Analog Devices Inc. LT8570EDD-1#PBF

Overview

LT8570EDD-1#PBF from Analog Devices (formerly Linear Technology) is a 65V, 0.25A monolithic PWM DC/DC converter IC supporting boost, SEPIC, and inverting topologies. It features adjustable 200kHz–1.5MHz switching frequency, integrated soft-start, synchronization capability, and user-configurable undervoltage lockout. It delivers stable bias voltage for TFT-LCD panels in industrial display systems.

For engineers reviewing the LT8570EDD-1#PBF datasheet, LT8570EDD-1#PBF pinout, LT8570EDD-1#PBF application, or LT8570EDD-1#PBF equivalent, key selection considerations include its 0.25A current limit, 2.55V–40V input range, 65V switch rating, thermal performance in 3mm × 3mm DFN, and compatibility with SEPIC/inverting configurations for isolated or polarity-inverted outputs.

Technical Context

The LT8570EDD-1#PBF employs constant-frequency current-mode control with internal slope compensation to ensure stability at duty cycles >50%. Its dual-feedback architecture supports both positive (1.204V reference) and negative (3mV reference) FBX configurations, enabling seamless topology reconfiguration without external op-amps.

It integrates a high-gain SHDN pin accepting slowly ramping enable signals, frequency foldback during soft-start (reducing minimum duty cycle to 1/6 nominal), and a 280kΩ internal SS charging resistor. The 0.08Ω typical switch R_CE(SAT) at 0.2A enables low conduction loss in compact layouts.

Key Specifications

Pinout & Package

LT8570EDD-1#PBF is housed in an 8-lead 3mm × 3mm plastic DFN package with exposed GND pad (Pin 9), requiring soldering to PCB ground plane for thermal and electrical integrity (θ_JA = 43°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DC/DC converter applications.

Compared with LTC3589EUF#PBF, LT8570EDD-1#PBF provides superior high-voltage topology support and simpler analog control, while versus LT3580EMS#PBF it adds frequency foldback and tighter SHDN thresholds-critical for reliable bias supply sequencing in industrial displays.

Availability

LT8570EDD-1#PBF is available at Aetrix Electronics and suitable for TFT-LCD bias supplies, VFD display power, and GPS receiver LNA bias requiring stable component supply across extended temperature and long production lifecycles.

Supply support for LT8570EDD-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 precision analog and power management portfolio. Linear's legacy emphasizes high-reliability, thermally robust, and application-ready ICs for industrial and automotive markets.

The LT8570 family was designed specifically for compact, high-voltage DC/DC bias generation in display, telecom, and instrumentation systems-prioritizing topology flexibility, rugged input handling, and ease of compensation over digital configurability.

FAQ

What is the maximum output voltage achievable with LT8570EDD-1#PBF in boost configuration?

The LT8570EDD-1#PBF does not impose a hard limit on output voltage beyond its 65V switch rating and practical layout constraints. In boost mode, V_OUT is limited by the breakdown voltage of external components (diode, output capacitor) and PCB creepage. With proper 100V-rated diodes and capacitors, outputs up to 60V are routinely achieved. The LT8570EDD-1#PBF's 65V switch ensures safe operation under transient overvoltage conditions typical in industrial environments.

Can LT8570EDD-1#PBF be used in SEPIC topology with a single coupled inductor?

Yes, the LT8570EDD-1#PBF supports SEPIC operation with either coupled or uncoupled inductors. When using a coupled inductor, correct phasing must be observed per Figure 1 in the datasheet to ensure proper energy transfer and prevent saturation. The LT8570EDD-1#PBF's current-mode control and slope compensation maintain stability regardless of coupling coefficient, making it well-suited for space-constrained SEPIC designs where a single magnetic component replaces two discrete inductors.

How does the SHDN pin on LT8570EDD-1#PBF differ from standard enable inputs?

The SHDN pin on LT8570EDD-1#PBF features high-gain comparators with 40mV hysteresis (1.21V to 1.40V transition) and accepts slowly varying signals-unlike conventional CMOS enable pins that require fast logic edges. This allows direct connection to thermistors or RC networks for temperature-based shutdown or programmable UVLO. The LT8570EDD-1#PBF also restarts full soft-start upon SHDN reactivation, preventing inrush current issues common in bias supplies driving large capacitive loads.

What is the purpose of frequency foldback in LT8570EDD-1#PBF, and when is it active?

Frequency foldback in the LT8570EDD-1#PBF reduces switching frequency to 1/6 of nominal when the FBX pin voltage falls within 300mV–920mV-typically during soft-start or light-load regulation. This increases minimum off-time, improving current control accuracy at low duty cycles and preventing subharmonic oscillation. It deactivates automatically once FBX exits this range, restoring full-frequency operation. This feature is intrinsic to the LT8570EDD-1#PBF and requires no external configuration.

Is LT8570EDD-1#PBF pin-compatible with other members of the LT8570 family?

Yes, LT8570EDD-1#PBF shares identical pinout, package (3mm × 3mm DFN), and footprint with all LT8570 and LT8570-1 variants-including LT8570EDD#PBF, LT8570IDD-1#PBF, and LT8570HDD-1#PBF. The "-1" suffix denotes the 0.25A current limit variant, while temperature grade (E/I/H) and package type (DD/MS8E) are orthogonal attributes. This enables one PCB design to support multiple current and reliability grades via BOM change only.