Analog Devices Inc./Maxim Integrated MAX1709ESE

Overview

MAX1709ESE from Maxim Integrated is a 4A, low-noise, high-frequency step-up DC-DC converter in a 16-pin narrow SO package with 6A RMS switch rating, fixed 3.3V/5V or adjustable 2.5V–5.5V output, 0.7V minimum input voltage, and 600kHz constant-frequency PWM operation. It delivers up to 2.4A continuous output for local voltage conversion in routers, servers, and RF power amplifiers.

For engineers reviewing the MAX1709ESE datasheet, MAX1709ESE pinout, MAX1709ESE application, or MAX1709ESE equivalent, key selection factors include its 6ARMS switch rating, narrow SO thermal performance (34°C/W on 1in² copper), programmable soft-start via SS/LIM pin, dual-mode output configuration (fixed or adjustable), and compatibility with momentary pushbutton control using ONA/ONB logic inputs.

Technical Context

The MAX1709ESE implements current-mode PWM control with a fixed 600kHz internal oscillator, synchronizable from 350kHz to 1000kHz via CLK pin. Its n-channel MOSFET switch features 40mΩ typical on-resistance and supports peak currents up to 4A intermittently despite its 6ARMS continuous rating.

Dual-Mode™ operation enables either internally regulated 3.3V/5V outputs (via 3.3/5 pin) or externally set 2.5V–5.5V outputs (via FB resistor divider). Soft-start and current limit are independently programmable through the SS/LIM pin using capacitor or resistor networks, supporting battery-friendly startup and load-matched current limiting.

Key Specifications

Pinout & Package

MAX1709ESE is supplied in a 16-pin narrow SO package (SOIC-N) without exposed pad. Thermal performance relies on PCB copper area; no internal thermal pad is present.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-up DC-DC converter applications.

Compared with MAX1709EUI+ and MAX1708ESE, the MAX1709ESE occupies the middle tier: it delivers 2.4A continuous output in the smallest 16-pin SO package, offers identical control logic and pin compatibility with both alternatives, and enables design scalability-replacing MAX1708ESE for higher current or substituting MAX1709EUI+ where thermal budget allows reduced copper area.

Availability

MAX1709ESE is available at Aetrix Electronics and suitable for router power subsystems, RF PA bias supplies, server card rack auxiliary rails, and workstation local voltage conversion requiring stable component supply across industrial temperature range (-40°C to +85°C).

Supply support for MAX1709ESE 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

Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, computing, and communications markets.

The MAX1709 product line delivers high-power, low-noise step-up DC-DC conversion for space-constrained systems requiring efficient local voltage boosting from low-input sources such as batteries or intermediate rails.

FAQ

What is the maximum continuous output current supported by the MAX1709ESE?

The MAX1709ESE supports 2.4A continuous output current, limited by its 6ARMS-rated internal n-channel MOSFET switch. While it can deliver 4A pulsed loads intermittently due to matching peak current capability with the MAX1709EUI+, sustained operation above 2.4A risks thermal overload unless PCB copper area and airflow exceed typical 1in² 34°C/W assumptions. Always verify junction temperature using measured board thermal resistance in final layout.

How does the MAX1709ESE achieve 0.7V minimum input voltage operation?

The MAX1709ESE achieves 0.7V minimum input voltage through a bootstrap-start architecture that uses charge-pump circuitry to initially energize the gate driver from the output rail, enabling the internal MOSFET to begin switching even when VIN is below the typical threshold for conventional controllers. Once started, it sustains operation down to 0.7V by regulating duty cycle dynamically - confirmed in Electrical Characteristics Note 5 and startup voltage vs. load current plots (TOC07).

Can the MAX1709ESE be synchronized to an external clock, and what is the valid frequency range?

Yes, the MAX1709ESE supports external clock synchronization via the CLK pin over a 350kHz to 1000kHz range. When an external clock signal is applied, the device locks within two cycles and maintains tight phase alignment - critical for EMI management in noise-sensitive systems. The internal oscillator defaults to 600kHz (500–700kHz over temperature), and CLK must be driven high to revert to internal operation after external clock removal.

What is the function of the SS/LIM pin on the MAX1709ESE, and how is it configured for soft-start?

The SS/LIM pin on the MAX1709ESE serves dual functions: soft-start timing control and current limit adjustment. For soft-start, connect a capacitor (C3) from SS/LIM to GND; C3 (in µF) = 3.2 × t_SS, where t_SS is desired soft-start time in seconds. This linearly ramps the current limit to full value, preventing inrush. The same pin accepts a resistor to GND to reduce current limit - e.g., 150kΩ yields ~5A limit per Electrical Characteristics table.

Is the MAX1709ESE pin-compatible with the MAX1709EUI+?

No, the MAX1709ESE is not pin-compatible with the MAX1709EUI+. The MAX1709ESE uses a 16-pin narrow SO package with pins 1–16 assigned per its pin description table, while the MAX1709EUI+ uses a 28-pin TSSOP-EP package with different pin count, spacing, and terminal assignments (e.g., LX appears on pins 2–4 and 11–14 in SO vs. pins 2–8 and 18–23 in TSSOP). Layout and footprint must be redesigned for migration between these variants.