MAX5988BEVKIT# Maxim Integrated, MAX5988BEVKIT# Datasheet - Page 12

• Manufacturer Part Number: MAX5988BEVKIT#
• Description: Power Management IC Development Tools MAX5988B Eval Kit
• Manufacturer: Maxim Integrated

Specifications of MAX5988BEVKIT#

• Rohs: yes

The MAX5988A/MAX5988B include complete interface
functions for a PD to comply with the IEEE 802.3af stan-
dard as a Class 1/Class 2 PD. The devices provide the
detection and classification signatures using a single
external signature resistor. An integrated MOSFET pro-
vides isolation from the buck converter when the PSE has
not applied power. The devices guarantee a leakage cur-
rent offset of less than 10µA during the detection phase.
The devices feature power-mode undervoltage-lockout
(UVLO) with wide hysteresis and long deglitch time to
compensate for twisted-pair-cable resistive drop and to
ensure glitch-free transitions between detection, classifi-
cation, and power-on/-off modes.
The devices operate in three different modes depending
on V
tion mode, and power mode. The device is in detection
mode when V
tion mode when V
power mode when the input voltage exceeds V
In detection mode, the devices provide a signature
differential resistance to V
power-sourcing equipment (PSE) applies two voltages to
V
increment. The PSE computes the differential resistance
to ensure the presence of the 24.9kω signature resis-
tor. Connect the 24.9kω signature resistor (R
RREF to GND for proper signature detection. The device
applies V
V
The DC offset due to protection diodes does not signifi-
cantly affect the signature resistance measurement.
In classification mode, the devices sink Class 1/Class 2
classification currents. The PSE applies a classification
voltage between 12.6V and 20V, and measures the clas-
sification currents. The devices use the external 24.9kω
resistor (R
Maxim Integrated
IEEE 802.3af-Compliant, High-Efficiency, Class 1/Class 2,
DD
DD
, both between 1.4V and 10.1V with a minimum 1V
DD
offset current due to the device is less than 10µA.
Powered Devices with Integrated DC-DC Converter
. The three modes are detection mode, classifica-
DD
SIG
to RREF when in detection mode, and the
) and the CLASS2 pin to set the classifi-
DD
Classification Mode (12.6V < V
is between 1.4V and 10.1V, classifica-
Detection Mode (1.4V < V
DD
is between 12.6V and 20V, and
Detailed Description
DD
. During detection, the
Operating Modes
PD Interface
DD
DD
SIG
ON
< 10.1V)
< 20V)
.
) from
cation current at 10.5mA (Class 1, CLASS1 = GND) or
18mA (Class 2, CLASS2 = VDRV). The PSE uses this to
determine the maximum power to deliver. The classifica-
tion current includes current drawn by the supply current
of the device so the total current drawn by the PD is with-
in the IEEE 802.3af standard. The classification current
is turned off when the device leaves classification mode.
In power mode, the devices have the isolation MOSFET
between V
buck regulator enabled and the LDO enabled. The
devices can be in either wake mode, sleep mode, or
ultra-low-power mode. The buck regulator and LDO are
only enabled in wake mode.
The devices enter power mode when V
the undervoltage lockout threshold (V
rises above V
nel isolation MOSFET to connect V
current limit internally set to 49mA (typ). The isolation
MOSFET is fully turned on when V
inrush current is below the inrush limit. Once the isola-
tion MOSFET is fully turned on, the device changes the
current limit to 321mA (typ). The buck converter turns on
123ms after the isolation MOSFET turns on fully.
The devices operate with up to a 60V supply voltage
with a turn-on UVLO threshold (V
a turn-off UVLO threshold (V
the input voltage is above V
mode and the internal isolation MOSFET is turned on.
When the input voltage is below V
t
The devices drive an LED, or multiple LEDs in series, with
a maximum LED voltage of 6.5V. In sleep mode and ultra-
low-power mode, the LED current is pulse width modu-
lated with a duty cycle of 25% and the amplitude is set by
R
from 10mA to 20mA using R
where R
OFF_DLY
SL
. The LED driver current amplitude is programmable
MAX5988A/MAX5988B
SL
, the MOSFET and the buck converter are off.
DD
is in kω.
ON
and V
, the device turns on the internal p-chan-
I
LED
CC
= 646/R
fully on. The devices have the
ON
Undervoltage Lockout
SL
OFF
Power Mode (V
SL
, the device enters power
according to the formula:
ON
CC
) at 31.5V (typ). When
(mA)
CC
) at 38.8V (typ), and
is near V
OFF
to V
ON
DD
DD
for more than
). When V
LED Driver
rises above
DD
DD
with inrush
and the
> V
ON
DD
12
)