Analog Devices Inc./Maxim Integrated MAX1708EEE+

Overview

The MAX1708EEE+ from Maxim Integrated is a high-frequency, high-power, low-noise step-up DC-DC converter with an integrated 5A RMS N-channel MOSFET switch, delivering up to 2A output at 3.3V or 5V from inputs as low as 0.7V, operating at a fixed 600kHz switching frequency with external clock synchronization capability (350–1000kHz), and featuring dual-mode output voltage selection (fixed 3.3V/5V or adjustable 2.5–5.5V) for battery-powered RF power amplifiers and local voltage conversion in routers and servers.

For engineers reviewing the MAX1708EEE+ datasheet, MAX1708EEE+ pinout, MAX1708EEE+ application, or MAX1708EEE+ equivalent, key selection considerations include its 0.7V minimum input voltage, programmable soft-start and current limit via SS/LIM pin, dual push-button on/off control logic (ONA/ONB), 1.24V feedback reference, and QSOP-16 package thermal and layout requirements for high-current LX/PGND routing.

Technical Context

The MAX1708EEE+ employs constant-frequency current-mode PWM control with internal 600kHz oscillator or external clock synchronization, enabling predictable noise spectrum placement for EMI-sensitive applications like RF PA biasing. Its Dual Mode™ architecture supports both fixed-output (3.3V/5V selected by 3.3/5 pin) and externally resistor-adjusted output (2.5–5.5V via FB divider), with feedback regulation referenced to 1.24V.

Control logic uses ONA and ONB with ~0.15V hysteresis: device enables when ONA = high or ONB = low, disables only when ONA = low and ONB = high. The SS/LIM pin serves dual function-soft-start timing controlled by capacitor to GND (t_SS = 4ms + 110 × C₃), and current limit reduction via resistor to GND (ILIM = 312kΩ / R1).

Key Specifications

Pinout & Package

MAX1708EEE+ is housed in a 16-pin QSOP package (5.0mm × 6.2mm, 0.635mm pitch) with exposed thermal pad connected to PGND pins (12–14); requires wide copper traces for LX (pins 3–5) and PGND (pins 12–14) to manage 5A RMS switch current and thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX1709EEE+, the MAX1708EEE+ offers lower cost and sufficient current for most 2A-class applications; versus TPS61088RHLR, it provides simpler system-level control (ONA/ONB pushbutton interface) and integrated voltage selection but narrower input range.

Availability

MAX1708EEE+ is available at Aetrix Electronics and suitable for routers, RF power amplifiers, and workstation card racks requiring stable component supply with guaranteed long-term availability and RoHS-compliant packaging.

Supply support for MAX1708EEE+ 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) designs precision analog, mixed-signal, and power management ICs for demanding industrial, communications, and computing applications.

The MAX1708EEE+ belongs to Maxim's high-power boost converter product line, engineered specifically for low-noise, high-efficiency local voltage conversion in space-constrained, battery-sensitive systems like handheld radios and network equipment.

FAQ

What is the minimum input voltage required for MAX1708EEE+ startup and continuous operation?

The MAX1708EEE+ starts up at a minimum input voltage of 0.9V (typical) under light load and operates continuously down to 0.7V once running, thanks to bootstrap operation. This enables use with single-cell alkaline, NiMH, or Li-ion batteries across their full discharge curve. Startup voltage varies with output load and temperature - at -40°C and 1A load, startup requires ~1.5V, per typical operating characteristics.

How does the MAX1708EEE+ implement push-button on/off control using ONA and ONB?

The MAX1708EEE+ uses complementary logic on ONA and ONB: device turns on when ONA = high OR ONB = low, and turns off only when ONA = low AND ONB = high. A momentary switch pulls ONB low to initiate startup; a microcontroller then asserts ONA high to latch the device on. To shut down, the controller pulls ONA low, and release of the button lets ONB float high, disabling the part. Hysteresis (~0.15V) prevents chatter during transitions.

Can the MAX1708EEE+ be synchronized to an external clock, and what is the supported frequency range?

Yes, the MAX1708EEE+ supports external clock synchronization via the CLK pin, accepting input frequencies from 350kHz to 1000kHz. When an external clock is applied, the device locks within two cycles and maintains tight phase alignment. If the external clock stops, MAX1708EEE+ reverts to its internal 600kHz oscillator within ~40μs. This capability enables EMI reduction by avoiding beat frequencies in multi-regulator systems.

What is the purpose of the SS/LIM pin on the MAX1708EEE+, and how is it configured for soft-start vs. current limiting?

The SS/LIM pin on the MAX1708EEE+ serves dual functions: connecting a capacitor to GND sets soft-start time (t_SS = 4ms + 110 × C₃), while connecting a resistor to GND scales the current limit from 5A down to as low as 1.8A (ILIM = 312kΩ / R1). During shutdown, SS/LIM is internally pulled to GND to discharge the soft-start capacitor. Both functions share the same pin but are mutually exclusive in implementation - capacitor for timing, resistor for current scaling.

Does the MAX1708EEE+ require external components for stable operation, and which ones are mandatory?

Yes, the MAX1708EEE+ requires several external components for stable operation: a 2.2μH power inductor (L1), Schottky catch diode (D1), input bypass capacitor (C1 ≥150μF), output filter capacitor (C2 ≥150μF, ESR <30mΩ), 0.1μF ceramic bypass on OUT pin with 2Ω series resistor, 0.22μF capacitor on REF, and resistor divider on FB for adjustable outputs. The 3.3/5 pin must be tied high/low or grounded depending on configuration. Layout best practices - especially star grounding of PGND pins - are mandatory for thermal and noise performance.