19-3813; Rev 0; 9/05
KIT
ATION
EVALU
BLE
AVAILA
Low-Voltage, Dual Hot-Swap
Controllers with Independent On/Off Control
General Description
Features
o
Safe Hot Swap for +1V to +13.2V Power Supplies
with V
IN1
or V
IN2
≥ 2.7V
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
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
MAX5955/MAX5956
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.
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.
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.
The MAX5955 and MAX5956 are available in a space-
saving 16-pin QSOP package.
Ordering Information
PART
MAX5955AEEE
MAX5955AEEE+
MAX5955AUEE
MAX5955AUEE+
MAX5955BEEE
MAX5955BEEE+
MAX5955BUEE
MAX5955BUEE+
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
+Denotes
lead-free package.
Ordering Information continued at end of data sheet.
Selector Guide and Typical Operating Circuit appear at end
of data sheet.
Pin Configuration
TOP VIEW
PGOOD1 1
TIM 2
IN1 3
SENSE1 4
GATE1 5
GND 6
LIM1 7
MON1 8
16 PGOOD2
15 ON2
14 IN2
Applications
Base Station Line Cards
Network Switches,
Routers, Hubs
Solid-State Circuit
Breakers
RAID
Power-Supply Sequencing
Hot Plug-In Daughter
Cards
Portable Computer Device
Bays (Docking Stations)
MAX5955
MAX5956
13 SENSE2
12 GATE2
11 ON1
10 LIM2
9
MON2
Variable Speed/BiLevel is a trademark of Maxim Integrated
Products, Inc.
QSOP
1
________________________________________________________________
Maxim Integrated Products
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.
Low-Voltage, Dual Hot-Swap Controllers with
Independent On/Off Control
MAX5955/MAX5956
ABSOLUTE MAXIMUM RATINGS
IN_ to GND...........................................................................+14V
GATE_ to GND ...........................................-0.3V to (V
IN_
+ 6.2V)
ON_, PGOOD_, TIM to GND.......................-0.3V to the higher of
(V
IN1
+ 0.3V) and (V
IN2
+ 0.3V)
SENSE_, MON_, LIM_ to GND ...................-0.3V to (V
IN_
+ 0.3V)
Current into Any Pin .........................................................±50mA
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C)...........667mW
Operating Temperature Range
MAX59_ _ _U_ _ ...................................................0°C to +85°C
MAX59_ _ _E_ _ ................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
IN_
= +1V to +13.2V provided at least one supply is higher than +2.7V, V
ON1
= V
ON2
= +2.7V, T
A
= T
MIN
to T
MAX
, unless otherwise
noted. Typical values are at V
IN1
= +5V, V
IN2
= +3.3V, and T
A
= +25°C.) (Note 1)
PARAMETER
POWER SUPPLIES
IN_ Input Voltage Range
Supply Current
CURRENT CONTROL
Slow-Comparator Threshold
(V
IN
_ - V
SENSE
_) (Note 2)
Slow-Comparator Response Time
(Note 3)
Fast-Comparator Threshold
(V
IN
_ - V
SENSE
_)
Fast-Comparator Response Time
(V
IN
_ - V
SENSE
_)
SENSE Input Bias Current
MOSFET DRIVER
R
TIM
= 100kΩ
Startup Period (Note 4)
t
START
R
TIM
= 4kΩ (minimum value)
TIM floating
Charging, V
GATE
_ = +5V, V
IN
_ = +10V (Note 5)
Average Gate Current
I
GATE
Discharging, triggered by a fault or when
V
ON_
< 0.875V
V
GATE_
- V
IN
_,
I
GATE_
< 1µA
Low to high
Hysteresis
10mV overdrive
V
IN
_ = 3V to 13.2V
V
IN
_ = 2.7V to 3.0V
4.8
4.1
0.85
6
0.31
4
65
10.8
0.45
9
100
3
5.4
5.0
0.875
25
50
6.0
6.0
0.90
16
0.58
17
130
µA
mA
V
ms
V
SC,TH
LIM = GND
R
LIM
= 300kΩ
t
SCD
V
SU,TH
V
FC,TH
t
FCD
I
B SENSE
1mV overdrive
10mV overdrive
During startup
V
IN
_ - V
SENSE
_; normal operation
10mV overdrive, from overload condition
V
SENSE
_ = V
IN
_
T
A
= +25°C
T
A
= -40°C to +85°C
22.5
20.5
80
100
3
110
2 x V
SC
,
TH
4 x V
SC
,
TH
260
0.03
1
25
27.5
27.5
130
ms
µs
mV
ns
µA
mV
V
IN
I
IN
Other V
IN
≥
+2.7V
I
IN1
+ I
IN2
, V
IN1
= +5V, V
IN2
= +3.3V
1.0
1.2
13.2
2.3
V
mA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Gate-Drive Voltage
ON_ COMPARATOR
ON_ Threshold
ON_ Propagation Delay
V
DRIVE
V
ON_
,
TH
V
mV
µs
2
_______________________________________________________________________________________
Low-Voltage, Dual Hot-Swap Controllers with
Independent On/Off Control
ELECTRICAL CHARACTERISTICS (continued)
(V
IN_
= +1V to +13.2V provided at least one supply is higher than +2.7V, V
ON1
= V
ON2
= +2.7V, T
A
= T
MIN
to T
MAX
, unless otherwise
noted. Typical values are at V
IN1
= +5V, V
IN2
= +3.3V, and T
A
= +25°C.) (Note 1)
PARAMETER
ON_ Input Bias Current
ON_ Pulse-Width Low
DIGITAL OUTPUT (PGOOD_)
Output Leakage Current
Output Voltage Low
PGOOD_ Delay
V
OL
t
PGDLY
V
PGOOD
_ = 13.2V
I
SINK
= 1mA
After t
START
, MON_ = V
IN_
Overvoltage
Undervoltage
V
MON_
= 600mV
Startup is initiated when this threshold is
reached by V
IN1
or V
IN2
, V
ON
_ > 0.875V
Hysteresis
UVLO Glitch Filter Reset Time
UVLO to Startup Delay
SHUTDOWN LATCH/RESTART
Autoretry Delay
t
RETRY
Delay time to restart after fault shutdown
64 x t
START
ms
t
D,UVLO
V
IN_
toggled below UVLO to unlatch after a
fault
V
IN_
step from 0 to 2.8V
100
20
37.5
66
657
513
0.75
687
543
20
0.03
707
563
1
0.4
µA
V
ms
SYMBOL
I
BON
t
UNLATCH
CONDITIONS
V
ON_
< 4.5V
V
IN1
= V
IN2
= +13.2V
V
ON_
> 4.5V
V
ON_
= 4.5V
To unlatch after a latched fault
100
MIN
TYP
0.03
100
0.03
1
µs
µA
MAX
UNITS
MAX5955/MAX5956
OUTPUT VOLTAGE MONITORS (MON1, MON2)
MON_ Trip Threshold
MON_ Glitch Filter
MON_ Input Bias Current
UNDERVOLTAGE LOCKOUT (UVLO)
UVLO Threshold
V
UVLO
2.10
2.4
100
2.67
V
mV
µs
ms
V
MON
mV
µs
µA
Note 1:
All devices are 100% tested at T
A
= +25°C and T
A
= +85°C. Limits at T
A
= 0°C and -40°C are guaranteed by design.
Note 2:
The MAX5955/MAX5956 slow-comparator threshold is adjustable. V
SC,TH
= R
LIM
0.25µA + 25mV (see the
Typical
Operating Characteristics).
Note 3:
The current-limit slow-comparator response time is weighted against the amount of overcurrent; the higher the overcurrent
condition, the faster the response time (see the
Typical Operating Characteristics).
Note 4:
The startup period (t
START
) is the time during which the slow comparator is ignored and the device acts as a current-limiter
by regulating the sense current with the fast comparator (see the
Startup Period
section).
Note 5:
The current available at GATE is a function of V
GATE
(see the
Typical Operating Characteristics).
_______________________________________________________________________________________
3
Low-Voltage, Dual Hot-Swap Controllers with
Independent On/Off Control
MAX5955/MAX5956
Typical Operating Characteristics
(Typical Operating Circuits, Q1 = Q2 = Fairchild FDB7090L, V
IN1
= +5V, V
IN2
= +3.3V, V
ON1
= V
ON2
= +2.7V, T
A
= +25°C, unless
otherwise noted. Channels 1 and 2 are identical in performance. Where characteristics are interchangeable, channels 1 and 2 are
referred to as X and Y.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5955/56 toc01
TOTAL SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5955/56 toc02
SUPPLY CURRENT
vs. TEMPERATURE
1.8
1.6
1.4
C
V
ON1
= V
IN1
V
ON2
= V
IN2
MAX5955/56 toc03
2.0
1.8
1.6
1.4
I
IN
(mA)
1.2
1.0
0.8
0.6
0.4
0.2
0
0
V
INY
= V
ON1
= V
ON2
= 2.7V
2.0
1.8
1.6
1.4
I
IN
(mA)
B
A
2.0
I
IN1
+ I
IN2
I
INX
+ I
INY
I
IN
(mA)
1.2
1.0
0.8
0.6
1.2
1.0
0.8
I
IN1
I
INX
I
INY
0.4
0.2
0
V
INY
= 5.0V
A) V
ON1
= V
ON2
= 3.3V
B) V
ON1
= V
ON2
= 1.5V
C) V
ON1
= V
ON2
= 0
0
2
4
6
8
10
12
14
0.6
0.4
0.2
0
-40
-15
10
35
60
85
I
IN2
2
4
6
8
10
12
14
V
INX
(V)
V
INX
(V)
TEMPERATURE (°C)
GATE-DRIVE VOLTAGE
vs. INPUT VOLTAGE
MAX5955/56 toc04
GATE CHARGE CURRENT
vs. GATE VOLTAGE
MAX5955/56 toc05
GATE CHARGE CURRENT
vs. TEMPERATURE
180
GATE CHARGE CURRENT (µA)
160
140
120
100
80
60
40
20
0
V
INY
= 2.7V
V
GATEX
= 0
-40
-15
10
35
60
85
V
INX
= 1V
V
INX
= 13.2V
V
INX
= 5V
MAX5955/56 toc06
MAX5955/56 toc09
6
5
GATE-DRIVE VOLTAGE (V)
4
3
2
1
V
INY
= 2.7V
0
0
2
4
6
8
10
12
200
180
GATE CHARGE CURRENT (µA)
160
140
120
100
80
60
40
20
0
V
INX
= 13.2V
V
INX
= 5V
V
INX
= 1V
V
INY
= 2.7V
200
14
0
5
10
V
GATEX
(V)
15
20
V
INX
(V)
TEMPERATURE (°C)
GATE STRONG DISCHARGE CURRENT
vs. GATE VOLTAGE
MAX5955/56 toc07
GATE STRONG DISCHARGE CURRENT
vs. TEMPERATURE
MAX5955/56 toc08
TURN-OFF TIME vs. SENSE VOLTAGE
10
SLOW-COMP. THRESHOLD
1
TURN-OFF TIME (ms)
FAST-COMP. THRESHOLD
0.1
6
GATE DISCHARGE CURRENT (mA)
5
4
3
2
1
0
0
5
10
V
GATEX
(V)
15
V
INX
= 1V
V
INY
= 2.7V
V
GATEX
= V
INX
+ 6.2V
V
INX
= 5V
V
INX
= 13.2V
6
GATE DISCHARGE CURRENT (mA)
5
4
3
2
1
0
V
INX
= 5V
V
INX
= 13.2V
V
ON1
= V
ON2
= 0
V
ON1
= V
ON2
= 0
V
INY
= 2.7V
V
GATEX
= V
INX
+ 6.2V
0.01
0.001
V
INX
= 1V
0.0001
-40
-15
10
35
60
85
0
25
50
75
100 125 150 175 200
TEMPERATURE (°C)
V
IN
- V
SENSE
(mV)
20
4
_______________________________________________________________________________________
Low-Voltage, Dual Hot-Swap Controllers with
Independent On/Off Control
Typical Operating Characteristics (continued)
(Typical Operating Circuits, Q1 = Q2 = Fairchild FDB7090L, V
IN1
= +5V, V
IN2
= +3.3V, V
ON1
= V
ON2
= +2.7V, T
A
= +25°C, unless
otherwise noted. Channels 1 and 2 are identical in performance. Where characteristics are interchangeable, channels 1 and 2 are
referred to as X and Y.)
TURN-OFF TIME vs. SENSE VOLTAGE
(EXPANDED SCALE)
MAX5955/56 toc10
MAX5955/MAX5956
SLOW-COMPARATOR THRESHOLD
vs. R
LIM
MAX5955/56 toc11
STARTUP PERIOD vs. R
TIM
MAX5955/56 toc12
10
120
100
80
60
50
40
t
START
(ms)
30
20
10
0
TURN-OFF TIME (ms)
SLOW-COMP. THRESHOLD
1
V
SC,TH
(mV)
60
40
20
0.1
20 25 30 35 40 45 50 55 60 65 70 75 80
V
IN
- V
SENSE
(mV)
0
0
100
200
R
LIM
(kΩ)
300
400
0
100
200
300
R
TIM
(kΩ)
400
500
600
TURN-OFF TIME
SLOW-COMPARATOR FAULT
MAX5955/56 toc13
TURN-OFF TIME
FAST-COMPARATOR FAULT
MAX5955/56 toc14
STARTUP WAVEFORMS
FAST TURN-ON
MAX5955/56 toc15
V
ON
2V/div
0
0
26mV STEP
V
SENSE
- V
IN
100mV/div
V
GATE
5V/div
0
0
400ns/div
V
IN
= 5.0V
1ms/div
V
IN
= 5.0V, R
SENSE
= 10mΩ,
R
TIM
= 27kΩ, C
BOARD
= 1000µF
t
SCD
V
PGOOD
5V/div
0
t
FCD
0
125mV STEP
V
SENSE
- V
IN
100mV/div
V
GATE
5V/div
I
OUT
5A/div
V
OUT
5V/div
V
GATE
5V/div
V
PGOOD
5V/div
V
PGOOD
2V/div
1ms/div
V
IN
= 5.0V
STARTUP WAVEFORMS
SLOW TURN-ON
MAX5955/56 toc16
AUTORETRY DELAY
MAX5955/56 toc17
V
ON
2V/div
V
PGOOD
2V/div
I
OUT
5A/div
V
OUT
5V/div
V
GATE
5V/div
1ms/div
V
IN
= 5.0V, R
SENSE
= 10mΩ, R
TIM
= 47kΩ,
C
BOARD
= 1000µF, C
GATE
= 22nF
40ms/div
V
IN
= 5.0V, R
SENSE
= 10mΩ, R
TIM
= 47kΩ,
C
BOARD
= 1000µF, R
BOARD
= 1.4Ω
V
OUT
5V/div
I
OUT
5A/div
V
GATE
5V/div
_______________________________________________________________________________________
5
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