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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:1,071
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Product details
Overview
MAX1971EEE from Maxim Integrated is a dual-output, current-mode PWM buck regulator operating at 700kHz with 180° out-of-phase switching. It delivers up to 750mA per output from a 2.6V–5.5V input, supports adjustable outputs (0.8V–VIN) or preset voltages (1.8V/3.3V and 1.5V/2.5V), and features ±1% output accuracy over load, line, and temperature - used in USB-powered xDSL modems for compact, low-noise dual-rail power.
For engineers reviewing the MAX1971EEE datasheet, MAX1971EEE pinout, MAX1971EEE application, or MAX1971EEE equivalent, this page provides verified technical context, confirmed pin functions, real-world use cases in xDSL and SFP modules, and validated alternative regulators with documented functional differences.
Technical Context
The MAX1971EEE implements a fixed-frequency (700kHz), current-mode PWM control architecture with integrated high- and low-side MOSFETs, using RDS(ON)-based current sensing and slope compensation for stability. Its two regulators switch 180° out of phase to minimize input ripple and enable smaller ceramic input capacitors.
It integrates a dedicated reset input (RSI) that forces POR low for 175ms after deassertion, distinguishing it from the MAX1970/MAX1972 variants which feature PFO instead. Soft-start is controlled via REF pin with 25µA charging current, and undervoltage lockout activates below 2.35V on VCC.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 700kHz - enables use of smaller inductors (3.3–6.8µH) and ceramic capacitors while staying outside xDSL band. |
| Output Current (per channel) | 750mA guaranteed - sufficient for powering dual-core DSPs or SFP transceivers without external boost stages. |
| Input Voltage Range | 2.6V to 5.5V - compatible with single-cell Li-ion, USB 5V, and regulated 3.3V rails. |
| Output Accuracy | ±1% over load, line, and temperature - ensures stable core/logic rail regulation without post-regulation LDOs. |
| POR Delay Time | 175ms - provides reliable system reset timing for USB-powered devices after input stabilization. |
| RSI Function | Active-high reset input - allows software-controlled system reset with 1µs minimum pulse width and 175ms POR hold time. |
| Thermal Protection | Junction shutdown at +170°C with 20°C hysteresis - prevents damage during sustained overload or poor PCB thermal design. |
Pinout & Package
MAX1971EEE is housed in a 16-pin QSOP package (5.0mm × 6.2mm, 0.635mm pitch) with exposed pad for thermal enhancement. Pin functions are validated per Maxim's official datasheet revision 1 (2/09).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LX1 / LX2 | Power switch node (high-/low-side) | Connects to inductor; internal synchronous rectification eliminates external Schottky diodes. |
| IN / PGND / GND | Main power input and ground returns | PGND carries high di/dt switching current; separate GND minimizes noise coupling to analog circuitry. |
| FB1 / FB2 | Output voltage feedback inputs | Support both preset (via FBSELx) and adjustable (0.8V–VIN) configurations using resistor dividers. |
| FBSEL1 / FBSEL2 | Feedback mode select | Logic-level inputs: GND/VCC sets 1.8V/3.3V (OUT1) or 1.5V/2.5V (OUT2); floating enables external divider. |
| RSI | Reset input (MAX1971 only) | Drives POR low when asserted; 175ms delay resumes after deassertion - enables firmware-triggered resets. |
| EN | Enable control | Active-high logic input; pulls supply current to ≤100µA in shutdown - supports low-power standby modes. |
| POR | Open-drain power-on reset | Asserts low until both outputs reach 92% regulation + 175ms delay - synchronizes microcontroller boot sequence. |
| COMP1 / COMP2 | Compensation nodes | Accept RC networks for loop stability tuning - critical for maintaining phase margin with ceramic output caps. |
| REF | Soft-start reference | Charged at 25µA to 1.2V; controls startup ramp rate - limits inrush into downstream capacitance. |
Key Features
| Feature | Design Value |
|---|---|
| 180° out-of-phase dual regulation | Reduces RMS input ripple by ~70%, allowing 47µF ceramic input cap instead of 100µF tantalum. |
| All-ceramic capacitor support | Eliminates ESR-dependent output instability - enables ultra-thin designs for SFP/GBIC modules. |
| Sub-1V output capability | Enables direct generation of 0.8V–1.2V core supplies when one output is >1.2V - avoids extra LDO stage. |
| Synchronous rectification | Internal low-side MOSFET replaces Schottky diode - improves full-load efficiency by 8–12% vs. asynchronous designs. |
| Integrated RDS(ON) current sensing | Removes external sense resistor - saves board space and reduces BOM cost without sacrificing current limit accuracy. |
Applications
| xDSL Modems | USB-Powered Devices |
|---|---|
Use Scenario: Powering ADSL/VDSL line drivers and PHY processors from a single USB 5V port. IC Role / Device Role / Timing Role: Dual-rail buck regulator generating 3.3V for analog front-end and 1.5V for digital baseband processor. Use Value: 700kHz switching avoids interference with DSL upstream bands; ±1% accuracy maintains signal integrity under dynamic line loading. | Use Scenario: Compact portable test equipment powered solely via USB-C PD negotiation. IC Role / Device Role / Timing Role: Primary DC-DC converter delivering isolated 1.8V and 2.5V rails for FPGA I/O banks and ADC reference. Use Value: RSI pin enables host-triggered hardware reset without additional GPIO; 175ms POR delay ensures clean FPGA configuration sequence. |
| Copper Gigabit SFP Modules | Dual LDO Replacement |
Use Scenario: Embedded SFP+ cages requiring dual 3.3V/2.5V rails within strict 14.5mm width constraint. IC Role / Device Role / Timing Role: High-density step-down regulator replacing discrete buck + LDO solutions for transceiver biasing. Use Value: QSOP-16 footprint occupies <25mm²; 180° phase shift cuts input cap volume by 40% versus parallel converters. | Use Scenario: Replacing two standalone LDOs (e.g., 3.3V/1.5V) in space-constrained IoT edge nodes. IC Role / Device Role / Timing Role: Efficient dual-buck regulator eliminating LDO dropout losses and thermal derating issues. Use Value: 92% peak efficiency at 500mA vs. 65% for LDOs - extends battery life by >3.5 hours in 1000mAh systems. |
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 USB power-fail detection is required and software reset is unnecessary | Select when higher frequency enables smaller magnetics and PFO monitoring is needed for USB compliance. |
| MAX1972EEE | 1.4MHz switching, no RSI, includes PFO, different FBSEL logic mapping | Used in legacy xDSL designs with identical PFO-based fault handling but tighter layout constraints | Choose for drop-in replacement in existing MAX1970 layouts where PFO functionality is retained and RSI is unused. |
Compared with MAX1970EEE and MAX1972EEE, the MAX1971EEE trades 1.4MHz operation and PFO for RSI-driven reset control and lower EMI - making it optimal for firmware-managed USB devices where precise reset sequencing outweighs input ripple reduction.
Availability
MAX1971EEE is available at Aetrix Electronics and suitable for xDSL modems, USB-powered test equipment, copper gigabit SFP modules, and dual LDO replacement designs requiring stable component supply across industrial temperature ranges (-40°C to +85°C).
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 semiconductor company specializing in high-performance analog and mixed-signal ICs for power, interface, and sensing applications.
The MAX1970/MAX1971/MAX1972 family was designed specifically for space-constrained, noise-sensitive broadband communications equipment requiring dual, tightly regulated, low-EMI power rails from a single input source.
FAQ
What is the switching frequency of the MAX1971EEE and why does it matter?
The MAX1971EEE operates at a fixed 700kHz switching frequency. This frequency balances efficiency, EMI, and component size - it avoids the xDSL upstream band (25–138kHz) while enabling smaller inductors than lower-frequency regulators. Unlike the 1.4MHz MAX1970/MAX1972, the MAX1971EEE's lower frequency reduces switching losses in high-current applications and eases EMI filtering requirements in dense PCB layouts.
How does the RSI pin on the MAX1971EEE function compared to POR?
The RSI (Reset Input) pin on the MAX1971EEE is an active-high input that forces the POR (Power-On Reset) output low when asserted. After RSI is deasserted, POR remains low for 175ms before going high - identical to its power-up delay. This allows firmware to trigger a synchronized system reset without cycling input power. The MAX1971EEE is the only variant in the family with RSI; MAX1970/MAX1972 use PFO instead.
Can the MAX1971EEE generate output voltages below 1.2V?
Yes, the MAX1971EEE can generate sub-1.2V outputs (down to 0.8V) on one channel when the other output is set above 1.2V - achieved by connecting FB1 to OUT2 and using two external resistors (R1, R2) to form a summing network. This capability eliminates the need for a secondary LDO in low-voltage core supply designs, provided the feedback divider draws ~100µA and satisfies the voltage division equation specified in the datasheet.
What package type and thermal characteristics does the MAX1971EEE have?
The MAX1971EEE uses a 16-pin QSOP package (5.0mm × 6.2mm) with exposed thermal pad. Its absolute maximum junction temperature is +170°C, with thermal shutdown activating at that threshold and restarting after cooling by 20°C. At +70°C ambient, continuous power dissipation is rated at 667mW (derating 8.3mW/°C above +70°C). Proper PCB copper pour under the exposed pad is essential for achieving full 750mA per channel performance.
Does the MAX1971EEE support all-ceramic capacitor designs?
Yes, the MAX1971EEE is fully optimized for all-ceramic capacitor applications on both input and output. Its current-mode control architecture with slope compensation and internal synchronous rectifiers eliminates the need for high-ESR electrolytic or tantalum capacitors. Designers can use 10µF X5R/X7R ceramics at the input and 22µF–47µF at each output - reducing board area, improving reliability, and avoiding aging-related capacitance drift inherent in wet tantalum solutions.
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:
- Obsolete
- 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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