General Description
The MAX5927A/MAX5929A–MAX5929D +1V to +15V
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
+15V, provided one supply is at or above +2.7V. The
input voltage rails (channels) can be configured to
sequentially turn-on/off, track each other, or have com-
pletely 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 connec-
tors and components, or momentarily collapse the back-
plane power supply leading to a system reset. The
MAX5927A/MAX5929A–MAX5929D 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 MAX5929C/
MAX5929D automatically restart after a fault condition,
while the MAX5929A/MAX5929B must be unlatched. The
MAX5927A fault management mode is selectable.
The MAX5927A/MAX5929A–MAX5929D 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 elimi-
nate external timing resistors and capacitors. The
MAX5929B/MAX5929D provide an open-drain, active-low
status output for each channel, the MAX5929A/
MAX5929C provide an open-drain, active-high status out-
put for each channel, and the MAX5927A status output
polarity is selectable.
The MAX5927A is available in a 32-pin thin QFN package
and the MAX5929A–MAX5929D are available in a 24-pin
QSOP package. All devices are specified over the -40°C
to +85°C extended temperature range.
Applications
Features
o Safe Hot Swap for +1V to +15V Power Supplies
with Any Input Voltage (V
IN_
≥ 2.7V)
o Adjustable Circuit-Breaker/Current-Limit
Threshold from 25mV to 100mV
o Configurable Tracking, Sequencing, or
Independent Operation Modes
o VariableSpeed/BiLevel Circuit-Breaker Response
o Internal Charge Pumps Generate n-Channel
MOSFET Gate Drives
o Inrush Current Regulated at Startup
o Autoretry or Latched Fault Management
o Programmable Undervoltage Lockout
o Status Outputs Indicate Fault/Safe Condition
MAX5927A/MAX5929A–MAX5929D
Low-Voltage, Quad, Hot-Swap
Controllers/Power Sequencers
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Maxim Integrated Products
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