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Analog Devices Inc./Maxim Integrated MAX5935CAX+
- Part No.:
- MAX5935CAX+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Power Over Ethernet (PoE) Controllers
- Package:
- 36-BSOP (0.295", 7.50mm Width)
- Datasheet:
-
MAX5935CAX+.pdf
- Description:
- IC POE CNTRL 4 CHANNEL 36SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,405
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Product details
Overview
MAX5935CAX+ from Maxim Integrated is a quad-port IEEE 802.3af-compliant network power controller for Power over Ethernet (PoE) power-sourcing equipment (PSE), delivering PD discovery, classification, programmable current limiting (202–222 mV sense threshold), DC/AC load disconnect detection, and hardware watchdog supervision. It operates on -48V analog rail with 3.0–5.5V digital supply and supports both endpoint (LAN switch) and midspan (injector) PSE topologies.
For engineers reviewing the MAX5935CAX+ datasheet, MAX5935CAX+ pinout, MAX5935CAX+ application, or MAX5935CAX+ equivalent, this device is selected for robust, software-configurable PoE port control requiring fault-resilient operation, I²C-based system integration, and dual-mode (endpoint/midspan) deployment in enterprise switching and industrial PoE infrastructure.
Technical Context
The MAX5935CAX+ implements four independent port state machines with fully autonomous or I²C-controlled operation, supporting IEEE 802.3af Class 0–4 PD classification and class-over-current detection. Its architecture integrates gate drivers with programmable charge/discharge currents, 9-bit ADC-based sensing, and dedicated AC disconnect circuitry tied to OSC_IN input.
It features dual ground domains (AGND/DGND), separate SDAIN/SDAOUT lines for optocoupler-isolated I²C, and hardware-level fault response via INT output and individual SHD_ shutdown inputs. The cadence timing engine enables precise midspan detection delay (2.0–2.4 s), while the watchdog timer (164 ms period) ensures fail-safe recovery from firmware lockup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| IEEE Standard Compliance | Fully compliant with IEEE 802.3af for PSE operation, including detection, classification, and power delivery sequencing. |
| Port Count & Voltage Range | Four independent -32V to -60V ports; supports -48V nominal analog supply (VEE) with VAGND = +48V reference. |
| Current Limit Threshold | Programmable 202–222 mV default VSENSE clamp (Class 0/3/4); foldback starts at VOUT ≥30V, reaches final limit at ≥50V. |
| Digital Interface | I²C-compatible 3-wire serial interface (SCL, SDAIN, SDAOUT) with 400 kHz Fast Mode support and addressable via A0–A3 (16 addresses). |
| Protection Functions | VEE UVLO (28.5 V), VEE OV (62.5 V), thermal shutdown (+150°C), short-circuit pulldown (100 mA), and PGOOD monitoring (2.0 V threshold). |
| DC/AC Disconnect Detection | DC disconnect at 2.5–5 mV SENSE threshold; AC disconnect enabled via OSC_IN (100 Hz ±10%, 2 VPP ±5%, +1.2 V offset). |
| Operating Temperature | Commercial grade: 0°C to +70°C ambient; packaged in 36-pin SSOP (A36-2) with 941 mW max power dissipation. |
Pinout & Package
MAX5935CAX+ is housed in a 36-pin SSOP (Shrink Small Outline Package) with exposed pad not specified; footprint compatible with A36-2 package code. Pin functions are validated per Maxim's official datasheet Rev 3 (May 2007).
| 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) | Topology mode select | Pull high to enable midspan injector mode; internal 50 kΩ pulldown defaults to endpoint (switch/router) mode. |
| INT (Pin 3) | Open-drain fault interrupt | Active-low signal indicating any port fault (overcurrent, thermal, UV/OV); sinks up to 80 mA. |
| SCL (Pin 4) | I²C clock line | Supports 400 kHz Fast Mode; referenced to DGND; requires external pullup. |
| SDAOUT (Pin 5) | I²C data output | Isolated output for optocoupler-driven systems; connects to optocoupler LED anode. |
| SDAIN (Pin 6) | I²C data input | Isolated input from optocoupler phototransistor collector; referenced to DGND. |
| A0–A3 (Pins 7–10) | Slave address bits | Set lower 4 bits of I²C address (MSB fixed as 010); internal 50 kΩ pullups to VDD. |
| DET1–DET4 (Pins 11–14) | PD detection/classification voltage source | Drive detection probe voltages (3.8–4.2 V, 9.0–9.6 V) and classification (16–20 V) onto PD signature resistors. |
| DGND (Pin 15) | Digital ground reference | Separate ground domain for digital logic and I²C interface; must be isolated from AGND/VEE. |
| VDD (Pin 16) | Digital supply input | 3.0–5.5 V supply referenced to DGND; powers logic, I²C, and register file. |
| SHD1–SHD4 (Pins 17–20) | Independent port shutdown | Active-low direct control of port FETs; internal 50 kΩ pullups to VDD ensure safe-off default. |
| AGND (Pin 21) | Analog ground reference | High-side analog return; connects to +48 V supply rail; must be star-connected to minimize noise. |
| SENSE1–SENSE4 (Pins 22,25,29,32) | Current-sense negative input | Connects to MOSFET source; measures VSENSE across external sense resistor (e.g., 0.5 Ω). |
| GATE1–GATE4 (Pins 23,26,30,33) | External FET gate driver | Drives N-channel MOSFET gates; internally clamped to 11.4 V above VEE; supports programmable charge/discharge. |
| OUT1–OUT4 (Pins 24,27,31,34) | Drain voltage sense | Low-leakage (<2 µA) input for monitoring FET drain voltage; used for PGOOD and open-circuit detection. |
| VEE (Pin 28) | Analog supply return | Connects to -48 V rail; bypassed with 1 µF capacitor between AGND and VEE. |
| AUTO (Pin 35) | Operation mode select | Pull high to enter automatic mode post-reset; internal 50 kΩ pulldown defaults to shutdown mode. |
| OSC_IN (Pin 36) | AC disconnect oscillator input | Accepts 100 Hz sine wave for AC load removal detection; disabled if left unconnected or below 1.8 V. |
Key Features
| Feature | Design Value |
|---|---|
| Quad-port IEEE 802.3af PSE control | Enables single-chip management of four PoE ports in switches or injectors without external microcontroller coordination. |
| Programmable current-limit foldback | Reduces delivered current as output voltage rises beyond 30 V, preventing thermal runaway during cable faults or long runs. |
| Dual-disconnect detection (DC + AC) | DC disconnect triggers on <5 mV SENSE; AC disconnect uses OSC_IN to detect loss of AC signature on powered devices. |
| Hardware watchdog with graceful takeover | Resets port control to safe state if I²C communication stalls, using 164 ms timer and dedicated WDT logic block. |
| Midspan cadence timing engine | Generates precise 2.0–2.4 s detection delay required by IEEE 802.3af midspan PSE specification, eliminating external timing components. |
| Optocoupler-ready I²C interface | Separated SDAIN/SDAOUT pins allow galvanic isolation without level shifters, simplifying safety-certified PoE system design. |
Applications
| Enterprise LAN Switches | Midspan PoE Injectors |
|---|---|
Use Scenario: 24- or 48-port managed Ethernet switch delivering PoE to IP phones, wireless APs, and security cameras. IC Role / Device Role / Timing Role: Quad-port PSE controller managing four adjacent switch ports per IC; handles full IEEE 802.3af handshake autonomously. Use Value: Reduces BOM count vs. discrete solutions; enables per-port current limiting (202–222 mV) and fast fault shutdown (<1 ms) to protect upstream DC-DC converters. |
Use Scenario: Standalone 4-port PoE injector adding power capability to legacy non-PoE switches or routers. IC Role / Device Role / Timing Role: Midspan PSE controller implementing cadence-timed detection (2.0–2.4 s) and classification per IEEE 802.3af Section 13.2.2. Use Value: Eliminates need for external timing capacitors or microcontrollers; supports hot-swap insertion and per-port reset via SHD_ inputs. |
| Industrial IoT Gateways | Smart Building Controllers |
Use Scenario: Ruggedized edge gateway powering PoE-enabled sensors, actuators, and PLC I/O modules in factory automation. IC Role / Device Role / Timing Role: PSE controller operating in semi-auto mode-detects/classifies PDs on request, then waits for host MCU command to power up. Use Value: Enables deterministic power sequencing in time-sensitive control loops; watchdog ensures fail-safe port disable if host firmware hangs. |
Use Scenario: HVAC or lighting controller integrating PoE-powered occupancy sensors, thermostats, and dimmer modules. IC Role / Device Role / Timing Role: Quad-port controller managing mixed-class PDs (Class 0–4) with class-over-current detection to prevent overload on shared 30 W supplies. Use Value: Prevents brownouts by detecting >75 mA classification current violations; provides PGOOD status for system-level power-good sequencing. |
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 |
|---|---|---|---|
| MAX5980ATJ+ | IEEE 802.3at (PoE+) compliant; supports up to 30 W per port; higher VEE range (-57 V to -50 V); integrated 100 V HotSwap™ FET drivers. | Required for Class 4 (30 W) PDs; not backward-compatible with MAX5935CAX+ register map or timing behavior. | Select MAX5980ATJ+ when upgrading to PoE+ or needing integrated high-voltage gate drivers. |
| TPS23861PWR | Texas Instruments part; IEEE 802.3af/at compliant; 4-port; I²C interface; built-in 100 V gate drivers; different fault reporting scheme (single ALERT# vs. per-port INT). | Lacks AC disconnect and cadence timing; requires external oscillator for midspan mode; no SDAIN/SDAOUT isolation support. | Choose TPS23861PWR for TI ecosystem designs where optocoupler isolation is not required and PoE+ headroom is needed. |
Compared with MAX5935CAX+, MAX5980ATJ+ delivers higher per-port power and integrated FET drive but requires layout and firmware changes; TPS23861PWR offers PoE+ compatibility and TI toolchain support but omits AC disconnect and isolated I²C, increasing system-level isolation complexity.
Availability
MAX5935CAX+ is available at Aetrix Electronics and suitable for enterprise switching, midspan PoE injection, and industrial IoT gateway designs requiring stable component supply, commercial-temperature-grade reliability, and IEEE 802.3af compliance.
Supply support for MAX5935CAX+ 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+ belongs to Maxim's Power over Ethernet (PoE) PSE controller product line, designed specifically for cost-effective, highly integrated IEEE 802.3af-compliant power sourcing equipment in endpoint and midspan configurations.
FAQ
What is the maximum number of MAX5935CAX+ devices that can share the same I²C bus?
Up to 16 MAX5935CAX+ devices can operate on a single I²C bus, enabled by the four hardware address inputs (A0–A3) that configure unique 7-bit slave addresses. Each device latches its address at power-up or reset, and the fixed 3-bit prefix (010) ensures no conflict with other Maxim I²C peripherals. This scalability supports multi-slot chassis or high-port-count switches without bus arbitration overhead.
Does MAX5935CAX+ support IEEE 802.3at (PoE+) or only 802.3af?
MAX5935CAX+ is strictly IEEE 802.3af-compliant and does not support IEEE 802.3at (PoE+). It delivers up to 15.4 W per port (Class 0–4), with current-limit thresholds optimized for 802.3af classes (e.g., 202–222 mV for Class 3/4). For PoE+ applications requiring 30 W per port, Maxim recommends the MAX5980ATJ+ or similar 802.3at-compliant controllers instead of MAX5935CAX+.
How does the MAX5935CAX+ handle AC load disconnect detection?
MAX5935CAX+ performs AC load disconnect detection using the OSC_IN pin (Pin 36), which accepts a 100 Hz ±10% sine wave. When ACD_EN_ is enabled, the internal oscillator buffer compares DET_ current against a programmable threshold (300–350 µA). If current falls below threshold for ≥300–400 ms, the port shuts down. The feature requires external oscillator circuitry and is disabled if OSC_IN is left unconnected or biased below 1.8 V.
Can MAX5935CAX+ operate in both endpoint and midspan PSE modes simultaneously?
No - MAX5935CAX+ operates in either endpoint or midspan mode, selected at power-up/reset via the MIDSPAN pin (Pin 2). Endpoint mode (MIDSPAN = low) is default; midspan mode (MIDSPAN = high) activates cadence timing (2.0–2.4 s detection delay) and modifies detection waveform timing per IEEE 802.3af Section 13.2.2. The mode is latched and cannot be changed dynamically during operation without reset.
What is the purpose of the separate SDAIN and SDAOUT pins on MAX5935CAX+?
The separate SDAIN and SDAOUT pins on MAX5935CAX+ enable optocoupler-based galvanic isolation of the I²C bus, critical for safety-certified PoE systems. SDAOUT drives the optocoupler LED; SDAIN receives the phototransistor output. This eliminates the need for bidirectional level shifters or complex isolation ICs, simplifying compliance with UL/IEC 62368-1 creepage/clearance requirements in end equipment using MAX5935CAX+.
MAX5935CAX+ 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:
- 0°C ~ 70°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-SSOP
MAX5935CAX+ FAQ
1.How can I place an order for MAX5935CAX+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX5935CAX+ 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+ reliable?
The price and inventory of MAX5935CAX+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX5935CAX+ is usually 5 days.
3.What payment methods are accepted for MAX5935CAX+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX5935CAX+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX5935CAX+?
MAX5935CAX+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX5935CAX+ 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+?
For technical support, including MAX5935CAX+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX5935CAX+ requirements.
6.How does Aetrix verify that MAX5935CAX+ is sourced from the original manufacturer or authorized distributors?
All MAX5935CAX+ 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+ meets industry standards.
7.What is the process for return or replacement of MAX5935CAX+?
All MAX5935CAX+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX5935CAX+, 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+ part is unused and in its original packaging.
Return procedure for MAX5935CAX+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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