Typical operating characteristics – Rainbow Electronics MAX5940B User Manual
Page 4
MAX5940A/MAX5940B
IEEE 802.3af PD Interface Controller
For Power-Over-Ethernet
4
_______________________________________________________________________________________
I
IN
I
INi + 1
I
INi
I
OFFSET
dR
i
1V
V
INi
V
INi + 1
I
OFFSET
≅ I
INi
-
V
INi
dR
i
dR
i
≅
(V
INi + 1
- V
INi
)
=
1V
(I
INi + 1
- I
INi
)
(I
INi + 1
- I
INi
)
V
IN
Figure1 . Effective Differential Input Resistance/Offset Current
DETECTION CURRENT vs. INPUT VOLTAGE
MAX5940A/B toc01
INPUT VOLTAGE (V)
DETECTION CURRENT (mA)
8
6
4
2
0.1
0.2
0.3
0.4
0.5
0
0
10
R
DISC
= 25.5k
Ω
I
IN
+ I
RDISC
CLASSIFICATION CURRENT vs. INPUT VOLTAGE
MAX5940A/B toc02
INPUT VOLTAGE (V)
CLASSIFICATION CURRENT (mA)
25
20
15
10
5
10
20
30
40
50
0
0
30
CLASS 0
CLASS 1
CLASS 2
CLASS 3
CLASS 4
EFFECTIVE DIFFERENTIAL INPUT
RESISTANCE vs. INPUT VOLTAGE
MAX5940A/B toc03
INPUT VOLTAGE (V)
EFFECTIVE DIFFERENTIAL INPUT RESISTANCE (M
Ω
)
10
8
6
4
2
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
0
12
INPUT OFFSET CURRENT
vs. INPUT VOLTAGE
MAX5940A/B toc04
INPUT VOLTAGE (V)
INPUT OFFSET CURRENT (
µ
A)
9
7
5
3
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0
-3.5
1
11
NORMALIZED UVLO
vs. TEMPERATURE
MAX5940A/B toc05
TEMPERATURE (
°C)
NORMALIZED UVLO
60
35
10
-15
0.992
0.994
0.996
0.998
1.000
1.002
1.004
1.006
1.008
1.010
0.990
-40
85
UVLO = V
EE
PGOOD OUTPUT LOW VOLTAGE
vs. CURRENT
MAX5940A/B toc06
I
SINK
(mA)
V
PGOOD
(mV)
15
10
5
50
100
150
200
250
0
0
20
Typical Operating Characteristics
(V
IN
= (GND - V
EE
) = 48V, GATE = PGOOD = PGOOD = OUT = OPEN, UVLO = V
EE
(MAX5940B), T
A
= -40°C to +85°C. Typical values
are at T
A
= +25°C. All voltages are referenced to V
EE
, unless otherwise noted.)