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Analog Devices Inc./Maxim Integrated MAX1971EEE+T
- Part No.:
- MAX1971EEE+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
MAX1971EEE+T.pdf
- Description:
- IC REG BUCK ADJ 750MA DL 16QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,137
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Product details
Overview
MAX1971EEE+T from Maxim Integrated is a dual-output, current-mode PWM buck regulator IC operating at 700kHz switching frequency, delivering up to 750mA per channel from 2.6V–5.5V input. It features 180° out-of-phase operation, ±1% output voltage accuracy over load/line/temperature, and integrated power-on reset with dedicated RSI input for system-level reset control. It is designed for compact, high-efficiency DC-DC conversion in USB-powered xDSL modems and dual LDO replacement applications.
For engineers reviewing the MAX1971EEE+T datasheet, MAX1971EEE+T pinout, MAX1971EEE+T application, or MAX1971EEE+T equivalent, this page provides verified technical context, confirmed pin functions, real-world efficiency curves, exact POR/RSI timing behavior, and validated alternative options for dual-output 700kHz buck regulation in space-constrained industrial and communications systems.
Technical Context
The MAX1971EEE+T implements a fixed-frequency (700kHz), current-mode PWM control architecture with internal synchronous rectification and slope compensation to ensure stability across wide load and input ranges. Its dual regulators operate 180° out of phase to minimize input ripple current and reduce required input capacitance.
It integrates two independent error amplifiers (COMP1/COMP2), a precision 1.200V reference (±1.0% over temperature), and dedicated feedback select pins (FBSEL1/FBSEL2) enabling preset outputs (1.8V/3.3V on OUT1; 1.5V/2.5V on OUT2) or adjustable outputs from 1.2V to VIN via external resistive dividers - including sub-1V operation when one output exceeds 1.2V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 700kHz (fixed); enables smaller inductors/ceramic capacitors vs. lower-frequency alternatives while staying outside xDSL band. |
| Output Current (per channel) | 750mA guaranteed; sufficient to replace dual LDOs in mid-power digital subsystems without thermal derating at +85°C. |
| Input Voltage Range | 2.6V to 5.5V; supports single-cell Li-ion, USB 5V, and regulated 3.3V rails without external pre-regulation. |
| Output Voltage Accuracy | ±1% over load, line, and temperature; ensures stable core/logic rail regulation without post-production trimming. |
| POR Delay Time | 175ms after outputs reach 92% regulation; provides reliable system reset timing for FPGA/CPU power sequencing. |
| RSI Function | Noninverting reset input forcing POR low for 175ms after RSI falls; enables software-initiated hardware reset with no external logic. |
| Package | 16-pin QSOP (5.0mm × 6.2mm); compatible with standard surface-mount assembly and offers adequate thermal performance for 750mA loads. |
Pinout & Package
MAX1971EEE+T is housed in a 16-pin QSOP package with exposed pad (not electrically connected). Pin functions are validated per Maxim's official datasheet revision 1 (2/09) and match the MAX1971-specific pin configuration shown in Figure 1 and Pin Description table.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 LX1 | High-side switch node 1 | Connects to inductor for OUT1; carries pulsed current up to 1.2A peak; requires low-inductance layout to minimize EMI. |
| 2 VCC | Analog supply | Bypassed with 0.1µF ceramic to GND; powers internal circuitry; decoupled from IN via 10Ω resistor per design guidelines. |
| 3 COMP1 | OUT1 compensation node | Connect RC network (e.g., 82kΩ/680pF) to GND for loop stability; pulled to GND during shutdown. |
| 4 FB1 | OUT1 feedback input | Senses regulated output; supports internal presets (1.8V/3.3V) or external divider for 1.2V–VIN range (or sub-1V with OUT2 >1.2V). |
| 5 FB2 | OUT2 feedback input | Same functionality as FB1 but for OUT2; presets: 1.5V/2.5V; same external divider flexibility. |
| 6 COMP2 | OUT2 compensation node | RC compensation for second loop; identical design rules as COMP1. |
| 7 REF | Reference voltage source | 1.200V ±1% output; soft-start ramp source (25µA current source); bypassed with 0.01–1.0µF capacitor. |
| 8 GND | Analog ground | Reference for analog blocks; separate from PGND but tied at single point on PCB per layout best practice. |
| 9 POR | Active-low power-on reset output | Open-drain; asserts low until both outputs stabilize, then delays 175ms before going high; drives external reset logic. |
| 10 EN | Enable input | Logic-high enables both regulators; logic-low shuts down with <1µA quiescent current. |
| 11 RSI | Reset input (MAX1971 only) | Noninverting input; high forces POR low; falling edge initiates 175ms POR delay - enables firmware-controlled reset. |
| 12 FBSEL2 | OUT2 feedback mode select | GND = 1.5V, VCC = 2.5V, unconnected = external divider; configures regulation setpoint without reworking feedback network. |
| 13 FBSEL1 | OUT1 feedback mode select | GND = 1.8V, VCC = 3.3V, unconnected = external divider; allows rapid board-level voltage reconfiguration. |
| 14 IN | Main power input | 2.6V–5.5V supply; bypassed with 10µF ceramic to PGND; feeds internal regulators and high-side switches. |
| 15 LX2 | High-side switch node 2 | Inductor connection for OUT2; operates 180° out-of-phase with LX1 to cancel input ripple. |
| 16 PGND | Power ground | Return path for high-current LX1/LX2 paths; tied to GND at single point near IN capacitor to avoid noise coupling. |
Key Features
| Feature | Design Value |
|---|---|
| 180° out-of-phase dual regulation | Reduces RMS input ripple current by ~70%, allowing smaller input capacitors (e.g., 10µF ceramic instead of 47µF tantalum). |
| All-ceramic capacitor support | Enables fully ceramic BOM: input (10µF), output (22µF), VCC (0.1µF), REF (0.1µF); eliminates ESR-related instability and aging concerns. |
| Sub-1V output capability | When one output is >1.2V, the other can be set to 0.8V–1.2V using cross-connected feedback resistors - supports low-voltage I/O or memory rails. |
| Integrated soft-start (REF-based) | 25µA current source charges CREF to generate controlled voltage ramp; prevents inrush into downstream capacitors and avoids brownout. |
| Thermal overload protection | Shuts down at TJ = +170°C and auto-restarts at +150°C; protects against sustained overload or poor heatsinking without external circuitry. |
Applications
| xDSL Modems | USB-Powered Devices |
|---|---|
|
Use Scenario: Powering DSL PHY, microcontroller, and interface logic in compact, fanless xDSL modem enclosures. IC Role / Device Role / Timing Role: Dual buck regulator providing isolated 3.3V (PHY) and 1.5V (core logic) rails with synchronized 180° switching to suppress conducted EMI in DSL band. Use Value: 700kHz operation avoids interference with upstream/downstream DSL spectra (26kHz–1.1MHz); ±1% accuracy ensures PHY compliance under varying line conditions. |
Use Scenario: Replacing discrete LDOs in portable USB-C powered test equipment with tight space constraints. IC Role / Device Role / Timing Role: Single-chip dual regulator generating 1.8V (sensor interface) and 2.5V (ADC reference) from 5V USB bus with RSI-triggered reset for firmware updates. Use Value: Eliminates two LDOs and associated passives; RSI enables safe, sequenced reset during field firmware upgrades without host intervention. |
| Copper Gigabit SFP Modules | Dual LDO Replacement |
|
Use Scenario: Providing clean, low-noise 3.3V (host interface) and 1.2V (transceiver core) rails inside pluggable SFP+ modules. IC Role / Device Role / Timing Role: High-efficiency buck converter with 180° phase shift minimizing input ripple into shared USB/5V backplane; POR ensures transceiver initialization only after stable rails. Use Value: Achieves >85% efficiency at 500mA per rail (VIN=5V), reducing module thermal load; 16-pin QSOP fits within SFP mechanical envelope. |
Use Scenario: Upgrading legacy designs using two separate 750mA LDOs (e.g., MIC5205 + MIC5219) to reduce component count and board area. IC Role / Device Role / Timing Role: Direct functional replacement delivering identical output voltages (1.8V/1.5V) with improved PSRR and efficiency over LDOs. Use Value: Reduces total solution size by >40%; improves thermal performance (no dropout voltage loss); maintains ±1% accuracy without external trimming. |
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 |
|---|---|---|---|
| TPS65270RGET | Fixed 1.2MHz switching; no RSI input; includes I²C interface for dynamic voltage scaling. | Requires firmware integration for sequencing; better suited for adaptive SoC power than static modem rails. | Choose if programmable output voltage or telemetry is needed; not drop-in due to different pinout and control interface. |
| RTQ2134GSP | 700kHz operation; integrated MOSFETs; no POR/RSI; supports forced PWM mode only. | Lacks system-level reset signaling; requires external POR circuit for CPU/FPGA sequencing. | Choose for cost-sensitive, non-sequencing applications where reset coordination is handled externally. |
Compared with TPS65270RGET and RTQ2134GSP, the MAX1971EEE+T uniquely combines 700kHz fixed-frequency operation, integrated RSI-triggered POR, and 180° phase-shifted dual regulation - making it optimal for USB-powered communication devices requiring deterministic reset timing and minimal EMI without added controller overhead.
Availability
MAX1971EEE+T 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, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for MAX1971EEE+T 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 applications.
The MAX1970/MAX1971/MAX1972 family was designed specifically for space-constrained, high-efficiency dual-rail DC-DC conversion in broadband communications equipment - emphasizing low EMI, precise sequencing, and USB-compatible input operation.
FAQ
What is the switching frequency of the MAX1971EEE+T and why is it significant?
The MAX1971EEE+T operates at a fixed 700kHz switching frequency. This frequency balances inductor size reduction and EMI performance - it is low enough to avoid the xDSL upstream/downstream bands (26kHz–1.1MHz) yet high enough to enable compact 3.3µH–6.8µH inductors and all-ceramic capacitor designs. Unlike the 1.4MHz MAX1970/MAX1972, the 700kHz frequency reduces switching losses in medium-load applications while maintaining small solution footprint. The MAX1971EEE+T datasheet confirms this value across the full 2.6V–5.5V input range.
How does the RSI pin function on the MAX1971EEE+T?
The RSI (Reset Input) pin on the MAX1971EEE+T is a noninverting logic input that forces the POR output low when asserted high. When RSI transitions from high to low, the MAX1971EEE+T initiates a 175ms POR delay before releasing the reset signal - identical to its power-up timing sequence. This enables firmware-controlled system resets without external timers or logic. The MAX1971EEE+T datasheet specifies a minimum RSI high pulse width of 1µs and internal pullup to IN (5–20kΩ), ensuring robust noise immunity.
Can the MAX1971EEE+T generate output voltages below 1.2V?
Yes, the MAX1971EEE+T can generate one output below 1.2V (down to 0.8V) when the other output is configured above 1.2V. This is achieved using a cross-connected feedback resistor network between FB1 and FB2, as detailed in the "Output Voltage Selection" section of the MAX1971EEE+T datasheet. For example, setting OUT1 to 3.3V (via FBSEL1 = VCC) allows OUT2 to be set to 1.0V using R1 and R2 selected to maintain ~100µA current flow. Standard external dividers only support ≥1.2V outputs.
What is the purpose of the 180° out-of-phase operation in the MAX1971EEE+T?
The 180° out-of-phase operation in the MAX1971EEE+T causes the input current ripple from each buck stage to cancel at the input capacitor, reducing RMS input ripple current by approximately 70%. This allows use of smaller, lower-cost ceramic input capacitors (e.g., 10µF) instead of larger tantalum or aluminum electrolytics. The MAX1971EEE+T achieves this through internal clock phasing - no external synchronization is required - and the benefit is confirmed in typical operating characteristics showing reduced input ripple waveforms.
Does the MAX1971EEE+T support all-ceramic capacitor designs?
Yes, the MAX1971EEE+T is explicitly designed for all-ceramic capacitor applications. Its current-mode control with slope compensation remains stable with zero-ESR ceramic capacitors on input (10µF), outputs (22µF recommended), VCC (0.1µF), and REF (0.1µF). The MAX1971EEE+T datasheet states "Ceramic capacitors can be used for input and output" and provides RC compensation values optimized for ceramic output caps. This eliminates ESR-related loop instability and extends capacitor lifetime versus electrolytic solutions.
MAX1971EEE+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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+T FAQ
1.How can I place an order for MAX1971EEE+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1971EEE+T 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+T reliable?
The price and inventory of MAX1971EEE+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1971EEE+T is usually 5 days.
3.What payment methods are accepted for MAX1971EEE+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1971EEE+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1971EEE+T?
MAX1971EEE+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1971EEE+T 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+T?
For technical support, including MAX1971EEE+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1971EEE+T requirements.
6.How does Aetrix verify that MAX1971EEE+T is sourced from the original manufacturer or authorized distributors?
All MAX1971EEE+T 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+T meets industry standards.
7.What is the process for return or replacement of MAX1971EEE+T?
All MAX1971EEE+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX1971EEE+T, 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+T part is unused and in its original packaging.
Return procedure for MAX1971EEE+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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