Datasheet

5Maxim Integrated
MAX5988A/MAX5988B
IEEE 802.3af-Compliant, High-Efficiency, Class 1/Class 2,
Powered Devices with Integrated DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= 48V, R
SIG
= 24.9kω, LED, V
CC
, SL, ULP, WK, RESET, LDO_OUT unconnected, WAD = LDO_EN = LDO_IN = PGND = GND,
C1 = 68nF, C2 = 10µF, C3 = 1µF (see Figure 3), V
FB
= V
AUX
= 0V, LX unconnected, CLASS2 = 0V, MPS = 0V. All voltages are refer-
enced to GND, unless otherwise noted. T
A
= T
J
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 3)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
LDO FB Leakage Current -1 +1 µA
Dropout V
DROPOUT
V
LDO_IN
= 5V, V
LDO_FB
= V
DRV
,
I
LOAD
= 80mA
300 mV
Load Regulation I
LOAD
from 1mA to 80mA 0.5 mV/mA
Line Regulation VLDO_IN from 4.5V to 14V 1.4 mV/V
Overcurrent Protection
Threshold
I
OVC
85 mA
LDO_FB Rising Threshold 3.3 3.7 V
LDO_FB Hysteresis 2.3 2.4 V
DC-DC CONVERTER INPUT SUPPLY
V
DD
Voltage Range
V
DD,RISING
V
CC
= V
DD
= V
WAD
- 0.3V, rising 8 60
V
V
DD,FALLING
V
CC
= V
DD
= V
WAD
- 0.3V, falling 7.7 60
WAD Detection Rising Threshold V
WAD,RISE
(Note 7) 8.8 V
WAD Detection Falling Threshold V
WAD,FALL
(Note 7) 5.8 V
WAD Detection Hysteresis 0.6 V
POWER MOSFETs
High-Side pMOS On-Resistance R
DSON-H
I
LX
= 0.5A (sourcing) 0.54 ω
Low-Side nMOS On-Resistance R
DSON-L
I
LX
= 0.5A (sinking) 0.14 ω
LX Leakage Current I
LX-LKG
V
DD
= V
CC
= 28V, V
LX
= (V
PGND
+ 1V) to (V
CC
- 1V)
-5 +5 µA
SOFT-START (SS)
Soft-Start Time t
SS-TH
10 ms
FEEDBACK (FB)
FB Regulation Voltage V
FB-RG
1.203 1.226 1.252 V
FB Input Bias Current I
FB
V
FB
= 1.224V 10 200 nA
OUTPUT VOLTAGE
Output Voltage Range V
OUT
MAX5988A 3.0 5.6
V
MAX5988B 5.4 14
Cycle-by-Cycle Overvoltage
Protection
V
OUT-OV
Rising (Note 8) 100.5 103 108
%
Falling (Note 8) 98.5 101.1 104