Rainbow Electronics MAX5953D - Manual (Page 4)

MAX5953A/MAX5953B/MAX5953C/MAX5953D
IEEE 802.3af PD Interface and PWM Controllers
with Integrated Power MOSFETs
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (DC-DC Controller)
(All voltages referenced to GND, unless otherwise noted. V HVIN = +48V, C INBIAS = 1µF, C REGOUT = 2.2µF, R RTCT = 25k Ω, C
RTCT =
100pF, C BST = 0.22µF, V CSS = V CS = 0V, V RAMP = V DCUVLO = 3V, T J = 0°C to +125°C, unless otherwise noted. Typical values are at
T J = +25°C, unless otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Supply Range V HVIN 11 76 V
OSCILLATOR (RTCT)
PWM Frequency f S 250 kHz
Maximum PWM Duty Cycle D MAX 47 %
Maximum RTCT Frequency f RTCTMAX (Note 12) 1 MHz
RTCT Peak Trip Level V TH,RTCT 0.51 x V REGOUT V
RTCT Valley Trip Level V TL,RTCT 1 V
RTCT Input Bias Current I IN,RTCT ±1 µA
RTCT Discharge MOSFET
R
DS(ON)
R DIS,RTCT Sinking 50mA 35 85 Ω
RTCT Discharge Pulse Width 50 ns
LOOK-AHEAD LOGIC (PPWM)
PPWM to Output Propagation
Delay
t PPWM V PPWM rising to V XFRMRL falling 110 ns
PPWM Output High V OH,PPWM Sourcing 2mA 7.0 11.0 V
PPWM Output Low V OL,PPWM Sinking 2mA 0.2 V
PWM COMPARATOR (OPTO, RAMP, RCFF)
Common-Mode Input Range V
CM_PWM
0 5.5 V
Input Offset Voltage 10 mV
Input Bias Current -2 +2 µA
RAMP to XFRMRL Propagation
Delay
t COMPARATOR
From V RAMP (50mV overdrive) rising to
V XFRMRL rising
100 ns
Minimum OPTO Voltage V CSS = 0V, OPTO sinking 2mA 1.47 V
Minimum RCFF Voltage RCFF sinking 2mA 2.18 V
REGOUT LDO (REGOUT)
INBIAS unconnected,
V
HVIN = 11V to 76V
8.3 8.75 9.2
REGOUT Voltage Set Point V REGOUT
V INBIAS = V HVIN = 11V to 76V 9.5 10.6 11.0
V
INBIAS unconnected, V HVIN = 15V,
I REGOUT = 0 to 30mA
0.25
REGOUT Load Regulation
V INBIAS = V HVIN = 15V,
I
REGOUT
= 0 to 30mA
0.25
V
INBIAS unconnected, I REGOUT = 30mA 1.25
REGOUT Dropout Voltage
V INBIAS = V HVIN , I REGOUT = 30mA 1.25
V
REGOUT Undervoltage
Lockout Threshold
REGOUT rising 6.6 7.0 7.4 V
REGOUT Undervoltage
Lockout Threshold Hysteresis
REGOUT falling 0.7 V