19-3813; Rev 0; 9/05
Low-Voltage, Dual Hot-Swap
Controllers with Independent On/Off Control
/MAX956
General Description
Features
o Safe Hot Swap for +1V to +13.2V Power Supplies
The MAX5955 and MAX5956 are +1V to +13.2V dual
hot-swap controllers with independent on/off control for
complete protection of dual-supply systems. They allow
the safe insertion and removal of circuit cards into live
backplanes. The MAX5955 and MAX5956 operate
down to 1V provided one of the inputs is above 2.7V.
with V
or V
≥ 2.7V
IN1
IN2
o Independent On/Off Control for Each Channel
o Internal Charge Pumps Generate n-Channel
MOSFET Gate Drives
o Inrush Current Regulated at Startup
o Circuit-Breaker Function
The discharged filter capacitors of the circuit card pro-
vide 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 MAX5955 and MAX5956 hot-swap controllers pre-
vent 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 completed, two on-chip
comparators provide VariableSpeed/BiLevel™ protection
against short-circuit and overcurrent faults, as well as
immunity against system noise and load transients. In the
event of a fault condition, the load is disconnected. The
MAX5955B and MAX5956B must be unlatched after a
fault, and the MAX5955A and MAX5956A automatically
restart after a fault.
o Adjustable Circuit Breaker/Current-Limit
Threshold from 25mV to 100mV
o VariableSpeed/BiLevel Circuit Breaker Response
o Autoretry or Latched Fault Management
o Status Outputs Indicate Fault/Safe Condition
o Output Undervoltage and Overvoltage Monitoring
or Protection
Ordering Information
PART
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
0°C to +85°C
0°C to +85°C
-40°C to +85°C
-40°C to +85°C
0°C to +85°C
0°C to +85°C
PIN-PACKAGE
16 QSOP
16 QSOP
16 QSOP
16 QSOP
16 QSOP
16 QSOP
16 QSOP
16 QSOP
MAX5955AEEE
MAX5955AEEE+
MAX5955AUEE
MAX5955AUEE+
MAX5955BEEE
MAX5955BEEE+
MAX5955BUEE
MAX5955BUEE+
The MAX5955 and MAX5956 integrate an on-board
charge pump to drive the gates of low-cost, external n-
channel MOSFETs. The devices offer integrated fea-
tures like startup current regulation and current glitch
protection to eliminate external timing resistors and
capacitors. These devices provide open-drain status
outputs, an adjustable startup timer, and adjustable
current limits. The MAX5955 provides output undervolt-
age/overvoltage protection for each channel, while the
MAX5956 provides undervoltage/overvoltage monitor-
ing for each channel.
+Denotes lead-free package.
Ordering Information continued at end of data sheet.
Selector Guide and Typical Operating Circuit appear at end
of data sheet.
The MAX5955 and MAX5956 are available in a space-
saving 16-pin QSOP package.
Pin Configuration
TOP VIEW
Applications
Power-Supply Sequencing
PGOOD1
TIM
1
2
3
4
5
6
7
8
16 PGOOD2
15 ON2
Base Station Line Cards
IN1
14 IN2
Network Switches,
Routers, Hubs
Hot Plug-In Daughter
Cards
SENSE1
GATE1
GND
MAX5955
MAX5956
13 SENSE2
12 GATE2
11 ON1
Solid-State Circuit
Breakers
Portable Computer Device
Bays (Docking Stations)
RAID
LIM1
10 LIM2
MON1
9
MON2
Variable Speed/BiLevel is a trademark of Maxim Integrated
Products, Inc.
QSOP
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.