1. Products
  2. Product
  3. MAX5940B


Features and Benefits

  • Fully Integrated IEEE 802.3af-Compliant PD Interface
  • PD Detection and Programmable Classification Signatures
  • Less than 10µA Leakage Current Offset During Detection
  • Integrated MOSFET For Isolation and Inrush Current Limiting
  • 90V Absolute Maximum Rating (MAX5940C/MAX5940D)
  • Gate Output Allows External Control of the Internal Isolation MOSFET
  • Programmable Inrush Current Control
  • Programmable Undervoltage Lockout (MAX5940B/MAX5940D Only)
  • Wide UVLO Hysteresis Accommodates Twisted-Pair Cable Voltage Drop
  • PGOOD/Active-Low PGOOD Outputs to Enable Downstream DC-DC Converters
  • -40°C to +85°C Operating Temperature Range

Product Details

The MAX5940A/MAX5940B/MAX5940C/MAX5940D provide complete interface function for a powered device (PD) to comply with the IEEE® 802.3af standard in a power-over-ethernet system. MAX5940A/MAX5940B/MAX5940C/MAX5940D provide the PD with a detection signature, a classification signature, and an integrated isolation switch with programmable inrush current control. These devices also feature power-mode undervoltage lockout (UVLO) with wide hysteresis and power-good outputs. The MAX5940A/MAX5940B are available with an absolute maximum rating of 80V and the MAX5940C/MAX5940D are rated for an absolute maximum rating of 90V.

An integrated MOSFET provides PD isolation during detection and classification. All devices guarantee a leakage current offset of less than 10µA during the detection phase. A programmable current limit prevents high inrush current during power-on. The device features power-mode UVLO with wide hysteresis and long deglitch time to compensate for twisted-pair cable resistive drop and to assure glitch-free transition between detection, classification, and power-on/-off phases.

The MAX5940A/MAX5940C provide an active-high (PGOOD) open-drain output and a fixed UVLO threshold. The MAX5940B/MAX5940D provide both active-high (PGOOD) and active-low (active-low PGOOD) outputs and have an adjustable UVLO threshold with the default value compliant to the 802.3af standard. All devices are designed to work with or without an external diode bridge.

The MAX5940A/MAX5940B/MAX5940C/MAX5940D are available in 8-pin SO packages and are rated over the extended temperature range of -40°C to +85°C.


  • Computer Telephony
  • IP Phones Security Cameras
  • Wireless Access Nodes IEEE 802.3af Power Devices

Product Categories

Product Lifecycle icon-recommended Production

At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.

Evaluation Kits (1)

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.

Part Number Material Declaration Reliability Data Pin/Package Drawing CAD Symbols, Footprints & 3D Models
MAX5940AESA+ Material Declaration Reliability Data Small-Outline IC, Narrow (0.15in)
MAX5940AESA+T Material Declaration Reliability Data Small-Outline IC, Narrow (0.15in)
MAX5940BESA+ Material Declaration Reliability Data Small-Outline IC, Narrow (0.15in)
MAX5940BESA+T Material Declaration Reliability Data Small-Outline IC, Narrow (0.15in)
MAX5940CESA+ Material Declaration Reliability Data Small-Outline IC, Narrow (0.15in)
MAX5940CESA+T Material Declaration Reliability Data Small-Outline IC, Narrow (0.15in)
MAX5940DESA+ Material Declaration Reliability Data Small-Outline IC, Narrow (0.15in)
MAX5940DESA+T Material Declaration Reliability Data Small-Outline IC, Narrow (0.15in)
Wafer Fabrication Data

PCN-PDN Information

Select a model from the dropdown below to subscribe to PCN/PDN notifications and view past notifications as well.

Sample & Buy

Ordering FAQs

See our Ordering FAQs for answers to questions about online orders, payment options and more.


Buy Now Pricing

(**) Displayed Buy Now Price and Price Range is based on small quantity orders.


List Pricing

(*)The 1Ku list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.


Lead Times

Please see the latest communication from our CCO regarding lead times.



A Sample link will be shown above, next to the part, only for parts that are included in our sample program. Selecting the Sample button will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.

Price Table Help