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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:
- QUAD NETWORK POWER CONTROLLER
- Quantity:
- Payment:
- Shipping:
Inventory:935
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Product details
Overview
MAX5935CAX from Maxim Integrated is a quad-channel IEEE 802.3af-compliant network power controller for Power Sourcing Equipment (PSE), supporting both endpoint (LAN switch/router) and midspan (power injector) topologies. It delivers PD detection, classification, programmable current limiting (202–222 mV sense threshold), DC/AC load disconnect detection, and hardware watchdog supervision. Designed for -48V Ethernet power delivery, it operates across 0°C to +70°C in 36-pin SSOP.
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-responsive shutdown, I²C-based register programming, and dual-mode (endpoint/midspan) PSE deployment with integrated thermal and overvoltage protection.
Technical Context
The MAX5935CAX implements four independent state machines-one per port-with autonomous detection/classification logic and configurable timing (e.g., tSTART = 50–70 ms, tFAULT = 50–70 ms). Its architecture integrates analog sensing (SENSE1–4), gate drivers (GATE1–4), and digital control via an I²C-compatible 3-wire interface (SDAIN/SDAOUT/SCL) with optocoupler support.
It features hardware-level safety mechanisms including VEE undervoltage lockout (28.5 V), overtemperature shutdown (+150°C), short-circuit pulldown (100 mA), and class-overcurrent detection. The cadence timing function and MIDSPAN pin enable precise synchronization for midspan PSE operation, while the AUTO pin selects fully autonomous or software-managed mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Compliance | IEEE 802.3af Power Sourcing Equipment (PSE) compliant - ensures interoperability with standard PoE-powered devices. |
| Ports | 4 independent Ethernet ports - enables single-chip control of full quad-port PSE systems without external multiplexing. |
| Current Limit Threshold | 202–222 mV default SENSE voltage - sets ±1% accurate 0.404–0.444 A limit with 0.5 Ω sense resistor. |
| Operating Temp | 0°C to +70°C - commercial-grade rating suitable for indoor LAN switches and managed power injectors. |
| Package | 36-pin SSOP (A36-2) - surface-mount footprint compatible with standard PCB assembly and thermal relief design. |
| I²C Interface | 400 kHz Fast Mode, 3-wire (SDAIN/SDAOUT/SCL) - supports isolated communication via optocouplers in high-noise environments. |
| Supply Range | VDD = 3.0–5.5 V (vs DGND); VEE = -32V to -60V - accommodates standard telecom -48V rail with wide digital supply tolerance. |
Pinout & Package
MAX5935CAX is housed in a 36-pin SSOP (Small Outline Package) with 0.025" lead pitch, JEDEC MS-012AC compliant, and rated for commercial temperature operation (0°C to +70°C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RESET | Hardware reset input | Pull low ≥300 µs to reset all registers and latch AUTO/MIDSPAN states; internal 50 kΩ pullup to VDD. |
| MIDSPAN | Topology selection | Pulled low by default (endpoint mode); drive high to enable midspan PSE operation with cadence timing. |
| INT | Open-drain fault interrupt | Active-low signal indicating any port fault (overcurrent, overtemp, UVLO); requires external pullup. |
| SDAIN / SDAOUT | I²C data isolation interface | Separate input/output lines allow optocoupler-based galvanic isolation between host MCU and MAX5935CAX. |
| A0–A3 | I²C slave address inputs | Set lower 4 bits of 7-bit address (MSB = 010); internal 50 kΩ pullups enable 16 unique addresses on shared bus. |
| DET1–DET4 | PD detection/classification probe outputs | Generate controlled voltage (3.8–9.6 V phases, 16–20 V classification) across PD signature resistors. |
| SENSE1–SENSE4 | Current-sense negative inputs | Connect to MOSFET source; measure voltage drop across sense resistor for real-time current limiting. |
| GATE1–GATE4 | External N-channel MOSFET gate drivers | Drive gate of high-side FETs; internally clamped to 11.4 V above VEE to prevent overdrive damage. |
| OUT1–OUT4 | Drain voltage monitoring inputs | High-impedance sense node (≤2 µA leakage) for output voltage validation and power-good signaling. |
| SHD1–SHD4 | Independent port shutdown controls | Asynchronous active-low inputs enabling immediate FET turn-off per port without software intervention. |
Key Features
| Feature | Design Value |
|---|---|
| DC & AC load disconnect detection | Enables compliance with IEEE 802.3af section 33.3.3 - detects open-circuit (≥12.5 µA) and short-circuit (≤1.62 V) faults plus AC disconnect via OSC_IN (300–350 µA threshold). |
| Programmable current foldback | Reduces current-limit threshold from 222 mV to 64 mV as OUT voltage rises from 30 V to 50 V - prevents thermal runaway during startup into capacitive loads. |
| Watchdog-enabled graceful takeover | Hardware timer (164 ms period) resets port control to safe state if I²C commands stall - eliminates firmware lockup risks in unattended PSE deployments. |
| Class-overcurrent protection | Detects when connected PD draws >class-defined current (e.g., Class 3 = 21–25 mA) - triggers fault interrupt and shutdown to protect upstream power budget. |
| Four independent shutdown inputs | SHD1–SHD4 provide <1 µs response time to external fault signals (e.g., board-level overtemp, fuse trip) - bypasses software latency for critical safety events. |
Applications
| LAN Switch PSE Port Control | Midspan Power Injector |
|---|---|
Use Scenario: 24-port managed Ethernet switch providing PoE to IP phones, cameras, and wireless APs. IC Role / Device Role / Timing Role: Quad-port PSE controller managing four adjacent switch ports; performs autonomous detection/classification within 320 ms and enforces per-port current limits. Use Value: Enables compact, thermally efficient port density with hardware-fault responsiveness - eliminates need for discrete supervisor ICs per port group. |
Use Scenario: Standalone 8-port PoE injector inserting power between non-PoE switch and VoIP endpoints. IC Role / Device Role / Timing Role: Midspan PSE controller using MIDSPAN pin and cadence timing to coordinate multi-port power-up sequences aligned with IEEE 802.3af timing windows. Use Value: Guarantees compliant 2.4 s detection delay and synchronized port activation - avoids false disconnects due to timing skew across ports. |
| Industrial IoT Gateway | Smart Building Controller |
Use Scenario: Ruggedized edge gateway powering sensors, actuators, and field controllers over industrial Ethernet. IC Role / Device Role / Timing Role: PSE controller operating in semi-auto mode - performs continuous detection but waits for host MCU command before powering up each port. Use Value: Supports deterministic boot sequencing and remote diagnostics - allows host to validate PD identity before enabling power. |
Use Scenario: Central HVAC or lighting controller delivering PoE to occupancy sensors, thermostats, and dimmer modules. IC Role / Device Role / Timing Role: Quad-port controller with programmable restart duty cycle (RSTR bits) and thermal shutdown (+150°C) for unattended operation in enclosed enclosures. Use Value: Prevents sustained overtemperature events in confined spaces - auto-recovery after cooling avoids manual reset requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad-port PoE PSE applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX5980ATL+ | Single-port IEEE 802.3at (PoE+) compliant; supports up to 30W per port; includes integrated DC-DC controller. | Targeted at higher-power endpoints (e.g., PTZ cameras); lacks quad integration and midspan cadence timing. | Select MAX5980ATL+ only when upgrading to PoE+ and requiring per-port DC-DC regulation - not a drop-in replacement for MAX5935CAX. |
| NCP1095DR2G | Quad-port IEEE 802.3af PSE controller; no I²C interface - uses dedicated pin-strapped configuration; no watchdog or programmable foldback. | Suitable for cost-sensitive, fixed-function PSE designs where software configurability is unnecessary. | Choose NCP1095DR2G for simplified BOM and layout where register-level tuning and fault logging are not required. |
Compared with MAX5935CAX, MAX5980ATL+ offers higher per-port power but requires redesign for PoE+ compliance and loses quad integration, while NCP1095DR2G provides pin-compatible quad control at lower flexibility - MAX5935CAX remains optimal for software-defined, midspan-capable, and fault-resilient PSE systems.
Availability
MAX5935CAX is available at Aetrix Electronics and suitable for LAN switch PSE port control, midspan power injector modules, industrial IoT gateways, smart building controllers, and enterprise VoIP infrastructure requiring stable component supply and long-term lifecycle support.
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 IEEE 802.3af-compliant power sourcing equipment requiring quad-port integration, hardware safety features, and software configurability in commercial-temperature environments.
FAQ
What is the operating temperature range for the MAX5935CAX?
The MAX5935CAX is rated for commercial temperature operation from 0°C to +70°C. This specification is explicitly defined in the Ordering Information table and Absolute Maximum Ratings section of the datasheet. The device is distinct from the extended-range MAX5935EAX (-40°C to +85°C), and thermal shutdown activates at +150°C junction temperature. Operation outside the 0°C to +70°C ambient range may result in undefined behavior or failure to meet guaranteed specifications.
Does the MAX5935CAX support both endpoint and midspan PSE configurations?
Yes, the MAX5935CAX supports both endpoint and midspan PSE topologies. The MIDSPAN pin (Pin 2) configures the mode: pulled low by default for endpoint operation (LAN switches/routers), or driven high for midspan operation (power injectors). The cadence timing feature and dedicated midspan detection delay (tDMID = 2.0–2.4 s) ensure full IEEE 802.3af compliance in either configuration. This dual-mode capability is confirmed in the General Description and Detailed Description sections.
How does the MAX5935CAX implement current limiting and foldback?
The MAX5935CAX uses a precision SENSE pin comparator with a default 202–222 mV clamp voltage (VSU_LIM) to enforce current limit. When output voltage exceeds 30 V, the current-limit threshold folds back linearly to 64 mV at 50 V (VFLBK_ST/VFLBK_END), reducing delivered current under high-voltage, high-capacitance startup conditions. This foldback behavior is programmable via I²C register R22h and prevents thermal stress on external FETs and sense resistors.
What interfaces does the MAX5935CAX use for system communication?
The MAX5935CAX uses an I²C-compatible 3-wire serial interface consisting of SCL (clock), SDAIN (data input), and SDAOUT (data output). This separation enables optocoupler-based galvanic isolation between host microcontroller and the MAX5935CAX. It operates in Fast Mode at up to 400 kHz and supports 16 unique slave addresses via A0–A3 pins. No SPI or UART interface is present - all configuration and status access occurs exclusively through this I²C channel.
Can the MAX5935CAX detect and classify Power Devices automatically?
Yes, the MAX5935CAX performs full IEEE 802.3af-compliant PD detection and classification autonomously in AUTO mode. It applies two-phase detection voltages (3.8–4.2 V and 9.0–9.6 V) to DET pins, measures resulting current (1.5–2.0 mA detection, 50–75 mA classification), and validates signature resistance (19–26.5 kΩ). Classification current thresholds (e.g., 21–25 mA for Class 3) are enforced, and results are reported via INT and internal status registers - all without host intervention when AUTO = high.
MAX5935CAX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 36-BSOP (0.295", 7.50mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- Controller (PSE)
- Number of Channels:
- 4
- Power - Max:
- 941 mW
- Internal Switch(s):
- No
- Auxiliary Sense:
- No
- Standards:
- 802.3af (PoE)
- Voltage - Supply:
- 0V ~ 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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