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Analog Devices Inc./Maxim Integrated MAX5941AESE+
- Part No.:
- MAX5941AESE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Power Over Ethernet (PoE) Controllers
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
MAX5941AESE+.pdf
- Description:
- IC IEEE 802.3AF-COMP POE 16-SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,913
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Product details
Overview
MAX5941AESE+ from Maxim Integrated is an IEEE 802.3af-compliant powered device (PD) interface and current-mode PWM controller for PoE-powered equipment. It integrates detection/classification circuitry, an internal N-channel isolation MOSFET (RON = 0.8–1.5 Ω), programmable inrush control, and a 275kHz ±10% fixed-frequency DC-DC controller optimized for flyback converters with up to 85% duty cycle. Used in IP phones and security cameras requiring isolated 48V PoE input-to-3.3/5/12V output conversion.
For engineers reviewing the MAX5941AESE+ datasheet, MAX5941AESE+ pinout, MAX5941AESE+ application, or MAX5941AESE+ equivalent, key selection criteria include IEEE 802.3af PD compliance, integrated isolation FET with <10µA detection leakage, 18–67V wide-input PWM operation, 275kHz oscillator tolerance, and SO-16 package compatibility with thermal design for -40°C to +85°C industrial environments.
Technical Context
The MAX5941AESE+ implements dual-domain power management: a PD front-end compliant with IEEE 802.3af detection (ΔV/ΔI signature), classification (RCL-programmable Class 0–3), and power-on sequencing with UVLO hysteresis (7.4V) and deglitch delay (0.32ms); plus a current-mode PWM controller featuring high-voltage startup (18–67V), leading-edge blanking, soft-start (2–6.5µA source), and VCC regulation from V+ or VDD.
Its architecture separates PD interface logic (referenced to VEE) from PWM control logic (referenced to V−), enabling flexible grounding schemes. The GATE pin drives the internal isolation FET, while NDRV provides external high-side gate drive - supporting both isolated flyback (MAX5941A) and nonisolated designs without external diode bridge dependency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IEEE Compliance | Fully compliant with IEEE 802.3af PD detection, classification (Class 0–3), and power-on sequencing - ensures interoperability with standard PSEs. |
| Input Voltage Range | 18V to 67V on V+ pin - supports full PoE voltage range including worst-case cable drop and transient margins. |
| Switching Frequency | 275kHz ±10% - enables compact magnetics and EMI-filtering components; trimmed internally, no external timing resistor required. |
| Max Duty Cycle | 85% - enables high-voltage-ratio flyback topologies (e.g., 48V-to-5V) with minimal turns ratio and reduced transformer stress. |
| Detection Leakage | <10µA offset current - meets IEEE 802.3af requirement for reliable signature resistance measurement during detection phase. |
| UVLO Hysteresis | 7.4V (VUVLO,ON = 38.6V, VUVLO,OFF = 30V) - prevents oscillation during brown-out conditions caused by twisted-pair IR drop. |
| Isolation FET RON | 0.8Ω (typ) at TA = +25°C - limits conduction loss and thermal rise during sustained 300mA load; specified up to +85°C. |
Pinout & Package
MAX5941AESE+ is housed in a 16-pin SO (Small Outline) package, S16M-6 footprint, with exposed pad not electrically connected. Pin functions are fully decoupled between PD interface (VEE-referenced) and PWM controller (V−-referenced) domains to support floating ground configurations in isolated topologies.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| V+ | High-voltage startup input | Directly connects to PoE input (18–67V); powers internal VCC regulator during startup before tertiary winding takes over. |
| GATE | Internal isolation FET gate driver | Sources 10µA to turn on integrated N-MOSFET; external capacitor from GATE to VOUT sets inrush current slew rate. |
| RCL | Classification current setting | Resistor from RCL to VEE selects IEEE 802.3af Class (0–3); e.g., 255Ω = Class 3 (6.49–12.95W). |
| UVLO | Power-mode undervoltage lockout input | Default tied to VEE for 38.6V turn-on; externally biased via 25.5kΩ divider to program custom threshold within 12–67V range. |
| PGOOD / PGOOD | Dual power-good status outputs | PGOOD (active-high, referenced to OUT) and PGOOD (active-low, referenced to VEE) enable independent monitoring of output regulation and gate voltage. |
| NDRV | External high-side gate driver | Drives external N-MOSFET in forward/flyback topologies; low-side resistance 1.6–4Ω, high-side 4–12Ω - supports fast switching with controlled dV/dt. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated PD isolation switch | On-resistance 0.8Ω (typ) eliminates need for external hot-swap MOSFET and associated gate-drive circuitry. |
| Programmable inrush control | GATE pin capacitance-based slew-rate limiting prevents input surge current exceeding PSE current-limit thresholds during power-up. |
| Wide-input current-mode PWM | Operates from 18–67V input with internal high-voltage startup - removes external bias supply and startup resistor in flyback designs. |
| Dual power-good signaling | Simultaneous active-high (PGOOD) and active-low (PGOOD) outputs simplify system-level power sequencing and fault reporting. |
| Thermal shutdown with hysteresis | Triggers at 150°C with 25°C hysteresis - protects against sustained overload or poor heatsinking without nuisance tripping. |
Applications
| IP Phones | Wireless Access Nodes |
|---|---|
|
Use Scenario: Powered via Category 5 Ethernet cabling in enterprise VoIP deployments with centralized PoE switches. IC Role / Device Role / Timing Role: PD interface authenticates to PSE, negotiates Class 2 (3.84W) power, then regulates 48V PoE input to 3.3V/5V rails for baseband processor and codec. Use Value: Integrated isolation FET and classification eliminate discrete protection ICs; 85% duty cycle enables efficient single-transformer 48V-to-3.3V flyback design. |
Use Scenario: Outdoor Wi-Fi access points deployed in campus networks where PoE simplifies installation and avoids AC outlets. IC Role / Device Role / Timing Role: Provides IEEE 802.3af-compliant PD handshaking and generates stable 12V/5V outputs for RF transceiver, MAC controller, and memory. Use Value: 275kHz switching frequency reduces transformer size and EMI filter volume; UVLO hysteresis prevents reset during cable voltage sag under load. |
| Security Cameras | Computer Telephony |
|
Use Scenario: PTZ (pan-tilt-zoom) cameras requiring >12W PoE power delivery with motor drive and image sensor support. IC Role / Device Role / Timing Role: Enables Class 3 (6.49–12.95W) operation using 255Ω RCL resistor; PWM controller delivers regulated 12V for motors and 3.3V for CMOS image sensor. Use Value: Dual PGOOD signals allow independent monitoring of main rail and auxiliary rail; soft-start current (2–6.5µA) ensures controlled camera boot sequence. |
Use Scenario: USB-based VoIP handsets and conference phones drawing power and data over single Ethernet cable. IC Role / Device Role / Timing Role: Acts as PD front-end and DC-DC controller for USB 5V rail generation; supports optional diode bridge for polarity insensitivity. Use Value: <10µA detection leakage guarantees reliable PSE handshake; NDRV gate drive supports external synchronous rectifier for >90% efficiency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar powered-device interface and PWM controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX5941BESE+ | 50% max duty cycle; optimized for forward converters; lacks flyback-specific timing margin. | Used where lower duty cycle suits forward topology with tertiary winding feedback; not suitable for high-ratio flyback. | Select MAX5941BESE+ only when designing forward converters requiring <50% duty cycle and tighter peak-current control. |
| LT4275AIMSE#PBF | IEEE 802.3at (PoE+) compliant; supports Class 4 (25.5W); higher UVLO threshold (42.5V); no integrated PWM controller. | Requires external DC-DC controller; targets higher-power applications like PTZ cameras with heaters or pan/tilt motors. | Choose LT4275AIMSE#PBF when upgrading to PoE+ and adding external controller for >13W loads; not drop-in compatible. |
Compared with MAX5941BESE+, the MAX5941AESE+ enables higher-efficiency flyback designs via 85% duty cycle and simplified transformer design; compared with LT4275AIMSE#PBF, it integrates the PWM controller but lacks PoE+ classification - making it optimal for cost-sensitive, mid-power IEEE 802.3af systems.
Availability
MAX5941AESE+ is available at Aetrix Electronics and suitable for IP phones, wireless access nodes, security cameras, and computer telephony equipment requiring stable component supply across industrial temperature ranges (-40°C to +85°C) and long-term PoE infrastructure deployment.
Supply support for MAX5941AESE+ 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 analog, mixed-signal, and power-management ICs for communications, computing, and industrial applications.
The MAX5941A/B product line was designed specifically for IEEE 802.3af-compliant powered devices needing integrated PD interface and flyback/forward DC-DC control - targeting space-constrained, thermally demanding PoE endpoints.
FAQ
What is the maximum allowable input voltage for MAX5941AESE+?
The MAX5941AESE+ supports an absolute maximum input voltage of 67V on the V+ pin, with operational range specified from 18V to 67V. This accommodates full IEEE 802.3af PoE voltage range (37–57V at PSE) plus worst-case cable drop and transient overshoot. Exceeding 67V risks permanent damage per Absolute Maximum Ratings.
Does MAX5941AESE+ require an external diode bridge for polarity protection?
No - the MAX5941AESE+ is designed to operate with or without an external diode bridge. Its PD interface circuitry remains functional regardless of input polarity, and internal protection structures prevent damage if reverse voltage is applied. External diodes may still be used for enhanced robustness but are not mandatory for basic IEEE 802.3af compliance.
How is the power classification set on MAX5941AESE+?
Power classification on MAX5941AESE+ is set by connecting a precision resistor (RCL) from the RCL pin to VEE. Values are defined in Table 1: 10kΩ for Class 0, 732Ω for Class 1, 392Ω for Class 2, and 255Ω for Class 3. The MAX5941AESE+ measures current through this resistor during classification mode to determine power budget allocation by the PSE.
What is the purpose of the SS_SHDN pin on MAX5941AESE+?
The SS_SHDN pin on MAX5941AESE+ serves dual functions: it connects to an external capacitor to set soft-start ramp time (~0.45ms/nF), and it acts as a shutdown input - pulling below 0.25V disables the PWM controller. Tying SS_SHDN to PGOOD enables automatic PWM enable after successful PD power-up, ensuring regulated output before DC-DC operation begins.
Can MAX5941AESE+ drive an external MOSFET directly?
Yes - the NDRV pin on MAX5941AESE+ is a dedicated high-side gate driver capable of sourcing 570mA and sinking 1000mA peak current, with low-side resistance of 1.6–4Ω and high-side resistance of 4–12Ω. It is intended to drive external N-channel MOSFETs in forward or synchronous flyback topologies, eliminating need for external driver ICs in many designs.
MAX5941AESE+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Type:
- Controller (PD)
- Number of Channels:
- 1
- Power - Max:
- 12.95 W
- Internal Switch(s):
- No
- Auxiliary Sense:
- No
- Standards:
- 802.3af (PoE)
- Voltage - Supply:
- 18V ~ 67V
- Current - Supply:
- 400µA
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
MAX5941AESE+ FAQ
1.How can I place an order for MAX5941AESE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX5941AESE+ 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 MAX5941AESE+ reliable?
The price and inventory of MAX5941AESE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX5941AESE+ is usually 5 days.
3.What payment methods are accepted for MAX5941AESE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX5941AESE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX5941AESE+?
MAX5941AESE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX5941AESE+ 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 MAX5941AESE+?
For technical support, including MAX5941AESE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX5941AESE+ requirements.
6.How does Aetrix verify that MAX5941AESE+ is sourced from the original manufacturer or authorized distributors?
All MAX5941AESE+ 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 MAX5941AESE+ meets industry standards.
7.What is the process for return or replacement of MAX5941AESE+?
All MAX5941AESE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX5941AESE+, 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 MAX5941AESE+ part is unused and in its original packaging.
Return procedure for MAX5941AESE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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