PM8800A - IEEE 802.3af PoE-PD Controller with PWM | ST

IP Security Cameras

Network cameras are the largest category of IEEE 802.3af powered devices, and the PM8800A fits them directly: its on-chip 802.3af PD interface performs detection, classification and inrush limiting without extra components, while the integrated current mode PWM controller converts the extracted ~48 V cable power into efficient low-voltage rails for the image sensor, ISP and network SoC. The -0.3 V to 100 V input tolerance covers PoE voltage transients on long cable runs. Because the interface and PWM are monolithic, camera PCB area stays small enough for dome and bullet form factors. Placed at the Ethernet magnetics secondary, the part accepts the rectified PoE pair and its PWM stage typically drives an isolated or non-isolated buck/flyback stage; the current mode control yields tight, cycle-by-cycle current limiting that protects the camera electronics during cable faults.

Wireless Access Points

802.11 access points draw power through the Ethernet cable in ceiling-mount installations, making an 802.3af PD front-end mandatory. The PM8800A provides the compliant detection and classification handshake with the PoE switch, then its current mode PWM controller generates the 5 V/3.3 V-class rails consumed by the radio, baseband processor and Ethernet PHY. The device's support of an external source is especially valuable in access points that optionally run from a local DC jack: the auxiliary input lets the unit prioritize wall power and fall back to PoE transparently. With 100 V absolute input tolerance, it survives PoE voltage transients and miswiring events. The monolithic integration keeps the compact AP power section to one controller IC plus a small magnetics and capacitor set, while cycle-by-cycle current limiting adds robustness against radio load transients during TX bursts.

VoIP Telephones

Enterprise IP phones are classic IEEE 802.3af powered devices: they must operate solely from the desk switch's Ethernet port. The PM8800A handles the required detection signature and class advertisement so the PSE allocates the correct power budget, then its current mode PWM controller steps the extracted voltage down to rails for the handset DSP, display and Ethernet PHY. Input tolerance from -0.3 V to 100 V gives margin against cable transients and reversal events common in large office wiring plants. Because ST integrates the PD interface and PWM control on one die, the phone's power section stays compact on a crowded handset PCB, and the external-source support allows premium phone models to also accept an AC adapter where local power is preferred. Cycle-by-cycle current limiting protects the phone during hot-plug and fault conditions.

Building Automation and Access Control Nodes

Door controllers, sensors and automation nodes increasingly use PoE to avoid dedicated power wiring. The PM8800A serves these designs by providing the full IEEE 802.3af powered device interface - detection, classification, inrush limiting - together with a current mode PWM controller that converts cable power into logic and actuator rails. The -0.3 V to 100 V input rating tolerates the voltage excursions typical of long building cable runs shared with noisy electrical environments. The external-source support lets nodes use a backup battery or local adapter during PoE switch maintenance, improving system availability. Monolithic integration reduces component count in sealed, convection-limited enclosures, and the 16-HTSSOP exposed-pad package provides a thermal path for the switching losses of the downstream conversion stage. Current mode control simplifies loop compensation across wide industrial temperature ranges.

Network-Attached Lighting and Signage

PoE-connected LED luminaires and digital signage are powered entirely through structured cabling, requiring an 802.3af PD interface at the fixture. The PM8800A detects and classifies against the PoE switch, then its current mode PWM controller drives the conversion stage that feeds LED drivers or display electronics. The wide -0.3 V to 100 V input window absorbs surges on long horizontal cable runs, and cycle-by-cycle current limiting protects downstream LED strings during faults. Because detection, classification and PWM control are integrated monolithically, fixture designers fit the complete power front-end on a small driver board inside the luminaire housing where thermal dissipation is limited - the 16-HTSSOP exposed pad helps conduct switching losses into the fixture chassis. The external-source option enables hybrid fixtures that can run from either PoE or a local supply for emergency lighting operation.

Ethernet-Connected Industrial IoT Gateways

Industrial IoT gateways combine a network processor, radios and sensor front-ends, and many are deployed where only the Ethernet drop is available. The PM8800A provides the IEEE 802.3af PD interface required to draw power from the switch, advertising its class so the PSE reserves adequate budget, while the integrated current mode PWM controller generates the primary low-voltage rails for the gateway electronics. The 100 V input tolerance handles the transients and wiring faults typical of factory cabling, and the auxiliary-source support lets gateways fall back to a DIN-rail mounted supply when PoE is down - a common requirement in industrial availability specs. Monolithic integration of the PD interface and PWM control minimizes the power section footprint on dense gateway boards, and the current mode topology's inherent current limiting protects the processor load during cable short events.