MAX5940CESA+ Maxim Integrated Products, MAX5940CESA+ Datasheet - Page 8

• Manufacturer Part Number: MAX5940CESA+
• Description: IC IEEE 802.3AF PD INTFC 8-SOIC
• Manufacturer: Maxim Integrated Products

Specifications of MAX5940CESA+

• Controller Type: Powered Device Interface Controller (PD)
• Interface: IEEE 802.3af
• Voltage - Supply: 48V
• Current - Supply: 1mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

IEEE 802.3af PD Interface Controller
For Power-Over-Ethernet
To adjust the UVLO threshold (MAX5940B/MAX5940D
only), connect an external resistor-divider from GND to
UVLO and from UVLO to V
to calculate R1 and R2 for a desired UVLO threshold:
where V
resistor-divider replaces the 25.5kΩ PD detection resis-
tor, ensure that the sum of R1 and R2 equals 25.5kΩ
±1%. When using the external resistor-divider, the
MAX5940B/MAX5940D has an external reference volt-
age hysteresis of 20% (typ). When UVLO is pro-
grammed externally, the turn-off threshold is 80% (typ)
of the new UVLO threshold.
Figure 2. Block Diagram
8
_______________________________________________________________________________________
IN,EX
(UVLO)
GATE
GND
is the desired UVLO threshold. Since the
R
( ) MAX5940B.
2
=
R1 = 25.5kΩ - R2
UVLO
25 5
.
R1
R2
R3
k
GND
200mV
EE
Ω
. Use the following equations
x
V
REF UVLO
2.46V
V
REF
IN EX
,
,
V
EE
V
GATE
20%
EN
Q2
Figure 3. Setting Undervoltage Lockout with an External
Resistor-Divider
MAX5940B
MAX5940D
V
IN
= 12V TO 67V
EN
1.2V, REF
5V, REF
R2
CLASSIFICATION
R1
Q1
UVLO
6.8V
MAX5940D
MAX5940B
GND
V
EE
Q4
Q3
OUT
RCLASS
(PGOOD)
PGOOD