Analog Devices Inc. LT8304ES8E-1#TRPBF

Overview

LT8304ES8E-1#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic micropower isolated flyback controller IC with integrated 150V/2A DMOS switch, operating from 3V to 100V input and delivering up to 24W isolated output power. It enables opto-isolator–free regulation via primary-side flyback pulse sampling, supports boundary mode and low-ripple Burst Mode® operation, and targets high step-up applications such as 4V–80V_IN/5V_OUT auxiliary supplies in industrial and automotive systems.

For engineers reviewing the LT8304ES8E-1#TRPBF datasheet, LT8304ES8E-1#TRPBF pinout, LT8304ES8E-1#TRPBF application, or LT8304ES8E-1#TRPBF equivalent, key selection considerations include its 116µA sleep-mode quiescent current, 150V SW pin rating, 390µA active-mode IQ, quasi-resonant boundary conduction mode, and temperature-compensated output voltage programming using RFB/RREF/RTC resistors.

Technical Context

The LT8304ES8E-1#TRPBF implements primary-side sensing via flyback pulse amplitude sampling at the SW node, eliminating need for opto-isolators or third transformer windings. Its sample-and-hold error amplifier operates only when secondary current reaches zero, ensuring accurate regulation without load compensation components.

This variant is specifically optimized for high step-up output applications (e.g., ≥5:1 turns ratio), featuring enhanced immunity to SW-node current ringing during turn-on-critical under high-V_IN/light-load conditions where standard LT8304 may experience false current comparator triggering after its 160ns blanking time.

Key Specifications

Pinout & Package

LT8304ES8E-1#TRPBF is housed in an 8-lead plastic SO package (S8E) with exposed thermal pad (Pin 9, GND). The exposed pad must be soldered directly to the PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar isolated flyback controller applications.

Compared with LT8304ES8E#TRPBF and LT3748EMS#TRPBF, the LT8304ES8E-1#TRPBF uniquely balances integration, step-up resilience, and ultra-low IQ - making it optimal for compact, high-reliability 5–12V isolated supplies where transformer turns ratio exceeds 5:1 and ambient temperature spans –40°C to +125°C.

Availability

LT8304ES8E-1#TRPBF is available at Aetrix Electronics and suitable for industrial auxiliary power, automotive housekeeping supplies, medical isolated monitoring, and telecom remote PHY power requiring stable component supply across extended temperature and high-reliability lifecycles.

Supply support for LT8304ES8E-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, 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 LT8304 product line delivers highly integrated, micropower isolated flyback controllers optimized for space-constrained, high-reliability applications where opto-isolator elimination and wide input voltage operation are critical design requirements.

FAQ

What is the key functional difference between LT8304ES8E-1#TRPBF and LT8304ES8E#TRPBF?

The LT8304ES8E-1#TRPBF is specifically optimized for high step-up output applications (≥5:1 transformer turns ratio), offering enhanced immunity to SW-node current ringing during switch turn-on. This prevents false triggering of the current comparator under high-V_IN/light-load conditions where the standard LT8304ES8E#TRPBF may require longer blanking time or layout mitigation. Both share identical pinout, package, and core regulation architecture.

How does LT8304ES8E-1#TRPBF achieve opto-isolator–free regulation?

The LT8304ES8E-1#TRPBF samples the isolated output voltage directly from the primary-side flyback pulse waveform at the SW pin. When the secondary current reaches zero, the flyback voltage amplitude (V_FLBK) equals (V_OUT + V_F) × N_PS, which is converted to a current through RFB and compared against the internal 1.00V reference via RREF. This eliminates dependency on opto-isolators or third windings while maintaining ±1.5% output accuracy over temperature.

What is the minimum load requirement for stable operation of LT8304ES8E-1#TRPBF?

The LT8304ES8E-1#TRPBF maintains stable regulation down to <0.5% of full output load in low-ripple Burst Mode® operation. This is enabled by its minimum 11kHz switching frequency and controlled sleep/active mode transitions, ensuring sufficient sampling of the flyback pulse even at very light loads - critical for always-on auxiliary supplies powering standby circuitry.

Can LT8304ES8E-1#TRPBF support output voltage temperature compensation?

Yes. The LT8304ES8E-1#TRPBF includes a dedicated TC pin (Pin 8) providing a PTAT voltage (3.35mV/°C, 1.00V at 25°C) that can be used with an external RTC resistor between TC and RREF to compensate for the negative temperature coefficient of the output diode (–1 to –2mV/°C). This achieves <±2% total output variation over –40°C to +125°C for low-voltage outputs like 3.3V or 5V.

What thermal management guidance applies to LT8304ES8E-1#TRPBF in high-power operation?

The LT8304ES8E-1#TRPBF uses an 8-lead SO package (S8E) with an exposed thermal pad (Pin 9) that must be soldered directly to a large PCB ground plane. With θ_JA = 33°C/W, continuous 24W operation requires adequate copper area and airflow; for sustained >15W output, thermal vias under the pad and adjacent ground planes are strongly recommended to maintain junction temperature ≤125°C in ambient up to 85°C.