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. |
MIN | MAX | UNIT | ||
---|---|---|---|---|
Input voltage | VDD, DEN | –0.3 | 100 | V |
RTN(2) | –0.6 | 100 | ||
CLS(3) | –0.3 | 6.5 | ||
APD to RTN | –0.3 | 19 | ||
[CDB, T2P] to RTN | –0.3 | 100 | ||
Sinking current | RTN(4) | Internally limited | mA | |
CDB, T2P | 5 | |||
DEN | 1 | |||
Sourcing current | CLS | 65 | mA | |
TJMAX | Maximum junction temperature | Internally limited | °C | |
Tstg | Storage temperature | –65 | 150 | °C |
VALUE | UNIT | ||||
---|---|---|---|---|---|
V(ESD) | Electrostatic discharge | Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins(1) | 2000 | V | |
Charged device model (CDM), per JEDEC specification JESD22-C101, all pins(2) | 500 | ||||
IEC 61000-4-2 contact discharge(3) | 8000 | ||||
IEC 61000-4-2 air-gap discharge(3) | 15000 |
MIN | NOM | MAX | UNIT | ||
---|---|---|---|---|---|
Input voltage range | RTN, VDD | 0 | 57 | V | |
APD to RTN | 0 | 18 | |||
CDB, T2P to RTN | 0 | 57 | |||
Sinking current | RTN | 0.85 | A | ||
CDB, T2P | 2 | mA | |||
Resistance | CLS(1) | 60 | Ω | ||
Junction temperature | –40 | 125 | °C |
THERMAL METRIC(1) | TPS2378 | UNIT | |
---|---|---|---|
SO-8 PowerPad™ | |||
8 PINS | |||
RθJA | Junction-to-ambient thermal resistance | 45.9 | °C/W |
RθJC(top) | Junction-to-case (top) thermal resistance | 51.9 | °C/W |
RθJB | Junction-to-board thermal resistance | 28.8 | °C/W |
ψJT | Junction-to-top characterization parameter | 8.9 | °C/W |
ψJB | Junction-to-board characterization parameter | 28.7 | °C/W |
RθJC(bot) | Junction-to-case (bottom) thermal resistance | 6.7 | °C/W |
PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT | |
---|---|---|---|---|---|---|
DETECTION (DEN) | ||||||
Bias current | DEN open, VVDD = 10.1 V, Measure ISUPPLY(VDD, RTN, DEN), Not in mark | 3 | 4.8 | 12 | µA | |
Detection current | Measure ISUPPLY(VDD, RTN, DEN), VDD = 1.4 V | 53.8 | 56.5 | 58.3 | µA | |
Measure ISUPPLY(VDD, RTN, DEN), VDD = 10.1 V, Not in mark | 395 | 410 | 417 | |||
VPD_DIS | Disable threshold | DEN falling | 3 | 3.7 | 5 | V |
Hysteresis | 50 | 113 | 200 | mV | ||
AUXILIARY POWER DETECTION (APD) | ||||||
VAPDEN | Voltage threshold | VAPD rising, measure to VRTN | 1.4 | 1.5 | 1.6 | V |
VAPDH | Hysteresis, measure to VRTN | 0.27 | 0.3 | 0.33 | ||
Sinking current | V(APD–RTN) = 5 V, measure IAPD | 1 | 1.73 | 3 | µA | |
CLASSIFICATION (CLS) | ||||||
ICLS | Classification current | 13 V ≤ VVDD ≤ 21 V, Measure IVDD + IDEN + IRTN | ||||
RCLS = 1270 Ω | 1.8 | 2.17 | 2.6 | mA | ||
RCLS = 243 Ω | 9.9 | 10.6 | 11.2 | |||
RCLS = 137 Ω | 17.6 | 18.6 | 19.4 | |||
RCLS = 90.9 Ω | 26.5 | 27.9 | 29.3 | |||
RCLS = 63.4 Ω | 38 | 39.9 | 42 | |||
VCL_ON | Class lower threshold | VVDD rising, ICLS ↑ | 11.9 | 12.5 | 13 | V |
VCL_H | Hysteresis | 1.4 | 1.6 | 1.7 | ||
VCU_ON | Class upper threshold | VVDD rising, ICLS↓ | 21 | 22 | 23 | V |
VCU_H | Hysteresis | 0.5 | 0.78 | 0.9 | ||
VMSR | Mark reset threshold | VVDD falling | 3 | 3.9 | 5 | V |
Mark state resistance | 2-point measurement at 5 V and 10.1 V | 6 | 10 | 12 | kΩ | |
Leakage current | VVDD = 57 V, VCLS = 0 V, measure ICLS | 1 | µA | |||
PASS DEVICE (RTN) | ||||||
rDS(on) | On resistance | 0.2 | 0.42 | 0.75 | Ω | |
Input bias current | VVDD = VRTN = 30 V, measure IRTN | 30 | µA | |||
Current limit | VRTN =1.5 V | 0.85 | 1 | 1.2 | A | |
Inrush current limit | VRTN = 2 V, VVDD: 20 V → 48 V | 100 | 140 | 180 | mA | |
Inrush termination | Percentage of inrush current | 80% | 90% | 99% | ||
Foldback threshold | VRTN rising | 11 | 12.3 | 13.6 | V | |
Foldback deglitch time | VRTN rising to when current limit changes to inrush current limit | 500 | 800 | 1500 | µs | |
CONVERTER DISABLE (CDB) | ||||||
Output low voltage | Measure VCDB – VRTN, ICDB = 2 mA, VRTN = 2 V, VDD: 20 V → 48 V |
0.27 | 0.5 | V | ||
Leakage current | VCDB = 57 V, VRTN = 0 V | 10 | μA | |||
TYPE 2 PSE INDICATION (T2P) | ||||||
VT2P | Output low voltage | IT2P = 2 mA, after 2-event classification and inrush is complete, VRTN = 0 V | 0.26 | 0.6 | V | |
Leakage current | VT2P = 57 V, VRTN = 0 V | 10 | µA | |||
UVLO | ||||||
VUVLO_R | UVLO rising threshold | VVDD rising | 36.3 | 38.1 | 40 | V |
UVLO falling threshold | VVDD falling | 30.5 | 32 | 33.6 | ||
VUVLO_H | UVLO hysteresis | 6.1 | V | |||
THERMAL SHUTDOWN | ||||||
Shutdown | TJ↑ | 135 | 145 | °C | ||
Hysteresis (1) | 20 | |||||
BIAS CURRENT | ||||||
Operating current | 40 V ≤ VVDD ≤ 57 V | 285 | 500 | µA |