Analog Devices Inc. LT3595AEUHH#PBF

Overview

LT3595AEUHH#PBF from Analog Devices (formerly Linear Technology) is a 16-channel buck-mode LED driver IC designed for high-precision, uniform-brightness LED string control in large-area displays. It delivers up to 50mA per channel with ±4% channel-to-channel current matching, 7% LED current accuracy, and 5000:1 True Color PWM dimming at 100Hz - enabling flicker-free video billboard and stadium display operation.

For engineers reviewing the LT3595AEUHH#PBF datasheet, LT3595AEUHH#PBF pinout, LT3595AEUHH#PBF application, or LT3595AEUHH#PBF equivalent, key selection criteria include input voltage range (4.5V–45V), internal 100mA/45V switches, 2MHz switching frequency, RSET-programmable current (10–50mA), and open-LED fault reporting via OPENLED pin.

Technical Context

The LT3595AEUHH#PBF implements a fixed-frequency (1.6–2.4MHz), current-mode buck architecture with sixteen independent switching regulators sharing one oscillator and V-I converter. Each channel integrates a 100mA/45V NPN switch, internal Schottky diode, and dedicated PWM comparator with synchronized rising-edge dimming control.

Operation relies on external RSET to set master LED current (I_LED = 1.21 × 1240 / R_SET), while thermal protection, open-LED detection, and shutdown (SHDN < 0.4V) are implemented on-die. The 56-pin QFN package supports 1-sided PCB layout with exposed pad tied to GND for thermal management.

Key Specifications

Pinout & Package

LT3595AEUHH#PBF is housed in a 56-pin plastic QFN package (5mm × 9mm × 0.75mm) with exposed thermal pad (Pin 57) soldered to PCB ground. Pin assignment follows UHH package drawing LTC DWG #05-08-1727 Rev A.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-channel LED driver applications.

Compared with LT3595AEUHH#PBF, LT3590EFE#PBF offers higher input voltage but zero channel scalability, while LT3475EFE#PBF provides greater per-channel current at the cost of channel count, integration, and dimming resolution - making LT3595AEUHH#PBF uniquely suited for high-channel-count, high-uniformity display systems.

Availability

LT3595AEUHH#PBF is available at Aetrix Electronics and suitable for LED video billboards, LCD television backlights, and stadium display systems requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance across –40°C to 125°C.

Supply support for LT3595AEUHH#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 product lines with rigorous qualification and long-term support.

The LT3595A product line was designed specifically for large-format, multi-string LED displays demanding precise current matching, wide dimming range, and robust fault reporting - targeting signage, broadcast, and architectural lighting markets.

FAQ

What is the maximum LED string voltage supported by the LT3595AEUHH#PBF?

The LT3595AEUHH#PBF does not specify a fixed maximum LED string voltage; instead, it depends on input voltage, duty cycle limit (80–85%), switch saturation voltage (~450mV), and Schottky forward drop (~0.8V). With VIN = 45V and DCMAX = 85%, the practical maximum V_LED is approximately 37V - sufficient for 10-series white LEDs (3.5V each) or 12-series red LEDs (2.2V each). Always verify against the specific application's duty cycle equation.

How does the LT3595AEUHH#PBF achieve 5000:1 PWM dimming without color shift?

The LT3595AEUHH#PBF achieves 5000:1 True Color PWM dimming by maintaining constant LED current amplitude during each PWM on-time, regardless of duty cycle. Its current-mode control ensures peak inductor current - and thus LED current - remains precisely regulated down to 2μA average (at 10mA full scale). This preserves chromaticity because LED spectral output depends on instantaneous current, not average value.

Can the LT3595AEUHH#PBF drive more than 10 LEDs per string?

Yes, the LT3595AEUHH#PBF can drive more than 10 LEDs per string provided the total forward voltage stays within the achievable output swing: V_OUT ≤ VIN × DCMAX − V_CE(SAT) − V_F(SCHOTTKY). For example, with VIN = 45V, DCMAX = 85%, V_CE(SAT) = 450mV, and V_F = 0.8V, V_OUT ≤ ~37V - enough for 12–13 standard white LEDs (3.0–3.2V each). Thermal limits and efficiency should also be verified per design.

What is the role of the exposed pad (Pin 57) on the LT3595AEUHH#PBF?

The exposed pad (Pin 57) on the LT3595AEUHH#PBF is electrically connected to GND and serves as the primary thermal conduction path. It must be soldered to a solid copper thermal pad on the PCB with multiple vias to inner-layer ground planes. Proper attachment reduces θ_JA from 31°C/W to ~15°C/W, enabling reliable operation at full load across the –40°C to 125°C junction temperature range.

Does the LT3595AEUHH#PBF require external compensation components?

No, the LT3595AEUHH#PBF integrates all compensation components internally. Its current-mode architecture with built-in ramp generator and error amplifier eliminates the need for external RC networks or type-II/type-III compensators. This reduces design complexity, saves board space, and ensures stable operation across the full input (4.5V–45V) and output voltage range without tuning.