MAXIM MAX5930

19-3032; Rev 0; 10/03
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
Features
The MAX5930/MAX5931 +1V to +13.2V triple hot-swap
controllers provide complete protection for multisupply
systems. They allow the safe insertion and removal of
circuit cards into live backplanes. These devices hot
swap multiple supplies ranging from +1V to +13.2V,
provided one supply is at or above +2.7V and only one
supply is above 11V. The input voltage rails (channels)
can be configured to sequentially turn-on/off, track
each other, or have completely independent operation.
The discharged filter capacitors of the circuit card provide low impedance to the live backplane. High inrush
currents from the backplane to the circuit card can burn
up connectors and components, or momentarily collapse
the backplane power supply leading to a system reset.
The MAX5930/MAX5931 hot-swap controllers prevent
such problems by gradually ramping up the output voltage and regulating the current to a preset limit when the
board is plugged in, allowing the system to stabilize
safely. After the startup cycle is complete, on-chip comparators provide VariableSpeed/BiLevel™ protection
against short-circuit and overcurrent faults, and provide
immunity against system noise and load transients.
The load is disconnected in the event of a fault condition. The MAX5930/MAX5931 fault-management mode
is selectable, allowing latched fault or autoretry after a
fault condition.
The MAX5930/MAX5931 offer a variety of options to
reduce external component count and design time. All
devices integrate an on-board charge pump to drive
the gates of low-cost, external N-channel MOSFETs, an
adjustable startup timer, and an adjustable current limit.
The devices offer integrated features like startup current regulation and current glitch protection to eliminate
external timing resistors and capacitors. The
MAX5931L provides an open-drain, active-low status
output for each channel, the MAX5931H provides an
open-drain, active-high status output for each channel,
and the MAX5930 status output polarity is selectable.
The MAX5930 is available in a 24-pin QSOP package,
and the MAX5931 is available in a 20-pin QSOP package. All devices are specified over the extended -40°C
to +85°C temperature range.
♦ Safe Hot Swap for +1V to +13.2V Power Supplies
with Any Input Voltage (VIN_) ≥ 2.7V and Only One
VIN_ > 11.0V
Applications
Network Switches, Routers,
Hubs
Hot Plug-In Daughter Cards
RAID
Solid-State Circuit Breakers
Power-Supply
Sequencing/Tracking
Base-Station Line Cards
Portable Computer Device
Bays (Docking Stations)
♦ Adjustable Circuit Breaker/Current-Limit
Threshold from 25mV to 100mV
♦ Configurable Tracking, Sequencing, or
Independent Operation Modes
♦ VariableSpeed/BiLevel Circuit-Breaker Response
♦ Internal Charge Pumps Generate N-Channel
MOSFET Gate Drives
♦ Inrush Current Regulated at Startup
♦ Autoretry or Latched Fault Management
♦ Programmable Undervoltage Lockout
♦ Status Outputs Indicate Fault/Safe Condition
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX5930EEG
-40°C to +85°C
24 QSOP
MAX5931LEEP*
-40°C to +85°C
20 QSOP
MAX5931HEEP*
-40°C to +85°C
20 QSOP
*Future product—contact factory for availability.
Selector Guide and Typical Operating Circuit appear at end
of data sheet.
Pin Configurations
TOP VIEW
POL 1
24 MODE
ON2 2
23 ON3
ON1 3
22 LIM2
LIM1 4
IN1 5
21 IN2
MAX5930
20 SENSE2
SENSE1 6
19 GATE2
GATE1 7
18 LIM3
STAT1 8
17 IN3
STAT2 9
16 SENSE3
TIM 10
15 GATE3
LATCH 11
14 GND
STAT3 12
13 BIAS
QSOP
Pin Configurations continued at end of data sheet.
VariableSpeed/BiLevel is a trademark of Maxim Integrated
Products, Inc.
________________________________________________________________ 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
MAX5930/MAX5931
General Description
MAX5930/MAX5931
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND, unless otherwise noted.)
IN_ ..........................................................................-0.3V to +14V
GATE_.............................................................-0.3V to (IN_ + 6V)
BIAS (Note 1) .............................................. (VIN - 0.3V) to +14V
ON_, STAT_, LIM_ (MAX5930), TIM, MODE,
LATCH, POL (MAX5930) ..........................-0.3V to (VIN + 0.3V)
SENSE_........................................................-0.3V to (IN_ + 0.3V)
Current into Any Pin..........................................................±50mA
Continuous Power Dissipation (TA = +70°C)
20-Pin QSOP (derate 9.1mW/°C above +70°C)............727mW
24-Pin QSOP (derate 9.5mW/°C above +70°C)............762mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature .....................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1: VIN is the largest of VIN1, VIN2, and VIN3.
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 larger than or equal to +2.7V and only one supply is > 11.0V, TA = -40°C to +85°C,
unless otherwise noted. Typical values are at VIN1 = 12.0V, VIN2 = 5.0V, VIN3 = 3.3V, VON_ = +3.3V, and TA = +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
13.2
V
2.5
5
mA
25
27.5
POWER SUPPLIES
IN_ Input Voltage Range
Supply Current
VIN_
IQ
At least one VIN_ ≥ +2.7V and only one
VIN_ > 11.0V
1.0
IIN1 + IIN2 + IIN3, VON_ = 2.7V,
VIN_ = +13.2V, after STAT_ high
CURRENT CONTROL
Slow-Comparator Threshold
(VIN_ - VSENSE_)
(Note 3)
VSC,TH
LIM_ = GND
(MAX5930),
MAX5931
(Note 4)
TA = +25°C
22.5
TA = -40°C to +85°C
21.0
27.5
80
125
RLIM_ = 10kΩ (MAX5930)
RLIM_ x 7.5 x
10-6 + 25mV
RLIM_ from LIM_ to GND (MAX5930)
Slow-Comparator Response Time
(Note 4)
Fast-Comparator Threshold
(VIN_ - VSENSE_)
Fast-Comparator Response Time
SENSE_ Input Bias Current
tSCD
1mV overdrive
3
ms
50mV overdrive
130
µs
2x
VFC,TH
tFCD
IB SENSE_
mV
mV
VSC,TH
10mV overdrive, from overload condition
200
VSENSE_ = VIN_
0.03
ns
1
µA
MOSFET DRIVER
Startup Period (Note 5)
tSTART
RTIM = 100kΩ
8.0
10.8
13.6
RTIM = 4kΩ (minimum value)
0.30
0.4
0.55
5
9
14
TIM floating (default)
2
_______________________________________________________________________________________
ms
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
(VIN_ = +1V to +13.2V provided at least one supply is larger than or equal to +2.7V and only one supply is > 11.0V, TA = -40°C to +85°C,
unless otherwise noted. Typical values are at VIN1 = 12.0V, VIN2 = 5.0V, VIN3 = 3.3V, VON_ = +3.3V, and TA = +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
Charging, VGATE_ = GND, VIN_ = +5V
(Note 6)
MIN
TYP
MAX
80
100
125
Discharging, during startup
Average Gate Current
IGATE
Discharging, normal turn-off or triggered by
the slow comparator after startup; VGATE_ =
5V, VIN_ = 10V, VON_ = 0V
UNITS
µA
100
2
3
7
mA
Gate-Drive Voltage
VDRIVE
Discharging, triggered by a fault after
startup; VGATE_ = 5V, VIN_ = 10V, (VIN_ VSENSE_) > VFC,TH_ (Note 7)
30
50
120
VGATE_ - VIN_, IGATE_ = 1µA
4.9
5.3
5.6
V
Low to high
0.85
0.875
0.90
V
ON COMPARATOR
ON_ Threshold
VON_,TH
ON_ Propagation Delay
ON_ Voltage Range
ON_ Input Bias Current
ON_ Pulse-Width Low
Hysteresis
25
10mV overdrive
10
VON_
Without false output inversion
IBON
VON_ = VIN
tUNLATCH
To unlatch after a latched fault
0.03
mV
µs
VIN
V
1
µA
100
µs
DIGITAL OUTPUTS (STAT_)
VSTAT_ ≤ 13.2V
Output Leakage Current
Output Voltage Low
VOL_
POL = floating (MAX5930), ISINK = 1mA
UVLO Threshold
VUVLO
Startup is initiated when this threshold is
reached by any VIN_ and VON_ > 0.9V
(Note 8)
UVLO Hysteresis
VUVLO,HYST
1
µA
0.4
V
2.65
V
UNDERVOLTAGE LOCKOUT (UVLO)
UVLO Glitch Filter Reset Time
UVLO to Startup Delay
tD,GF
tD,UVLO
Input Power-Ready Threshold
VPWRRDY
Input Power-Ready Hysteresis
VPWRHYST
2.25
2.45
250
VIN < VUVLO maximum pulse width to reset
mV
10
µs
Time input voltage must exceed VUVLO
before startup is initiated
20
37.5
60
ms
Any channel, while VIN > VUVLO (Note 9)
0.9
0.95
1.0
V
50
mV
LOGIC AND TIMING
POL Input Pullup
IPOL
LATCH Input Pullup
MODE Input Voltage
POL = GND (MAX5930)
2
4
6
µA
ILATCH
LATCH = GND
2
4
6
µA
VMODE
MODE floating (default to sequencing
mode)
1.0
1.25
1.5
V
0.4
V
Independent-Mode Selection
Threshold
VINDEP,TH
VMODE rising
Tracking-Mode Selection
Threshold
VTRACK,TH
VMODE rising
2.7
V
_______________________________________________________________________________________
3
MAX5930/MAX5931
ELECTRICAL CHARACTERISTICS (continued)
ELECTRICAL CHARACTERISTICS (continued)
(VIN_ = +1V to +13.2V provided at least one supply is larger than or equal to +2.7V and only one supply is > 11.0V, TA = -40°C to +85°C,
unless otherwise noted. Typical values are at VIN1 = 12.0V, VIN2 = 5.0V, VIN3 = 3.3V, VON_ = +3.3V, and TA = +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
MODE Input Impedance
CONDITIONS
MIN
TYP
RMODE
Autoretry Delay
MAX
UNITS
200
tRETRY
kΩ
64 x
Delay time to restart after fault shutdown
ms
tSTART
Note 2: All devices are 100% tested at TA = +25°C. Limits over temperature are guaranteed by design.
Note 3: The slow-comparator threshold is adjustable. VSC,TH = RLIM x 7.5µA + 25mV (see the Typical Operating Characteristics).
Note 4: The current-limit slow-comparator response time is weighed 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).
Note 6: The current available at GATE is a function of VGATE (see the Typical Operating Characteristics).
Note 7: After a fault triggered by the fast comparator, the gate is discharged by the strong discharge current.
Note 8: Each channel input while the other inputs are at +1V.
Note 9: Each channel input while any other input is at +2.7V.
Typical Operating Characteristics
(Typical Operating Circuits, Q1 = Q2 = Q3 = Fairchild FDB7090L, VIN1 = +12.0V, VIN2 = +5.0V, VIN3 = +1V, TA = +25°C, unless otherwise noted. Channels 1 through 3 are identical in performance. Where characteristics are interchangeable, channels 1 through 3
are referred to as X, Y, and Z.)
TOTAL SUPPLY CURRENT
vs. INPUT VOLTAGE
VINY = VINZ = 2.7V
IINX + IINY + IINZ
3
IIN = IIN1 + IIN2 + IIN3
VIN = VINX = VINY = VINZ
VON = VON1 = VON2 = VON3
3.0
2.5
VON_ = VINY = VINZ = 2.7V
VINX = 2.8V
IINY + IINZ
4.0
MAX5930 toc03
5.0
MAX5930 toc01
4
SUPPLY CURRENT
vs. TEMPERATURE
MAX5930 toc02
SUPPLY CURRENT vs. INPUT VOLTAGE
IINX
2
IIN (mA)
IIN (mA)
2.0
IIN (mA)
MAX5930/MAX5931
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
VON = 0V
3.0
1.0
VON = 3.3V
1
IINX
1.5
2.0
0.5
IINY + IINZ
IINY + IINZ
0
1.0
0
4
2
4
6
8
VINX (V)
10
12
14
0
2
4
6
8
VIN (V)
10
12
14
-40
-15
10
35
TEMPERATURE (°C)
_______________________________________________________________________________________
60
85
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
GATE CHARGE CURRENT
vs. GATE VOLTAGE
VINX = 5V
90
60
VINX = 1V
30
4
6
8
10
12
80
10
15
VGATEX (V)
STRONG GATE DISCHARGE CURRENT
vs. GATE VOLTAGE
STRONG GATE DISCHARGE CURRENT
vs. TEMPERATURE
4
VINX = 5V
3
VINX = 3.3V
2
1
VINX = 13.2V
3
VINX = 3.3V
2
1
-15
10
35
60
85
TURN-OFF TIME
vs. SENSE VOLTAGE
VINX = 5V
4
-40
TEMPERATURE (°C)
VONX = 0V
VINY = VINZ = 2.7V
5
20
10
RLIMX = 100Ω
1
TURN-OFF TIME (ms)
VINX = 13.2V
6
GATE DISCHARGE CURRENT (mA)
5
0
5
VINX (V)
VONX = 0V
VINY = VINZ = 2.7V
VINX = 1V
40
VONX = VINY = VINZ = 2.7V
VGATEX = 0V
0
14
MAX5930 toc07
6
2
MAX5930 toc06
VINX = 5V
MAX5930 toc08
0
0.1
0.01
SLOW-COMPARATOR
THRESHOLD
0.001
FAST-COMPARATOR
THRESHOLD
VINX = 1V
VINX = 1V
0
0.0001
0
4
0
8
12
16
20
-40
-15
10
35
60
0
85
25
50
75
VGATEX (V)
TEMPERATURE (°C)
VINX - VSENSEX (mV)
TURN-OFF TIME vs. SENSE VOLTAGE
(EXPANDED SCALE)
SLOW-COMPARATOR THRESHOLD
vs. RLIMX
STARTUP PERIOD
vs. RTIM
RLIMX = 100Ω
120
100
400
500
40
tSTART (ms)
VSC,TH (mV)
125
60
80
1
100
MAX5930 toc12
10
MAX5930 toc10
GATE DISCHARGE CURRENT (mA)
120
0
0
TURN-OFF TIME (ms)
VINX = 13.2V
160
MAX5930 toc09
2
VINX = 13.2V
120
200
GATE CHARGE CURRENT (µA)
4
VONW = VINY = VINZ = 2.7V
MAX5930 toc11
VDRIVEX (V)
6
150
GATE CHARGE CURRENT
vs. TEMPERATURE
MAX5930 toc05
VINY = VINZ = 2.7V
GATE CHARGE CURRENT (µA)
8
MAX5930 toc04
GATE-DRIVE VOLTAGE
vs. INPUT VOLTAGE
60
40
20
20
SLOW-COMPARATOR THRESHOLD
0
0.1
20
25
30
35
40
VINX - VSENSEX (mV)
45
50
0
0
2
4
6
RLIMX (kΩ)
8
10
0
100
200
300
RTIM (kΩ)
_______________________________________________________________________________________
5
MAX5930/MAX5931
Typical Operating Characteristics (continued)
(Typical Operating Circuits, Q1 = Q2 = Q3 = Fairchild FDB7090L, VIN1 = +12.0V, VIN2 = +5.0V, VIN3 = +1V, TA = +25°C, unless otherwise noted. Channels 1 through 3 are identical in performance. Where characteristics are interchangeable, channels 1 through 3
are referred to as X, Y, and Z.)
Typical Operating Characteristics (continued)
(Typical Operating Circuits, Q1 = Q2 = Q3 = Fairchild FDB7090L, VIN1 = +12.0V, VIN2 = +5.0V, VIN3 = +1V, TA = +25°C, unless otherwise noted. Channels 1 through 3 are identical in performance. Where characteristics are interchangeable, channels 1 through 3
are referred to as X, Y, and Z.)
TURN-OFF TIME
SLOW-COMPARATOR FAULT
VSTATX
2V/div
0V
VSTATX
2V/div
0V
VINX - VSENSEX
25mV/div
AC-COUPLED
VINX - VSENSEX
100mV/div
0V
VGATEX
5V/div
0V
VGATEX
5V/div
0V
STARTUP WAVEFORMS FAST TURN-ON
(CGATE = 0nF, CBOARD = 1000µF)
STARTUP WAVEFORMS SLOW TURN-ON
(CGATE = 0.22µF, CBOARD = 1000µF)
VSTATX
5V/div
IOUTX
2A/div
MAX5930 toc16
100ns/div
MAX5930 toc15
1ms/div
VONX
5V/div
VON
5V/div
VSTATX
5V/div
IOUTX
2A/div
VGATEX
10V/div
VOUTX
5V/div
VGATEX
10V/div
VOUTX
5V/div
2ms/div
AUTORETRY DELAY
TURN-ON IN
VOLTAGE-TRACKING MODE
VINX
2V/div
MAX5930 toc18
2ms/div
VGATEX
2V/div
0V
VPWRRDY
0V
VONX
2V/div
VOUTX
2V/div
0V
VGATEY
IOUTX
500mA/div
5V/div
0V
0V
100ms/div
6
MAX5930 toc14
MAX5930 toc13
TURN-OFF TIME
FAST-COMPARATOR FAULT
MAX5930 toc17
MAX5930/MAX5931
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
VGATEX
4ms/div
_______________________________________________________________________________________
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
MAX5930 toc19
VPWRRDY
VINX
2V/div
0V
VONX
2V/div
VPWRRDY
0V
VONX
2V/div
0V
VGATEY
5V/div
0V
VINX
2V/div
MAX5930 toc20
TURN-ON IN
XXXX
POWER-SEQUENCING
MODE
TURN-OFF IN
XXXX
VOLTAGE-TRACKING
MODE
VGATEY
5V/div
VGATEX
VGATEX
0V
4ms/div
4ms/div
TURN-OFF IN
XXXX
POWER-SEQUENCING
MODE
MAX5930 toc22
VPWRRDY
MAX5930 toc21
VINX
2V/div
0V
TURN-ON IN
XXXX MODE
INDEPENDENT
VINX
2V/div
0V
VONX
2V/div
VONX
2V/div
0V
VGATEY
VGATEY
VGATEX
5V/div
0V
VGATEX
4ms/div
TURN-OFF IN
XXXX MODE
INDEPENDENT
STRONG GATE DISCHARGE CURRENT
vs. OVERDRIVE
VPWRRDY
VGATEY
5V/div
VGATEX
50
GATE DISCHARGE CURRENT (mA)
VINX
2V/div
0V
VONX
2V/div
40
MAX5930 toc24
4ms/div
MAX5930 toc23
5V/div
0V
VONX = VIN
VGATE = 5V
AFTER STARTUP
LIM_ = GND VINX = 12V
VINX = 5V
30
20
VINX = 2.7V
10
0V
0
4ms/div
20
25
30
35
40
45
50
VIN_ - VSENSE_ (mV)
_______________________________________________________________________________________
7
MAX5930/MAX5931
Typical Operating Characteristics (continued)
(Typical Operating Circuits, Q1 = Q2 = Q3 = Fairchild FDB7090L, VIN1 = +12.0V, VIN2 = +5.0V, VIN3 = +1V, TA = +25°C, unless otherwise noted. Channels 1 through 3 are identical in performance. Where characteristics are interchangeable, channels 1 through 3
are referred to as X, Y, and Z.)
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
MAX5930/MAX5931
Pin Description
PIN
8
NAME
FUNCTION
MAX5930
MAX5931
1
—
POL
STAT Output-Polarity Select (See Table 3 and the Status Output Section)
2
1
ON2
On/Off Channel 2 Control Input (See the Mode Section)
3
2
ON1
On/Off Channel 1 Control Input (See the Mode Section)
4
—
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. Do not leave LIM1 open.
5
3
IN1
6
4
SENSE1
7
5
GATE1
Channel 1 Gate-Drive Output. Connect to gate of external N-channel MOSFET.
Channel 1 Supply Input. Connect to a 1V to 13.2V supply voltage and to one end of
RSENSE1. Bypass with a 0.1µF capacitor to ground.
Channel 1 Current-Sense Input. Connect SENSE1 to the drain of an external MOSFET
and to one end of RSENSE1.
8
6
STAT1
Open-Drain Status Signal for Channel 1. STAT1 asserts when hot swap is successful and
tSTART has elapsed. STAT1 deasserts if ON1 is low, or if channel 1 is turned off for any fault
condition.
9
7
STAT2
Open-Drain Status Signal for Channel 2. STAT2 asserts when hot swap is successful and
tSTART has elapsed. STAT2 deasserts if ON2 is low, or if channel 2 is turned off for any fault
condition.
10
8
TIM
11
9
LATCH
Latch/Autoretry Selection Input. Connect LATCH to GND for autoretry mode after a fault.
Leave LATCH open for latch mode.
12
10
STAT3
Open-Drain Status Signal for Channel 3. STAT3 asserts when hot swap is successful and
tSTART has elapsed. STAT3 deasserts if ON3 is low, or if channel 3 is turned off for any
fault condition.
13
11
BIAS
Supply Reference Output. The highest supply is available at BIAS for filtering. Connect a
1nF to 10nF ceramic capacitor from BIAS to GND. No other connections are allowed to
BIAS.
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. RTIM must be between
4kΩ and 500kΩ.
14
12
GND
15
13
GATE3
Channel 3 Gate-Drive Output. Connect to gate of external N-channel MOSFET.
Ground
16
14
SENSE3
Channel 3 Current-Sense Input. Connect SENSE3 to the drain of an external MOSFET
and to one end of RSENSE3.
17
15
IN3
Channel 3 Supply Input. Connect to a supply voltage from 1V to 13.2V and to one end of
RSENSE3. Bypass with a 0.1µF capacitor to ground.
18
—
LIM3
Channel 3 Current-Limit Setting. Connect a resistor from LIM3 to GND to set current-trip
level. Connect to GND for the default 25mV threshold. Do not leave LIM3 open.
19
16
GATE2
Channel 2 Gate-Drive Output. Connect to gate of external N-channel MOSFET.
20
17
SENSE2
Channel 2 Current-Sense Input. Connect SENSE2 to the drain of an external MOSFET
and to one end of RSENSE2.
21
18
IN2
Channel 2 Supply Input. Connect to a 1V to 13.2V supply voltage and to one end of
RSENSE2. Bypass with a 0.1µF capacitor to ground.
_______________________________________________________________________________________
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
PIN
NAME
MAX5930
MAX5931
22
—
LIM2
23
19
ON3
24
20
MODE
FUNCTION
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. Do not leave LIM2 open.
On/Off Channel 3 Control Input (See the Mode Section)
Mode Configuration Input. Mode is configured according to Table 1 as soon as one of
the IN_ voltages exceeds UVLO and before turning on OUT_ (see the Mode section).
Detailed Description
The MAX5930/MAX5931 are circuit-breaker ICs for hotswap applications where a line card is inserted into a
live backplane. The MAX5930/MAX5931 operate down
to 1V provided one of the inputs is above 2.7V and only
one supply is above 11V. 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
MAX5930/MAX5931 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 on-chip comparators. The startup period
and current-limit threshold of the MAX5930/MAX5931
can be adjusted with external resistors. Figure 1 shows
the MAX5930/MAX5931 functional diagram.
The MAX5930 offers three programmable current limits,
selectable fault-management mode, and selectable
STAT_ output polarity. The MAX5930 features fixed current limits, selectable fault-management mode, and
fixed STAT_ output polarity.
Mode
The MAX5930/MAX5931 supports three modes of operation: voltage-tracking, power-sequencing, and independent mode. Select the appropriate mode according
to Table 1.
Voltage-Tracking Mode
Connect MODE high to enter voltage-tracking mode.
While in voltage-tracking mode, all channels turn on
and off together. To turn all channels on:
• At least one VIN_ must exceed VUVLO (2.45V) for the
UVLO to startup delay (37.5ms).
• All VIN_ must exceed VPWRRDY (0.95V).
• All VON_ must exceed VON,TH (0.875V).
• No faults may be present on any channel.
The MAX5930/MAX5931 turns off all channels if any of
the above conditions are not met. After a fault-latched
shutdown, cycle any of the ON_ pins to unlatch and
restart all channels.
Power-Sequencing Mode
Leave MODE floating to enter power-sequencing
mode. While in power-sequencing mode, the
MAX5930/MAX5931 turn on and off each channel
depending on the state of the corresponding VON_. To
turn on a given channel:
• At least one VIN_ must exceed VUVLO (2.45V) for the
UVLO to startup delay (37.5ms).
• All VIN_ must exceed VPWRRDY (0.95V).
• The corresponding V ON_ must exceed V ON,TH
(0.875V).
• No faults may be present on any channel.
The MAX5930/MAX5931 turn off all channels if any of the
above conditions are not met. After a fault-latched shutdown, cycle any of the ON_ pins to unlatch and restart all
channels, dependent on the corresponding VON_ state.
Independent Mode
Tie MODE to GND to enter independent mode. While in
independent mode the MAX5930/MAX5931 provide
complete independent control for each channel. To turn
on a given channel:
• At least one VIN_ must exceed VUVLO (2.45V) for the
UVLO to startup delay (37.5ms).
• The corresponding V IN_ must exceed V PWRRDY
(0.95V).
• The corresponding V ON_ must exceed V ON,TH
(0.875V).
Table 1. Operational Mode Selection
MODE
High (Connect to BIAS)
OPERATION
Voltage Tracking
OPEN
Voltage Sequencing
GND
Independent
_______________________________________________________________________________________
9
MAX5930/MAX5931
Pin Description (continued)
MAX5930/MAX5931
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
RLIM1
RTIM
LIM1*
RLIM2
1nF
LTIM
BIAS
LIM2*
POL*
IN1
IN2
VSC, TH
VFC, TH
VFC, TH
STARTUP
OSCILLATOR
VSC, TH
RSENSE1
RSENSE2
FAST COMP
SENSE1
UVLO
BIAS AND
REFERENCES
2.45V
UVLO
SENSE2
TIMING
OSCILLATOR
SLOW COMP
FAST COMP
SLOW COMP
GATE1
GATE2
CURRENT CONTROL
AND
STARTUP LOGIC
CHARGE
PUMP
Q1
OUT1
3mA
50mA
CURRENT CONTROL
AND
STARTUP LOGIC
DEVICE CONTROL
LOGIC
SLOW DISCHARGE
FAST DISCHARGE
CHARGE
PUMP
Q2
OUT2
SLOW DISCHARGE
FAST DISCHARGE
3mA
50mA
100µA
100µA
STAT1
STAT2
LIM3*
RLIM3
IN3
VSC, TH
VFC, TH
MAX5930
MAX5931
RSENSE3
FAST COMP
UVLO
SENSE3
SLOW COMP
GATE3
CHARGE
PUMP
Q3
OUT3
CURRENT CONTROL
AND
STARTUP LOGIC
SLOW DISCHARGE
FAST DISCHARGE
3mA
50mA
*MAX5930 ONLY.
100µA
STAT3
FAULT
MANAGEMENT
ON
INPUT
COMPARATORS
OPERATION
MODE
LATCH*
ON1 ON2 ON3
MODE
Figure 1. Functional Diagram
The MAX5930/MAX5931 turn off the corresponding
channel if any of the above conditions are not met.
During a fault condition on a given channel only, the
affected channel is disabled. After a fault-latched shutdown, recycle the corresponding ON_ inputs to unlatch
and restart only the corresponding channel.
10
Startup Period
RTIM sets the duration of the startup period from 0.4ms
(RTIM = 4kΩ) to 51ms (RTIM = 500kΩ) (see the Setting
the Startup Period, RTIM section). The default startup
period is fixed at 9ms when TIM is floating. The startup
period begins after the turn-on conditions are met as
described in the Mode section, and the device is not
latched or in its autoretry delay (see the Latched and
Autoretry Overcurrent Fault Management section).
______________________________________________________________________________________
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
MAX5930/MAX5931
ON1
ON2
ON3
VUVLO (2.45V)
ANY
IN_
VPWRRDY (0.95V)
IN2
VPWRRDY (0.95V)
IN3
VPWRRDY (0.95V)
OUT1*
OUT2*
OUT3*
*THE OUT_ DISCHARGE RATE IS A RESULT OF NATURAL DECAY OF THE LOAD RESISTANCE AND CAPACITANCE.
Figure 2. Voltage-Tracking Timing Diagram (Provided tD, UVLO Requirement is Met)
______________________________________________________________________________________
11
MAX5930/MAX5931
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
ON1
ON2
ON3
VUVLO (2.45V)
ANY
IN_
VPWRRDY (0.95V)
IN2
VPWRRDY (0.95V)
IN3
VPWRRDY (0.95V)
*
OUT1
*
OUT2
*
*
OUT3
*THE OUT_ DISCHARGE RATE IS A RESULT OF NATURAL DECAY OF THE LOAD RESISTANCE AND CAPACITANCE.
Figure 3. Power-Sequencing Timing Diagram (Provided tD, UVLO Requirement is Met)
12
______________________________________________________________________________________
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
Figure 6 shows the startup waveforms. STAT_ is asserted immediately after the startup period if no fault condition is present.
ON1 = ON2 = ON3
OVERCURRENT
FAULT
CONDITION
VariableSpeed/BiLevel Fault Protection
*
OUT1
*
OUT2
*
OUT3
*THE OUT_ DISCHARGE RATE IS A RESULT OF NATURAL DECAY
OF THE LOAD RESISTANCE AND CAPACITANCE.
Figure 4. Power-Sequencing Fault Turn-Off
The MAX5930/MAX5931 limit the load current if an
overcurrent fault occurs during startup instead of completely turning off the external MOSFETs. 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 limited to 100µA and decreases with the increase of the gate
voltage (see the Typical Operating Characteristics). This
allows the controller to slowly enhance the MOSFETs. If
the fast comparator detects an overcurrent, the
MAX5930/MAX5931 regulate the gate voltage to ensure
that the voltage across the sense resistor does not
VariableSpeed/BiLevel fault protection incorporates
comparators with different thresholds and response
times to monitor the load current (Figure 7). 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
the MOSFET gates with a strong 3mA/50mA pulldown
current in response to a fault condition. After a fault,
STAT_ is deasserted. Use the LATCH input to control
whether the STAT_ outputs latch off or autoretry (see
the Latched and Autoretry Fault Management section).
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 adjustable from
25mV to 100mV. The slow-comparator response time is
3ms for a 1mV overdrive. The response time decreases
to 100µs with a large overdrive. The variable-speed
response time allows the MAX5930/MAX5931 to ignore
low-amplitude momentary glitches, thus increasing system noise immunity. After an extended overcurrent condition, a fault is generated, STAT_ outputs are deasserted
and the MOSFET gates are discharged with a 3mA pulldown current.
Fast-Comparator Startup Period
During the startup period, the fast comparator regulates the gate voltages to ensure that the voltage
across the sense resistor does not exceed the startup
fast-comparator threshold voltage (VSU,TH), VSU,TH is
scaled to two times the slow-comparator threshold
(VSC,TH).
______________________________________________________________________________________
13
MAX5930/MAX5931
exceed VSU,TH. This effectively regulates the inrush current during startup.
MAX5930/MAX5931
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
ON1
ON2
ON3
VUVLO (2.45V)
IN1
VPWRRDY (0.95V)
IN2
VPWRRDY (0.95V)
IN3
VPWRRDY (0.95V)
tD,UVLO
*
OUT1
*
OUT2
*
OUT3
*THE OUT_ DISCHARGE RATE IS A RESULT OF NATURAL DECAY OF THE LOAD RESISTANCE AND CAPACITANCE.
Figure 5. Independent-Mode Timing Diagram
14
______________________________________________________________________________________
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
MAX5930/MAX5931
ON_
STAT_
SLOW
COMPARATOR
tSTART
VDRIVE
VOUT_
VGATE_
VOUT_
3ms
TURN-OFF TIME
VGATE_
FAST
COMPARATOR
VTH
130µs
CBOARD_ = LARGE
VFC,TH
200ns
RSENSE_
CBOARD_ = 0
VSC,TH
ILOAD_
tON
VFC,TH
(2 x VSC,TH)
SENSE VOLTAGE (VIN - VSENSE)
Figure 6. Independent-Mode Startup Waveforms
Figure 7. VariableSpeed/BiLevel Response
Fast-Comparator Normal Operation
In normal operation, if the load current reaches the fastcomparator threshold, a fault is generated, STAT_ is
deasserted, and the MOSFET gates are discharged
with a strong 50mA pulldown current. This happens in
the event of a serious current overload or a dead short.
The fast-comparator threshold voltage (V FC,TH ) is
scaled to two times the slow-comparator threshold
(VSC,TH). This comparator has a fast response time of
200ns (Figure 7).
Bringing all input supplies below the UVLO threshold for
longer than tD,GF reinitiates tD,UVLO and the startup period, tSTART. See Figure 8 for an example of automatic
turn-on function.
Undervoltage Lockout (UVLO)
The UVLO prevents the MAX5930/MAX5931 from turning
on the external MOSFETs until one input voltage
exceeds the UVLO threshold (2.45V) for tD,UVLO. The
MAX5930/MAX5931 use power from the highest input
voltage rail for the charge pumps. This allows for more
efficient charge-pump operation. The highest VIN_ is provided as an output at BIAS. 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 voltages are stable.
The MAX5930/MAX5931 includes a UVLO glitch filter
(tD,GF) to reject all input voltage noise and transients.
Latched and Autoretry Fault Management
The MAX5930 can be configured to either latch the
external MOSFETs off or to autoretry (see Table 2).
Toggling ON_ below 0.875V for at least 100µs clears
the MAX5930/MAX5931 (LATCH = FLOAT) fault and
reinitiates the startup period. Similarly, the MAX5930/
MAX5931 (LATCH = GND) turn the external MOSFETs
off when an overcurrent fault is detected, then automatically restart after the autoretry delay that is internally
set to 64 times tSTART.
Status Outputs (STAT_)
The status (STAT_) outputs are open-drain outputs that
assert when hot swap is successful and tSTART has
elapsed. STAT_ deasserts if ON_ is low or if the channel is turned off for any fault condition.
The polarity of the STAT_ outputs is selected using POL
for the MAX5930 (see Table 3). Tables 4 and 5 contain
the MAX5930/MAX5931 truth tables.
______________________________________________________________________________________
15
MAX5930/MAX5931
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
Table 2. Selecting Fault-Management
Mode (MAX5930)
LATCH
FAULT MANAGEMENT
Floating
Fault condition latches MOSFETs off
Low
Autoretry mode
BACKPLANE
REMOVABLE CARD
V1
V2
V3
Table 3. Selecting STAT_ Polarity
(MAX5930)
POL
STAT_
Low
Asserts low
Floating
Asserts high (open-drain)
ON1
ON1
ON2
ON2
ON3
ON3
Applications Information
Component Selection
N-Channel MOSFETs
Select the external MOSFETs according to the application’s current levels. Table 6 lists recommended components. The MOSFET’s on-resistance (R DS(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 autoretry mode (see
the MOSFET Thermal Considerations section).
Using these devices 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 7 lists some
recommended MOSFET manufacturers.
Sense Resistor
The slow-comparator threshold voltage is adjustable
from 25mV to 100mV. 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 full load current. The fast-comparator threshold is two times the slow-comparator threshold in normal operating mode. Choose the senseresistor power rating to be greater than or equal to 2 x
(IOVERLOAD) x VSC,TH. Table 7 lists some recommended sense-resistor manufacturers.
16
MAX5930
MAX5931
GND
GND
Figure 8. Automatic Turn-On When Input Voltages are Above
their Respective Undervoltage Lockout Threshold (Provided
tD,UVLO Requirement is Met)
Slow-Comparator Threshold, RLIM (MAX5930)
The slow-comparator threshold voltage is adjustable
from 25mV to 100mV, allowing 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. To adjust the slow-comparator threshold, calculate RLIM as follows:
V − 25mV
RLIM = TH
7.5µA
where VTH is the desired slow-comparator threshold
voltage. Shorting LIM_ to GND sets VTH to 25mV. Do
not leave LIM_ open.
______________________________________________________________________________________
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
MAX5930/MAX5931
Table 4. Status Output Truth Table: Voltage-Tracking and Power-Sequencing Modes
CHANNEL 1
FAULT
PART
CHANNEL 2
FAULT
CHANNEL 3
FAULT
STAT1/
GATE1*
STAT2/
GATE2*
STAT3/
GATE3*
Yes
X
X
L/OFF
L/OFF
L/OFF
X
Yes
X
L/OFF
L/OFF
L/OFF
X
X
Yes
L/OFF
L/OFF
L/OFF
L/OFF
MAX5930 (POL = 1),
MAX5931H
X
X
X
L/OFF
L/OFF
No
No
No
H/ON
H/ON
H/ON
Yes
X
X
H/OFF
H/OFF
H/OFF
X
Yes
X
H/OFF
H/OFF
H/OFF
X
X
Yes
H/OFF
H/OFF
H/OFF
X
X
X
H/OFF
H/OFF
H/OFF
No
No
No
L/ON
L/ON
L/ON
MAX5930 (POL = 0),
MAX5931L
*L = Low, H = High.
Table 5. Status Output Truth Table: Independent Mode
CHANNEL 1
FAULT
CHANNEL 2
FAULT
CHANNEL 3
FAULT
STAT1/
GATE1
STAT2/
GATE2
STAT3/
GATE3
Yes
Yes
Yes
Yes
Yes
No
Unasserted/OFF
Unasserted/OFF
Unasserted/OFF
Unasserted/OFF
Unasserted/OFF
Yes
No
Yes
Unasserted/OFF
Asserted/ON
Asserted/ON
Unasserted/OFF
Yes
No
No
Unasserted/OFF
Asserted/ON
Asserted/ON
No
Yes
Yes
Asserted/ON
Unasserted/OFF
Unasserted/OFF
No
Yes
No
Asserted/ON
Unasserted/OFF
Asserted/ON
No
No
Yes
Asserted/ON
Asserted/ON
Unasserted/OFF
No
No
No
Asserted/ON
Asserted/ON
Asserted/ON
Note: STAT_ is asserted when hot swap is successful and tON has elapsed. STAT_ is unasserted during a fault.
Table 6. Recommended N-Channel MOSFETs
PART NUMBER
MANUFACTURER
IRF7413
IRF7401
International Rectifier
MMSF3300
20mΩ, 8-pin SO, 30V
Motorola
FDS6670A
FDB8030L
30mΩ, 8-pin SO, 20V
14mΩ, D2PAK, 50V
MTB60N05H
ND8426A
22mΩ, 8-pin SO, 20V
6mΩ, D2PAK, 20V
IRL3502S
MMSF5N02H
DESCRIPTION
11mΩ, 8-pin SO, 30V
10mΩ, 8-pin SO, 30V
Fairchild
13.5mΩ, 8-pin SO, 20V
4.5mΩ, D2PAK, 30V
______________________________________________________________________________________
17
MAX5930/MAX5931
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
Table 7. Component Manufacturers
COMPONENT
Sense Resistors
MOSFETs
MANUFACTURER
WEBSITE
402-562-3131
www.vishay.com
IRC
704-264-8861
www.irctt.com
Fairchild
888-522-5372
www.fairchildsemi.com
International Rectifier
310-233-3331
www.irf.com
Motorola
602-224-3576
www.mot-sps.com/ppd
Setting the Startup Period, RTIM
The startup period (tSTART) is adjustable from 0.4ms to
50ms. The adjustable startup period feature allows systems to be customized for MOSFET gate capacitance
and board capacitance (CBOARD). The startup period
is adjusted with a resistor connected from TIM to GND
(RTIM). RTIM must be between 4kΩ and 500kΩ. The
startup period has a default value of 9ms when TIM is
left floating. Calculate RTIM with the following equation:
t START
RTIM =
128 × 800pF
where tSTART is the desired startup period.
Startup Sequence
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 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.
• 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 100µA gate-charging current effectively limits
the output voltage dV/dt. Connecting an external
capacitor between GATE and GND extends the turnon time. The time required to charge/discharge a
MOSFET is as follows:
18
PHONE
Dale-Vishay
t=
CGATE × ∆VGATE + QGATE
IGATE
where:
C GATE is the external gate to ground capacitance
(Figure 9),
∆VGATE is the change in gate charge,
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
MAX5930/MAX5931 have a 100µA gate charging current and a 3mA/50mA normal/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:
6µF
× 100µA + 0 = 1A
600pF + 0
0 × 10.4V + 60nC
t CHARGE =
= 0.6ms
100µA
0 × 10.4V + 60nC
tDISCHARGE(NORMAL) =
= 0.02ms
3mA
0 × 10.4V + 60nC
= 1.2µs
tDISCHARGE(STRONG) =
50mA
IINRUSH =
______________________________________________________________________________________
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
VOUT_
VIN
CBOARD
RPULLUP
R1
SENSE_
IN_
GATE_
CGATE
IN_
SENSE_
GATE_
ON_
STAT_
MAX5930
MAX5931
R2
MAX5930
MAX5931
VTURN-ON -
(R2 x R1) VON, TH
R2
ON_
GND
Figure 9. Operating with an External Gate Capacitor
Figure 10. Adjustable Undervoltage Lockout
With a 22nF gate capacitor, the inrush current, charge,
and discharge times are:
under this condition, an external gate capacitor is
not required.
6µF
× 100µA + 0 = 26.5mA
600pF + 22nF
22nF × 10.4V + 60nC
t CHARGE =
= 2.89ms
100µA
22nF × 10.4V + 60nC
tDISCHARGE(NORMAL) =
= 0.096ms
3mA
22nF × 10.4V + 60nC
= 5.8µs
tDISCHARGE(STRONG) =
50mA
IINRUSH =
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 VFC,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:
ON Comparators
The ON comparators control the on/off function of the
MAX5930/MAX5931. ON_ is also used to reset the fault
latch (latch mode). Pull VON_ low for 100µs, tUNLATCH,
to reset the shutdown latch. ON_ also programs the
UVLO threshold (see Figure 10). A resistive-divider
between VIN_, VON_, and GND sets the user-programmable turn-on voltage. In power-sequencing mode, an
RC circuit can be used at ON_ to set the delay timing
(see Figure 11).
Using the MAX5930/MAX5931 on the
Backplane
Using the MAX5930/MAX5931 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 12).
Input Transients
C
× VIN × RSENSE
t ON = BOARD
VFC,TH
The maximum inrush current in this case is:
IINRUSH =
VFC,TH
RSENSE
Figure 6 shows the waveforms and timing diagrams for
a startup transient with current regulation (see the
Typical Operating Characteristics). When operating
The voltage at IN1, IN2, or IN3 must be above VUVLO during inrush and fault conditions. When a short-circuit condition occurs on the board, the fast-comparator trips
cause the external MOSFET gates to be discharged at
50mA according to the mode of operation (see the Mode
section). The main system power supply must be able to
sustain a temporary fault current, without dropping below
the UVLO threshold of 2.45V, until the external MOSFET is
completely off. If the main system power supply collapses
below UVLO, the MAX5930/MAX5931 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
______________________________________________________________________________________
19
MAX5930/MAX5931
RSENSE_
VIN_
MAX5930/MAX5931
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
RSENSEY
Q1
VY
OUTY
CBOARDY
INY
R1
ON
VEN
SENSEY
GATEY
ON
OFF
MAX5930
MAX5931
C1
GND
GND
INZ
SENSEZ
GATEZ
OUTZ
VZ
Q2
RSENSEZ
VEN
CBOARDZ
(V
VEN
VONZ, TH
(V
VEN
)
EN - VONY, TH
t1 = -R1C1 ln
VON
VONY, TH
VY
)
EN - VONZ, TH
t2 = -R1C1 ln
VZ
( VV
tDELAY = -R1C1 ln
t0
t1
)
EN - VONY, TH
EN - VONZ, TH
t2
tDELAY
Figure 11. Power Sequencing: Channel Z Turns On tDELAY After Channel Y
backplane delivering the power to the external card must
have low inductance to minimize voltage transients
caused by this high di/dt.
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 P D = I LOAD 2 x R DS(ON) . The most
power dissipation occurs during the turn-on and turn-off
transients when the MOSFETs are in their linear regions.
By taking 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: MAX5930/MAX5931 (LATCH = high or floating).
20
2) The continuous autoretry after a fault: MAX5930/
MAX5931 (LATCH = low).
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/(tSTART + tRETRY). Calculate the required transient thermal resistance with the following equation:
Z θJA(MAX) ≤
TJMAX − TA
VIN × ISTART
where ISTART = VSU,TH / RSENSE.
______________________________________________________________________________________
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
HIGH-CURRENT PATH
POWER
SUPPLY
VIN
VOUT
CBOARD
IN_
SENSE_ GATE_
SENSE RESISTOR
MAX5930
MAX5931
ON_
MAX5930
MAX5931
Figure 12. Using the MAX5930/MAX5931 on a Backplane
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 MAX5930/MAX5931 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 13).
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 topside of the board.
Figure 13. Kelvin Connection for the Current-Sense Resistors
Pin Configurations (continued)
TOP VIEW
ON2 1
20 MODE
ON1 2
19 ON3
IN1 3
18 IN2
17 SENSE2
SENSE1 4
GATE1 5
MAX5931
16 GATE2
STAT1 6
15 IN3
STAT2 7
14 SENSE3
TIM 8
13 GATE3
LATCH 9
12 GND
STAT3 10
11 BIAS
QSOP
______________________________________________________________________________________
21
MAX5930/MAX5931
BACKPLANE
REMOVABLE CARD
WITH NO HOT-INSERTION
PROTECTION
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
BACKPLANE
REMOVABLE CARD
RSENSE1
Q1
V1
RSENSE2
V2
RSENSE3
ON3
STAT3
RLIM**
BIAS
TIM
RLIM3**
MODE
POL*
LATCH*
RLIM2**
LIM3*
RLIM1**
LIM2*
GND
STAT1
STAT2
MAX5930
MAX5931
LIM1*
GND
GATE2
ON3
OUT3
GATE3
ON2
SENSE3
SENSE2
SENSE1
IN3
IN2
IN1
ON1
ON2
OUT2
Q3
V3
ON1
OUT1
Q2
GATE1
MAX5930/MAX5931
Typical Operating Circuit
1nF
16V
*MAX5930 ONLY.
**OPTIONAL COMPONENT.
Selector Guide
CURRENT LIMIT
FAULT MANAGEMENT
MAX5930EEG
PART
Programmable
Selectable
Selectable
STAT_ POLARITY
MAX5931LEEP
Fixed
Selectable
Asserted Low
MAX5931HEEP
Fixed
Selectable
Asserted High (Open-Drain)
Chip Information
TRANSISTOR COUNT: 7704
PROCESS: BiCMOS
22
______________________________________________________________________________________
Low-Voltage, Triple, Hot-Swap Controllers/
Power Sequencers/Voltage Trackers
QSOP.EPS
PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH
21-0055
E
1
1
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 23
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
MAX5930/MAX5931
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.)