The MAX5927/MAX5929 +1V to +13.2V quad hot-swap
controllers provide complete protection for multisupply
systems. They allow the safe insertion and removal of circuit
cards into live backplanes. These devices hot swap
multiple supplies ranging from +1V to +13.2V, provided
one supply is at or above +2.7V and only one supply is
above +11.0V. The input voltage rails (channels) can be
configured to sequentially turn-on/off, track each other,
or have completely independent operation.
The discharged filter capacitors of the circuit card provide
low impedance to the live backplane. High inrush
currents from the backplane to the circuit card can burn
up connectors and components, or momentarily collapse
the backplane power supply leading to a system reset.
The MAX5927/MAX5929 hot-swap controllers prevent
such problems by gradually ramping up the output voltage
and regulating the current to a preset limit when the
board is plugged in, allowing the system to stabilize
safely. After the startup cycle is complete, on-chip comparators
provide VariableSpeed/BiLevel™ protection
against short-circuit and overcurrent faults, and provide
immunity against system noise and load transients. The
load is disconnected in the event of a fault condition. The
MAX5929A automatically restarts after a fault condition,
while the MAX5929L must be unlatched. The MAX5927
fault management mode is selectable.
The MAX5927/MAX5929 offer a variety of options to
reduce external component count and design time. All
devices integrate an on-board charge pump to drive
the gates of low-cost external N-channel MOSFETs, an
adjustable startup timer, and an adjustable current limit.
The devices offer integrated features like startup current
regulation and current glitch protection to eliminate
external timing resistors and capacitors. The
MAX5929_L provides an open-drain active-low status
output for each channel, the MAX5929_H provides an
open-drain active-high status output for each channel,
and the MAX5927 status output polarity is selectable.
The MAX5927 is available in a 32-pin thin QFN package
and the MAX5929 is available in a 24-pin QSOP package.
All devices are specified over the extended temperature
range, -40°C to +85°C.
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