Analog Devices Inc. LTC3220EPF-1#TRPBF

Overview

LTC3220EPF-1#TRPBF from Analog Devices (formerly Linear Technology) is an 18-channel universal LED driver IC with integrated multi-mode charge pump, I²C-controlled 6-bit linear DACs, and independent blink/gradation control per channel. It delivers up to 20mA per channel (360mA total), operates from 2.9V–5.5V input, and supports 1x/1.5x/2x charge pump modes for dynamic efficiency optimization in keypad, QVGA+ display, and RGB lighting systems.

For engineers reviewing the LTC3220EPF-1#TRPBF datasheet, LTC3220EPF-1#TRPBF pinout, LTC3220EPF-1#TRPBF application, or LTC3220EPF-1#TRPBF equivalent, this page provides verified technical context, validated pin functions, confirmed I²C address (0011101), exact package mapping (28-lead UTQFN, 4mm × 4mm, 0.55mm height), and real-world design implications of its dropout-driven mode switching and GPO-capable ULED outputs.

Technical Context

The LTC3220EPF-1#TRPBF implements a non-overlapping 850kHz switched-capacitor charge pump with automatic 1x → 1.5x → 2x mode transitions triggered by LED current source dropout detection (≥400µs hold time). Each of the 18 ULED outputs features a dedicated 6-bit linear DAC (64-step, 0–20mA range) and independent register control for on/off, blinking (1.25s/2.5s period), and gradation (0.24s/0.48s/0.96s ramp).

Its I²C interface uses static logic registers, supports 400kHz bus speed, and employs two factory-programmed addresses (LTC3220 = 0011100, LTC3220-1 = 0011101); the -1 suffix confirms this part uses address 0011101. The device includes slew-limited flying capacitor pins (C1P/C1M/C2P/C2M) to reduce EMI, internal soft-start (125µs), and thermal/short-circuit protection.

Key Specifications

Pinout & Package

28-lead ultrathin QFN (UTQFN), 4mm × 4mm, 0.55mm height. Exposed pad (Pin 29) is GND and must be soldered to PCB ground plane.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IS31FL3218-QFLS4-TR and MAX20050ATG/V+T, the LTC3220EPF-1#TRPBF uniquely combines linear DAC precision, autonomous charge pump mode switching, and integrated gradation/blink timing-enabling flicker-free dimming and adaptive efficiency in space-constrained, low-VIN portable lighting.

Availability

LTC3220EPF-1#TRPBF is available at Aetrix Electronics and suitable for keypad backlighting, QVGA+ display lighting, and RGB status indicator applications requiring stable component supply, full production traceability, and long-term lifecycle support.

Supply support for LTC3220EPF-1#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 product support, datasheets, and application notes for the LTC portfolio. Linear's legacy focus on precision analog and power management remains central to the brand's engineering identity.

The LTC3220 series belongs to Linear's high-integration LED driver product line, designed specifically for portable multi-display and keypad lighting where minimal external components, low EMI, and autonomous power optimization are critical.

FAQ

What is the I²C slave address for LTC3220EPF-1#TRPBF?

The LTC3220EPF-1#TRPBF uses a factory-programmed 7-bit I²C slave address of 0011101 (0x3D in hexadecimal). This distinguishes it from the standard LTC3220 (0011100 / 0x3C). The address is hardwired and cannot be modified; proper pull-up resistors on SCL/SDA and correct address byte formatting (R/W = 0) are required for communication with the LTC3220EPF-1#TRPBF.

How does the charge pump mode switching work in LTC3220EPF-1#TRPBF?

The LTC3220EPF-1#TRPBF starts in 1x mode (VIN directly connected to CPO). When any enabled ULED output enters dropout-defined as inability to maintain programmed current due to insufficient headroom-the device switches to 1.5x mode after ~400µs. A second dropout triggers 2x mode. Mode reverts to 1x after any I²C register write, gradation ramp-down completion, or blink cycle end. This behavior is intrinsic to the LTC3220EPF-1#TRPBF and requires no host intervention.

Can ULED pins on LTC3220EPF-1#TRPBF be used as general-purpose outputs?

Yes - each ULED pin on the LTC3220EPF-1#TRPBF 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 output supports strong-pull-down (≤3µA quiescent) or current-limited (≤20mA) operation, and dropout detection is disabled - preventing unintended charge pump mode changes during GPO use.

What is the maximum total output current supported by LTC3220EPF-1#TRPBF?

The LTC3220EPF-1#TRPBF supports up to 360mA total output current, derived from 18 channels × 20mA maximum per channel. This rating assumes proper thermal management: the 28-lead UTQFN package has θJA = 37°C/W, and the exposed pad (Pin 29) must be soldered to a sufficient PCB ground plane. Continuous operation above 360mA risks thermal shutdown or current derating per channel.

Does LTC3220EPF-1#TRPBF require external capacitors, and what values are specified?

Yes - the LTC3220EPF-1#TRPBF requires five external ceramic capacitors: one 2.2µF input cap (VIN), two 2.2µF flying caps (C1, C2 across C1P–C1M and C2P–C2M), one 0.1µF DVCC bypass cap, and one 4.7µF CPO output cap. All must be X5R or X7R dielectric; placement and layout per the datasheet are critical to achieve specified efficiency (>91%) and low-noise operation of the LTC3220EPF-1#TRPBF.