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Analog Devices Inc./Maxim Integrated MAX1971EEE+
- Part No.:
- MAX1971EEE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
MAX1971EEE+.pdf
- Description:
- IC REG BUCK ADJ 750MA DL 16QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,518
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Product details
Overview
The MAX1971EEE+ from Maxim Integrated is a dual-output, current-mode PWM buck regulator IC operating at 700kHz with 180° out-of-phase switching. It delivers up to 750mA per output from a 2.6V–5.5V input, supports programmable or preset output voltages (e.g., 1.8V/3.3V on OUT1, 1.5V/2.5V on OUT2), and features ±1% output accuracy over load, line, and temperature. It is used in USB-powered xDSL modems for compact, low-noise dual-rail power conversion.
For engineers reviewing the MAX1971EEE+ datasheet, MAX1971EEE+ pinout, MAX1971EEE+ application, or MAX1971EEE+ equivalent, key selection criteria include its 700kHz switching frequency (vs. 1.4MHz in MAX1970/MAX1972), integrated RSI reset input, soft-start control via REF pin, ±1% regulation accuracy, and QSOP-16 package compatibility with all-ceramic capacitor designs.
Technical Context
The MAX1971EEE+ implements a fixed-frequency, current-mode PWM control architecture with internal slope compensation to ensure stability across wide duty-cycle ranges. Its two synchronous buck regulators operate 180° out of phase to minimize input ripple current and reduce required input capacitance.
It integrates dual high-side and low-side MOSFETs with on-resistance-based current sensing (no external sense resistor), a 1.2V reference with soft-start ramp (25µA current source), and a dedicated noninverting reset input (RSI) that forces POR low for 175ms after deassertion - a feature exclusive to the MAX1971 variant within the family.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 700kHz (fixed); enables smaller magnetics than 1.4MHz parts while staying outside xDSL band. |
| Output Current (each) | 750mA guaranteed; sufficient for powering dual-core DSPs or SFP transceivers without external boost. |
| Input Voltage Range | 2.6V to 5.5V; compatible with single-cell Li-ion, USB 5V, and regulated 3.3V/5V rails. |
| Output Accuracy | ±1% over load, line, and temperature; eliminates need for post-regulation trimming in precision analog subsystems. |
| POR Delay Time | 175ms; provides extended system reset hold time for firmware initialization in embedded modems. |
| RSI Function | Noninverting reset input; allows software-controlled system reset with 1µs minimum pulse width. |
| Package | 16-pin QSOP; surface-mount, thermally enhanced footprint with PGND and GND separation for noise isolation. |
Pinout & Package
MAX1971EEE+ is housed in a 16-pin QSOP (Quad Small Outline Package) with exposed thermal pad (not electrically connected). Pin 1 is marked by a dot; pin numbering follows standard counter-clockwise orientation. The package supports reflow soldering per JEDEC J-STD-020 and has 1.27mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LX1 | High-side switch node 1 | Connects to inductor for OUT1; carries pulsed high-current switching waveform; requires low-inductance layout. |
| VCC | Analog supply rail | Bypassed with 0.1µF ceramic to GND; powers internal reference, comparators, and logic; decoupled from IN via 10Ω resistor. |
| COMP1 | OUT1 compensation node | Connects RC network to GND for loop stability; pulled to GND during shutdown to disable feedback path. |
| FB1 | OUT1 feedback input | Senses regulated voltage; supports internal presets (1.8V/3.3V) or external divider for 1.2V–VIN range (or sub-1V with cross-coupling). |
| FB2 | OUT2 feedback input | Same function as FB1; presets are 1.5V/2.5V; floating FBSEL2 enables full external adjustment. |
| COMP2 | OUT2 compensation node | Independent compensation for second regulator; identical design role as COMP1. |
| REF | Reference soft-start node | Charged by 25µA current source; controls startup ramp rate; bypassed with 0.01–1.0µF capacitor. |
| GND | Analog ground reference | Return for feedback, reference, and compensation circuits; separate from PGND to avoid noise coupling. |
| POR | Active-low power-on reset output | Open-drain; asserts low until both outputs reach 92% regulation + 175ms delay; resets microcontrollers. |
| EN | Enable input | Logic-high enables both regulators; logic-low reduces quiescent current to ≤100µA (shutdown mode). |
| RSI | Reset input (MAX1971 only) | Noninverting; drives POR low when high; POR releases 175ms after RSI falls; enables firmware-triggered reset. |
| FBSEL2 | OUT2 feedback select | Connect to GND → 1.5V; VCC → 2.5V; unconnected → external resistor divider. |
| FBSEL1 | OUT1 feedback select | Connect to GND → 1.8V; VCC → 3.3V; unconnected → external resistor divider. |
| IN | Main power input | 2.6V–5.5V supply; bypassed with 10µF ceramic to PGND; feeds internal LDO for VCC generation. |
| LX2 | High-side switch node 2 | Connects to inductor for OUT2; 180° out-of-phase with LX1 to cancel input ripple. |
| PGND | Power ground | Return path for high-current LX1/LX2 switching; separated from GND to prevent ground bounce in sensitive analog sections. |
Key Features
| Feature | Design Value |
|---|---|
| 180° out-of-phase dual regulation | Reduces RMS input ripple current by ~70%, allowing smaller input capacitors and lower EMI in space-constrained modems. |
| All-ceramic capacitor support | Eliminates electrolytic or tantalum caps; improves reliability, lifetime, and temperature stability in industrial USB devices. |
| Integrated RSI reset input | Enables deterministic, software-initiated system reset without external logic; unique to MAX1971 among family members. |
| Sub-1V output capability | Allows one output to be set below 1.2V (e.g., 1.0V) when the other is ≥1.2V - critical for modern low-voltage I/O domains. |
| ±1% output accuracy | Meets tight tolerance requirements for ADC references, RF bias rails, and FPGA core supplies without calibration. |
| Thermal overload protection | Shuts down at TJ = +170°C and auto-restarts at +150°C; prevents catastrophic failure during sustained overload or poor heatsinking. |
Applications
| USB-Powered xDSL Modem | xDSL Router Power Subsystem |
|---|---|
Use Scenario: Compact, fanless DSL modem powered solely from USB 5V bus with strict size and thermal constraints. IC Role / Device Role / Timing Role: Dual-rail DC-DC converter generating 3.3V for PHY and 1.5V for digital baseband processor; RSI enables firmware reset during line retraining. Use Value: Eliminates need for discrete LDOs or secondary converters; 700kHz operation avoids interference with upstream/downstream xDSL bands. | Use Scenario: Multi-port xDSL router requiring independent, well-regulated rails for Ethernet MAC, memory, and analog front-end. IC Role / Device Role / Timing Role: Primary dual-output buck regulator delivering 1.8V (core) and 2.5V (I/O) with coordinated soft-start and POR sequencing. Use Value: 180° phase shift cuts input capacitor size by 50%; ±1% accuracy ensures stable DDR interface timing margins. |
| Copper Gigabit SFP Module | Dual LDO Replacement |
Use Scenario: Hot-pluggable SFP transceiver module drawing power from host board's 3.3V rail with minimal PCB area. IC Role / Device Role / Timing Role: Efficient step-down regulator converting 3.3V input to 1.8V laser driver bias and 2.5V serializer supply; REF pin enables precise startup timing. Use Value: Higher efficiency (>85% at 500mA) vs. LDOs reduces thermal load in sealed modules; QSOP-16 fits standard SFP keep-out zones. | Use Scenario: Legacy design migrating from dual discrete LDOs to reduce BOM count, improve transient response, and lower dropout losses. IC Role / Device Role / Timing Role: Drop-in replacement for two 750mA LDOs; preserves same footprint and feedback configuration while adding RSI and POR. Use Value: Achieves >20% higher efficiency at full load; eliminates LDO thermal derating issues; maintains pin-compatible upgrade path. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX1970EEE+ | 1.4MHz switching, no RSI, includes PFO | Preferred where input ripple minimization and USB power-fail detection are critical | Select when higher frequency enables smaller inductors and PFO monitoring is needed instead of RSI. |
| MAX1972EEE+ | 1.4MHz switching, no RSI, includes PFO, different preset combinations | Better suited for systems needing 3.3V/2.5V or 1.8V/1.5V simultaneous outputs with power-fail alert | Choose when 1.4MHz operation is mandatory and PFO functionality outweighs RSI requirement. |
Compared with MAX1970EEE+ and MAX1972EEE+, the MAX1971EEE+ trades higher switching frequency and PFO for the unique RSI reset input and lower 700kHz operation - making it optimal for firmware-controlled, noise-sensitive, USB-powered systems where reset coordination matters more than absolute size reduction.
Availability
MAX1971EEE+ is available at Aetrix Electronics and suitable for USB-powered xDSL modems, copper gigabit SFP modules, and dual-rail embedded processors requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature.
Supply support for MAX1971EEE+ 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and computing markets.
The MAX1970/MAX1971/MAX1972 product line was designed specifically for space-constrained, USB-powered broadband communication equipment - emphasizing dual-rail efficiency, noise-aware layout, and integrated system-level functions like POR and RSI.
FAQ
What is the switching frequency of the MAX1971EEE+ and how does it differ from other family members?
The MAX1971EEE+ operates at a fixed 700kHz switching frequency. This differs from the MAX1970EEE+ and MAX1972EEE+, which operate at 1.4MHz. The lower frequency reduces EMI sensitivity in xDSL bands and eases filter design, while still enabling compact magnetics. All three share the same 180° out-of-phase dual-output architecture and 750mA per channel rating.
Does the MAX1971EEE+ support sub-1V output voltages, and if so, under what conditions?
Yes, the MAX1971EEE+ supports sub-1V outputs (e.g., 1.0V) on one channel when the other output is configured above 1.2V - achieved using cross-coupled feedback resistors between FB1 and OUT2 (or FB2 and OUT1). This capability is documented in the Output Voltage Selection section and requires careful resistor selection to maintain 100µA divider current and regulation accuracy.
How does the RSI pin on the MAX1971EEE+ function, and what is its timing behavior?
The RSI pin on the MAX1971EEE+ is a noninverting reset input. When driven high, it forces the POR output low immediately. After RSI returns low, POR remains low for exactly 175ms before going high - matching the power-on reset delay. A minimum 1µs high pulse on RSI is required to trigger this sequence, enabling reliable firmware-initiated system resets without external circuitry.
What is the purpose of the REF pin on the MAX1971EEE+, and how is it used in design?
The REF pin on the MAX1971EEE+ provides access to the internal 1.2V reference and controls soft-start timing. It is charged by a 25µA current source during startup; regulation begins once REF reaches 1.2V. A capacitor (0.01µF–1.0µF) from REF to GND sets the ramp time. During shutdown or UVLO, REF is pulled to GND, ensuring controlled turn-off and preventing output overshoot.
Can the MAX1971EEE+ use all-ceramic capacitors for input and output filtering, and why is this beneficial?
Yes, the MAX1971EEE+ is fully compatible with all-ceramic input and output capacitors - a key design advantage over older buck controllers requiring bulk electrolytics. Ceramic caps offer superior ESR, longevity, temperature stability, and size efficiency. This simplifies layout, improves reliability in harsh environments, and eliminates aging-related failures common with tantalum or aluminum electrolytics.
MAX1971EEE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable (Programmable)
- Number of Outputs:
- 2
- Voltage - Input (Min):
- 2.6V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 1.2V (1.5V, 1.8V, 2.5V, 3.3V)
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 750mA
- Frequency - Switching:
- 700kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QSOP
MAX1971EEE+ FAQ
1.How can I place an order for MAX1971EEE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1971EEE+ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MAX1971EEE+ reliable?
The price and inventory of MAX1971EEE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1971EEE+ is usually 5 days.
3.What payment methods are accepted for MAX1971EEE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1971EEE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1971EEE+?
MAX1971EEE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1971EEE+ order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MAX1971EEE+?
For technical support, including MAX1971EEE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1971EEE+ requirements.
6.How does Aetrix verify that MAX1971EEE+ is sourced from the original manufacturer or authorized distributors?
All MAX1971EEE+ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MAX1971EEE+ meets industry standards.
7.What is the process for return or replacement of MAX1971EEE+?
All MAX1971EEE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX1971EEE+, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MAX1971EEE+ part is unused and in its original packaging.
Return procedure for MAX1971EEE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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