MAX5920 Datasheet, PDF (8/18 Pages) Maxim Integrated Products – -48V Hot-Swap Controller with External RSENSE

-48V Hot-Swap Controller
with External R_SENSE
Pin Description
PIN
MAX5920A MAX5920B
1
—
NAME
PWRGD
FUNCTION
Power-Good Signal Output. PWRGD is an active-low open-drain status output referenced
to V_EE. PWRGD is latched low when V_DRAIN - V_EE ≤ V_DL and V_GATE > (∆V_GATE - V_GH),
indicating a power-good condition. PWRGD is open drain otherwise.
Power-Good Signal Output. PWRGD is an active-high open-drain status output referenced
—
1
PWRGD
to DRAIN. PWRGD latches in a high-impedance state when V_DRAIN - V_EE ≤ V_DL and
V_GATE > (∆V_GATE - V_GH), indicating a power-good condition. PWRGD is pulled low to
DRAIN otherwise.
Input Pin for Overvoltage Detection. OV is referenced to V_EE. When OV is pulled above
2
2
OV
V_OVH voltage, the GATE pin is immediately pulled low. The GATE pin remains low until the
OV pin voltage reduces to V_OVL.
Input Pin for Undervoltage Detection. UV is referenced to V_EE. When UV is pulled above
V_UVH voltage, the GATE is enabled. When UV is pulled below V_UVL, GATE is pulled low.
3
3
UV
UV is also used to reset the circuit breaker after a fault condition. To reset the circuit
breaker, pull UV below V_UVL. The reset command can be issued immediately after a fault
condition; however, the device does not restart until a t_OFF delay time has elapsed after
the fault.
4
4
V_EE
Device Negative Power-Supply Input. Connect to the negative power-supply rail.
Current-Sense Voltage Input. Connect to an external sense resistor and the external
5
5
SENSE ^{MOSFET source. The voltage drop across the external sense resistor is monitored to detect}
overcurrent or short-circuit fault conditions. Connect SENSE to V_EE to disable the current-
limiting feature.
6
6
GATE Gate Drive Output. Connect to gate of the external N-channel MOSFET.
Output-Voltage Sense Input. Connect to the output-voltage node (drain of external
7
7
DRAIN N-channel MOSFET). Place the MAX5920_ so the DRAIN pin is close to the DRAIN of the
external MOSFET for the best thermal protection.
8
8
V_DD
Positive Power-Supply Rail Input. This is the power ground in the negative-supply voltage
system. Connect to the higher potential of the power-supply inputs.
Detailed Description
The MAX5920A/MAX5920B are integrated hot-swap
controllers for -48V power systems. They allow circuit
boards to be safely hot plugged into a live backplane
without causing a glitch on the power-supply rail. When
circuit boards are inserted into a live backplane, the
bypass capacitors at the input of the board’s power
module or switching power supply can draw large
inrush currents as they charge. The inrush currents can
cause glitches on the system power-supply rail and
damage components on the board.
The MAX5920A/MAX5920B provide a controlled turn-on
to circuit cards preventing glitches on the power-supply
rail and damage to board connectors and components.
Both the MAX5920A and MAX5920B provide undervolt-
age, overvoltage, and overcurrent protection. The
MAX5920A/MAX5920B ensure the input voltage is sta-
ble and within tolerance before applying power to the
load. The devices also provide protection against input
voltage steps. During an input voltage step, the
MAX5920A/MAX5920B limit the current drawn by the
load to a safe level without turning off power to the load.
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