Analog Devices Inc. LT8570EMS8E-1#PBF

Overview

LT8570EMS8E-1#PBF from Analog Devices (formerly Linear Technology) is a 0.25A, 65V monolithic PWM DC/DC converter IC configured as boost/SEPIC/inverting regulator for bias supply generation. It features adjustable 200kHz–1.5MHz switching frequency, integrated soft-start, synchronization capability, and user-configurable undervoltage lockout. Used in TFT-LCD and VFD bias supplies where input voltage ranges from 2.55V to 40V.

For engineers reviewing the LT8570EMS8E-1#PBF datasheet, LT8570EMS8E-1#PBF pinout, LT8570EMS8E-1#PBF application, or LT8570EMS8E-1#PBF equivalent, key selection criteria include its 0.25A current limit, 65V switch rating, MSOP-8 package thermal performance (θ_JA = 35–40°C/W), and dual-mode feedback architecture supporting both positive and negative output configurations.

Technical Context

The LT8570EMS8E-1#PBF implements constant-frequency current-mode control with internal slope compensation, enabling stable operation up to 50% duty cycle without external ramp injection. Its dual-path error amplifier (A1/A2) selects between 1.204V reference for noninverting topologies and 3mV reference for inverting topologies based on FBX pin bias polarity.

Frequency foldback reduces switching frequency to 1/6 of nominal when FBX voltage falls within 300–920mV - a feature critical for controlled start-up under heavy load or low-input conditions. The SHDN pin accepts slowly ramping enable signals with 40mV hysteresis and supports programmable UVLO via external resistor divider.

Key Specifications

Pinout & Package

LT8570EMS8E-1#PBF is housed in an 8-lead plastic MSOP package (MS8E) with exposed thermal pad (Pin 9 = GND). The package measures 3mm × 3mm × 1.1mm and requires soldering of the exposed pad to the PCB ground plane for thermal integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT8570EMS8E#PBF, the LT8570EMS8E-1#PBF trades peak current capability for improved light-load efficiency and smaller passive components, while LT3580EMS8E#PBF sacrifices topology flexibility and advanced start-up features for lower BOM cost in fixed-output boost designs.

Availability

LT8570EMS8E-1#PBF is available at Aetrix Electronics and suitable for TFT-LCD bias supplies, VFD display systems, and GPS receiver LNA power rails requiring stable component supply across industrial temperature ranges (–40°C to 125°C).

Supply support for LT8570EMS8E-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, documentation, and manufacturing continuity for all Linear-branded power management ICs.

The LT8570 family was designed specifically for compact, high-voltage bias supply generation in space-constrained displays and communication interfaces - emphasizing topology flexibility, wide input range, and robust start-up behavior.

FAQ

What topology configurations does the LT8570EMS8E-1#PBF support?

The LT8570EMS8E-1#PBF supports three distinct DC/DC topologies: boost (step-up), SEPIC (step-up/step-down with input-output isolation), and inverting (negative output generation). Configuration is determined solely by external component connections - no internal configuration bits or mode pins are required. Each topology uses the same LT8570EMS8E-1#PBF IC and leverages its dual-reference feedback architecture to maintain regulation accuracy across all modes.

How is the output voltage set on the LT8570EMS8E-1#PBF?

The LT8570EMS8E-1#PBF uses a single external resistor (R_FBX) connected between V_OUT and the FBX pin to set output voltage. For noninverting topologies (boost/SEPIC), R_FBX = (V_OUT − 1.204V) / 83.3µA; for inverting topologies, R_FBX = (V_OUT + 3mV) / 83.3µA. This resistor-based method eliminates need for voltage-divider networks or precision references, simplifying design and reducing component count.

What is the purpose of the frequency foldback feature in the LT8570EMS8E-1#PBF?

Frequency foldback in the LT8570EMS8E-1#PBF reduces switching frequency to 1/6 of nominal when FBX pin voltage falls within 300–920mV - a condition typically occurring during start-up under heavy load or low-input voltage. This extends minimum off-time, improves current control at low duty cycles, and prevents switch current runaway. The feature is fully automatic and requires no external components or configuration.

Can the LT8570EMS8E-1#PBF be synchronized to an external clock?

Yes, the LT8570EMS8E-1#PBF supports external clock synchronization via the SYNC pin. Driving SYNC above 1.3V synchronizes switching to the external clock; driving below 0.4V reverts to internal free-running operation. The IC accepts clock frequencies matching its 200kHz–1.5MHz operating range and tolerates duty cycles from 35% to 65%, enabling EMI reduction in noise-sensitive systems.

What thermal considerations apply to the LT8570EMS8E-1#PBF in MSOP-8 package?

The LT8570EMS8E-1#PBF in MS8E package has a junction-to-ambient thermal resistance (θ_JA) of 35–40°C/W, dependent on PCB copper area and airflow. To ensure reliable operation at 125°C ambient, the exposed GND pad (Pin 9) must be soldered to a minimum 100mm² copper pour connected to internal ground planes. Thermal vias under the pad (≥4×0.3mm diameter) are strongly recommended to transfer heat to inner layers.