Analog Devices Inc. LT8570HDD-1#PBF

Overview

LT8570HDD-1#PBF from Analog Devices (formerly Linear Technology) is a 65V, 0.25A monolithic PWM DC/DC converter optimized for boost, SEPIC, and inverting topologies in space-constrained industrial power supplies. It features adjustable 200kHz–1.5MHz switching frequency, integrated soft-start, synchronization capability, and user-configurable undervoltage lockout. Its 3mm × 3mm DFN package supports high-density TFT-LCD bias and GPS receiver power designs.

For engineers reviewing the LT8570HDD-1#PBF datasheet, LT8570HDD-1#PBF pinout, LT8570HDD-1#PBF application, or LT8570HDD-1#PBF equivalent, key selection considerations include its 0.25A current limit, –40°C to 150°C junction temperature rating, 2.55V–40V input range, 1.204V positive feedback reference, and thermal-enhanced DFN package with exposed ground pad.

Technical Context

The LT8570HDD-1#PBF employs constant-frequency current-mode control with internal slope compensation to ensure stability across duty cycles up to 85% at 200kHz. Its dual-feedback architecture (1.204V for noninverting, 3mV for inverting configurations) enables seamless topology reconfiguration without external component changes.

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 soft-start charging resistor. The 65V NPN switch exhibits 250mV V_CE(SAT) at 0.2A, supporting efficient operation in high-voltage step-up and polarity-inverting applications.

Key Specifications

Pinout & Package

LT8570HDD-1#PBF is housed in an 8-lead, 3mm × 3mm plastic DFN package with exposed thermal pad (Pin 9 = GND). The thermally enhanced layout enables high-power density while maintaining low θ_JA = 43°C/W. The exposed pad must be soldered directly to the PCB ground plane for electrical and thermal integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT8570HDD#PBF, the LT8570HDD-1#PBF trades half the switch current for tighter thermal performance at 150°C, while retaining full topology configurability and synchronization. Against LT3580HDE#PBF, it offers superior design flexibility and smaller footprint at the expense of minor pin-count increase and external frequency programming.

Availability

LT8570HDD-1#PBF is available at Aetrix Electronics and suitable for TFT-LCD bias supplies, GPS receiver power management, DSL modem local supplies, and VFD display bias generation requiring stable component supply across extended temperature ranges.

Supply support for LT8570HDD-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 full product support, datasheets, and application engineering for the LT® series. Linear pioneered high-performance analog and power ICs for demanding industrial and communications applications.

The LT8570 family was designed specifically for high-voltage, multi-topology DC/DC conversion in space- and thermal-constrained applications such as display bias, RF power, and telecom infrastructure-prioritizing integration, thermal resilience, and topology agility over raw current output.

FAQ

What is the maximum allowable junction temperature for LT8570HDD-1#PBF?

The LT8570HDD-1#PBF is fully specified and guaranteed over a junction temperature range of –40°C to 150°C. Thermal shutdown activates at approximately 165°C to protect the device during overload conditions. Continuous operation above 150°C requires derating per the manufacturer's lifetime curves, and the exposed GND pad must be properly soldered to maintain thermal resistance.

Can LT8570HDD-1#PBF be used in a SEPIC configuration, and what external components are required?

Yes, LT8570HDD-1#PBF supports SEPIC topology using two inductors (coupled or uncoupled), one capacitor, one diode, and a feedback resistor (R_FBX) from V_OUT to FBX. For a 12V output from 5V input, R_FBX = (12V − 1.204V)/83.3µA ≈ 129kΩ. The datasheet provides detailed equations for duty cycle, inductor sizing, and stability compensation specific to SEPIC operation.

How does the SHDN pin function differ between LT8570HDD-1#PBF and standard enable pins?

The SHDN pin of LT8570HDD-1#PBF features high-gain circuitry that accepts slowly varying input signals (e.g., from thermistors or RC networks) without false triggering. Its active-high threshold has 40mV hysteresis (1.21V to 1.40V), enabling robust undervoltage lockout implementation. Unlike basic enable pins, it also restarts the full soft-start sequence upon activation, ensuring controlled output ramp-up.

What is the purpose of the FBX pin's dual-reference architecture in LT8570HDD-1#PBF?

The FBX pin in LT8570HDD-1#PBF accepts either a 1.204V reference (for noninverting topologies like boost/SEPIC) or a 3mV reference (for inverting topologies), selected solely by how the external R_FBX resistor connects to V_OUT. This eliminates the need for external op-amps or topology-specific IC variants-enabling hardware reuse across multiple power architectures with identical LT8570HDD-1#PBF footprints.

Is LT8570HDD-1#PBF pin-compatible with other members of the LT8570 family?

Yes, LT8570HDD-1#PBF shares identical pinout, package dimensions, and footprint with all 8-lead DFN variants of the LT8570 and LT8570-1 families-including LT8570HDD#PBF, LT8570IDD-1#PBF, and LT8570EDD#PBF. This allows drop-in substitution for current limit or temperature grade changes without PCB revision, provided layout accommodates the 150°C thermal profile.