Datasheet

TPS2378
V
DD
DE N
CLS
1
2
3
4
APD
T2P
CDB
RTN
8
7
6
5
PowerPad™
V
SS
TPS2378
SLVSB99B –MARCH 2012–REVISED NOVEMBER 2013 www.ti.com
ELECTRICAL CHARACTERISTICS (continued)
40 V ≤ V
VDD
≤ 57 V, R
DEN
= 24.9 kΩ, V
CDB
, V
CLS
, and V
T2P
open; V
APD
= V
RTN
; –40°C ≤ T
J
≤ 125°C. Positive currents are into
pins. Typical values are at 25°C. All voltages are with respect to V
VSS
unless otherwise noted.
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
RTN
rising to when current limit changes to inrush current
Foldback deglitch time 500 800 1500 µs
limit
CONVERTER DISABLE (CDB)
Measure V
CDB
– V
RTN
, I
CDB
= 2 mA,
Output low voltage 0.27 0.50 V
V
RTN
= 2 V, V
DD
: 20 V → 48 V
Leakage current V
CDB
= 57 V, V
RTN
= 0 V 10 μA
TYPE 2 PSE INDICATION (T2P)
I
T2P
= 2 mA, after 2-event classification and inrush is
V
T2P
Output low voltage 0.26 0.60 V
complete, V
RTN
= 0 V
Leakage current V
T2P
= 57 V, V
RTN
= 0 V 10 µA
UVLO
UVLO rising threshold V
VDD
rising 36.3 38.1 40.0
V
UVLO_R
V
UVLO falling threshold V
VDD
falling 30.5 32.0 33.6
V
UVLO_H
UVLO hysteresis 6.1 V
THERMAL SHUTDOWN
Shutdown T
J
↑ 135 145
°C
Hysteresis
(1)
20
BIAS CURRENT
Operating current 40 V ≤ V
VDD
≤ 57 V 285 500 µA
(1) Parameters provided for reference only, and do not constitute part of TI published specifications for purposes of TI product warranty.
PIN FUNCTIONS
NAME NO. I/O DESCRIPTION
V
DD
1 I Connect to positive PoE input power rail. Bypass with 0.1 µF to V
SS
.
DEN 2 I/O Connect 24.9 kΩ to V
DD
for detection. Pull to V
SS
disable pass MOSFET.
CLS 3 O Connect resistor from CLS to V
SS
to program classification current.
V
SS
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 V
SS
. A large fill area is required to assist in heat dissipation.
4 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated
Product Folder Links: TPS2378