This 8-pin integrated circuit contains all of the features needed to implement an IEEE802.3at type-2 powered device (PD). The low 0.5-Ω internal switch resistance, combined with the enhanced thermal dissipation of the PowerPAD™ package, enables this controller to continuously handle up to 0.85 A. The TPS2378 features an auxiliary power detect (APD) input, providing priority for an external power adapter. It also features a 100-V pass transistor, 140-mA inrush current limiting, type-2 indication, auto-retry fault protection, and an open-drain power-good output.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
TPS2378 | HSOP (8) | 4.89 mm × 3.90 mm |
Changes from B Revision (November 2012) to C Revision
Changes from A Revision (March 2012) to B Revision
Changes from * Revision (March 2012) to A Revision
PIN | I/O | DESCRIPTION | |
---|---|---|---|
NAME | NO. | ||
VDD | 1 | I | Connect to positive PoE input power rail. Bypass with 0.1 µF to VSS. |
DEN | 2 | I/O | Connect 24.9 kΩ to VDD for detection. Pull to VSS disable pass MOSFET. |
CLS | 3 | O | Connect resistor from CLS to VSS to program classification current. |
VSS | 4 | — | Connect to negative power rail derived from PoE source. |
RTN | 5 | — | Drain of PoE pass MOSFET. |
CDB | 6 | O | Active low, open-drain converter disable output, referenced to RTN. |
T2P | 7 | O | Active low indicates type 2 PSE connected or APD active. |
APD | 8 | I | Raise 1.5 V above RTN to disable pass MOSFET and force T2P active. |
Pad | — | — | The PowerPad™ must be connected to VSS. A large fill area is required to assist in heat dissipation. |