting and keypad lighting applications.

For engineers reviewing the LTC3220IPF-1#PBF datasheet, LTC3220IPF-1#PBF pinout, LTC3220IPF-1#PBF application, or LTC3220IPF-1#PBF equivalent, key selection considerations include its 28-pin 4mm × 4mm UTQFN package, –40°C to +125°C industrial temperature grade, dual I²C address (0011101), and ability to configure ULED pins as open-drain GPOs - critical for compact multi-LED system integration.

Technical Context

The LTC3220IPF-1#PBF integrates an 850kHz non-overlapping switched-capacitor charge pump with automatic dropout-triggered mode transitions: 1x (direct VIN-to-CPO) → 1.5x (series-parallel flying cap) → 2x (dual-phase boost), enabling stable CPO regulation up to 5.1V across varying LED forward voltages. Its 18 universal current sources each feature independent 64-step linear DAC control via I²C sub-addressing (REG1–REG18) and dedicated gradation/blink timing registers (REG19).

Each ULED output supports dual operational modes: precision current source (0–20mA, ±1.5% matching) or I²C-configurable open-drain GPO (strong pull-down or current-limited), with dropout detection disabled in GPO mode. Internal soft-start limits inrush current during mode transitions, while slew-limited flying capacitor pins (C1P/C1M/C2P/C2M) reduce conducted EMI.

Key Specifications

Pinout & Package

28-pin UTQFN (4mm × 4mm, 0.55mm profile) with exposed thermal pad (Pin 29 = GND). Pin pitch: 0.5mm. Requires soldering of exposed pad to PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED driver applications.

Compared with IS31FL3729-QFLS4-TR and MAX20050ATG/V+T, the LTC3220IPF-1#PBF uniquely combines 18-channel precision current sourcing, auto-adaptive charge pump modes, and per-output gradation/blinking in a thermally optimized UTQFN package - making it ideal for space-constrained industrial and premium consumer displays where firmware offload and V_F flexibility are critical.

Availability

LTC3220IPF-1#PBF is available at Aetrix Electronics and suitable for QVGA+ display backlighting, keypad illumination, and RGB indicator arrays requiring stable component supply across extended temperature ranges.

Supply support for LTC3220IPF-1#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 acquired Linear Technology in 2017 and maintains its high-performance analog and power management portfolio. Linear's legacy design ethos emphasizes precision, efficiency, and integration in power conversion and signal conditioning ICs.

The LTC3220IPF-1#PBF belongs to Linear's universal LED driver family, engineered specifically for compact, multi-zone display and UI lighting systems requiring high channel density, low EMI, and autonomous power management - eliminating external boost converters and timing peripherals.

FAQ

What is the I²C address of the LTC3220IPF-1#PBF?

The LTC3220IPF-1#PBF uses a fixed 7-bit I²C slave address of 0011101 (0x3A in 8-bit write format). This distinguishes it from the LTC3220 (0011100), allowing both variants to share the same I²C bus. The address is factory-programmed and not user-configurable. Communication requires standard I²C write protocol with sub-addressing for register access (e.g., REG1 for ULED1 current setting).

How does the LTC3220IPF-1#PBF handle varying LED forward voltages?

The LTC3220IPF-1#PBF automatically adapts to changing LED V_F using its multi-mode charge pump: it starts in 1x mode (VIN directly to CPO), switches to 1.5x mode upon first dropout detection, then to 2x mode upon subsequent dropout. This maintains sufficient headroom for all 18 ULED channels without manual intervention. Each mode regulates CPO to ≤4.6V (1.5x) or ≤5.1V (2x), ensuring stable 20mA current delivery across V_F from 1.8V to 4.8V.

Can ULED pins on the LTC3220IPF-1#PBF be used as general-purpose outputs?

Yes - each ULED1–ULED18 pin on the LTC3220IPF-1#PBF can be configured as an I²C-controlled open-drain general-purpose output (GPO) by setting Bits 6 and 7 of its corresponding data register (REG1–REG18) to '1'. In GPO mode, the pin supports strong pull-down (<3µA quiescent) or current-limited (≤20mA) operation, and dropout detection is disabled - preventing unintended charge pump mode changes during logic-level switching.

What is the maximum total output current capability of the LTC3220IPF-1#PBF?

The LTC3220IPF-1#PBF supports up to 360mA total output current - derived from 18 independent current sources each capable of 20mA (18 × 20mA). This rating assumes proper thermal management: the 4mm × 4mm UTQFN package has θ_JA = 37°C/W, and junction temperature must remain ≤125°C. At full load with 3.6V VIN, typical efficiency exceeds 91% in 1.5x mode, minimizing self-heating.

Does the LTC3220IPF-1#PBF include built-in protection features?

Yes - the LTC3220IPF-1#PBF integrates short-circuit protection on the CPO pin (with indefinite safe short duration) and thermal shutdown that activates above T_J = 125°C. It also features internal soft-start to limit inrush current during power-up and mode transitions, slew-limited flying capacitor pins to reduce EMI, and undervoltage lockout on both VIN and DVCC rails to prevent erratic operation during brownout conditions.