STMicroelectronics PM8803

Overview

PM8803 from STMicroelectronics is an IEEE 802.3at-compliant integrated PoE-PD interface and current-mode PWM controller in HTSSOP20 package. It integrates a 100 V/0.45 Ω hot-swap MOSFET, supports dual power sources (PoE or auxiliary), delivers up to 1 A DC current limit, and enables flyback/forward/active-clamp topologies with synchronous rectification support - used in VoIP phones and security cameras.

For engineers reviewing the PM8803 datasheet, PM8803 pinout, PM8803 application, or PM8803 equivalent, key selection criteria include IEEE 802.3at Layer 1 classification indication (T2P signal), programmable oscillator frequency (100–1000 kHz), dual gate drivers (GAT1/GAT2) with 1 A peak sink-source capability, and auxiliary source priority logic (SP/SA pins).

Technical Context

The PM8803 implements hardware-based IEEE 802.3at detection and two-event classification with dedicated DET and CLS pins, plus T2P open-drain flag for PSE compatibility verification. Its integrated hot-swap MOSFET handles inrush limiting (140 mA typ.) and DC current control (up to 1 A via DCCL resistor), with UVLO thresholds at 35 V (rising) and 31 V (falling).

The PWM section features a programmable oscillator (RT resistor), adjustable slope compensation, dual complementary low-side drivers (GAT1/GAT2), 80% max duty cycle, and internal thermal shutdown at 160 °C. Gate timing includes programmable delay (DT pin) and leading-edge blanking (60 ns typ.) for stable current-mode operation.

Key Specifications

Pinout & Package

PM8803 is housed in a thermally enhanced HTSSOP20 package with exposed pad (EP) tied to VSS for improved heat dissipation. Pin layout supports separate analog (ARTN) and power (RTN1/RTN2) grounds to minimize noise coupling in mixed-signal PoE-PD designs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PoE-PD interface and PWM controller applications.

Compared with LT4275A and NCP1095, the PM8803 uniquely integrates both IEEE 802.3at PD interface and dual-gate PWM controller in one HTSSOP20 package - reducing board area by ~35%, eliminating inter-IC timing skew, and enabling single-chip PoE+ designs up to 30 W.

Availability

PM8803 is available at Aetrix Electronics and suitable for VoIP phones, WLAN access points, security cameras, and PoE+ powered appliances requiring stable component supply across industrial temperature ranges (−40 °C to +85 °C ambient).

Supply support for PM8803 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, with design centers and manufacturing facilities across Europe, Asia, and the Americas.

The PM8803 belongs to ST's Power Over Ethernet product line, engineered specifically to simplify high-efficiency, standards-compliant powered device designs for enterprise and industrial networking equipment.

FAQ

What is the function of the T2P pin on the PM8803?

The T2P pin is an open-drain active-low indicator that asserts when the PM8803 successfully completes IEEE 802.3at two-event classification with a compatible PSE. It connects to a microcontroller GPIO or status LED to confirm PoE+ readiness before enabling downstream loads. Its 75 Ω pull-down resistance ensures reliable logic-level signaling without external components.

How does the PM8803 handle power source priority between PoE and auxiliary inputs?

The PM8803 uses SA (rear auxiliary) and SP (front auxiliary) pins to configure priority: pulling SA high gives wall adapter precedence over PoE, while SP enables low-voltage auxiliary start-up below 35 V. Internal diode-OR logic ensures automatic, glitch-free switchover without software involvement - validated in Figure 15 of the datasheet.

Can the PM8803 support synchronous rectification in flyback topologies?

Yes - the GAT2 driver provides precisely timed, 1 A peak sink-source output optimized for synchronous rectifier MOSFETs. Combined with programmable DT delay and 60 ns leading-edge blanking on CS, it enables zero-voltage switching and >92% efficiency in synchronous flyback configurations, as shown in Figure 2 of the datasheet.

What is the maximum DC current limit achievable with the DCCL pin?

The DCCL pin supports a programmable DC current limit from 140 mA to 1 A using an external resistor (R_DCCL = 30 kΩ to 150 kΩ). At 1 A, the PM8803 exceeds IEEE 802.3at's 600 mA limit, enabling custom high-power PD designs - verified by Table 5's ±15% tolerance and 1000 mA max specification.