NCP1081
http://onsemi.com
7
Recommended Operating Conditions
Operating conditions define the limits for functional operation and parametric characteristics of the device. Note that the
functionality of the device outside the operating conditions described in this section is not warranted. Operating outside the
recommended operating conditions for extended periods of time may affect device reliability.
All values concerning the DC−DC controller, VDDH, VDDL, and nCLASS_AT blocks are with respect to ARTN. All others
are with respect to VPORTN
1,2
(unless otherwise noted).
Table 3. OPERATING CONDITIONS
Symbol Parameter Min. Typ. Max. Units Conditions
INPUT SUPPLY
VPORT
Input supply voltage 0 57 V VPORT = VPORTP −
VPORTN
1,2
SIGNATURE DETECTION
Vsignature
Input supply voltage signature detection
range
1.4 9.5 V
Rsignature Signature resistance (Note 4) 23.75 26.25
kW
Offset_current I_VportP + I_Rtn − 1.8 5
mA
VPORTP = RTN = 1.4 V
Sleep_current I_VportP + I_Rtn − 15 25
mA
VPORTP = RTN = 9.5 V
CLASSIFICATION
Vcl
Input supply voltage classification range 13 20.5 V
V_mark Mark event voltage range
(VPORTP falling)
5.4 − 9.7 V
I_mark Current consumption I(VPORTP) +
I(Rdet) in Mark Event range
0.5 − 2.0 mA 5.4 V ≤ VPORT ≤ 9.5 V
dR_mark Input signature during Mark Event (Note 7) − − 12
kW
For information only
Vreset Classification Reset range
(VPORTP falling)
4.3 4.9 5.4 V
Iclass0
Class 0: Rclass 10 kW (Note 6)
0 − 4 mA Iclass0 = I_VportP + I_Rdet
Iclass1
Class 1: Rclass 130 W (Note 6)
9 − 12 mA Iclass1 = I_VportP + I_Rdet
Iclass2
Class 2: Rclass 69.8 W (Note 6)
17 − 20 mA Iclass2 = I_VportP + I_Rdet
Iclass3
Class 3: Rclass 44.2 W (Note 6)
26 − 30 mA Iclass3 = I_VportP + I_Rdet
Iclass4
Class 4: Rclass 30.9 W (Note 6)
36 − 44 mA Iclass4 = I_VportP + I_Rdet
Iclass5
Class 5: Rclass 22.1 W (Notes 5 and 6)
(for proprietary high power applications)
50 − 60 mA Iclass5 = I_VportP + I_Rdet
IDC
class
Internal current consumption during classi-
fication (Note 8)
− 600 −
mA
For information only
CLASSIFICATION INDICATOR
nCLASS_AT_i
nCLASS_AT current source 13 20 27
mA
NCLASS_AT_pd R
DS,ON
of NCLASS_AT pull down
transistor
130
W
For information only
4. Test done according to the IEEE802.3af 2 Point Measurement. The minimum probe voltages measured at the PoE−PD are 1.4 V and 2.4 V,
and the maximum probe voltages are 8.5 V and 9.5 V.
5. This extended classification range can be used with a PSE which also uses this classification range to deliver more current than specified
by IEEE802.3.
6. Measured with an external Rdet of 25.5 kW between VPORTP and VPORTN
1,2
, and for 13 V < VPORT < 20.5 V (with VPORT = VPORTP
– VPORTN
1,2
). Resistors are assumed to have 1% accuracy.
7. Measured with the 2 Point Measurement defined in the IEEE802.3af standard with 5.4 V and 9.5 V the extreme values for V2 and V1.
8. This typical current excludes the current in the Rclass and Rdet external resistors.
