MAX5940

The MAX5940A/MAX5940B 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 provide the PD with a detection signature, a classification signature, and an integrated isolation switch with programmable inrush current con-trol. These devices also feature power-mode undervolt-age lockout (UVLO) with wide hysteresis, and power-good outputs.An integrated MOSFET provides PD isolation during detection and classification. The MAX5940A/MAX5940B guarantee a leakage current offset of less than 10µA dur-ing 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 provides an active-high (PGOOD) open-drain output and a fixed UVLO threshold. The MAX5940B provides both active-high (PGOOD) and active-low(PGOOD )outputs and has an adjustable UVLO threshold with the default value compliant to the 802.3af standard.The MAX5940A/MAX5940B are designed to work with or without an external diode bridge.The MAX5940A/MAX5940B are available in 8-pin SO packages and are rated over the extended temperature range of -40°C to +85°C.