Datasheet
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 Ω
NDRV Low-Side Driver
Resistance
R
OL
V
CC
= 11V, externally forced, NDRV sinking
50mA
1.6 4 Ω
ERROR AMPLIFIER
FB Input Resistance R
IN
50 kΩ
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
%