Analog Devices Inc./Maxim Integrated MAX1970EEE+

Overview

MAX1970EEE+ from Maxim Integrated is a dual-output, current-mode PWM buck regulator IC operating at a fixed 1.4MHz switching frequency, delivering up to 750mA per output from a 2.6V–5.5V input. It features 180° out-of-phase operation to reduce input ripple, ±1% output voltage accuracy over load/line/temperature, and integrated power-on reset (POR) with 16.6ms delay. It is used in USB-powered xDSL modems for compact, efficient dual-rail power conversion.

For engineers reviewing the MAX1970EEE+ datasheet, MAX1970EEE+ pinout, MAX1970EEE+ application, or MAX1970EEE+ equivalent, key selection considerations include its fixed 1.4MHz frequency, dual independent feedback select (FBSEL1/FBSEL2), open-drain PFO monitoring V_IN trip at 3.94V, QSOP-16 package compatibility, and support for sub-1V output configuration when one rail exceeds 1.2V.

Technical Context

The MAX1970EEE+ implements a current-mode PWM control architecture with slope compensation, using internal high-side and low-side MOSFETs (R_DS(ON) ≈ 0.28Ω / 0.16Ω at V_IN = 2.6V) for synchronous rectification. Its dual regulators operate 180° out of phase to minimize input capacitor RMS current and enable all-ceramic designs.

It integrates a 1.2V reference (±1% tolerance), soft-start via REF pin (25µA current source), and POR logic that asserts low until both outputs reach 92% of nominal voltage, then holds for 16.6ms before going high. The PFO output monitors V_IN and asserts high when V_IN falls below 3.94V - critical for USB power-fail detection in xDSL applications.

Key Specifications

Pinout & Package

The MAX1970EEE+ is housed in a 16-pin QSOP (Quarter-Size Outline Package) with exposed thermal pad on underside (PGND-connected). Pin pitch is 0.025", body width 0.150", and total dimensions 3.9mm × 4.9mm × 1.45mm. Thermal resistance θ_JA = 120°C/W (typ).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-output buck regulator applications.

Compared with MAX1972EEE+, the MAX1970EEE+ offers faster system reset release (16.6ms vs. 175ms), making it ideal for USB-hosted devices with tight boot timing. Against TPS65270RGET, it trades higher current and LDO integration for superior USB power-fail responsiveness, smaller footprint, and lower component count in dual-buck-only designs.

Availability

MAX1970EEE+ is available at Aetrix Electronics and suitable for xDSL modems, USB-powered field instruments, and copper Gigabit SFP modules requiring stable component supply, long-term production continuity, and guaranteed RoHS-compliant sourcing.

Supply support for MAX1970EEE+ 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, communications, and computing markets.

The MAX1970EEE+ belongs to Maxim's high-frequency dual buck regulator product line, designed specifically for space-constrained, USB-powered broadband communication equipment requiring precise dual-rail generation and robust power-fail detection.

FAQ

What is the switching frequency of the MAX1970EEE+ and why is it important?

The MAX1970EEE+ operates at a fixed 1.4MHz switching frequency. This high frequency allows use of small 3.3µH–6.8µH inductors and ceramic capacitors, reducing solution size and cost. Crucially, it places switching noise outside the xDSL upstream/downstream frequency bands (up to 1.1MHz), preventing interference with DSL signal integrity - a key requirement validated in MAX1970EEE+ application circuits for modems.

Does the MAX1970EEE+ support sub-1V output voltages?

Yes, the MAX1970EEE+ can generate sub-1V outputs (down to 0.8V) on one channel when the other output is set above 1.2V - for example, 1.0V on OUT2 while OUT1 is at 1.8V. This is achieved using a resistor divider between FB1 and OUT2, as specified in the Output Voltage Selection section of the MAX1970EEE+ datasheet. The feature eliminates need for an external LDO in low-voltage core rail designs.

How does the PFO (Power-Fail Output) function in the MAX1970EEE+?

The PFO pin on the MAX1970EEE+ is an open-drain output that goes high when the input voltage (V_IN) falls below 3.94V (typical falling threshold). It is specifically designed for USB-powered applications to detect loss of valid 5V bus voltage. When asserted, PFO signals upstream circuitry to initiate controlled shutdown - a documented behavior confirmed across MAX1970EEE+ electrical characteristics and typical operating curves.

What is the purpose of the FBSEL1 and FBSEL2 pins on the MAX1970EEE+?

The FBSEL1 and FBSEL2 pins on the MAX1970EEE+ configure each output's feedback mode: connecting to GND selects 1.8V (OUT1) or 1.5V (OUT2); connecting to VCC selects 3.3V (OUT1) or 2.5V (OUT2); leaving unconnected enables external resistor-divider programming from 1.2V to V_IN. This triple-mode flexibility is a defined feature of the MAX1970EEE+ and enables rapid design reuse across multiple voltage combinations without changing the IC.

Can the MAX1970EEE+ be used with all-ceramic capacitors?

Yes, the MAX1970EEE+ is fully compatible with all-ceramic capacitor designs for both input and output filtering. Its current-mode control architecture and internal compensation are optimized for low-ESR ceramic capacitors, eliminating the need for aluminum or tantalum bulk capacitors. This capability is explicitly verified in MAX1970EEE+ typical application circuits and supported by stability analysis in the datasheet's Compensation Design section.