MAXIM MAX5904ESA

19-2238; Rev 0; 10/01
KIT
ATION
EVALU
E
L
B
A
IL
AVA
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
Applications
Features
♦ Safe Hot Swap for +1V to +13.2V Power Supplies
♦ Low 25mV Default Current-Limit Threshold
♦ Internal Charge Pumps Generate N-Channel
MOSFET Gate Drives
♦ Inrush Current Regulated at Startup
♦ Circuit Breaker Function
♦ Adjustable Circuit Breaker/Current-Limit
Threshold
♦ VariableSpeed/BiLevel Circuit-Breaker Response
♦ Auto-Retry or Latched Fault Management
♦ On/Off Sequence Programming
♦ Status Output Indicates Fault/Safe Condition
♦ Output Undervoltage and Overvoltage Monitoring
and/or Protection
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
-40°C to +85°C
8 SO
MAX5905ESA
-40°C to +85°C
8 SO
MAX5906EEE
-40°C to +85°C
16 QSOP
MAX5907EEE
-40°C to +85°C
16 QSOP
MAX5908EEE
-40°C to +85°C
16 QSOP
MAX5909EEE
-40°C to +85°C
16 QSOP
MAX5904ESA
Pin Configurations
TOP VIEW
Basestation Line Cards
Network Switches or Routers
Solid-State Circuit Breaker
Power-Supply Sequencing
Hot Plug-In Daughter Cards
IN1
1
SENSE1
2
GATE1
3
MAX5904
MAX5905
GND 4
8
IN2
7
SENSE2
6
GATE2
5
ON
RAID
Portable Computer Device Bays
VariableSpeed/BiLevel is a trademark of Maxim Integrated
Products, Inc.
NARROW SO
Pin Configurations continued at end of data sheet.
Selector Guide and Typical Operating Circuits appear at end
of data sheet.
________________________________________________________________ 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.
1
MAX5904–MAX5909
General Description
The MAX5904–MAX5909 +1V to +13.2V dual hot-swap
controllers provide complete protection for dual-supply
systems. They allow the safe insertion and removal of circuit cards into live backplanes.
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 MAX5904 family of hot-swap controllers prevents 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 MAX5905/MAX5907/MAX5909 must be unlatched
after a fault, and the MAX5904/MAX5906/MAX5908 automatically 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 integrated features like startup current regulation and current
glitch protection to eliminate external timing resistors and
capacitors. The MAX5906–MAX5909 provide an opendrain 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 packages. The MAX5906–MAX5909 are available in spacesaving 16-pin QSOP packages. All devices are specified
over the extended temperature range, -40°C to +85°C.
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
ABSOLUTE MAXIMUM RATINGS
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 Range ...........................-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
(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
Supply Current
VIN_
IIN
Other VIN = +2.7V
IIN1 + IIN2
1.0
13.2
V
1.2
2.3
mA
25
27.5
CURRENT CONTROL
MAX5904/MAX5905
Slow-Comparator Threshold
(VIN - VSENSE) (Note 2)
Slow-Comparator Response Time
(Note 3)
Fast-Comparator Threshold
Fast-Comparator Response Time
SENSE Input Bias Current
VSC,TH
MAX5906–MAX5909
tSCD
TA = +25°C
22.5
TA = -40°C to +85°C
20.5
LIM = GND
22.5
25
27.5
80
100
125
RLIM = 300kΩ
27.5
1mV overdrive
3
ms
50mV overdrive
110
µs
VSU,TH
VIN_ - VSENSE_; during startup
2 x VSC, TH
VFC,TH
VIN_ - VSENSE_; normal operation
4 x VSC, TH
tFCD
IB SEN
mV
mV
10mV overdrive, from overload condition
260
ns
VSEN_ = VIN_
0.03
6
8
10.8
13.6
µA
MOSFET DRIVER
RTIM = 100kΩ
Startup Period
(Note 4)
Average Gate Current
tSTART
IGATE
RTIM = 4kΩ (minimum value)
0.35
0.45
0.55
TIM floating for MAX5906–MAX5909
fixed for MAX5904/MAX5905
5
9
14
Charging, VGATE = +5V, VIN = +10V
(Note 5)
80
100
130
Weak discharge, during startup when current
limit is active or when 0.4V < VON < 0.8V
Strong discharge, triggered by a fault or
when VON < 0.4V
Gate Drive Voltage
VDRIVE
VGATE_ - VIN_, IGATE_ < 1µA
ms
µA
100
µA
3
mA
4.8
5.4
5.8
V
0.375
0.4
0.425
V
mV
ON COMPARATOR
Fast Pulldown ON Threshold
2
VONFP,TH
Low to high
Hysteresis
25
_______________________________________________________________________________________
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
(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
Channel 1 ON Threshold
VON1,TH
Channel 2 ON Threshold
VON2,TH
CONDITIONS
Low to high
MIN
TYP
MAX
0.80
0.825
0.85
1.95
25
2.025
Hysteresis
Low to high
Hysteresis
ON Propagation Delay
tON
10mV overdrive
ON Input Bias Current
IBON
VIN1 = VIN2 = +13.2V
0.03
VON > 4.5V
100
0.03
VON = 4V
ON Pulse Width Low
tUNLATCH
To unlatch after a latched fault
V
mV
2.07
25
50
VON < 4.5V
UNITS
V
mV
µs
µA
1
100
µs
DIGITAL OUTPUT (PGOOD)
Output Leakage Current
VPGOOD = 13.2V
Output Voltage Low
VOL
tPGDLY
PGOOD Delay
1
ISINK = 1mA
0.4
After tSTART, MON_ = VIN_
0.75
µA
V
ms
OUTPUT VOLTAGE MONITORS (MON1, MON2)
MON_ Trip Threshold
VMON_
Overvoltage
657
687
707
Undervoltage
513
543
563
MON_ Glitch Filter
MON_ Input Bias Current
VMON_ = 600mV
mV
20
µs
0.03
µA
UNDERVOLTAGE LOCKOUT (UVLO)
UVLO Threshold
VUVLO
Startup is initiated when this threshold is reached
by VIN1 or VIN2, VON > 0.8V, VIN_ increasing
2.1
Hysteresis
UVLO Glitch Filter Reset Time
UVLO to Startup Delay
2.4
2.67
100
VIN_ = 0, to unlatch after a fault
100
tD,UVLO
VIN_ step from 0 to 2.8V
20
tRETRY
Delay time to restart after a fault shutdown
MAX5904/MAX5906/MAX5908
V
mV
µs
37.5
60
ms
SHUTDOWN RESTART
Auto-Retry Delay
64 x tSTART
ms
UNCOMMITTED COMPARATOR
INC+ Trip Threshold Voltage
VC,TH
Propagation Delay
OUTC Voltage Low
VOL
INC+ Bias Current
OUTC Leakage Current
IOUTC
Low to high
1.206
1.236
Hysteresis
10
10mV overdrive
50
ISINK = 1mA
1.266
V
mV
µs
0.4
V
VINC+ = 5V
0.02
1
µA
VOUTC = 13.2V
0.02
1
µA
Note 1: Limits are 100% tested at TA = +25°C and +85°C. Limits at -40° are guaranteed by characterization but are not production tested.
Note 2 The MAX5906–MAX5909 slow-comparator threshold is adjustable. VSC,TH = RLIM x 0.25µA + 25mV (see 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 Typical Operating Characteristics.
Note 4: 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.
Note 5: The current available at GATE is a function of VGATE (see Typical Operating Characteristics).
_______________________________________________________________________________________
3
MAX5904–MAX5909
ELECTRICAL CHARACTERISTICS (continued)
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.)
1.8
1.6
IINX
0.8
0.6
IINY
0.4
8
10
12
VINY = 5.0V
A) VON = 3.3V
B) VON = 1.5V
C) VON = 0
14
0.2
2
4
6
8
10
12
-40
14
GATE CHARGE CURRENT
vs. TEMPERATURE
140
VINX = 13.2V
120
VINX = 5V
100
VINX = 1V
80
60
40
180
20
4
6
8
10
12
14
VINX = 13.2V
140
VINX = 5V
120
100
80
VINX = 1V
60
40
VON = VINY = 2.7V
VGATEX = 0
20
0
2
160
0
0
5
10
20
15
-40
-15
10
35
60
VINX (V)
VGATEX (V)
TEMPERATURE (°C)
GATE WEAK DISCHARGE CURRENT
vs. GATE VOLTAGE
GATE WEAK DISCHARGE CURRENT
vs. TEMPERATURE
GATE STRONG DISCHARGE CURRENT
vs. GATE VOLTAGE
120
100
VINX = 1V
60
40
20
5
10
VGATEX (V)
15
160
VINX = 5V
VINX = 13.2V
140
120
100
VINX = 1V
80
60
40
VINY = 2.7V
VGATEX = VINX + 6.2V
20
VINY = 2.7V
0
VON = 0.6V
180
VINX = 13.2V
VINX = 5V
5
85
4
3
VON = 0
2
VINX = 1V
1
VINY = 2.7V
VGATEX = VINX + 6.2V
0
0
20
6
GATE DISCHARGE CURRENT (mA)
VINX = 13.2V
VINX = 5V
200
MAX5904 toc08
VON = 0.6V
GATE DISCHARGE CURRENT (µA)
MAX5904 toc07
200
85
MAX5904 toc06
160
200
GATE CHARGE CURRENT (µA)
MAX5904 toc05
VON = VINY = 2.7V
180
GATE CHARGE CURRENT (µA)
MAX5904 toc04
200
0
0
60
GATE CHARGE CURRENT
vs. GATE VOLTAGE
VINY = 2.7V
80
35
GATE DRIVE VOLTAGE vs.
INPUT VOLTAGE
1
140
10
TEMPERATURE (°C)
2
160
-15
VINX (V)
3
180
IIN2
0.4
0
0
4
0
IIN1
VINX (V)
5
GATE DRIVE VOLTAGE (V)
0.6
0.4
6
4
0.8
0
6
1.0
0.6
0.2
4
1.2
0.8
0
2
B
1.0
0.2
0
1.4
C
1.2
IIN (mA)
IIN (mA)
1.0
IIN1 + IIN2
1.6
A
1.4
1.2
VON = VIN1
1.8
MAX5904 toc09
IINX + IINY
1.4
2.0
MAX5904 toc02
VINY = VON = 2.7V
1.6
IIN (mA)
2.0
MAX5904 toc01
2.0
1.8
SUPPLY CURRENT
vs. TEMPERATURE
TOTAL SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX5904 toc03
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
GATE DISCHARGE CURRENT (µA)
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
-40
-15
10
35
TEMPERATURE (°C)
60
85
0
5
10
VGATEX (V)
_______________________________________________________________________________________
15
20
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
SLOW-COMP. THRESHOLD
1
TURN-OFF TIME (ms)
VINX = 13.2V
VINX = 5V
3
VON = 0
VINY = 2.7V
VGATEX = VINX + 6.2V
2
VINX = 1V
TURN-OFF TIME (ms)
5
10
MAX5904 toc11
10
MAX5904 toc10
FAST-COMP. THRESHOLD
0.1
0.01
SLOW-COMP. THRESHOLD
1
0.001
1
0
0.1
0.0001
-40
-15
10
35
60
85
0
25
50
75
20 25 30 35 40 45 50 55 60 65 70 75 80
100 125 150 175 200
TEMPERATURE (°C)
VIN - VSENSE (mV)
VIN - VSENSE (mV)
SLOW-COMPARATOR THRESHOLD
vs. RLIM
STARTUP PERIOD vs. RTIM
TURN-OFF TIME
FAST-COMPARATOR FAULT
60
MAX5904 toc13
120
100
MAX5904 toc15
MAX5904 toc14
GATE DISCHARGE CURRENT (mA)
6
4
TURN-OFF TIME vs. SENSE VOLTAGE
(EXPANDED SCALE)
TURN-OFF TIME vs. SENSE VOLTAGE
MAX5904 toc12
GATE STRONG DISCHARGE CURRENT
vs. TEMPERATURE
50
tSTART (ms)
VSC, TH (mA)
40
VPGOOD
5V/div
tSCD
0
80
MAX5904–MAX5909
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.)
0
26mV STEP
30
VSENSE - VIN
100mV/div
40
20
VGATE
5V/div
20
10
60
0
0
0
0
100
200
300
400
0
100
200
RLIM (kΩ)
300
400
500
600
4ms/div
VIN = 5.0V
RTIM (kΩ)
TURN-OFF TIME
FAST-COMPARATOR FAULT
STARTUP WAVEFORMS
FAST TURN-ON
MAX5904 toc16
MAX5904 toc17
VON
2V/div
VPGOOD
5V/div
0
tFCD
VPGOOD
2V/div
0
IOUT
5A/div
125mV STEP
VSENSE - VIN
100mV/div
VOUT
5V/div
VGATE
5V/div
VGATE
5V/div
0
400ns/div
VIN = 5.0V
1ms/div
VIN = 5.0V, RSENSE = 10mΩ,
RTIM = 27kΩ, CBOARD = 1000µF
_______________________________________________________________________________________
5
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
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.)
STARTUP WAVEFORMS
SLOW TURN-ON
AUTO-RETRY DELAY
MAX5904 toc18
MAX5904 toc19
VON
2V/div
VGATE
5V/div
VPGOOD
2V/div
IOUT
5A/div
VOUT
5V/div
VOUT
5V/div
IOUT
5A/div
VGATE
5V/div
1ms/div
VIN = 5.0V, RSENSE = 10mΩ, RTIM = 47kΩ,
CBOARD = 1000µF, CGATE = 22nF
40ms/div
VIN = 5.0V, RSENSE = 10mΩ, RTIM = 47kΩ,
CBOARD = 1000µF, RBOARD = 1.4Ω
Pin Description
PIN
6
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.
—
2
TIM
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.
1
3
IN1
Channel 1 Supply Input. Connect to a supply voltage from 1V to 13.2V.
2
4
SENSE1
Channel 1 Current-Sense Input. Connect RSENSE1 from IN1 to SENSE1.
Channel 1 Gate-Drive Output. Connect to gate of external N-channel
MOSFET.
3
5
GATE1
4
6
GND
Ground
—
7
LIM1
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.
—
8
MON1
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.
—
9
MON2
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.
_______________________________________________________________________________________
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
PIN
MAX5904/
MAX5905
MAX5906–
MAX5909
NAME
FUNCTION
—
10
LIM2
5
11
ON
6
12
GATE2
7
13
SENSE2
Channel 2 Current-Sense Input. Connect RSENSE2 from IN2 to SENSE2.
8
14
IN2
Channel 2 Supply Input. Connect to a supply voltage from 1V to 13.2V.
—
15
INC+
Uncommitted Comparator Noninverting Input
—
16
OUTC
Uncommitted Comparator Open-Drain Output. Actively held low when
VINC+ is less than 1.236V.
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.
On Comparator Input
Channel 2 Gate-Drive Output. Connect to gate of external N-channel
MOSFET.
Detailed Description
The MAX5904–MAX5909 are circuit breaker ICs for hotswap applications where a line card is inserted into a
live backplane. 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
external N-channel MOSFETs, external current-sense
resistors, 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 current-limit threshold of the MAX5906–MAX5909 can be
adjusted with external resistors.
Startup Period
R TIM sets the duration of the startup period for the
MAX5906–MAX5909 from 0.4ms to 50ms (see the
Setting the Startup Period 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).
3) The device is not latched or in its auto-retry delay.
(See Latched and Auto-Retry Fault Management.)
The MAX5904–MAX5909 limit the load current if an
overcurrent fault occurs during startup. The slow comparator 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 currentsense resistor.
During the startup period the gate drive current is typically 100µA and decreases with the increase of the
gate voltage (see Typical Operating Characteristics).
This allows the controller to slowly enhance the
MOSFETs. If the fast comparator detects an overcurrent, 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 startup 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 3). 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 current in response to a fault condition. After a fault,
PGOOD is pulled low, the MAX5905/MAX5907/
_______________________________________________________________________________________
7
MAX5904–MAX5909
Pin Description (continued)
8
OUT1
Q1
RSENSE1
MON1
GATE1
SENSE1
IN1
1.236V
3mA
VSC, TH
INC+
RLIM1
UVLO
ON
DEVICE CONTROL
LOGIC
TIMING
OSCILLATOR
2.4V
SLOW COMP.
FAST COMP.
543mV
N
RTIM
OUTC
TIM
STARTUP
OSCILLATOR
TO STARTUP
LOGIC BLOCKS
0.4V
PGOOD
CHARGE PUMP
OSCILLATOR
543mV
687mV
687mV
0.825V
100µA
N
CHARGE
PUMP
100µA
TO STARTUP
LOGIC BLOCKS
CURRENT CONTROL
AND
STARTUP LOGIC
UVLO
FAST DISCHARGE
2.025V
2.4V
BIAS AND
REFERENCES
SLOW DISCHARGE
CURRENT CONTROL
AND
STARTUP LOGIC
SLOW COMP.
FAST COMP.
VFS, TH
FAST DISCHARGE
CHARGE
PUMP
VFS, TH
MAX5906
MAX5907
MAX5908
MAX5909
LIM2
SLOW DISCHARGE
LIM1
RLIM2
3mA
VSC, TH
MON2
GATE2
SENSE2
IN2
Q2
OUT2
RSENSE2
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
Figure 1. MAX5906–MAX5909 Functional Diagram
_______________________________________________________________________________________
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
MAX5904–MAX5909
ON
SLOW
COMPARATOR
PGOOD
tSTART + tPGDLY
3ms
4.8V TO 5.8V
VOUT
TURN-OFF TIME
VGATE
FAST
COMPARATOR
VTH
VGATE
VOUT
110µs
CBOARD = LARGE
VSU,TH
260ns
RSENSE
CBOARD = 0
VSC,TH
ILOAD
tON
VFC,TH
(4 x VSC,TH)
SENSE VOLTAGE (VIN - VSENSE)
Figure 2. Startup Waveforms
Figure 3. VariableSpeed/BiLevel Response
MAX5909 stay latched off and the MAX5904/MAX5906/
MAX5908 automatically restart.
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).
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 comparator 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 minimum of 110µs with a large overdrive voltage (Figure 3).
Response time is 3ms for a 1mV overdrive. The variable
speed response time allows the MAX5904–MAX5909 to
ignore low-amplitude momentary glitches, thus increasing system noise immunity. After an extended overcurrent condition, a fault is generated, PGOOD is pulled
low, and the MOSFET gates are discharged with a
strong 3mA pulldown current.
Fast Comparator Normal Operation
In normal operation, if the load current reaches the fastcomparator 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 3).
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 insufficient gate drive voltage. tD,UVLO ensures that the board
is fully inserted into the backplane and that the input
_______________________________________________________________________________________
9
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
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 Auto-Retry 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 automatically restart after the auto-retry delay that is internally set
to 64 times tSTART. During the auto-retry delay, toggling
ON below 0.4V does not clear the fault. The auto-retry
can be overridden causing the startup period to begin
immediately by toggling one of the supply voltages
below the UVLO threshold.
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 V MON _ is less than 543mV or greater than
687mV. If an output voltage fault is detected PGOOD
pulls low. When the MAX5906/MAX5907 detect an output voltage fault on either MON1 or MON2, the fault is
latched and both external MOSFET gates are discharged 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 application’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 voltage drop at full load to limit the MOSFET power dissipation. 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 MOSFET Thermal Considerations).
Using the MAX5905/MAX5907/MAX5909 in latched
mode allows the use of MOSFETs with lower power ratings. A MOSFET typically withstands single-shot pulses
with higher dissipation than the specified package rating. 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 slowcomparator threshold voltage at a current level above
Table 1. Status Output Truth Table
DEVICE IN
STARTUP
PERIOD
ON
OVERCURRENT
FAULT
OVER/UNDERVOLTAGE
FAULT
PART IN RETRY-TIMEOUT
PERIOD OR LATCHED OFF
PGOOD
Yes
X
X
X
X
X
Low
X
Yes
X
X
X
X
Low
X
X
Low
X
X
X
Low
X
X
X
Yes
X
X
Low
X
X
X
X
Yes
X
Low
DEVICE IN
UVLO DELAY
PERIOD
X
X
X
X
X
Yes
Low
No
No
High
No
No
No
High-Z
X = don’t care
10
______________________________________________________________________________________
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
PART NUMBER
MANUFACTURER
IRF7413
times the nominal load current. To adjust the slow-comparator threshold calculate RLIM as follows:
V − 25mV
RLIM = TH
0.25µA
DESCRIPTION
11mΩ, 8 SO, 30V
International
Rectifier
IRF7401
IRL3502S
22mΩ, 8 SO, 20V
6mΩ, D2PAK, 20V
MMSF3300
where VTH is the desired slow-comparator threshold
voltage.
20mΩ, 8 SO, 30V
Motorola
MMSF5N02H
30mΩ, 8 SO, 20V
MTB60N05H
14mΩ, D2PAK, 50V
FDS6670A
10mΩ, 8SO, 30V
Fairchild
NDS8426A
13.5mΩ, 8 SO, 20V
FDB8030L
4.5mΩ, D2PAK, 30V
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)2 x 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 dissipated by the sense resistor. Furthermore, the low 25mV
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 protection feature offers inherent system immunity against
load transients and noise. This allows the slow-comparator threshold to be set close to the maximum normal operating level without experiencing nuisance
faults. Typically, set the overload current at 1.2 to 1.5
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 resistance connected from TIM to GND (RTIM). RTIM must be
between 4kΩ and 500kΩ. The MAX5906–MAX5909 startup period has a default value of 9ms when TIM is left
floating. Calculate RTIM with the following equation:
RTIM =
t START
128 × 800pF
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 (C BOARD) is small, the
inrush current is low.
Table 3. Component Manufacturers
COMPONENT
Sense Resistors
MOSFETs
PHONE
WEBSITE
Dale-Vishay
MANUFACTURER
402-564-3131
www.vishay.com
IRC
704-264-8861
www.irctt.com
International Rectifier
310-233-3331
www.irf.com
Fairchild
888-522-5372
www.fairchildsemi.com
Motorola
602-244-3576
www.mot-sps.com/ppd
______________________________________________________________________________________
11
MAX5904–MAX5909
Table 2. Recommended N-Channel
MOSFETs
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
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 output 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:
t=
RSENSE
CBOARD
RPULLUP
SENSE
IN
CGATE × ∆VGATE + QGATE
IGATE
GATE
CGATE
MAX5906
MAX5907
MAX5908
MAX5909
PGOOD
ON
where:
C GATE is the external gate to ground capacitance
(Figure 4)
∆VGATE is the change in gate voltage
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.
IINRUSH =
CBOARD
× IGATE + ILOAD
Crss + CGATE
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 approximately 60nC of gate charge and Crss = 600pF. The
MAX5904–MAX5909 have a 100µA gate-charging current 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.
GND
Figure 4. Operating with an External Gate Capacitor
With no gate capacitor the inrush current, charge, and
discharge times are:
6µF
× 100µA + 0 = 1A
600pF + 0
0 × 10.4V + 60nC
t CHARGE =
= 0.6ms
100µA
IINRUSH =
tDISCHARGE _ SLOW =
tDISCHARGE _ FAST =
0 × 10.4V + 60nC
= 0.6ms
100µA
0 × 10.4V + 60nC
= 0.02ms
3mA
With a 22nF gate capacitor the inrush current, charge,
and discharge times are:
6µF
× 100µA + 0 = 26.5mA
600pF + 22nF
22nF × 10.4V + 60nC
t CHARGE =
= 2.89ms
100µA
IINRUSH =
tDISCHARGE _ SLOW =
tDISCHARGE _ FAST =
12
VOUT
VIN
22nF × 10.4V + 60nC
= 2.89ms
100µA
22nF × 10.4V + 60nC
= 0.096ms
3mA
______________________________________________________________________________________
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
MAX5904–MAX5909
RSENSE1
Q1
V1
OUT1
CBOARD1
IN1
R1
ON
VEN
SENSE1
GATE1
ON
OFF
MAX5904
MAX5905
C1
GND
GND
IN2
SENSE2
GATE2
OUT2
V2
Q2
RSENSE2
CBOARD2
VEN
(V
EN - VON1, TH
(V
EN - VON2, TH
t1 = -R1C1 ln
VON2, TH
VEN
)
VON
VON1, TH
V1
t2 = -R1C1 ln
VEN
)
V2
tDELAY = -R1C1 ln
t0
t1
( VV
)
EN - VON1, TH
EN - VON2, TH
t2
TDELAY
Figure 5. Power Sequencing: Channel 2 Turns On tDELAY After Channel 1
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
R SENSE 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 constant and the turn-on time is:
t ON =
CBOARD × VIN × RSENSE
VSU,TH
The maximum inrush current in this case is:
IINRUSH =
VSU,TH
RSENSE
Figure 2 shows the waveforms and timing diagrams for
a startup transient with current regulation. (See 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
______________________________________________________________________________________
13
MAX5904–MAX5909
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
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 channel 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 comparator is ideal for power sequencing (Figure 5).
Uncommitted Comparator
The MAX5906–MAX5909 feature an uncommitted comparator that increases system flexibility. This comparator can be used for voltage monitoring, or for
generating a power-on reset signal for on-card microprocessors (Figure 6).
The uncommitted comparator output (OUTC) is open
drain and is pulled low when the comparator input voltage (VINC+) is below its threshold voltage (1.236V).
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 7).
Input Transients
The voltage at IN1 or IN2 must be above the UVLO during inrush and fault conditions. When a short-circuit
condition occurs on the board, the fast comparator trips
causing the external MOSFET gates to be discharged
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 transients caused by this
high di/dt.
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 scenario 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 thermal resistance with the following equation:
−T
T
Z θJA(MAX ) ≤ JMAX A
VIN × ISTART
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–
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 connections (Figure 8).
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.
Chip Information
TRANSISTOR COUNT: 3230
PROCESS: BiCMOS
MOSFET Thermal Considerations
During normal operation, the external MOSFETs dissipate little power. The MOSFET RDS(ON) is low when the
MOSFET is fully enhanced. The power dissipated in
normal operation is PD = ILOAD2 x RDS(ON). The most
14
______________________________________________________________________________________
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
PART
OUTPUT UNDERVOLTAGE/OVERVOLTAGE
PROTECTION/MONITOR
FAULT MANAGEMENT
—
Auto-Retry
MAX5904ESA
MAX5905ESA
—
Latched
MAX5906EEE
Protection
Auto-Retry
MAX5907EEE
Protection
Latched
MAX5908EEE
Monitor
Auto-Retry
MAX5909EEE
Monitor
Latched
VIN
BACKPLANE
REMOVABLE CARD
WITH NO HOT-INSERTION
PROJECTION
VOUT
VIN
CBOARD
IN
SENSE
GATE
INC+
µP
IN
SENSE
GATE
MAX590_
MAX5906–MAX5909
OUTC
ON
RESET
Figure 6. Power-On Reset
HIGH-CURRENT PATH
Figure 7. Using the MAX5904–MAX5909 on a Backplane
Pin Configurations (continued)
SENSE RESISTOR
TOP VIEW
16 OUTC
PGOOD 1
TIM 2
15 INC+
IN1 3
MAX590_
SENSE1 4
GATE1 5
Figure 8. Kelvin Connection for the Current-Sense Resistors
GND 6
14 IN2
MAX5906
MAX5907
MAX5908
MAX5909
LIM1 7
13 SENSE2
12 GATE2
11 ON
10 LIM2
MON1 8
9
MON2
QSOP
______________________________________________________________________________________
15
MAX5904–MAX5909
Selector Guide
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
MAX5904–MAX5909
Typical Operating Circuits
BACKPLANE
REMOVABLE CARD
RSENSE1
Q1
V1
OUT1
CBOARD1
IN1
SENSE1
GATE1
ON
ON
MAX5904
MAX5905
GND
GND
IN2
SENSE2
GATE2
OUT2
V2
Q2
RSENSE2
CBOARD2
BACKPLANE
REMOVABLE CARD
RSENSE1
Q1
V1
OUT1
*
CBOARD1
*
IN1
SENSE1
GATE1
MON1
ON
ON
PGOOD
STAT
*
TIM
*
LIM1
*
LIM2
COMPOUT
MAX5906
MAX5907
MAX5908
MAX5909
COMP+
MON2
GND
GND
UNCOMMITTED
COMPARATOR
*
IN2
SENSE2
GATE2
*
OUT2
V2
RSENSE2
Q2
CBOARD2
*OPTIONAL
16
______________________________________________________________________________________
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
SOICN.EPS
______________________________________________________________________________________
17
MAX5904–MAX5909
Package Information
Low-Voltage, Dual Hot-Swap Controllers/Power
Sequencers
QSOP.EPS
MAX5904–MAX5909
Package Information (continued)
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.
18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2001 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.