Datasheet

MAX5986A–MAX5986C/MAX5987A
IEEE 802.3af-Compliant, High-Efficiency, Class 1/
Class 2, PDs with Integrated DC-DC Converter
6Maxim Integrated
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. All voltages are referenced 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
Cycle-by-Cycle Overvoltage
Protection
V
OUT-OV
Rising (Note 7)
100.5 100.3 108
%
Falling (Note 7)
98.5
INTERNAL COMPENSATION NETWORK
Compensation Network Zero-
Resistance
R
ZERO
200 kI
Compensation Network Zero-
Capacitance
C
ZERO
150 pF
CURRENT LIMIT
Peak Current-Limit Threshold
I
PEAK-LIMIT
MAX5986B/
MAX5986C
CLASS2 = GND 0.75 0.81
A
CLASS2 = VDRV
0.85 0.94
MAX5986A/
MAX5987A
CLASS2 = GND
1.45 1.64
CLASS2 = VDRV
1.66 1.79
Runaway Current-Limit Threshold
MAX5986B/
MAX5986C
CLASS2 = GND
0.93
CLASS2 = VDRV
1.07
MAX5986A/
MAX5987A
CLASS2 = GND
1.9
CLASS2 = VDRV
2.2
Valley Current-Limit Threshold
I
VALLEY-
LIMIT
MAX5986A/MAX5987A
1.5
A
MAX5986B/MAX5986C
0.75
ZX Threshold
I
ZX
25 mA
TIMINGS
Switching Frequency
f
SW
MAX5986A/MAX5986B/MAX5987A
190 215 238
kHz
MAX5986C
380 430 475
Frequency Foldback
f
SW-FOLD
MAX5986A/MAX5986B/MAX5987A
95 107.5 119
kHz
MAX5986C
195 215 238
Consecutive ZX Events for Entering
Foldback
8 Events
Consecutive ZX Events for Exiting
Foldback
8 Events
V
OUT
Undervoltage Trip Level to
Cause HICCUP
V
OUT-HICF
After soft-start completed (Note 7)
55 60 65 %
HICCUP Timeout
MAX5986A/MAX5986B/MAX5987A 154
ms
MAX5986C 77
Minimum On-Time
t
ON-MIN
113 140 ns
LX Dead Time 14 ns