General Description
The MAX5904–MAX5909 dual hot-swap controllers
provide complete protection for dual-supply systems.
These devices hot swap two supplies ranging from +1V
to +13.2V, provided one supply is at or above 2.7V,
allowing the safe insertion and removal of circuit cards
into live backplanes.
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 col-
lapse the backplane power supply leading to a system
reset. The MAX5904 family of hot-swap controllers pre-
vents 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™ protec-
tion 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 MAX5905/MAX5907/MAX5909 must be unlatched
after a fault, and the MAX5904/MAX5906/MAX5908 auto-
matically restart after a fault.
The MAX5904 family offers a variety of options to reduce
component count and design time. All devices integrate
an on-board charge pump to drive the gates of low-cost,
external n-channel MOSFETs. The devices offer integrat-
ed features like startup current regulation and current
glitch protection to eliminate external timing resistors and
capacitors. The MAX5906–MAX5909 provide an open-
drain status output, an adjustable startup timer, an
adjustable current limit, an uncommitted comparator,
and output undervoltage/overvoltage monitoring.
The MAX5904/MAX5905 are available in 8-pin SO pack-
ages. The MAX5906–MAX5909 are available in space-
saving 16-pin QSOP packages.
Applications
PCI-Express®Applications
Basestation Line Cards
Network Switches or Routers
Solid-State Circuit Breaker
Power-Supply Sequencing
Hot Plug-In Daughter Cards
RAID
Features
♦Safe Hot-Swap for +1V to +13.2V Power
Supplies
Requires One Input ≥2.7V
♦Low 25mV Default Current-Limit Threshold
♦Inrush Current Regulated at Startup
♦Circuit Breaker Function
♦Adjustable Circuit Breaker/Current-Limit
Threshold
♦VariableSpeed/BiLevel Circuit-Breaker Response
♦Autoretry or Latched Fault Management
♦On/Off Sequence Programming
♦Status Output Indicates Fault/Safe Condition
♦Output Undervoltage and Overvoltage Monitoring
and/or Protection
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
________________________________________________________________ Maxim Integrated Products 1
GATE2
ONGND
1
2
8
7
IN2
SENSE2SENSE1
GATE1
IN1
NARROW SO
TOP VIEW
3
4
6
5
MAX5904
MAX5905
Pin Configurations
Ordering Information
19-2238; Rev 3; 9/05
EVALUATION KIT
AVAILABLE
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.
PART TEMP RANGE PIN-
PACKAGE
PKG
CODE
MAX5904ESA*
-40°C to +85°C8 SO S8-4
MAX5904USA 0°C to +85°C8 SO S8-4
MAX5905ESA*
-40°C to +85°C8 SO S8-4
MAX5905USA 0°C to +85°C8 SO S8-4
MAX5906EEE*
-40°C to +85°C16 QSOP
E16-1
MAX5906UEE 0°C to +85°C16 QSOP
E16-1
MAX5907EEE*
-40°C to +85°C16 QSOP
E16-1
MAX5907UEE 0°C to +85°C16 QSOP
E16-1
MAX5908EEE*
-40°C to +85°C16 QSOP
E16-1
MAX5908UEE 0°C to +85°C16 QSOP
E16-1
MAX5909EEE*
-40°C to +85°C16 QSOP
E16-1
MAX5909UEE 0°C to +85°C16 QSOP
E16-1
Selector Guide and Typical Operating Circuits appear at end
of data sheet.
VariableSpeed/BiLevel is a trademark of Maxim Integrated
Products, Inc.
PCI-Express is a registered trademark of PCI-SIG Corp.
Pin Configurations continued at end of data sheet.
*Contact factory for availability.
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
2_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN_ = +1V to +13.2V provided at least one supply is higher than +2.7V, VON = +2.7V, TA= 0°C to +85°C, unless otherwise noted.
Typical values are at VIN1 = +5V, VIN2 = +3.3V, and TA= +25°C.) (Note 1)
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.
IN_ to GND...........................................................................+14V
GATE_ to GND..........................................+0.3V to (VIN_ + 6.2V)
ON, PGOOD, COMP+, COMPOUT, TIM
to GND.....-0.3V to the higher of (VIN1 + 0.3V) and (VIN2 + 0.3V)
SENSE_, MON_, LIM_ to GND...................-0.3V to (VIN_ + 0.3V)
Current into Any Pin .........................................................±50mA
Continuous Power Dissipation (TA= +70°C)
8-Pin Narrow SO (derate 5.9mW/°C above +70°C) ......471mW
16-Pin QSOP (derate 8.3mW/°C above +70°C)............667mW
Operating Temperature Ranges:
MAX590_U_ _ .....................................................0°C to +85°C
MAX590_E_ _ ...................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
POWER SUPPLIES
IN_ Input Voltage Range (Note 2)
VIN_Other VIN = +2.7V 1.0
13.2
V
Supply Current IIN IIN1 + IIN2 1.2 2.9 mA
CURRENT CONTROL
TA = +25°C
22.5
25
27.5
MAX5904/MAX5905 TA = 0°C to +85°C
20.5 27.5
LIM = GND
22.5
25
27.5
Slow-Comparator Threshold
(VIN - VSENSE) (Note 3)
VSC
,
TH
MAX5906–MAX5909
RLIM = 300kΩ80
100 125
mV
1mV overdrive 3 ms
Slow-Comparator Response Time
(Note 4) tSCD 50mV overdrive 110 µs
VSU
,
TH
VIN_ - VSENSE_; during startup 2 x VSC, TH
Fast-Comparator Threshold
VFC
,
TH
VIN_ - VSENSE_; normal operation 4 x VSC, TH
mV
Fast-Comparator Response Time
tFCD 10mV overdrive, from overload condition 260 ns
SENSE Input Bias Current
IB SEN
VSEN_ = VIN_0.03 6 µA
MOSFET DRIVER
RTIM = 100kΩ7.1 10.8
15.5
RTIM = 4kΩ (minimum value)
0.31 0.45 0.58
Startup Period
(Note 5)
tSTART
TIM floating for MAX5906–MAX5909
fixed for MAX5904/MAX5905 3.9 9
16.0
ms
Charging, VGATE = +5V, VIN = +10V
(Note 5) 80 100
130
µA
Weak discharge, during startup when current
limit is active or when 0.4V < VON < 0.8V 100 µA
Average Gate Current IGATE
Strong discharge, triggered by a fault or
when VON < 0.4V 3mA
VGATE_ - VIN_, IGATE_ < 1µA, VIN ≥ 3V
4.8
5.4 5.8
Gate-Drive Voltage
VDRIVE VGATE_ - VIN_, IGATE_ < 1µA, 2.7V ≤ VIN ≤ 3V 4.2
5.3 5.8 V
ON COMPARATOR
Low to high
0.375
0.4
0.425
V
Fast Pulldown ON Threshold
VONFP
,
TH
Hysteresis 25 mV
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VIN_ = +1V to +13.2V provided at least one supply is higher than +2.7V, VON = +2.7V, TA= 0°C to +85°C, unless otherwise noted.
Typical values are at VIN1 = +5V, VIN2 = +3.3V, and TA= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Low to high 0.80
0.825 0.85
V
Channel 1 ON Threshold
VON1
,
TH
Hysteresis 25 mV
Low to high
1.95 2.025 2.07
V
Channel 2 ON Threshold
VON2
,
TH
Hysteresis 25 mV
ON Propagation Delay tON 10mV overdrive 50 µs
VON < 4.5V 0.03
VON > 4.5V 100
ON Input Bias Current IBON
VIN1 = VIN2 = +13.2V
VON = 4V 0.03 1
µA
ON Pulse-Width Low
tUNLATCH
To unlatch after a latched fault 100 µs
DIGITAL OUTPUT (PGOOD)
Output Leakage Current VPGOOD = 13.2V 1 µA
Output-Voltage Low VOL ISINK = 1mA 0.4 V
PGOOD Delay
tPGDLY
After tSTART, MON_ = VIN_ 0.75 ms
OUTPUT VOLTAGE MONITORS (MON1, MON2)
Overvoltage 655 687
710
MON_ Trip Threshold
VMON_
Undervoltage 513 543
567
mV
MON_ Glitch Filter 20 µs
MON_ Input Bias Current VMON_ = 600mV 0.03 µA
UNDERVOLTAGE LOCKOUT (UVLO)
S tar tup i s i ni ti ated w hen thi s thr eshol d i s r eached
b y V
IN 1
or V
IN 2
, V
ON
> 0.8V , V
IN_ i ncr easi ng 2.1 2.4
2.67
V
UVLO Threshold
VUVLO
Hysteresis 100 mV
UVLO Glitch Filter Reset Time VIN_ = 0V, to unlatch after a fault 100 µs
UVLO to Startup Delay
tD
,
UVLO
VIN_ step from 0 to 2.8V 18 37.5 64 ms
SHUTDOWN RESTART
Autoretry Delay
tRETRY
Delay time to restart after a fault shutdown
MAX5904/MAX5906/MAX5908 64 x tSTART ms
UNCOMMITTED COMPARATOR
Low to high
1.206
1.25
1.290
V
INC+ Trip Threshold Voltage VC,TH Hysteresis 10 mV
Propagation Delay 10mV overdrive 50 µs
OUTC Voltage Low VOL ISINK = 1mA 0.4 V
INC+ Bias Current VINC+ = 5V 0.02 1 µA
OUTC Leakage Current
IOUTC
VOUTC = 13.2V 0.02 1 µA
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
4_______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS
(VIN_ = +1V to +13.2V provided at least one supply is higher than +2.7V, VON = +2.7V, TA= -40°C to +85°C, unless otherwise noted.
Typical values are at VIN1 = +5V, VIN2 = +3.3V, and TA= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
POWER SUPPLIES
IN_ Input Voltage Range (Note 2)
VIN_Other VIN = +2.7V 1.0
13.2
V
Supply Current IIN IIN1 + IIN2 1.2 2.9 mA
CURRENT CONTROL
TA = +25°C
22.5
25
27.5
MAX5904/MAX5905
TA = -40°C to +85°C 20.5 27.5
LIM = GND
22.5
25
27.5
Slow-Comparator Threshold
(VIN - VSENSE) (Note 3)
VSC
,
TH
MAX5906–MAX5909
RLIM = 300kΩ80
100 125
mV
1mV overdrive 3 ms
Slow-Comparator Response Time
(Note 4) tSCD 50mV overdrive 110 µs
VSU
,
TH
VIN_ - VSENSE_; during startup 2 x VSC, TH
Fast-Comparator Threshold
VFC
,
TH
VIN_ - VSENSE_; normal operation 4 x VSC, TH
mV
Fast-Comparator Response Time
tFCD 10mV overdrive, from overload condition 260 ns
SENSE Input Bias Current
IB SEN
VSEN_ = VIN_0.03 6 µA
MOSFET DRIVER
RTIM = 100kΩ7.1 10.8
15.5
RTIM = 4kΩ (minimum value)
0.31 0.45 0.58
Startup Period
(Note 5)
tSTART
TIM floating for MAX5906–MAX5909
fixed for MAX5904/MAX5905 3.9 9
16.0
ms
Charging, VGATE = +5V, VIN = +10V
(Note 5) 80 100
130
µA
Weak discharge, during startup when current
limit is active or when 0.4V < VON < 0.8V 100 µA
Average Gate Current IGATE
Strong discharge, triggered by a fault or
when VON < 0.4V 3mA
VGATE_ - VIN_, IGATE_ < 1µA, VIN ≥ 3V
4.8
5.4 5.8
Gate-Drive Voltage
VDRIVE VGATE_ - VIN_, IGATE_ < 1µA, 2.7V ≤ VIN ≤ 3V 3.6
5.8 V
ON COMPARATOR
Low to high
0.375
0.4
0.425
V
Fast Pulldown ON Threshold
VONFP
,
TH
Hysteresis 25 mV
Low to high 0.79
0.825 0.85
V
Channel 1 ON Threshold
VON1
,
TH
Hysteresis 25 mV
Low to high
1.93 2.025 2.07
V
Channel 2 ON Threshold
VON2
,
TH
Hysteresis 25 mV
ON Propagation Delay tON 10mV overdrive 50 µs
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS (continued)
(VIN_ = +1V to +13.2V provided at least one supply is higher than +2.7V, VON = +2.7V, TA= -40°C to +85°C, unless otherwise noted.
Typical values are at VIN1 = +5V, VIN2 = +3.3V, and TA= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
VON < 4.5V 0.03
VON > 4.5V 100
ON Input Bias Current IBON
VIN1 = VIN2 = +13.2V
VON = 4V 0.03 1
µA
ON Pulse-Width Low
tUNLATCH
To unlatch after a latched fault 100 µs
DIGITAL OUTPUT (PGOOD)
Output Leakage Current VPGOOD = 13.2V 1 µA
Output-Voltage Low VOL ISINK = 1mA 0.4 V
PGOOD Delay
tPGDLY
After tSTART, MON_ = VIN_ 0.75 ms
OUTPUT VOLTAGE MONITORS (MON1, MON2)
Overvoltage 655 687
710
MON_ Trip Threshold
VMON_
Undervoltage 513 543
567
mV
MON_ Glitch Filter 20 µs
MON_ Input Bias Current VMON_ = 600mV 0.03 µA
UNDERVOLTAGE LOCKOUT (UVLO)
S tar tup i s i ni ti ated w hen thi s thr eshol d i s r eached
b y V
IN 1
or V
IN 2
, V
ON
> 0.8V , V
IN_ i ncr easi ng 2.1 2.4
2.67
V
UVLO Threshold
VUVLO
Hysteresis 100 mV
UVLO Glitch Filter Reset Time VIN_ = 0V, to unlatch after a fault 100 µs
UVLO to Startup Delay
tD
,
UVLO
VIN_ step from 0 to 2.8V 18 37.5 64 ms
SHUTDOWN RESTART
Autoretry Delay
tRETRY
Delay time to restart after a fault shutdown
MAX5904/MAX5906/MAX5908 64 x tSTART ms
UNCOMMITTED COMPARATOR
Low to high
1.206
1.25
1.290
V
INC+ Trip Threshold Voltage VC,TH Hysteresis 10 mV
Propagation Delay 10mV overdrive 50 µs
OUTC Voltage Low VOL ISINK = 1mA 0.4 V
INC+ Bias Current VINC+ = 5V 0.02 1 µA
OUTC Leakage Current
IOUTC
VOUTC = 13.2V 0.02 1 µA
Note 1: Limits are 100% tested at TA= +25°C and +85°C. Limits at 0°C and -40° are guaranteed by characterization and are not produc-
tion tested.
Note 2: VIN rising slew rate must be less than 0.2V/µs.
Note 3: The MAX5906–MAX5909 slow-comparator threshold is adjustable. VSC,TH = RLIM x 0.25µA + 25mV (see the Typical
Operating Characteristics).
Note 4: 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 5: The startup period (tSTART) 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.
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
6_______________________________________________________________________________________
Typical Operating Characteristics
(Typical Operating Circuits, Q1 = Q2 = Fairchild FDB7090L, VIN1 = +5V, VIN2 = +3.3V, TA= +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.)
0
0.6
0.4
0.2
1.0
0.8
1.8
1.6
1.4
1.2
2.0
02468101214
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5904 toc01
VINX (V)
IIN (mA)
VINY = VON = 2.7V
IINX + IINY
IINX
IINY
0
0.6
0.4
0.2
1.0
0.8
1.8
1.6
1.4
1.2
2.0
02468101214
TOTAL SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5904 toc02
VINX (V)
IIN (mA)
VINY = 5.0V
A) VON = 3.3V
B) VON = 1.5V
C) VON = 0V
A
C
B
0
0.6
0.4
0.2
0.8
1.0
1.2
1.4
1.6
1.8
2.0
-40 10-15 35 60 85
SUPPLY CURRENT
vs. TEMPERATURE
MAX5904 toc03
TEMPERATURE (°C)
IIN (mA)
VON = VIN1
IIN1 + IIN2
IIN2
IIN1
0
2
1
4
3
5
6
06824 1012 14
GATE-DRIVE VOLTAGE vs.
INPUT VOLTAGE
MAX5904 toc04
VINX (V)
GATE-DRIVE VOLTAGE (V)
VINY = 2.7V
0
60
40
20
80
100
120
140
160
180
200
020
GATE-CHARGE CURRENT
vs. GATE VOLTAGE
MAX5904 toc05
VGATEX (V)
GATE-CHARGE CURRENT (µA)
51015
VON = VINY = 2.7V
VINX = 13.2V
VINX = 5V
VINX = 1V
0
60
40
20
80
100
120
140
160
180
200
-40 10-15 35 60 85
GATE-CHARGE CURRENT
vs. TEMPERATURE
MAX5904 toc06
TEMPERATURE (°C)
GATE-CHARGE CURRENT (µA)
VINX = 13.2V
VINX = 5V
VINX = 1V
VON = VINY = 2.7V
VGATEX = 0V
0
60
40
20
80
100
120
140
160
180
200
05 1510 20
GATE WEAK DISCHARGE CURRENT
vs. GATE VOLTAGE
MAX5904 toc07
VGATEX (V)
GATE DISCHARGE CURRENT (µA)
VON = 0.6V
VINY = 2.7V
VINX = 13.2V
VINX = 5V
VINX = 1V
0
60
40
20
80
100
120
140
160
180
200
-40 -15 35 6010 85
GATE WEAK DISCHARGE CURRENT
vs. TEMPERATURE
MAX5904 toc08
TEMPERATURE (°C)
GATE DISCHARGE CURRENT (µA)
VON = 0.6V
VINX = 13.2V
VINX = 5V
VINX = 1V
VINY = 2.7V
VGATEX = VINX + 6.2V
0
2
1
4
3
5
6
01051520
GATE STRONG DISCHARGE CURRENT
vs. GATE VOLTAGE
MAX5904 toc09
VGATEX (V)
GATE DISCHARGE CURRENT (mA)
VINX = 13.2V
VINX = 5V
VINX = 1V
VON = 0V
VINY = 2.7V
VGATEX = VINX + 6.2V
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
_______________________________________________________________________________________ 7
0
2
1
4
3
5
6
-40 10-15 35 60 85
GATE STRONG DISCHARGE CURRENT
vs. TEMPERATURE
MAX5904 toc10
TEMPERATURE (°C)
GATE DISCHARGE CURRENT (mA)
VINX = 13.2V
VINX = 5V
VINX = 1V
VON = 0V
VINY = 2.7V
VGATEX = VINX + 6.2V
0.0001
0.001
0.1
0.01
1
10
0507525 100 125 150 175 200
TURN-OFF TIME vs. SENSE VOLTAGE
MAX5904 toc11
VIN - VSENSE (mV)
TURN-OFF TIME (ms)
SLOW-COMP. THRESHOLD
FAST-COMP. THRESHOLD
0.1
1
10
20 30 3525 40 45 50 55 60 65 70 75 80
TURN-OFF TIME vs. SENSE VOLTAGE
(EXPANDED SCALE)
MAX5904 toc12
VIN - VSENSE (mV)
TURN-OFF TIME (ms)
SLOW-COMP. THRESHOLD
0
40
20
80
60
100
120
0200100 300 400
SLOW-COMPARATOR THRESHOLD
vs. RLIM
MAX5904 toc13
RLIM (kΩ)
VSC, TH (mV)
0
20
10
40
30
50
60
STARTUP PERIOD vs. RTIM
MAX5904 toc14
RTIM (kΩ)
tSTART (ms)
0200 300100 400 500 600
0V
0V
0V
VPGOOD
5V/div
VSENSE - VIN
100mV/div
VGATE
5V/div
TURN-OFF TIME
SLOW-COMPARATOR FAULT
MAX5904 toc15
1ms/div
VIN = 5.0V
tSCD
26mV STEP
0V
0V
0V VPGOOD
5V/div
VSENSE - VIN
100mV/div
VGATE
5V/div
TURN-OFF TIME
FAST-COMPARATOR FAULT
MAX5904 toc16
400ns/div
VIN = 5.0V
tFCD
125mV STEP
VON
2V/div
VPGOOD
2V/div
IOUT
5A/div
VOUT
5V/div
VGATE
5V/div
STARTUP WAVEFORMS
FAST TURN-ON
MAX5904 toc17
1ms/div
VIN = 5.0V, RSENSE = 10mΩ,
RTIM = 27kΩ, CBOARD = 1000µF
Typical Operating Characteristics (continued)
(Typical Operating Circuits, Q1 = Q2 = Fairchild FDB7090L, VIN1 = +5V, VIN2 = +3.3V, TA= +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.)
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
8_______________________________________________________________________________________
Pin Description
PIN
MAX5904/
MAX5905
MAX5906–
MAX5909
NAME FUNCTION
—1
PGOOD
Open-Drain Status Output. High impedance when startup is complete and no faults
are detected. Actively held low during startup and when a fault is detected.
—2TIM Startup Timer Setting. Connect a resistor from TIM to GND to set the startup period.
Leave TIM unconnected for the default startup period of 9ms.
13IN1 Channel 1 Supply Input. Connect to a supply voltage from 1V to 13.2V. Connect a
0.1µF ceramic bypass capacitor from IN1 to GND to filter high-frequency noise.
24
SENSE1
Channel 1 Current-Sense Input. Connect RSENSE1 from IN1 to SENSE1.
35
GATE1
Channel 1 Gate-Drive Output. Connect to gate of external n-channel MOSFET.
46GND Ground
—7LIM1 Channel 1 Current-Limit Setting. Connect a resistor from LIM1 to GND to set
current-trip level. Connect to GND for the default 25mV threshold.
—8MON1
Channel 1 Output Voltage Monitor. Window comparator input. Connect through a
resistive-divider from OUT1 to GND to set the channel 1 overvoltage and
undervoltage thresholds. Connect to IN1 to disable.
—9MON2
Channel 2 Output Voltage Monitor. Window comparator input. Connect through a
resistive-divider from OUT2 to ground to set the channel 2 overvoltage and
undervoltage thresholds. Connect to IN2 to disable.
IOUT
5A/div
VOUT
5V/div
VGATE
5V/div
AUTORETRY DELAY
MAX5904 toc19
40ms/div
VIN = 5.0V, RSENSE = 10mΩ, RTIM = 47kΩ,
CBOARD = 1000µF, RBOARD = 1.4Ω
VON
2V/div
VPGOOD
2V/div
IOUT
5A/div
VOUT
5V/div
VGATE
5V/div
STARTUP WAVEFORMS
SLOW TURN-ON
MAX5904 toc18
1ms/div
VIN = 5.0V, RSENSE = 10mΩ, RTIM = 47kΩ,
CBOARD = 1000µF, CGATE = 22nF
Typical Operating Characteristics (continued)
(Typical Operating Circuits, Q1 = Q2 = Fairchild FDB7090L, VIN1 = +5V, VIN2 = +3.3V, TA= +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.)
Detailed Description
The MAX5904–MAX5909 are circuit breaker ICs for hot-
swap applications where a line card is inserted into a
live backplane. These devices hot swap supplies rang-
ing from +1V to +13.3V, provided one supply is at or
above 2.7V. Normally, when a line card is plugged into
a live backplane, the card’s discharged filter capacitors
provide low impedance that can momentarily cause the
main power supply to collapse. The MAX5904–
MAX5909 reside either on the backplane or on the
removable card to provide inrush current limiting and
short-circuit protection. This is achieved by using exter-
nal n-channel MOSFETs, external current-sense resis-
tors, and two on-chip comparators. Figure 1 shows the
MAX5906–MAX5909 functional diagram.
The MAX5904/MAX5905 have a fixed startup period
and current-limit threshold. The startup period and cur-
rent-limit threshold of the MAX5906–MAX5909 can be
adjusted with external resistors.
Startup Period
RTIM sets the duration of the startup period for the
MAX5906–MAX5909 from 0.4ms to 50ms (see the
Setting the Startup Period, RTIM section). The duration
of the startup period is fixed at 9ms for the MAX5904/
MAX5905. The startup period begins after the following
three conditions are met:
1) VIN1 or VIN2 exceeds the UVLO threshold (2.4V) for
the UVLO to startup delay (37.5ms).
2) VON exceeds the channel 1 ON threshold (0.825V).
VON should be delayed from the application of a
steep rising edge at IN_ by inserting a minimum RC
time delay of 20µs.
3) The device is not latched or in its autoretry delay. (See
Latched and Autoretry Fault Management section.)
The MAX5904–MAX5909 limit the load current if an
overcurrent fault occurs during startup. The slow com-
parator is disabled during the startup period and the
load current can be limited in two ways:
1) Slowly enhancing the MOSFETs by limiting the
MOSFET gate charging current
2) Limiting the voltage across the external current-
sense resistor.
During the startup period, the gate drive current is typi-
cally 100µA and decreases with the increase of the
gate voltage (see the Typical Operating Character-
istics). This allows the controller to slowly enhance the
MOSFETs. If the fast comparator detects an overcur-
rent, the MAX5904–MAX5909 regulate the gate voltage
to ensure that the voltage across the sense resistor
does not exceed VSU,TH. This effectively regulates the
inrush current during startup. Figure 2 shows the start-
up waveforms. PGOOD goes high impedance 0.75ms
after the startup period if no fault condition is present.
VariableSpeed/BiLevel Fault Protection
VariableSpeed/BiLevel fault protection incorporates two
comparators with different thresholds and response
times to monitor the load current (Figure 9). During the
startup period, protection is provided by limiting the
load current. Protection is provided in normal operation
(after the startup period has expired) by discharging
both MOSFET gates with a strong 3mA pulldown cur-
rent in response to a fault condition. After a fault,
PGOOD is pulled low, the MAX5905/MAX5907/
MAX5909 stay latched off and the MAX5904/MAX5906/
MAX5908 automatically restart.
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
_______________________________________________________________________________________________________ 9
PIN
MAX5904/
MAX5905
MAX5906–
MAX5909
NAME FUNCTION
—10LIM2 Channel 2 Current-Limit Setting. Connect a resistor from LIM2 to GND to set
current-trip level. Connect to GND for the default 25mV threshold.
511ONOn Comparator Input
612
GATE2
Channel 2 Gate-Drive Output. Connect to gate of external n-channel MOSFET.
713
SENSE2
Channel 2 Current-Sense Input. Connect RSENSE2 from IN2 to SENSE2.
814IN2 Channel 2 Supply Input. Connect to a supply voltage from 1V to 13.2V. Connect a
0.1µF ceramic bypass capacitor from IN2 to GND to filter high-frequency noise.
—15INC+ Uncommitted Comparator Noninverting Input
—16OUTC Uncommitted Comparator Open-Drain Output. Actively held low when VINC+ is less
than 1.236V.
Pin Description (continued)
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
10 ______________________________________________________________________________________
UVLO
FAST COMP.
SLOW COMP.
SLOW DISCHARGE
FAST DISCHARGE
Q1
OUT1
2.4V 2.4V
BIAS AND
REFERENCES
TIMING
OSCILLATOR
STARTUP
OSCILLATOR
TO STARTUP
LOGIC BLOCKS
CHARGE
PUMP DEVICE CONTROL
LOGIC
VSC, TH VFS, TH
RLIM1
SENSE1
IN1
GATE1
RSENSE1
LIM1
N
RLIM2
N
100µA
3mA
687mV
543mV
1.236V
MON1
INC+ OUTC ON PGOOD
UVLO
FAST COMP.
SLOW COMP.
SLOW DISCHARGE
FAST DISCHARGE
Q2
OUT2
CHARGE PUMP
OSCILLATOR
TO STARTUP
LOGIC BLOCKS
CHARGE
PUMP
CURRENT CONTROL
AND
STARTUP LOGIC
CURRENT CONTROL
AND
STARTUP LOGIC
VSC, TH
VFS, TH
SENSE2
IN2
GATE2
RSENSE2
LIM2
100µA 3mA
687mV
543mV
MON2
MAX5906
MAX5907
MAX5908
MAX5909
2.025V
0.825V
0.4V
RTIM
TIM
Figure 1. MAX5906–MAX5909 Functional Diagram
Slow-Comparator Startup Period
The slow comparator is disabled during the startup
period while the external MOSFETs are turning on.
Disabling the slow comparator allows the device to
ignore the higher-than-normal inrush current charging
the board capacitors when a card is first plugged into a
live backplane.
Slow-Comparator Normal Operation
After the startup period is complete the slow compara-
tor is enabled and the device enters normal operation.
The comparator threshold voltage (VSC,TH) is fixed at
25mV for the MAX5904/MAX5905 and is adjustable
from 25mV to 100mV for the MAX5906–MAX5909. The
slow-comparator response time decreases to a mini-
mum of 110µs with a large overdrive voltage (Figure 9).
Response time is 3ms for a 1mV overdrive. The variable
speed response time allows the MAX5904–MAX5909 to
ignore low-amplitude momentary glitches, thus increas-
ing system noise immunity. After an extended overcur-
rent condition, a fault is generated, PGOOD is pulled
low, and the MOSFET gates are discharged with a
strong 3mA pulldown current.
Fast-Comparator Startup Period
During the startup period the fast comparator regulates
the gate voltage to ensure that the voltage across the
sense resistor does not exceed VSU,TH. The startup
fast-comparator threshold voltage (VSU,TH) is scaled to
two times the slow-comparator threshold (VSC,TH).
Fast-Comparator Normal Operation
In normal operation, if the load current reaches the fast-
comparator threshold, a fault is generated, PGOOD is
pulled low, and the MOSFET gates are discharged with
a strong 3mA pulldown current. This happens in the
event of a serious current overload or a dead short. The
fast-comparator threshold voltage (VFC,TH) is scaled to
four times the slow-comparator threshold (VSC,TH). This
comparator has a fast response time of 260ns (Figure 9).
Undervoltage Lockout (UVLO)
The undervoltage lockout prevents the MAX5904–
MAX5909 from turning on the external MOSFETs until
one input voltage exceeds the UVLO threshold (2.4V)
for tD,UVLO. The MAX5904–MAX5909 use power from
the higher input voltage rail for the charge pumps. This
allows for more efficient charge-pump operation. The
UVLO protects the external MOSFETs from an insuffi-
cient gate drive voltage. tD,UVLO ensures that the board
is fully inserted into the backplane and that the input
voltages are stable. Any input voltage transient on both
supplies below the UVLO threshold will reinitiate the
tD,UVLO and the startup period.
Latched and Autoretry Fault Management
The MAX5905/MAX5907/MAX5909 latch the external
MOSFETs off when a fault is detected. Toggling ON
below 0.4V or one of the supply voltages below the
UVLO threshold for at least 100µs clears the fault latch
and reinitiates the startup period. Similarly, the
MAX5904/MAX5906/MAX5908 turn the external
MOSFETs off when a fault is detected then automatical-
ly restart after the autoretry delay that is internally set to
64 times tSTART. During the autoretry delay, toggling
ON below 0.4V does not clear the fault. The autoretry
can be overridden causing the startup period to begin
immediately by toggling one of the supply voltages
below the UVLO threshold.
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
______________________________________________________________________________________ 11
tON
4.8V TO 5.8V
VGATE
VGATE
PGOOD
ON
VTH
VOUT
VOUT
ILOAD
tSTART + tPGDLY
CBOARD = LARGE
CBOARD = 0
VSU,TH
RSENSE
Figure 2. Startup Waveforms
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
12 ______________________________________________________________________________________
tPGDLY
VON_,TH
VON
VGATE_
VOUT_
INTERNAL SIGNAL
INTERNAL SIGNAL
PGOOD
tSTART
Figure 3. Power-Up with ON Pin Control (At Least One VIN_ is > VUVLO)
Timing Diagrams
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
______________________________________________________________________________________ 13
IOUT
VGATE_
VOUT_
PGOOD
tSCD
DISCHARGE RATE DEPENDS
ON OUTPUT LOADING
OVERCURRENT CONDITION
(VIN_ - VSENSE_ ≥ VSC_TH AND
VIN_ - VSENSE_ < VFC_TH)
Figure 4. Power-Down when an Overcurrent Fault Occurs
IOUT
VGATE_
VOUT_
PGOOD
tFCD
SHORT-CIRCUIT CONDITION
(VIN_ - VSENSE_ ≥ VFC_TH)
Figure 5. Power-Down when a Short-Circuit Fault Occurs
Timing Diagrams (continued)
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
14 ______________________________________________________________________________________
INTERNAL SIGNAL
VGATE_
VOUT_
PGOOD
DISCHARGE RATE DEPENDS
ON OUTPUT LOADING
MON_ GLITCH FILTER, 20µS
UV/OV CONDITION
Figure 6. Power-Down when an Undervoltage/Overvoltage Fault Occurs (MAX5906/MAX5907)
INTERNAL SIGNAL
UV/OV CONDITION
VGATE_
VOUT_
PGOOD
VGATE_ AND VOUT_ STAY ON
MON_ GLITCH FILTER, 20µS
Figure 7. Fault Report when an Undervoltage/Overvoltage Fault Occurs (MAX5908/MAX5909)
Timing Diagrams (continued)
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
______________________________________________________________________________________ 15
tPGDLY
tD,UVLO
VUVLO
VIN_
VGATE_
VOUT_
INTERNAL SIGNAL
INTERNAL SIGNAL
PGOOD
tSTART
Figure 8. Power-Up with Undervoltage Lockout Delay (VON = 2.7V, the Other VIN_ is Below VUVLO)
Timing Diagrams (continued)
MAX5904–MAX5909
Output Voltage Monitor
The MAX5905–MAX5909 monitor the output voltages
with the MON1 and MON2 window comparator inputs.
These voltage monitors are enabled after the startup
period. Once enabled, the voltage monitor detects a
fault if VMON_ is less than 543mV or greater than
687mV. If an output voltage fault is detected PGOOD
pulls low. When the MAX5906/MAX5907 detect an out-
put voltage fault on either MON1 or MON2, the fault is
latched and both external MOSFET gates are dis-
charged at 3mA. When the MAX5908/MAX5909 detect
an output voltage fault the external MOSFET gates are
not affected. The MAX5908/MAX5909 PGOOD goes
high impedance when the output voltage fault is
removed. The voltage monitors do not react to output
glitches of less than 20µs. A capacitor from MON_ to
GND increases the effective glitch filter time. Connect
MON1 to IN1 and MON2 to IN2 to disable the output
voltage monitors.
Status Output (PGOOD)
The status output is an open-drain output that pulls low
in response to one of the following conditions:
• Forced off (ON < 0.8V)
• Overcurrent fault
• Output voltage fault
PGOOD goes high impedance 0.75ms after the device
enters normal operation and no faults are present
(Table 1).
Applications Information
Component Selection
n-Channel MOSFET
Select the external MOSFETs according to the applica-
tion’s current levels. Table 2 lists some recommended
components. The MOSFET’s on-resistance (RDS(ON))
should be chosen low enough to have a minimum volt-
age drop at full load to limit the MOSFET power dissipa-
tion. High RDS(ON) causes output ripple if there is a
pulsating load. Determine the device power rating to
accommodate a short-circuit condition on the board at
startup and when the device is in automatic-retry mode
(see the MOSFET Thermal Considerations section).
Using the MAX5905/MAX5907/MAX5909 in latched
mode allows the use of MOSFETs with lower power rat-
ings. A MOSFET typically withstands single-shot pulses
with higher dissipation than the specified package rat-
ing. Table 3 lists some recommended manufacturers
and components.
Sense Resistor
The slow-comparator threshold voltage is set at 25mV
for the MAX5904/MAX5905 and is adjustable from
25mV to 100mV for the MAX5906–MAX5909. Select a
sense resistor that causes a drop equal to the slow-
comparator threshold voltage at a current level above
the maximum normal operating current. Typically, set
the overload current at 1.2 to 1.5 times the nominal load
current. The fast-comparator threshold is four times the
slow-comparator threshold in normal operating mode.
Choose the sense resistor power rating to be greater
than (IOVERLOAD)2x VSC,TH.
Slow-Comparator Threshold, RLIM
The slow-comparator threshold voltage of the
MAX5904/MAX5905 is fixed at 25mV and adjustable
from 25mV to 100mV for the MAX5906–MAX5909.
The adjustable slow-comparator threshold of the
MAX5906–MAX5909 allows designers to fine-tune the
current-limit threshold for use with standard value
sense resistors. Low slow-comparator thresholds allow
for increased efficiency by reducing the power dissipat-
ed by the sense resistor. Furthermore, the low 25mV
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
16 ______________________________________________________________________________________
Table 1. Status Output Truth Table
DEVICE IN
UVLO DELAY
PERIOD
DEVICE IN
STARTUP
PERIOD
ON OVERCURRENT
FAULT
OVER/UNDER-
VOLTAGE
FAULT
PART IN RETRY-TIMEOUT
PERIOD OR LATCHED OFF
PGOOD
Yes X X X X X Low
XYes X X X X Low
XX
Low
XX X Low
XXXYes X X Low
XXXX Yes X Low
XXXX X Yes Low
No No
High
No No No High
impedence
X = Don’t care.
slow-comparator threshold is beneficial when operating
with supply rails down to 1V because it allows a small
percentage of the overall output voltage to be used for
current sensing. The VariableSpeed/BiLevel fault pro-
tection feature offers inherent system immunity against
load transients and noise. This allows the slow-com-
parator threshold to be set close to the maximum nor-
mal operating level without experiencing nuisance
faults. Typically, set the overload current at 1.2 to 1.5
times the nominal load current. To adjust the slow-com-
parator threshold calculate RLIM as follows:
where VTH is the desired slow-comparator threshold
voltage.
Setting the Startup Period, RTIM
The startup period (tSTART) of the MAX5904/MAX5905 is
fixed at 9ms, and adjustable from 0.4ms to 50ms for the
MAX5906–MAX5909. The adjustable startup period of
the MAX5906–MAX5909 systems can be customized for
MOSFET gate capacitance and board capacitance
(CBOARD). The startup period is adjusted with the resis-
tance connected from TIM to GND (RTIM). RTIM must be
between 4kΩand 500kΩ. The MAX5906–MAX5909 start-
up period has a default value of 9ms when TIM is left
floating. Calculate RTIM with the following equation:
where tSTART is the desired startup period.
There are two ways of completing the startup
sequence. Case A describes a startup sequence that
slowly turns on the MOSFETs by limiting the gate
charge. Case B uses the current-limiting feature and
turns on the MOSFETs as fast as possible while still
preventing a high inrush current. The output voltage
ramp-up time (tON) is determined by the longer of the
two timings, case A and case B. Set the MAX5906–
MAX5909 startup timer tSTART to be longer than tON to
guarantee enough time for the output voltage to settle.
Case A: Slow Turn-On (Without Current Limit)
There are two ways to turn on the MOSFETs without
reaching the fast-comparator current limit:
If the board capacitance (CBOARD) is small, the
inrush current is low.
If the gate capacitance is high, the MOSFETs turn
on slowly.
In both cases, the turn-on time is determined only by the
charge required to enhance the MOSFET. The small
gate-charging current of 100µA effectively limits the out-
put voltage dV/dt. Connecting an external capacitor
between GATE and GND extends turn-on time. The time
required to charge/discharge a MOSFET is as follows:
where:
CGATE is the external gate to ground capacitance
(Figure 4)
∆VGATE is the change in gate voltage
tCVQ
I
GATE GATE GATE
GATE
=×∆ +
Rt
pF
TIM START
=×128 800
RVmV
A
LIM TH
=−25
025.µ
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
______________________________________________________________________________________ 17
COMPONENT MANUFACTURER PHONE WEBSITE
Dale-Vishay 402-564-3131 www.vishay.com
Sense Resistors IRC 704-264-8861 www.irctt.com
International Rectifier 310-233-3331 www.irf.com
Fairchild 888-522-5372 www.fairchildsemi.com
MOSFETs
Motorola 602-244-3576 www.mot-sps.com/ppd
PART NUMBER MANUFACTURER DESCRIPTION
IRF7413 11mΩ, 8 SO, 30V
IRF7401 22mΩ, 8 SO, 20V
IRL3502S
International
Rectifier
6mΩ, D2PAK, 20V
MMSF3300 20mΩ, 8 SO, 30V
MMSF5N02H 30mΩ, 8 SO, 20V
MTB60N05H
Motorola
14mΩ, D2PAK, 50V
FDS6670A 10mΩ, 8SO, 30V
NDS8426A 13.5mΩ, 8 SO, 20V
FDB8030L
Fairchild
4.5mΩ, D2PAK, 30V
Table 2. Recommended n-Channel
MOSFETs
Table 3. Component Manufacturers
MAX5904–MAX5909
QGATE is the MOSFET total gate charge
IGATE is the gate charging/discharging current
In this case, the inrush current depends on the MOSFET
gate-to-drain capacitance (Crss) plus any additional
capacitance from gate to GND (CGATE), and on any
load current (ILOAD) present during the startup period.
Example: Charging and discharging times using the
Fairchild FDB7030L MOSFET
If VIN1 = 5V then GATE1 charges up to 10.4V (VIN1 +
VDRIVE), therefore ∆VGATE = 10.4V. The manufacturer’s
data sheet specifies that the FDB7030L has approxi-
mately 60nC of gate charge and Crss = 600pF. The
MAX5904–MAX5909 have a 100µA gate-charging cur-
rent and a 100µA weak discharging current or 3mA
strong discharging current.
CBOARD = 6µF and the load does not draw any current
during the startup period.
With no gate capacitor the inrush current, charge, and
discharge times are:
With a 22nF gate capacitor the inrush current, charge,
and discharge times are:
Case B: Fast Turn-On (With Current Limit)
In applications where the board capacitance (CBOARD)
is high, the inrush current causes a voltage drop across
RSENSE that exceeds the startup fast-comparator
threshold. The fast comparator regulates the voltage
across the sense resistor to VSU,TH. This effectively
regulates the inrush current during startup. In this case,
the current charging CBOARD can be considered con-
stant and the turn-on time is:
The maximum inrush current in this case is:
Figures 2–8 show the waveforms and timing diagrams
for a startup transient with current regulation. (See the
Typical Operating Characteristics.) When operating
under this condition, an external gate capacitor is not
required.
ON Comparator
The ON comparator controls the on/off function of the
MAX5904–MAX5909. ON is the input to a precision
three-level voltage comparator that allows individual
control over channel 1 and channel 2. Drive ON high
(> 2.025V) to enable channel 1 and channel 2. Pull ON
low (<0.4V) to disable both channels. To enable chan-
nel 1 only, VON must be between the channel 1 ON
threshold (0.825V) and the channel 2 ON threshold
(2.025V). The device can be turned off slowly, reducing
inductive kickback, by forcing ON between 0.4V and
0.825V until the gates are discharged. The ON com-
parator is ideal for power sequencing (Figure 11).
Note that a minimum RC time delay of 20µs is applied
to the steeply rising voltage at IN_ before the input volt-
age reaches the ON_ terminal. This allows internal cir-
cuits to stabilize prior to the signal arriving at the ON_
terminal.
Uncommitted Comparator
The MAX5906–MAX5909 feature an uncommitted com-
parator that increases system flexibility. This compara-
tor can be used for voltage monitoring, or for
generating a power-on reset signal for on-card micro-
processors (Figure 12).
The uncommitted comparator output (OUTC) is open
drain and is pulled low when the comparator input volt-
age (VINC+) is below its threshold voltage (1.236V).
IV
R
INRUSH SUTH
SENSE
=,
tCVR
V
ON BOARD IN SENSE
SU TH
=××
,
IF
pF nF AmA
tnF V nC
Ams
tnF V nC
Ams
tnF V nC
mA ms
INRUSH
CHARGE
DISCHARGE SLOW
DISCHARGE FAST
=µ
+×µ+=
=×+
µ=
=×+
µ=
=×+=
6
600 22 100 0 26 5
22 10 4 60
100 289
22 10 4 60
100 289
22 10 4 60
30 096
.
..
..
..
_
_
IF
pF AA
tVnC
Ams
tVnC
Ams
tVnC
mA ms
INRUSH
CHARGE
DISCHARGE SLOW
DISCHARGE FAST
=µ
+×µ+=
=×+
µ=
=×+
µ=
=×+=
6
600 0 100 0 1
0104 60
100 06
0104 60
100 06
0104 60
3002
..
..
..
_
_
IC
CC II
INRUSH BOARD
rss GATE GATE LOAD
=+×+
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
18 ______________________________________________________________________________________
OUTC is high impedance when VINC+ is greater than
1.236V.
Using the MAX5904–MAX5909 on the
Backplane
Using the MAX5904–MAX5909 on the backplane allows
multiple cards with different input capacitance to be
inserted into the same slot even if the card does not
have on-board hot-swap protection. The startup period
can be triggered if IN is connected to ON through a
trace on the card (Figure 13).
Input Transients
The voltage at IN1 or IN2 must be above the UVLO dur-
ing inrush and fault conditions. When a short-circuit
condition occurs on the board, the fast comparator
trips causing the external MOSFET gates to be dis-
charged at 3mA. The main system power supply must
be able to sustain a temporary fault current, without
dropping below the UVLO threshold of 2.4V, until the
external MOSFET is completely off. If the main system
power supply collapses below UVLO, the
MAX5904–MAX5909 will force the device to restart
once the supply has recovered. The MOSFET is turned
off in a very short time resulting in a high di/dt. The
backplane delivering the power to the external card
must have low inductance to minimize voltage tran-
sients caused by this high di/dt.
MOSFET Thermal Considerations
During normal operation, the external MOSFETs dissi-
pate little power. The MOSFET RDS(ON) is low when the
MOSFET is fully enhanced. The power dissipated in
normal operation is PD= ILOAD2x RDS(ON). The most
power dissipation occurs during the turn-on and turn-
off transients when the MOSFETs are in their linear
regions. Take into consideration the worst-case sce-
nario of a continuous short-circuit fault, consider these
two cases:
1) The single turn-on with the device latched after a
fault (MAX5905/MAX5907/MAX5909)
2) The continuous automatic retry after a fault
(MAX5904/MAX5906/MAX5908)
MOSFET manufacturers typically include the package
thermal resistance from junction to ambient (RθJA) and
thermal resistance from junction to case (RθJC) which
determine the startup time and the retry duty cycle (d =
tSTART / tRETRY). Calculate the required transient ther-
mal resistance with the following equation:
where ISTART = VSU,TH / RSENSE
Layout Considerations
To take full tracking advantage of the switch response
time to an output fault condition, it is important to keep
all traces as short as possible and to maximize the
high-current trace dimensions to reduce the effect of
undesirable parasitic inductance. Place the MAX5904–
ZTT
VI
JA MAX JMAX A
IN START
θ()
≤×
−
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
______________________________________________________________________________________ 19
SENSE VOLTAGE (VIN - VSENSE)
TURN-OFF TIME
VSC,TH VFC,TH
(4 x VSC,TH)
3ms
110µs
260ns
SLOW
COMPARATOR
FAST
COMPARATOR
Figure 9. VariableSpeed/BiLevel Response
GATE
SENSE
GND
RSENSE VOUT
CGATE
CBOARD
VIN
IN
RPULLUP
PGOOD
*OPTIONAL COMPONENTS (SEE THE ON COMPARATOR SECTION).
MAX5906
MAX5907
MAX5908
MAX5909
ON
*
*
Figure 10. Operating with an External Gate Capacitor
MAX5904–MAX5909
MAX5909 close to the card’s connector. Use a ground
plane to minimize impedance and inductance. Minimize
the current-sense resistor trace length (<10mm), and
ensure accurate current sensing with Kelvin connec-
tions (Figure 14).
When the output is short circuited, the voltage drop
across the external MOSFET becomes large. Hence,
the power dissipation across the switch increases, as
does the die temperature. An efficient way to achieve
good power dissipation on a surface-mount package is
to lay out two copper pads directly under the MOSFET
package on both sides of the board. Connect the two
pads to the ground plane through vias, and use
enlarged copper mounting pads on the top side of the
board. See MAX5908 EV Kit.
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
20 ______________________________________________________________________________________
IN1 GATE1
IN2 GATE2
Q1
RSENSE1
SENSE1
RSENSE2
SENSE2
Q2
CBOARD2
OUT1
CBOARD1
OUT2
V1
C1
R1
VEN
V2
ON
OFF
GND
MAX5904
MAX5905
ON
GND
VON1, TH
VON2, TH
TDELAY
VEN
t1 = -R1C1 ln( )
VEN - VON1, TH
VEN
VON
V1
V2
> 20µs
t0t1t2
t2 = -R1C1 ln( )
VEN - VON2, TH
VEN
tDELAY = -R1C1 ln( )
VEN - VON1, TH
VEN - VON2, TH
Figure 11. Power Sequencing: Channel 2 Turns On tDELAY After Channel 1
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
______________________________________________________________________________________ 21
PART OUTPUT UNDERVOLTAGE/OVERVOLTAGE
PROTECTION/MONITOR FAULT MANAGEMENT
MAX5904ESA/MAX5904USA — Autoretry
MAX5905ESA/MAX5905USA — Latched
MAX5906EEE/MAX5906UEE Protection Autoretry
MAX5907EEE/MAX5907UEE Protection Latched
MAX5908EEE/MAX5908UEE Monitor Autoretry
MAX5909EEE/MAX5909UEE Monitor Latched
Selector Guide
OUTC
INC+
RESET
µP
IN GATE
VIN
SENSE
MAX5906–MAX5909
Figure 12. Power-On Reset
ON
IN GATE
VIN
VOUT
SENSE
MAX590_
CBOARD
BACKPLANE
REMOVABLE CARD
WITH NO HOT-INSERTION
PROJECTION
*
*
*OPTIONAL COMPONENTS (SEE THE ON COMPARATOR SECTION).
Figure 13. Using the MAX5904–MAX5909 on a Backplane
SENSE RESISTOR
HIGH-CURRENT PATH
MAX590_
Figure 14. Kelvin Connection for the Current-Sense Resistors
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
PGOOD OUTC
INC+
IN2
SENSE2
GATE2
ON
LIM2
MON2
TOP VIEW
MAX5906
MAX5907
MAX5908
MAX5909
QSOP
TIM
IN1
GND
SENSE1
GATE1
LIM1
MON1
Pin Configurations (continued)
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
22 ______________________________________________________________________________________
IN1 GATE1
IN2 GATE2
Q1
RSENSE1
SENSE1
RSENSE2
SENSE2
Q2 CBOARD2
OUT1
CBOARD1
OUT2
V1
V2
ON
GND
BACKPLANE REMOVABLE CARD
MAX5904
MAX5905
GND
0.1µF
0.1µF
ON
*
*
*OPTIONAL COMPONENTS
IN1 GATE1
IN2 GATE2
Q1
RSENSE1
SENSE1
RSENSE2
SENSE2
Q2
CBOARD2
OUT1
CBOARD1
OUT2
V1
V2
ON MON1
MON2
OUTC
INC+
STAT
GND
BACKPLANE REMOVABLE CARD
UNCOMMITTED
COMPARATOR
**
**
*OPTIONAL COMPONENTS
PGOOD
LIM1
LIM2
TIM
GND
*
*
*
MAX5906
MAX5907
MAX5908
MAX5909
0.1µF
0.1µF
ON
*
*
Typical Operating Circuits
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
______________________________________________________________________________________ 23
SOICN .EPS
PACKAGE OUTLINE, .150" SOIC
1
1
21-0041 B
REV.DOCUMENT CONTROL NO.APPROVAL
PROPRIETARY INFORMATION
TITLE:
TOP VIEW
FRONT VIEW
MAX
0.010
0.069
0.019
0.157
0.010
INCHES
0.150
0.007
E
C
DIM
0.014
0.004
B
A1
MIN
0.053A
0.19
3.80 4.00
0.25
MILLIMETERS
0.10
0.35
1.35
MIN
0.49
0.25
MAX
1.75
0.050
0.016L0.40 1.27
0.3940.386D
D
MINDIM
D
INCHES
MAX
9.80 10.00
MILLIMETERS
MIN MAX
16 AC
0.337 0.344 AB8.758.55 14
0.189 0.197 AA5.004.80 8
NMS012
N
SIDE VIEW
H0.2440.228 5.80 6.20
e0.050 BSC 1.27 BSC
C
HE
eBA1
A
D
0∞-8∞
L
1
VARIATIONS:
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
©2005 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
QSOP.EPS
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
Revision History
Pages changed at Rev 3: 1, 2, 3, 4, 5, 24
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Authorized Distributor
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Maxim Integrated:
MAX5904ESA+ MAX5904ESA+T MAX5904USA+ MAX5904USA+T MAX5905ESA+ MAX5905ESA+T
MAX5905USA+ MAX5905USA+T MAX5906EEE+ MAX5906EEE+T MAX5906UEE+ MAX5906UEE+T
MAX5907EEE+ MAX5907EEE+T MAX5907UEE+ MAX5907UEE+T MAX5908EEE+ MAX5908EEE+T
MAX5908UEE+ MAX5908UEE+T MAX5909EEE+ MAX5909EEE+T MAX5909UEE+ MAX5909UEE+T
