max5969a Maxim Integrated Products, Inc., max5969a Datasheet - Page 11

• Manufacturer Part Number: max5969a
• Description: Ieee 802.3af/at-compliant, Powered Device Interface Controllers With Integrated Power Mosfet
• Manufacturer: Maxim Integrated Products, Inc.

When the MAX5969A/MAX5969B are powered by a Type 2
PSE, the 2-event identification output 2EC asserts low
after the internal isolation n-channel MOSFET is fully
turned on. 2EC current sink is turned off when V
below the UVLO threshold (V
V
goes below V
PSE detection flag.
Alternatively, the 2EC output also serves as a wall adapt-
er detection output when the MAX5969A/MAX5969B are
powered by an external wall power adapter. See the Wall
Power Adapter Detection and Operation section for more
information.
The MAX5969A/MAX5969B enter power mode when V
rises above the undervoltage lockout threshold (V
When V
turn on the internal n-channel isolation MOSFET to con-
nect V
to 135mA (typ). The isolation MOSFET is fully turned on
when the voltage at RTN is near V
rent is reduced below the inrush limit. Once the isolation
MOSFET is fully turned on, the MAX5969A/MAX5969B
change the current limit to 800mA. The open-drain
power-good output (PG) remains low for a minimum of
t
downstream DC-DC converter disabled during inrush.
The MAX5969A/MAX5969B operate up to a 60V sup-
ply voltage with a turn-on UVLO threshold (V
35.4V/38.6V and a turn-off UVLO threshold (V
When the input voltage is above V
MAX5969B enter power mode and the internal MOSFET
is turned on. When the input voltage goes below V
more than t
DELAY
IEEE 802.3af/at-Compliant, Powered Device Interface
DD
goes above the UVLO threshold (V
SS
until the power MOSFET fully turns on to keep the
IN
to RTN with inrush current limit internally set
rises above V
OFF_DLY
THR
______________________________________________________________________________________
to reset the latched output of the Type 2
, the MOSFET turns off.
Controllers with
ON
, the MAX5969A/MAX5969B
Undervoltage Lockout
Power Mode (Wake Mode)
OFF
SS
) and turns on when
ON
and the inrush cur-
, the MAX5969A/
ON
), unless V
OFF
DD
) at 31V.
ON
OFF
goes
ON
) at
DD
for
IN
).
Integrated Power MOSFET
An open-drain output (PG) is used to allow disabling
downstream DC-DC converter until the n-channel isola-
tion MOSFET is fully turned on. PG is pulled low to V
for a period of t
MOSFET is fully turned on. The PG is also pulled low
when coming out of thermal shutdown.
The MAX5969A/MAX5969B include thermal protection
from excessive heating. If the junction temperature
exceeds the thermal-shutdown threshold of +140NC,
the MAX5969A/MAX5969B turn off the internal power
MOSFET and 2EC current sink. When the junction tem-
perature falls below +112NC, the devices enter inrush
mode and then return to power mode. Inrush mode
ensures the downstream DC-DC converter is turned off
as the internal power MOSFET is turned on.
For applications where an auxiliary power source such
as a wall power adapter is used to power the PD,
the MAX5969A/MAX5969B feature wall power adapter
detection. Once the input voltage (V
the mark event threshold, the MAX5969A/MAX5969B
enable wall adapter detection. The wall power adapt-
er is connected from WAD to RTN. The MAX5969A/
MAX5969B detect the wall power adapter when the
voltage from WAD to RTN is greater than 9V. When a
wall power adapter is detected, the internal n-channel
isolation MOSFET turns off, 2EC current sink turns on,
and classification current is disabled if V
sification range.
DELAY
Wall Power Adapter Detection
Thermal-Shutdown Protection
and until the internal isolation
Power-Good Output
DD
and Operation
IN
- V
is in the clas-
SS
) exceeds
11
SS