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19-2238; Rev 2; 11/03
KIT ATION EVALU ILABLE AVA
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers
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 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/BiLevelTM 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.
Features
o Safe Hot Swap for +1V to +13.2V Power Supplies Requires One Input 2.7V o o o o Low 25mV Default Current-Limit Threshold Inrush Current Regulated at Startup Circuit Breaker Function Adjustable Circuit Breaker/Current-Limit Threshold o VariableSpeed/BiLevel Circuit-Breaker Response o Auto-Retry or Latched Fault Management o On/Off Sequence Programming o Status Output Indicates Fault/Safe Condition o Output Undervoltage and Overvoltage Monitoring and/or Protection
MAX5904-MAX5909
Ordering Information
PART MAX5904ESA* MAX5904USA MAX5905ESA* MAX5905USA MAX5906EEE* MAX5906UEE MAX5907EEE* MAX5907UEE MAX5908EEE* MAX5908UEE MAX5909EEE* MAX5909UEE TEMP RANGE -40C to +85C 0C to +85C -40C to +85C 0C to +85C -40C to +85C 0C to +85C -40C to +85C 0C to +85C -40C to +85C 0C to +85C -40C to +85C 0C to +85C PIN-PACKAGE 8 SO 8 SO 8 SO 8 SO 16 QSOP 16 QSOP 16 QSOP 16 QSOP 16 QSOP 16 QSOP 16 QSOP 16 QSOP
*Contact factory for availability.
Applications
PCI-Express Applications Basestation Line Cards Network Switches or Routers Solid-State Circuit Breaker Power-Supply Sequencing Hot Plug-In Daughter Cards RAID
VariableSpeed/BiLevel is a trademark of Maxim Integrated Products, Inc.
GATE1 3 GND 4
Pin Configurations
TOP VIEW
IN1 SENSE1 1 2 8 7 IN2 SENSE2 GATE2 ON
MAX5904 MAX5905
6 5
NARROW SO
Pin Configurations continued at end of data sheet. Selector Guide and Typical Operating Circuits appear at end of data sheet. 1
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
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 = +70C) 8-Pin Narrow SO (derate 5.9mW/C above +70C) ......471mW 16-Pin QSOP (derate 8.3mW/C above +70C)............667mW Operating Temperature Ranges: MAX590_U_ _ .....................................................0C to +85C MAX590_E_ _ ...................................................-40C to +85C Storage Temperature Range .............................-65C to +150C
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 = TMIN to TMAX, unless otherwise noted. Typical values are at VIN1 = +5V, VIN2 = +3.3V, and TA = +25C.) (Note 1)
PARAMETER POWER SUPPLIES IN_ Input Voltage Range Supply Current CURRENT CONTROL MAX5904/MAX5905 Slow-Comparator Threshold (VIN - VSENSE) (Note 2) VSC,TH MAX5906-MAX5909 tSCD VSU,TH VFC,TH tFCD IB SEN 1mV overdrive 50mV overdrive VIN_ - VSENSE_; during startup VIN_ - VSENSE_; normal operation 10mV overdrive, from overload condition VSEN_ = VIN_ RTIM = 100k Startup Period (Note 4) tSTART RTIM = 4k (minimum value) TIM floating for MAX5906-MAX5909 fixed for MAX5904/MAX5905 Charging, VGATE = +5V, VIN = +10V (Note 5) Average Gate Current IGATE 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 ON COMPARATOR Fast Pulldown ON Threshold VONFP,TH Low to high Hysteresis 0.375 0.4 25 0.425 V mV VDRIVE VGATE_ - VIN_, IGATE_ < 1A 4.8 8 0.35 5 80 TA = +25C TA = TMIN to TMAX LIM = GND RLIM = 300k 22.5 20.5 22.5 80 25 100 3 110 2 x VSC, TH 4 x VSC, TH 260 0.03 10.8 0.45 9 100 100 3 5.4 5.8 6 13.6 0.55 14 130 A A mA V ms 25 27.5 27.5 27.5 125 ms s mV ns A mV VIN_ IIN Other VIN = +2.7V IIN1 + IIN2 1.0 1.2 13.2 2.3 V mA SYMBOL CONDITIONS MIN TYP MAX UNITS
Slow-Comparator Response Time (Note 3) Fast-Comparator Threshold Fast-Comparator Response Time SENSE Input Bias Current MOSFET DRIVER
2
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Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers
ELECTRICAL CHARACTERISTICS (continued)
(VIN_ = +1V to +13.2V provided at least one supply is higher than +2.7V, VON = +2.7V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VIN1 = +5V, VIN2 = +3.3V, and TA = +25C.) (Note 1)
PARAMETER Channel 1 ON Threshold Channel 2 ON Threshold ON Propagation Delay ON Input Bias Current ON Pulse Width Low DIGITAL OUTPUT (PGOOD) Output Leakage Current Output Voltage Low PGOOD Delay VOL tPGDLY VPGOOD = 13.2V ISINK = 1mA After tSTART, MON_ = VIN_ Overvoltage Undervoltage VMON_ = 600mV Startup is initiated when this threshold is reached by VIN1 or VIN2, VON > 0.8V, VIN_ increasing Hysteresis UVLO Glitch Filter Reset Time UVLO to Startup Delay SHUTDOWN RESTART Auto-Retry Delay UNCOMMITTED COMPARATOR INC+ Trip Threshold Voltage Propagation Delay OUTC Voltage Low INC+ Bias Current OUTC Leakage Current IOUTC VOL VC,TH Low to high Hysteresis 10mV overdrive ISINK = 1mA VINC+ = 5V VOUTC = 13.2V 0.02 0.02 1.206 1.236 10 50 0.4 1 1 1.266 V mV s V A A tRETRY Delay time to restart after a fault shutdown MAX5904/MAX5906/MAX5908 64 x tSTART ms tD,UVLO VIN_ = 0V, to unlatch after a fault VIN_ step from 0 to 2.8V 100 20 37.5 60 657 513 0.75 687 543 20 0.03 707 563 1 0.4 A V ms SYMBOL VON1,TH VON2,TH tON IBON tUNLATCH Low to high Hysteresis Low to high Hysteresis 10mV overdrive VON < 4.5V VIN1 = VIN2 = +13.2V VON > 4.5V VON = 4V To unlatch after a latched fault 100 1.95 CONDITIONS MIN 0.80 TYP 0.825 25 2.025 25 50 0.03 100 0.03 A 1 s MAX 0.85 2.07 UNITS V mV V mV s
MAX5904-MAX5909
OUTPUT VOLTAGE MONITORS (MON1, MON2) MON_ Trip Threshold MON_ Glitch Filter MON_ Input Bias Current UNDERVOLTAGE LOCKOUT (UVLO) UVLO Threshold VUVLO 2.1 2.4 100 2.67 V mV s ms VMON_ mV s A
Note 1: Limits are 100% tested at TA = +25C and +85C. Limits at 0C and -40 are guaranteed by characterization and are not production tested. Note 2 The MAX5906-MAX5909 slow-comparator threshold is adjustable. VSC,TH = RLIM x 0.25A + 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. _______________________________________________________________________________________ 3
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
Typical Operating Characteristics
(Typical Operating Circuits, Q1 = Q2 = Fairchild FDB7090L, VIN1 = +5V, VIN2 = +3.3V, TA = +25C, unless otherwise noted. Channels 1 and 2 are identical in performance. Where characteristics are interchangeable, channels 1 and 2 are referred to as X and Y.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX5904 toc01
TOTAL SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX5904 toc02
SUPPLY CURRENT vs. TEMPERATURE
1.8 1.6 1.4 C VON = VIN1 IIN1 + IIN2
MAX5904 toc03
2.0 1.8 1.6 1.4 IIN (mA) 1.2 1.0 0.8 0.6 0.4 0.2 0 0 2 4 6 8 10 12 IINY IINX IINX + IINY VINY = VON = 2.7V
2.0 1.8 1.6 1.4 IIN (mA) B A
2.0
IIN (mA)
1.2 1.0 0.8 0.6 0.4 0.2 0 VINY = 5.0V A) VON = 3.3V B) VON = 1.5V C) VON = 0V 0 2 4 6 8 10 12
1.2 1.0 0.8 0.6 0.4 0.2 0 IIN2 IIN1
14
14
-40
-15
10
35
60
85
VINX (V)
VINX (V)
TEMPERATURE (C)
GATE DRIVE VOLTAGE vs. INPUT VOLTAGE
MAX5904 toc04
GATE CHARGE CURRENT vs. GATE VOLTAGE
MAX5904 toc05
GATE CHARGE CURRENT vs. TEMPERATURE
180 GATE CHARGE CURRENT (A) 160 140 120 100 80 60 40 20 0 VON = VINY = 2.7V VGATEX = 0V -40 -15 10 35 60 85 VINX = 1V VINX = 13.2V VINX = 5V
MAX5904 toc06
6 5 GATE DRIVE VOLTAGE (V) 4 3 2 1 VINY = 2.7V 0 0 2 4 6 8 10 12
200 180 GATE CHARGE CURRENT (A) 160 140 120 100 80 60 40 20 0 VINX = 13.2V VINX = 5V VINX = 1V VON = VINY = 2.7V
200
14
0
5
10 VGATEX (V)
15
20
VINX (V)
TEMPERATURE (C)
GATE WEAK DISCHARGE CURRENT vs. GATE VOLTAGE
MAX5904 toc07
GATE WEAK DISCHARGE CURRENT vs. TEMPERATURE
MAX5904 toc08
GATE STRONG DISCHARGE CURRENT vs. GATE VOLTAGE
VON = 0V VINX = 5V VINX = 13.2V
MAX5904 toc09
200 180 GATE DISCHARGE CURRENT (A) 160 140 120 100 80 60 40 20 0 0 5 10 VGATEX (V) VINY = 2.7V 15 VINX = 1V VON = 0.6V VINX = 5V VINX = 13.2V
200 180 GATE DISCHARGE CURRENT (A) 160 140 120 100 80 60 40 20 0 VINY = 2.7V VGATEX = VINX + 6.2V -40 -15 10 35 60 VINX = 1V VON = 0.6V VINX = 5V VINX = 13.2V
6 GATE DISCHARGE CURRENT (mA) 5 4 3 2 1 0
VINX = 1V VINY = 2.7V VGATEX = VINX + 6.2V 0 5 10 VGATEX (V) 15 20
20
85
TEMPERATURE (C)
4
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Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
Typical Operating Characteristics (continued)
(Typical Operating Circuits, Q1 = Q2 = Fairchild FDB7090L, VIN1 = +5V, VIN2 = +3.3V, TA = +25C, 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.)
GATE STRONG DISCHARGE CURRENT vs. TEMPERATURE
MAX5904 toc10
TURN-OFF TIME vs. SENSE VOLTAGE
SLOW-COMP. THRESHOLD 1 TURN-OFF TIME (ms) FAST-COMP. THRESHOLD 0.1
MAX5904 toc11
TURN-OFF TIME vs. SENSE VOLTAGE (EXPANDED SCALE)
MAX5904 toc12
6 GATE DISCHARGE CURRENT (mA) 5 VINX = 13.2V 4 3 2 1 0 -40 -15 10 35 60 VINX = 5V
10
10
TURN-OFF TIME (ms)
SLOW-COMP. THRESHOLD 1
VON = 0V VINY = 2.7V VGATEX = VINX + 6.2V VINX = 1V
0.01
0.001
0.0001 85 0 25 50 75 100 125 150 175 200 TEMPERATURE (C) VIN - VSENSE (mV)
0.1 20 25 30 35 40 45 50 55 60 65 70 75 80 VIN - VSENSE (mV)
SLOW-COMPARATOR THRESHOLD vs. RLIM
MAX5904 toc13
STARTUP PERIOD vs. RTIM
MAX5904 toc14
TURN-OFF TIME SLOW-COMPARATOR FAULT
MAX5904 toc15
120 100 80
60 50 40 tSTART (ms) 30 20 10 0
0V VSC, TH (mV) 0V
tSCD 26mV STEP
VPGOOD 5V/div
60 40 20 0 0 100 200 RLIM (k) 300 400
VSENSE - VIN 100mV/div VGATE 5V/div 0V
0
100
200
300 RTIM (k)
400
500
600
1ms/div VIN = 5.0V
TURN-OFF TIME FAST-COMPARATOR FAULT
MAX5904 toc16
STARTUP WAVEFORMS FAST TURN-ON
MAX5904 toc17
VON 2V/div 0V tFCD 0V 125mV STEP VSENSE - VIN 100mV/div VGATE 5V/div 0V IOUT 5A/div VOUT 5V/div VGATE 5V/div VPGOOD 5V/div VPGOOD 2V/div
400ns/div VIN = 5.0V
1ms/div VIN = 5.0V, RSENSE = 10m, RTIM = 27k, CBOARD = 1000F
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5
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
Typical Operating Characteristics (continued)
(Typical Operating Circuits, Q1 = Q2 = Fairchild FDB7090L, VIN1 = +5V, VIN2 = +3.3V, TA = +25C, 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
MAX5904 toc18
AUTO-RETRY DELAY
MAX5904 toc19
VON 2V/div VPGOOD 2V/div IOUT 5A/div VOUT 5V/div VGATE 5V/div VOUT 5V/div IOUT 5A/div VGATE 5V/div
1ms/div VIN = 5.0V, RSENSE = 10m, RTIM = 47k, CBOARD = 1000F, CGATE = 22nF
40ms/div VIN = 5.0V, RSENSE = 10m, RTIM = 47k, CBOARD = 1000F, RBOARD = 1.4
Pin Description
PIN MAX5904/ MAX5905 -- -- 1 2 3 4 -- MAX5906- MAX5909 1 2 3 4 5 6 7 NAME FUNCTION 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. 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. Channel 1 Supply Input. Connect to a supply voltage from 1V to 13.2V. Connect a 0.1F ceramic bypass capacitor from IN1 to GND to filter high-frequency noise. Channel 1 Current-Sense Input. Connect RSENSE1 from IN1 to SENSE1. Channel 1 Gate-Drive Output. Connect to gate of external N-channel MOSFET. Ground 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. 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. 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.
PGOOD TIM IN1 SENSE1 GATE1 GND LIM1
--
8
MON1
--
9
MON2
6
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Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers
Pin Description (continued)
PIN MAX5904/ MAX5905 -- 5 6 7 8 -- -- MAX5906- MAX5909 10 11 12 13 14 15 16 NAME 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. On Comparator Input Channel 2 Gate-Drive Output. Connect to gate of external N-channel MOSFET. Channel 2 Current-Sense Input. Connect RSENSE2 from IN2 to SENSE2. Channel 2 Supply Input. Connect to a supply voltage from 1V to 13.2V. Connect a 0.1F ceramic bypass capacitor from IN2 to GND to filter high-frequency noise. Uncommitted Comparator Noninverting Input Uncommitted Comparator Open-Drain Output. Actively held low when VINC+ is less than 1.236V.
MAX5904-MAX5909
LIM2 ON GATE2 SENSE2 IN2 INC+ OUTC
Detailed Description
The MAX5904-MAX5909 are circuit breaker ICs for hotswap applications where a line card is inserted into a live backplane. These devices hot swap supplies ranging 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 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.
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 100A 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.
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).
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 current in response to a fault condition. After a fault,
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7
MAX5904-MAX5909
Figure 1. MAX5906-MAX5909 Functional Diagram
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers
8
RLIM1 LIM1 IN2 VFS, TH VFS, TH VSC, TH RSENSE2 FAST COMP. UVLO 2.4V TIMING OSCILLATOR SLOW COMP. GATE2 CHARGE PUMP DEVICE CONTROL LOGIC SLOW DISCHARGE FAST DISCHARGE 2.025V 100A 687mV 0.825V CURRENT CONTROL AND STARTUP LOGIC CURRENT CONTROL AND STARTUP LOGIC CHARGE PUMP SLOW DISCHARGE FAST DISCHARGE 100A 687mV MON2 0.4V 543mV TO STARTUP LOGIC BLOCKS TO STARTUP LOGIC BLOCKS 543mV 3mA Q2 OUT2 2.4V SLOW COMP. UVLO BIAS AND REFERENCES FAST COMP. SENSE2 LIM2 RLIM2 N STARTUP OSCILLATOR N CHARGE PUMP OSCILLATOR MAX5906 MAX5907 MAX5908 MAX5909 INC+ TIM RTIM OUTC ON PGOOD
IN1
VSC, TH
RSENSE1
SENSE1
GATE1
Q1
OUT1
3mA
MON1
_______________________________________________________________________________________
1.236V
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers
ON PGOOD tSTART + tPGDLY VGATE
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 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 9).
MAX5904-MAX5909
4.8V TO 5.8V
VOUT VTH VGATE VOUT VSU,TH RSENSE CBOARD = 0 ILOAD tON CBOARD = LARGE
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 voltages are stable. Any input voltage transient on both supplies below the UVLO threshold will reinitiate the tD,UVLO and the startup period.
Figure 2. Startup Waveforms
PGOOD is pulled low, the MAX5905/MAX5907/ MAX5909 stay latched off and the MAX5904/MAX5906/ MAX5908 automatically restart. 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 110s 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 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.
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 100s 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 out9
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Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
Timing Diagrams
VON
VON_,TH VGATE_
VOUT_
tSTART
INTERNAL SIGNAL
INTERNAL SIGNAL tPGDLY
PGOOD
Figure 3. Power-Up with ON Pin Control (At Least One VIN_ is > VUVLO)
10
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Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers
Timing Diagrams (continued)
OVERCURRENT CONDITION (VIN_ - VSENSE_ VSC_TH AND VIN_ - VSENSE_ < VFC_TH)
MAX5904-MAX5909
tSCD
IOUT
VGATE_
DISCHARGE RATE DEPENDS ON OUTPUT LOADING
VOUT_
PGOOD
Figure 4. Power-Down when an Overcurrent Fault Occurs
SHORT-CIRCUIT CONDITION (VIN_ - VSENSE_ VFC_TH)
tFCD
IOUT
VGATE_
VOUT_
PGOOD
Figure 5. Power-Down when a Short-Circuit Fault Occurs
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11
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
Timing Diagrams (continued)
UV/OV CONDITION INTERNAL SIGNAL
MON_ GLITCH FILTER, 20S
VGATE_
DISCHARGE RATE DEPENDS ON OUTPUT LOADING
VOUT_
PGOOD
Figure 6. Power-Down when an Undervoltage/Overvoltage Fault Occurs (MAX5906/MAX5907)
UV/OV CONDITION
INTERNAL SIGNAL
MON_ GLITCH FILTER, 20S VGATE_
VGATE_ AND VOUT_ STAY ON
VOUT_
PGOOD
Figure 7. Fault Report when an Undervoltage/Overvoltage Fault Occurs (MAX5908/MAX5909)
12
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Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers
Timing Diagrams (continued)
VIN_ VUVLO
MAX5904-MAX5909
VGATE_
VOUT_ tD,UVLO
tSTART
INTERNAL SIGNAL
INTERNAL SIGNAL tPGDLY
PGOOD
Figure 8. Power-Up with Undervoltage Lockout Delay (VON = 2.7V, the Other VIN_ is Below VUVLO)
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13
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
put 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 20s. 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. 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 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
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).
Table 1. Status Output Truth Table
DEVICE IN UVLO DELAY PERIOD Yes X X X X X No DEVICE IN STARTUP PERIOD X Yes X X X X No ON X X Low X X X High OVERCURRENT FAULT X X X Yes X X No OVER/UNDERVOLTAGE FAULT X X X X Yes X No PART IN RETRY-TIMEOUT PERIOD OR LATCHED OFF X X X X X Yes No PGOOD Low Low Low Low Low Low High-Z
X = don't care 14 ______________________________________________________________________________________
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers
Table 2. Recommended N-Channel MOSFETs
PART NUMBER IRF7413 IRF7401 IRL3502S MMSF3300 MMSF5N02H MTB60N05H FDS6670A NDS8426A FDB8030L Fairchild Motorola International Rectifier MANUFACTURER DESCRIPTION 11m, 8 SO, 30V 22m, 8 SO, 20V 6m, D2PAK, 20V 20m, 8 SO, 30V 30m, 8 SO, 20V 14m, D2PAK, 50V 10m, 8SO, 30V 13.5m, 8 SO, 20V 4.5m, D2PAK, 30V
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. 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 100A 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= CGATE x VGATE + QGATE IGATE
MAX5904-MAX5909
faults. Typically, set the overload current at 1.2 to 1.5 times the nominal load current. To adjust the slow-comparator threshold calculate RLIM as follows: V - 25mV RLIM = TH 0.25A 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 resistance connected from TIM to GND (RTIM). RTIM must be between 4k and 500k. 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 x 800pF
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.
where tSTART is the desired startup period.
Table 3. Component Manufacturers
COMPONENT Sense Resistors IRC International Rectifier MOSFETs Fairchild Motorola MANUFACTURER Dale-Vishay PHONE 402-564-3131 704-264-8861 310-233-3331 888-522-5372 602-244-3576 WEBSITE www.vishay.com www.irctt.com www.irf.com www.fairchildsemi.com www.mot-sps.com/ppd
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15
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
IINRUSH = CBOARD x IGATE + ILOAD Crss + CGATE t ON = CBOARD x VIN x RSENSE VSU,TH
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 100A gate-charging current and a 100A weak discharging current or 3mA strong discharging current. CBOARD = 6F and the load does not draw any current during the startup period. With no gate capacitor the inrush current, charge, and discharge times are: 6F x 100A + 0 = 1A 600pF + 0 0 x 10.4V + 60nC t CHARGE = = 0.6ms 100A tDISCHARGE _ SLOW = tDISCHARGE _ FAST = 0 x 10.4V + 60nC = 0.6ms 100A
The maximum inrush current in this case is: IINRUSH = VSU,TH RSENSE
Figures 2-8 show 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 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 11).
IINRUSH =
0 x 10.4V + 60nC = 0.02ms 3mA
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 12). 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.
With a 22nF gate capacitor the inrush current, charge, and discharge times are: IINRUSH = 6F x 100A + 0 = 26.5mA 600pF + 22nF 22nF x 10.4V + 60nC t CHARGE = = 2.89ms 100A tDISCHARGE _ SLOW = tDISCHARGE _ FAST = 22nF x 10.4V + 60nC = 2.89ms 100A
22nF x 10.4V + 60nC = 0.096ms 3mA
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).
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:
16
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
______________________________________________________________________________________
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers
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.
MAX5904-MAX5909
SLOW COMPARATOR 3ms
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 power dissipation occurs during the turn-on and turnoff 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 (RJA) and thermal resistance from junction to case (RJC) which determine the startup time and the retry duty cycle (d = tSTART / tRETRY). Calculate the required transient thermal resistance with the following equation:
VOUT CBOARD
TURN-OFF TIME
FAST COMPARATOR
110s 260ns
VSC,TH
VFC,TH (4 x VSC,TH)
SENSE VOLTAGE (VIN - VSENSE)
Figure 9. VariableSpeed/BiLevel Response
RSENSE VIN
-T T Z JA(MAX ) JMAX A VIN x ISTART
RPULLUP IN SENSE GATE CGATE
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 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.
17
PGOOD
MAX5906 MAX5907 MAX5908 MAX5909 GND
ON
Figure 10. Operating with an External Gate Capacitor
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
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Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
RSENSE1 V1 CBOARD1 ON VEN OFF C1 GND GND IN2 SENSE2 GATE2 MAX5904 MAX5905 R1 ON IN1 SENSE1 GATE1 Q1 OUT1
V2 RSENSE2
OUT2 Q2 CBOARD2
VEN t1 = -R1C1 ln( VON2, TH VON
VEN - VON1, TH VEN
)
VON1, TH V1 t2 = -R1C1 ln(
VEN - VON2, TH VEN
)
V2 VEN - VON1, TH VEN - VON2, TH
tDELAY = -R1C1 ln(
)
t0
t1 TDELAY
t2
Figure 11. Power Sequencing: Channel 2 Turns On tDELAY After Channel 1
Chip Information
TRANSISTOR COUNT: 3230 PROCESS: BiCMOS
18
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Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
VIN HIGH-CURRENT PATH
IN
SENSE
GATE INC+
SENSE RESISTOR P
MAX5906-MAX5909 OUTC RESET
MAX590_
Figure 12. Power-On Reset Figure 14. Kelvin Connection for the Current-Sense Resistors
REMOVABLE CARD WITH NO HOT-INSERTION PROJECTION VOUT CBOARD IN SENSE MAX590_ ON GATE
BACKPLANE VIN
Pin Configurations (continued)
TOP VIEW
PGOOD 1 TIM 2 IN1 3 SENSE1 4 GATE1 5 GND 6 LIM1 7 MON1 8 16 OUTC 15 INC+ 14 IN2
MAX5906 MAX5907 MAX5908 MAX5909
13 SENSE2 12 GATE2 11 ON 10 LIM2 9 MON2
QSOP
Figure 13. Using the MAX5904-MAX5909 on a Backplane
Selector Guide
PART MAX5904ESA/MAX5904USA MAX5905ESA/MAX5905USA MAX5906EEE/MAX5906UEE MAX5907EEE/MAX5907UEE MAX5908EEE/MAX5908UEE MAX5909EEE/MAX5909UEE OUTPUT UNDERVOLTAGE/OVERVOLTAGE PROTECTION/MONITOR -- -- Protection Protection Monitor Monitor FAULT MANAGEMENT Auto-Retry Latched Auto-Retry Latched Auto-Retry Latched
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19
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
Typical Operating Circuits
BACKPLANE V1 0.1F IN1 ON ON SENSE1 GATE1 CBOARD1 REMOVABLE CARD RSENSE1 Q1 OUT1
GND GND IN2 0.1F V2 RSENSE2
MAX5904 MAX5905 SENSE2 GATE2
OUT2 Q2 CBOARD2
BACKPLANE V1
REMOVABLE CARD RSENSE1 Q1 OUT1
*
CBOARD1
0.1F
*
IN1 ON STAT * * * GND ON PGOOD TIM LIM1 LIM2 GND
SENSE1
GATE1 MON1
OUTC MAX5906 MAX5907 MAX5908 MAX5909 INC+
UNCOMMITTED COMPARATOR
MON2
*
IN2 0.1F
SENSE2
GATE2
*
OUT2 RSENSE2 Q2 CBOARD2
V2
*OPTIONAL
20
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Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers
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
INCHES DIM A A1 B C e E H L MAX MIN 0.053 0.069 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050
MILLIMETERS MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 1.27
N
E
H
VARIATIONS:
1
INCHES
MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC
TOP VIEW
DIM D D D
MIN 0.189 0.337 0.386
MAX 0.197 0.344 0.394
D C
A e B A1
0 -8 L
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL DOCUMENT CONTROL NO. REV.
21-0041
B
1 1
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21
SOICN .EPS
Low-Voltage, Dual Hot-Swap Controllers/Power Sequencers MAX5904-MAX5909
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.)
QSOP.EPS
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.
22 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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