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Analog Devices Inc./Maxim Integrated MAX5935CAX+T
- Part No.:
- MAX5935CAX+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Power Over Ethernet (PoE) Controllers
- Package:
- 36-BSOP (0.295", 7.50mm Width)
- Datasheet:
-
MAX5935CAX+T.pdf
- Description:
- IC POE CNTRL 4 CHANNEL 36SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,533
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Product details
Overview
The MAX5935CAX+T from Maxim Integrated is a quad-channel IEEE 802.3af-compliant network power controller for Power Sourcing Equipment (PSE), delivering PD discovery, classification, programmable current limiting (202–222 mV sense threshold), DC/AC load disconnect detection, and hardware watchdog protection. It operates across -48V analog rails with 3.0–5.5V digital supply and supports both endpoint (LAN switch) and midspan (injector) PSE architectures.
For engineers reviewing the MAX5935CAX+T datasheet, MAX5935CAX+T pinout, MAX5935CAX+T application, or MAX5935CAX+T equivalent, this device is selected for robust, software-configurable PoE port control requiring fault-resilient operation, I²C-based system integration, and precise class-based overcurrent management in industrial Ethernet infrastructure.
Technical Context
The MAX5935CAX+T implements four independent state machines per port, each supporting auto/semi-auto/manual/shutdown modes and enabling real-time PD detection (320 ms max), classification (40 ms), and startup (60 ms typical) with programmable timing registers. Its architecture integrates dual-path sensing (SENSE_/DET_), gate drivers with 10V gate drive capability and 100 mA pulldown current, and separate SDAIN/SDAOUT lines for optocoupler-isolated I²C communication.
It features hardware-level protections including VEE undervoltage lockout (28.5 V), overtemperature shutdown (+150°C), short-circuit response (<4 µs), and foldback current limiting that scales trip voltage from 212 mV down to 64 mV as output voltage rises from 30 V to 50 V - all configurable via its 25+ register map over I²C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IEEE Compliance | Fully compliant with IEEE 802.3af for PSE detection, classification, and power delivery. |
| Port Count | Four independent Ethernet ports with dedicated GATE_, SENSE_, DET_, OUT_, and SHD_ terminals. |
| Current-Limit Threshold | Programmable 202–222 mV default (Class 0/3/4); enables precise per-class overcurrent enforcement. |
| Supply Range | Analog rail: -32 V to -60 V (VEE = 0 V, AGND = +48 V); Digital supply: 3.0–5.5 V referenced to DGND. |
| Interface | I²C-compatible 3-wire serial interface (SCL, SDAIN, SDAOUT) with 400 kHz fast-mode support and address flexibility (16 unique addresses). |
| Protection Features | DC/AC load disconnect detection, thermal shutdown (+150°C), VEE UVLO/OVLO, PGOOD monitoring, and watchdog-enabled graceful takeover on firmware crash. |
| Operating Temp | Commercial grade: 0°C to +70°C - validated for stable operation in LAN switches and midspan injectors. |
Pinout & Package
MAX5935CAX+T is housed in a 36-pin SSOP (Package Code A36-2), with exposed pad not electrically connected. The package supports surface-mount assembly and thermal dissipation up to 941 mW at +70°C ambient.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RESET | Hardware reset input | Pull low ≥300 µs to reset registers and latch AUTO/MIDSPAN states; internal 50 kΩ pullup to VDD. |
| MIDSPAN | Mode selection input | Pulled low by default (endpoint PSE); drive high to enable midspan injector operation with cadence timing. |
| INT | Open-drain fault interrupt | Active-low signal indicating any port fault (overcurrent, thermal, UVLO); sinks up to 15 mA. |
| SCL / SDAIN / SDAOUT | I²C clock/data interface | 3-wire isolation-ready interface: SDAIN receives host data; SDAOUT drives isolated slave side; SCL clocks both. |
| A0–A3 | Address inputs | Set lower 4 bits of I²C slave address (MSB fixed as '010'); internal 50 kΩ pullups to VDD. |
| DET1–DET4 | Detection/classification voltage source | Provide probe voltages (4.0 V / 9.3 V / 20 V) during PD detection and classification phases per port. |
| SHD1–SHD4 | Independent port shutdown | Active-low inputs for immediate FET gate disable; internal 50 kΩ pullups to VDD ensure safe default OFF. |
| GATE1–GATE4 | External MOSFET gate driver | Drive external N-channel FET gates with 10 V swing and 100 mA pulldown for fast turn-off during faults. |
| SENSE1–SENSE4 | Current-sense negative input | Connect to MOSFET source; measures voltage drop across sense resistor to enforce current limit (202 mV typ). |
| OUT1–OUT4 | Drain voltage monitor | High-impedance input (≤2 µA leakage) for sensing FET drain voltage; used for PGOOD and disconnect detection. |
| OSC_IN | AC disconnect oscillator input | Accepts 100 Hz ±10%, 2 VP-P sine wave; enables AC load removal detection when ACD_EN bit is set. |
Key Features
| Feature | Design Value |
|---|---|
| Quad-port IEEE 802.3af compliance | Full detection (320 ms), classification (40 ms), and powered-up operation per port - no external logic required. |
| Programmable current-limit foldback | Reduces current-limit threshold from 212 mV to 64 mV as VOUT–VEE rises from 30 V to 50 V, preventing thermal runaway under high-voltage loads. |
| Hardware watchdog with graceful takeover | 164 ms decrement timer resets port control to safe state if I²C commands stall - eliminates need for external supervisory IC. |
| Dual-path disconnect detection | Simultaneous DC disconnect (2.5–5 mV SENSE threshold) and AC disconnect (300–350 µA DET current threshold) per port. |
| Optocoupler-ready I²C interface | Separate SDAIN (input) and SDAOUT (output) pins eliminate bus contention and enable galvanic isolation without level shifters. |
| Configurable midspan cadence timing | Enables synchronized multi-port power-up in injector systems via MIDSPAN pin and internal timing registers. |
Applications
| LAN Switch Power Management | Midspan PoE Injector |
|---|---|
|
Use Scenario: 24-port enterprise switch delivering 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 Ethernet lanes per IC; handles concurrent detection/classification with <320 ms latency. Use Value: Enables compact, thermally efficient port density with per-port fault isolation - a single MAX5935CAX+T replaces discrete control logic and reduces BOM count by 4× vs. single-port solutions. |
Use Scenario: Standalone 8-port PoE injector adding power to legacy non-PoE switches. IC Role / Device Role / Timing Role: Midspan PSE controller operating in cadence mode; coordinates staggered port power-up to avoid inrush current overload on shared -48 V supply. Use Value: Eliminates need for external timing controllers or microcontrollers - built-in MIDSPAN logic and tDMID (2.4 s) delay ensures compliant power sequencing. |
| Industrial Ethernet Gateway | Smart Building Controller |
|
Use Scenario: Ruggedized gateway connecting field devices (sensors, actuators) over PoE-powered Ethernet. IC Role / Device Role / Timing Role: Endpoint PSE controller with watchdog and thermal shutdown; maintains port uptime in unattended environments with automatic recovery after firmware hang. Use Value: Provides deterministic fault response (<4 µs short-circuit shutdown) and autonomous restart - critical for zero-downtime industrial networks. |
Use Scenario: Central HVAC or lighting controller powering PoE-enabled occupancy sensors and thermostats. IC Role / Device Role / Timing Role: Class-over-current detector enforcing IEEE 802.3af Class 3 (15.4 W/port) limits; monitors PD current draw against programmed thresholds (e.g., 23 mA for Class 3). Use Value: Prevents overloading of centralized -48 V power supply by detecting and disabling ports drawing >25 mA - avoids cascading brownouts across building subsystems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad-port PoE PSE controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX5936CAX+T | Includes integrated 100 V hot-swap MOSFET drivers and higher VEE tolerance (-72 V); lacks separate SDAIN/SDAOUT pins. | Better suited for high-voltage industrial PSE where board space is constrained and isolation is handled externally. | Select MAX5936CAX+T only if integrated gate drivers and extended rail range outweigh loss of optocoupler-ready I²C flexibility. |
| TPS23861PWR | TI device with 4-port PSE control, but uses standard 2-wire I²C (no SDAIN/SDAOUT separation) and lacks AC disconnect detection. | Targeted at cost-sensitive endpoint PSE designs where midspan operation and AC load removal are not required. | Choose TPS23861PWR for simpler, lower-cost LAN switch implementations without midspan or AC-disconnect needs. |
Compared with MAX5935CAX+T, MAX5936CAX+T trades I²C isolation readiness for integrated high-voltage gate drivers, while TPS23861PWR offers lower system cost at the expense of AC disconnect capability and midspan timing - making MAX5935CAX+T optimal for isolated, dual-mode PoE infrastructure.
Availability
MAX5935CAX+T is available at Aetrix Electronics and suitable for LAN switch design, midspan PoE injector production, and industrial Ethernet gateway development requiring stable component supply across commercial temperature range and long-term lifecycle support.
Supply support for MAX5935CAX+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 communications, computing, and industrial applications.
The MAX5935CAX+T belongs to Maxim's Power over Ethernet (PoE) PSE controller product line, engineered specifically for IEEE 802.3af-compliant infrastructure equipment requiring reliable, software-configurable, multi-port power delivery with hardware fault resilience.
FAQ
What is the operating temperature range for the MAX5935CAX+T?
The MAX5935CAX+T is rated for the commercial temperature range of 0°C to +70°C. This specification is confirmed in the Ordering Information table and Absolute Maximum Ratings section of the official datasheet. The device is not rated for extended industrial temperatures; for -40°C to +85°C operation, the MAX5935EAX+T variant must be selected. Thermal shutdown activates at +150°C junction temperature with 20°C hysteresis.
Does the MAX5935CAX+T support both endpoint and midspan PSE configurations?
Yes, the MAX5935CAX+T supports both endpoint and midspan PSE operation. Configuration is controlled by the MIDSPAN pin (Pin 2): pulled low by default for endpoint use (e.g., LAN switches), or driven high for midspan mode (e.g., power injectors). The cadence timing feature and dedicated midspan detection delay (tDMID = 2.4 s) are enabled only when MIDSPAN is asserted, ensuring IEEE 802.3af compliance in either topology.
How does the MAX5935CAX+T implement AC load disconnect detection?
The MAX5935CAX+T performs AC load disconnect detection using the OSC_IN pin (Pin 36) and DETx pins. When ACD_EN bit is set, a 100 Hz ±10% sine wave is applied to OSC_IN; the internal oscillator buffer (gain = 2.9–3.1 V/V) conditions this signal, and current into DETx is monitored. Disconnect triggers if detected current falls below 300–350 µA (IACTH), with timeout configurable via register R29h. This function requires VDD–VDGND ≥3 V to operate.
Can the MAX5935CAX+T operate without an external microcontroller?
Yes, the MAX5935CAX+T can operate autonomously in AUTO mode. When the AUTO pin (Pin 35) is driven high before reset, the device executes full PD detection, classification, and power-up sequences independently. Hardware features - including watchdog timer, RESET input, and INT fault output - ensure safe operation even without continuous software supervision, making it suitable for standalone PSE modules.
What is the purpose of separate SDAIN and SDAOUT pins on the MAX5935CAX+T?
The separate SDAIN and SDAOUT pins enable optocoupler-based galvanic isolation of the I²C interface. SDAIN receives data from the system microcontroller side, while SDAOUT drives the isolated slave-side bus - eliminating contention and bidirectional signal conflicts. This architecture allows safe communication across isolation barriers without external level shifters or bus buffers, a key differentiator versus standard 2-wire I²C controllers.
MAX5935CAX+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 36-BSOP (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 0°C ~ 70°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-SSOP
MAX5935CAX+T FAQ
1.How can I place an order for MAX5935CAX+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX5935CAX+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 MAX5935CAX+T reliable?
The price and inventory of MAX5935CAX+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX5935CAX+T is usually 5 days.
3.What payment methods are accepted for MAX5935CAX+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX5935CAX+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX5935CAX+T?
MAX5935CAX+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX5935CAX+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 MAX5935CAX+T?
For technical support, including MAX5935CAX+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX5935CAX+T requirements.
6.How does Aetrix verify that MAX5935CAX+T is sourced from the original manufacturer or authorized distributors?
All MAX5935CAX+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 MAX5935CAX+T meets industry standards.
7.What is the process for return or replacement of MAX5935CAX+T?
All MAX5935CAX+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX5935CAX+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 MAX5935CAX+T part is unused and in its original packaging.
Return procedure for MAX5935CAX+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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