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Analog Devices Inc./Maxim Integrated MAX5945EAX+
- Part No.:
- MAX5945EAX+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Power Over Ethernet (PoE) Controllers
- Package:
- 36-BSOP (0.295", 7.50mm Width)
- Datasheet:
-
MAX5945EAX+.pdf
- Description:
- IC POE CNTRL 4 CHANNEL 36SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,269
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Product details
Overview
The MAX5945EAX+ from Maxim Integrated is a quad-port IEEE 802.3af-compliant network power controller for Power-Sourcing Equipment (PSE), delivering PD discovery, classification, programmable current-limit (202–220 mV sense threshold), DC/AC load disconnect detection, and -48V port control in endpoint or midspan configurations. It operates across -40°C to +85°C and integrates I²C-compatible 3-wire serial interface with separate SDAIN/SDAOUT for optocoupler isolation.
For engineers reviewing the MAX5945EAX+ datasheet, MAX5945EAX+ pinout, MAX5945EAX+ application, or MAX5945EAX+ equivalent, this device supports real-time fault response via four independent SHD_ inputs and INT output, programmable startup/fault timing (50–70 ms), class-overcurrent protection, and hardware watchdog takeover-critical for carrier-grade Ethernet switches and PoE injectors requiring high-reliability PSE control.
Technical Context
The MAX5945EAX+ implements four independent state machines per port, each supporting auto/semi-auto/manual/shutdown modes with cadence timing for midspan synchronization. Its architecture includes a 9-bit ADC for voltage sensing, internal 10V analog reference, and clamped gate drivers (9–11 V) with fast pulldown (100 mA max) for MOSFET control.
It features dual-supply monitoring: VEE UVLO (27–30 V) and OV (61–64 V), VDD UVLO (1.7 V), thermal shutdown at +150°C, and programmable foldback current limiting (VFLBK_ST = 30 V, VFLBK_END = 50 V). AC disconnect uses OSC_IN (100 Hz ±10%, 2 VP-P) with fail threshold of 1.8–2.1 V and configurable IACTH (300–350 µA).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IEEE Compliance | 802.3af-compliant PSE controller for PoE Class 0–4 PDs |
| Port Count & Voltage | Four independent -32V to -60V ports; VEE input rated to -48V nominal |
| Current-Limit Threshold | 202–220 mV default (programmable); enables precise 350 mA–1 A class-based limiting |
| I²C Interface | 3-wire, fast-mode (400 kHz); SDAIN/SDAOUT separation supports optocoupled isolation |
| Operating Temperature | -40°C to +85°C (extended grade); qualified for industrial PoE infrastructure |
| DC Load Disconnect | 3–5 mV VSENSE threshold; detects open-circuit or low-load faults without software intervention |
| AC Disconnect Sensitivity | 300–350 µA DET_ current threshold; enables reliable 100 Hz AC signature detection |
| Watchdog Timer | 164 ms clock period; triggers hardware takeover on firmware crash, ensuring fail-safe port shutdown |
Pinout & Package
MAX5945EAX+ is housed in a 36-pin SSOP package (body size 10.2 mm × 5.3 mm, 0.635 mm pitch), thermally optimized for high-power PoE applications with exposed pad not present. Pin functions are validated per Maxim's official pin description table and functional diagram (Rev 1, 9/05).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RESET (Pin 1) | Hardware reset input | Pull low ≥300 µs to reset registers and latch AUTO/MIDSPAN states; internal 50 kΩ pullup to VDD |
| MIDSPAN (Pin 2) | Mode selection | Pulldown defaults to endpoint PSE; drive high to enable midspan operation with cadence timing |
| INT (Pin 3) | Open-drain interrupt | Active-low fault indicator (overcurrent, thermal, UV/OV); sinks up to 15 mA |
| SCL (Pin 4) | I²C clock line | 400 kHz fast-mode compatible; requires external pullup to VDD |
| SDAOUT (Pin 5) | Serial data output | Drives optocoupler input; enables galvanic isolation in noisy PoE environments |
| SDAIN (Pin 6) | Serial data input | Receives optocoupler output; allows full-duplex 3-wire I²C with isolation |
| A0–A3 (Pins 7–10) | I²C address inputs | Set lower 4 bits of slave address (010xxxxx); 16 unique addresses via internal 50 kΩ pullups |
| DET1–DET4 (Pins 11–14) | Detection/classification voltage outputs | Drive PD probe voltages (VDPH1 = 3.8–4.2 V, VCL = 16–20 V); support AC disconnect when enabled |
| DGND (Pin 15) | Digital ground reference | Isolated from AGND; required for noise-free digital logic and I²C signaling |
| VDD (Pin 16) | +3.3 V digital supply | Operates from 3.0–5.5 V vs DGND; UVLO at 1.7 V ensures robust boot |
| SHD1–SHD4 (Pins 17–20) | Independent port shutdown | Active-low; direct hardware override of port FETs; internal 50 kΩ pullup to VDD |
| AGND (Pin 21) | Analog ground reference | High-side return for VEE, DET_, OUT_; must be star-connected to minimize noise coupling |
| SENSE1–SENSE4 (Pins 22,25,29,32) | Current-sense negative inputs | Connect to MOSFET source; measure VSENSE for current limiting (202–220 mV clamp) |
| GATE1–GATE4 (Pins 23,26,30,33) | External FET gate drivers | 10 V typical gate overdrive; 100 mA pulldown for fast turn-off during faults |
| OUT1–OUT4 (Pins 24,27,31,34) | Drain voltage sense inputs | Low-leakage (<2 µA); used for PGOOD (1.8–2.2 V threshold) and short-circuit detection (VDCP = 1.62 V) |
| VEE (Pin 28) | Negative analog supply | Accepts -32V to -60V; bypassed with 1 µF capacitor to AGND; UVLO at 27–30 V |
| AUTO (Pin 35) | Mode control input | Internal 50 kΩ pulldown; force high pre-reset to enter autonomous operation |
| OSC_IN (Pin 36) | AC disconnect oscillator input | Accepts 100 Hz ±10% sine wave; failsafe shutdown if peak <1.8 V; unused = float |
Key Features
| Feature | Design Value |
|---|---|
| IEEE 802.3af compliance | Fully implements PD detection (3.8–4.2 V / 9.0–9.6 V phases), classification (16–20 V), and class-based current limits (Class 0–4) |
| Programmable current foldback | VFLBK_ST = 30 V and VFLBK_END = 50 V define linear foldback region, preventing thermal runaway during overload |
| Dual disconnect detection | DC disconnect (3–5 mV VSENSE) and AC disconnect (300–350 µA DET_ current) ensure robust fault coverage across PoE topologies |
| Hardware watchdog mode | 164 ms decrementing timer forces graceful port shutdown and recovery if firmware hangs-no system reboot required |
| Midspan cadence timing | Enables synchronized multi-port power-up in injector systems using MIDSPAN pin and OSC_IN reference |
| Four independent SHD_ inputs | Allow microcontroller-level fault arbitration per port with sub-millisecond response, bypassing I²C latency |
Applications
| Enterprise Switch PSE | Midspan PoE Injector |
|---|---|
Use Scenario: 24- or 48-port Ethernet switch providing PoE to IP phones, wireless APs, and security cameras. IC Role / Device Role / Timing Role: Quad-port PSE controller managing four 10/100/1000BASE-T lanes per chip; handles concurrent detection, classification, and power ramp-up with tSTART = 50–70 ms. Use Value: Enables compact, thermally efficient PSE design with integrated fault handling-reducing need for external supervisors and discrete logic. |
Use Scenario: Standalone 8-port PoE injector adding power to existing LAN cabling between switch and endpoint devices. IC Role / Device Role / Timing Role: Midspan PSE controller operating in cadence mode; synchronizes port power-up using OSC_IN reference to avoid inrush current stacking. Use Value: Eliminates need for custom timing circuitry; supports hot-swap capability and IEEE 802.3af interoperability without host MCU coordination. |
| Industrial Ethernet Gateway | Carrier-Grade Router PSE |
Use Scenario: Ruggedized gateway powering field sensors, PLC I/O modules, and HMI displays in factory automation networks. IC Role / Device Role / Timing Role: PSE controller operating across -40°C to +85°C; monitors VEE UVLO (27–30 V) and thermal shutdown (+150°C) for harsh environments. Use Value: Ensures uninterrupted PoE delivery under brownout or overheating conditions-critical for uptime-sensitive OT infrastructure. |
Use Scenario: High-density service router delivering PoE to CPE devices (e.g., VoIP gateways, set-top boxes) in telco central offices. IC Role / Device Role / Timing Role: Quad-port controller with programmable tFAULT (50–70 ms) and autorestart duty cycle (16× to 64× tFAULT) for granular fault recovery policies. Use Value: Supports carrier-grade SLA requirements via deterministic fault clearing and zero-software-dependency watchdog recovery. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad-port PSE controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC4259A | Pin- and function-compatible per datasheet; identical 36-pin SSOP footprint and register map; same -40°C to +85°C rating. | Same endpoint/midspan use cases; no change in detection timing or classification thresholds. | Select LTC4259A for second-source assurance where Maxim supply continuity is constrained. |
| MAX5980ATJ+ | 8-port, IEEE 802.3at/af-compliant; higher integration (integrated MOSFET drivers, no external FETs); different package (48-pin TQFN). | Supports PoE+ (30 W/port); not drop-in-requires PCB redesign, new layout, and firmware adaptation. | Choose MAX5980ATJ+ only when upgrading to PoE+ and accepting full redesign effort. |
Compared with LTC4259A, the MAX5945EAX+ offers identical functionality and pinout for seamless substitution, while MAX5980ATJ+ provides higher port count and PoE+ support at the cost of non-interchangeable packaging and driver integration-making it unsuitable for drop-in replacement but viable for next-generation designs.
Availability
MAX5945EAX+ is available at Aetrix Electronics and suitable for enterprise switches, midspan PoE injectors, and industrial Ethernet gateways requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for MAX5945EAX+ 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 leader specializing in high-performance analog, mixed-signal, and power-management ICs for communications, computing, and industrial systems.
The MAX5945EAX+ belongs to Maxim's Power over Ethernet (PoE) PSE controller product line, engineered specifically for IEEE 802.3af-compliant infrastructure equipment requiring robust, software-configurable, quad-port power management with hardware fault resilience.
FAQ
What is the operating temperature range for the MAX5945EAX+?
The MAX5945EAX+ is rated for -40°C to +85°C, qualifying it for extended-temperature industrial and telecom applications. This range is explicitly defined in the Ordering Information table and confirmed in Absolute Maximum Ratings, distinguishing it from the commercial-grade MAX5945CAX+ (0°C to +70°C). Thermal shutdown activates at +150°C junction temperature with 20°C hysteresis.
Does the MAX5945EAX+ support both endpoint and midspan PSE configurations?
Yes, the MAX5945EAX+ supports both configurations via the MIDSPAN pin (Pin 2). When pulled low (default), it operates as an endpoint PSE (e.g., LAN switch); when driven high, it enables midspan mode with cadence timing for synchronized multi-port power-up. The functional diagram and Detailed Description confirm dual-mode operation without hardware modification.
How does the MAX5945EAX+ implement AC load disconnect detection?
The MAX5945EAX+ uses OSC_IN (Pin 36) to accept a 100 Hz ±10% sine wave. When ACD_EN_ is enabled, it measures current into DET_ pins; AC disconnect triggers if that current falls below 300–350 µA (IACTH). The OSC_IN fail threshold is 1.8–2.1 V-ports shut down if the oscillator peak drops below this level, ensuring fail-safe behavior.
Is the MAX5945EAX+ pin-compatible with any alternative PSE controllers?
Yes, the MAX5945EAX+ is explicitly stated as pin- and function-compatible with the LTC4259A in the General Description. Both share identical 36-pin SSOP packaging, matching pin functions (e.g., RESET, INT, SHD_, DET_, GATE_), and register-level compatibility-enabling direct substitution without layout changes.
What protection features does the MAX5945EAX+ provide beyond IEEE 802.3af compliance?
Beyond 802.3af detection/classification, the MAX5945EAX+ delivers VEE undervoltage lockout (27–30 V), overvoltage protection (61–64 V), VDD UVLO (1.7 V), thermal shutdown (+150°C), short-circuit protection with 100 mA gate pulldown, and programmable startup/fault timeouts. These are documented in Electrical Characteristics and Absolute Maximum Ratings sections.
MAX5945EAX+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 36-BSOP (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Type:
- Controller (PSE)
- Number of Channels:
- 4
- Power - Max:
- 15.4 W
- Internal Switch(s):
- No
- Auxiliary Sense:
- No
- Standards:
- 802.3af (PoE)
- Voltage - Supply:
- 32V ~ 60V
- Current - Supply:
- 4.2mA
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-SSOP
MAX5945EAX+ FAQ
1.How can I place an order for MAX5945EAX+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX5945EAX+ 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 MAX5945EAX+ reliable?
The price and inventory of MAX5945EAX+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX5945EAX+ is usually 5 days.
3.What payment methods are accepted for MAX5945EAX+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX5945EAX+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX5945EAX+?
MAX5945EAX+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX5945EAX+ 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 MAX5945EAX+?
For technical support, including MAX5945EAX+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX5945EAX+ requirements.
6.How does Aetrix verify that MAX5945EAX+ is sourced from the original manufacturer or authorized distributors?
All MAX5945EAX+ 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 MAX5945EAX+ meets industry standards.
7.What is the process for return or replacement of MAX5945EAX+?
All MAX5945EAX+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX5945EAX+, 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 MAX5945EAX+ part is unused and in its original packaging.
Return procedure for MAX5945EAX+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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