MAX5942A/MAX5942B
IEEE 802.3af Power-Over-Ethernet
Interface/PWM Controller for Power Devices
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (PWM Controller) (continued)
(All voltages referenced to V-. V
DD
= 13V, a 10µF capacitor connects V
CC
to V-, V
CS
= V-, V+ = 48V, 0.1µF capacitor connected to
SS_SHDN, NDRV = open circuit, V
FB
= 3V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
I
VDD
(
NS
)
V
DD
= 36V, driver not switching 0.9 1.6
V
DD
Supply Current
I
VDD(S)
V
DD
= 36V, driver switching, V
OPTO
= 4V 1.9 3.2
mA
V+ Shutdown Current V
SS_SHDN
= 0V, V+ = 67V
180
290 µA
V
DD
Shutdown Current V
SS_SHDN
= 0V 4 20 µA
PREREGULATORS/STARTUP
V+ Input Voltage 18 67 V
V
DD
Supply Voltage 13 36 V
INTERNAL REGULATORS
Powered from V+, I
CC
= 7.5mA, V
DD
= 0V 7.5 9.8 12
V
CC
Output Voltage
Powered from V
DD
, I
CC
= 7.5mA 9.0
10.0 11.0
V
V
CC
Undervoltage Lockout
V
CC_UVLO
V
CC
falling 6.6 V
OUTPUT DRIVER
Peak Source Current V
CC
= 11V (externally forced)
570
mA
Peak Sink Current V
CC
= 11V (externally forced)
1000
mA
NDRV High-Side Driver
Resistance
R
OH
V
CC
= 11V, externally forced, NDRV
sourcing 50mA
412
NDRV Low-Side Driver
Resistance
R
OL
V
CC
= 11V, externally forced, NDRV sinking
50mA
1.6 4
ERROR AMPLIFIER
FB Input Resistance R
IN
50 k
FB Input Bias Current I
FB
V
FB
= V
SS_SHDN
±1 µA
Error Amplifier Gain (Inverting) A
VCL
-20 V/V
Closed-Loop 3dB Bandwidth
200
kHz
FB Input Voltage Range 23V
SLOPE COMPENSATION
Slope Compensation
V
SCOMP
MAX5942A 26
mV/µs
THERMAL SHUTDOWN
Thermal Shutdown Temperature
+150
°C
Thermal Hysteresis 25 °C
CURRENT LIMIT
CS Threshold Voltage V
ILIM
FB = 4V
419 465
510 mV
CS Input Bias Current 0V V
CS
2V, FB = 4V -1 +1 µA
Current-Limit Comparator
Propagation Delay
25mV overdrive on CS, FB = V-
180
ns
CS Blanking Time
FB = GN D , onl y P W M com p ar ator i s b l anked
70 ns
OSCILLATOR
Clock Frequency Range FB = V-
235 275
314 kHz
MAX5942A, FB = V- 75 85
Max Duty Cycle
MAX5942B, FB = V- 44 50
%
MAX5942A/MAX5942B
IEEE 802.3af Power-Over-Ethernet
Interface/PWM Controller for Power Devices
_______________________________________________________________________________________ 5
I
IN
I
INi
+1
I
INi
I
OFFSET
dR
i
1VV
INi
V
INi
+1
I
OFFSET
I
INi
-
V
INi
dR
i
dR
i
(V
INi + 1
- V
INi
)
=
1V
(I
INi + 1
- I
INi
)
(I
INi + 1
- I
INi
)
Figure 1. Effective Differential Input Resistance/Offset Current
ELECTRICAL CHARACTERISTICS (PWM Controller) (continued)
(All voltages referenced to V-. V
DD
= 13V, a 10µF capacitor connects V
CC
to V-, V
CS
= V-, V+ = 48V, 0.1µF capacitor connected to
SS_SHDN, NDRV = open circuit, V
FB
= 3V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
Note 1: All min/max limits for the PD interface are production tested at +85°C (extended grade)/+70°C (commercial grade). Limits
at +25°C and -40°C are guaranteed by design. All PWM controller min/max limits are 100% production tested at +25°C
and +85°C (extended grade)/+70°C (commercial grade). Limits at -40°C are guaranteed by design, unless otherwise
noted.
Note 2: The input offset current is illustrated in Figure 1.
Note 3: Effective differential input resistance is defined as the differential resistance between GND and V
EE
without any external
resistance.
Note 4: Classification current is turned off whenever the IC is in power mode.
Note 5: See Table 2 in the PD Classification Mode section. R
DISC
and R
CL
must be 100ppm or better.
Note 6: See Thermal Dissipation section for details.
Note 7: When UVLO is connected to the midpoint of an external resistor-divider with a series resistance of 25.5k (±1%), the turn-
on threshold set point for the power mode is defined by the external resistor-divider. Make sure the voltage on the UVLO
pin does not exceed its maximum rating of 8V when V
IN
is at the maximum voltage.
Note 8: When the V
UVLO
is below V
TH, G, UVLO,
the MAX5942_ sets the turn-on voltage threshold internally (V
UVLO,ON
).
Note 9: An input voltage or V
UVLO
glitch below their respective thresholds shorter than or equal to t
OFF_DLY
will not cause the
MAX5942A/MAX5942B to exit power-on mode (as long as the input voltage remains above an operable voltage level of 12V).
Note 10: PGOOD references to OUT while PGOOD references to V
EE
.
Note 11: Guaranteed by design.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
SOFT-START
SS Source Current I
SSO
V
SS_SHDN
= V- 2.0 4.5 6.5 µA
SS Sink Current 1mA
Peak Soft-Start Voltage Clamp No external load
2.331 2.420 2.500
V
V
SS_SHDN
falling (Note 11)
0.25 0.37 0.41
Shutdown Threshold
V
SS_SHDN
rising (Note 11)
0.53 0.59 0.65
V
MAX5942A/MAX5942B
IEEE 802.3af Power-Over-Ethernet
Interface/PWM Controller for Power Devices
6 _______________________________________________________________________________________
DETECTION CURRENT vs.
INPUT VOLTAGE
MAX5942A/B toc01
INPUT VOLTAGE (V)
DETECTION CURRENT (mA)
8642
0.10
0.20
0.30
0.40
0.05
0.15
0.25
0.35
0.45
0
010
R
DISC
= 25.5k
GND = V+ = V- = OUT
CLASSIFICATION CURRENT
vs. INPUT VOLTAGE
MAX5942A/B toc02
INPUT VOLTAGE (V)
CLASSIFICATION CURRENT (mA)
252015
5
15
25
35
10
20
30
40
0
10 30
CLASS 0
CLASS 1
CLASS 2
CLASS 3
CLASS 4
EFFECTIVE DIFFERENTIAL INPUT
RESISTANCE vs. INPUT VOLTAGE
MAX5942A/B toc03
INPUT VOLTAGE (V)
EFFECTIVE DIFFERENTIAL INPUT RESISTANCE (M)
15105
0.5
1.5
2.5
1.0
2.0
3.0
3.5
0
0
OFFSET CURRENT
vs. INPUT VOLTAGE
MAX5942A/B toc04
INPUT VOLTAGE (V)
OFFSET CURRENT (µA)
8642910753
-2.0
-1.0
-3.0
-2.5
-1.5
-0.5
0
-3.5
111
NORMALIZED UVLO
vs. TEMPERATURE
MAX5942A/B toc05
TEMPERATURE (
°
C)
NORMALIZED UVLO
603510-15
0.996
1.004
0.992
0.994
1.000
1.008
1.002
0.998
1.006
1.010
0.990
-40 85
UVLO = V
EE
PGOOD OUTPUT LOW VOLTAGE
vs. CURRENT
MAX5942A/B toc06
I
SINK
(mA)
V
PGOOD
(mV)
161248
40
20
80
120
160
60
100
140
180
200
0
020
PGOOD OUTPUT LOW VOLTAGE
vs. CURRENT
MAX5942A/B toc07
I
SINK
(mA)
V
PGOOD
(mV)
161284
50
100
200
300
150
250
350
400
0
020
OUT LEAKAGE CURRENT
vs. TEMPERATURE
MAX5942A/B toc08
INPUT VOLTAGE (V)
OUT LEAKAGE CURRENT (nA)
603510-15
4
8
12
16
20
0
-40 85
V
OUT
= 67V
INRUSH CURRENT CONTROL
(V
IN
= 12V)
MAX5942A/B toc09
V
GATE
5V/div
I
INRUSH
100mA/div
V
OUT
10V/div
P
GOOD
10V/div
1ms/div
Typical Operating Characteristics
(V
IN
= (GND - V
EE
) = 48V, GATE = PGOOD = PGOOD = OUT = OPEN, UVLO = V
EE
, V
DD
= 13V, NDRV floating, T
A
= T
MIN
to T
MAX
.
Typical values are at T
A
= +25°C. All voltages are referenced to V
EE
(for graphs 1–11 in the Typical Operating Characteristics); all
voltages are referenced to V- (for graphs 12–30 in the Typical Operating Characteristics), unless otherwise noted.

MAX5942BCSE+T

Mfr. #:
Manufacturer:
Maxim Integrated
Description:
I/O Controller Interface IC IEEE 802.3af POE Int/PWM Controller
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
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