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19-1988; Rev 3; 1/07
+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers MAX5902/MAX5903
General Description
The MAX5902/MAX5903 are hot-swap controllers that allow a circuit card to be safely hot plugged into a live backplane without causing a glitch on the power-supply rail. These devices operate from +9V to +72V and provide the simplest hot-swap solution by eliminating all external components except the external p-channel MOSFET. The MAX5902/MAX5903 limit the inrush current to the load and provide a circuit-breaker function for overcurrent protection. During startup the circuit-breaker function is disabled and the MAX5902/MAX5903 limit the inrush current by gradually turning on the external MOSFET. Once the external MOSFET is fully enhanced, the circuit-breaker function is enabled and the MAX5902/MAX5903 provide overcurrent protection by monitoring the voltage drop across the external MOSFET's on-resistance. The MAX5902/MAX5903 include an undervoltage lockout (UVLO) function, ON/OFF control input, and a power-good status output, PGOOD (MAX5902) or PGOOD (MAX5903). A built-in thermal shutdown feature is also included to protect the external MOSFET in case of overheating. The MAX5902/MAX5903 offer latched or autoretry fault management and are available with 300mV, 400mV or 500mV circuit-breaker thresholds. Both the MAX5902 and MAX5903 are available in small SOT23 and TDFN packages, and are specified for the extended -40C to +85C temperature range. For specific ordering information, see the Selector Guide at the end of the data sheet. Wide +9V to +72V Operation Requires No External Sense Resistor Drives External p-Channel MOSFET Limits Inrush Current Circuit-Breaker Function Less than 2mA Quiescent Current ON/OFF Input Permits Load Power-Supply Control and Sequencing Adjustable Undervoltage Lockout Power-Good Output with +72V Rating Latching or Automatic Retry Fault Management Thermal Shutdown Helps Protect the External MOSFET Available in Two Small Packages 6-Pin TDFN and SOT23
Features
Ordering Information
PART TEMP RANGE PINPACKAGE 6 SOT23-6 6 TDFN-6 6 SOT23-6 6 TDFN-6 PKG CODE U6F+6 T633+2 U6F+6 T633+2
MAX5902_ _EUT-T+* -40C to +85C MAX5902_ _ETT-T+* MAX5903_ _ETT-T+* -40C to +85C -40C to +85C MAX5903_ _EUT-T+* -40C to +85C
Applications
Network Routers Network Switches Base Station Line Cards Servers RAID Industrial Systems
*For specific part numbers see the Selector Guide at end of data sheet. +Denotes lead-free package.
Typical Operating Circuits
50W ISOLATED POWER SUPPLY IRFR5410 HOT-SWAP CONTROLLER VIN (+) LUCENT JW050A1
Pin Configurations
BACKPLANE CIRCUIT CARD
TOP VIEW
VS 1 6 ON/OFF
+48V
MAX5902
DRAIN 2
MAX5902 MAX5903
5
PGOOD (PGOOD)
VS ON/OFF
GATE DRAIN PGOOD ON/OFF VIN (-)
GATE 3
4
GND
GND
GND
SOT23-6 ( ) ARE FOR MAX5903 ONLY.
Typical Operating Circuits continued at end of data sheet. Simple Swapper is a trademark of Maxim Integrated Products, Inc. 1
Pin Configurations continued 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.
+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers MAX5902/MAX5903
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND unless otherwise noted) VS, DRAIN, PGOOD, PGOOD ................................-0.3V to +76V ON/OFF ....................................................................-0.3V to +4V GATE to VS ............................................................-12V to +0.3V Current into any Pin ............................................................3mA Continuous Power Dissipation (TA = +70C) 6-Pin SOT23 (derate 9.1mW/C above +70C)..........727mW 6-Pin TDFN (derate 18.2mW/C above +70C) .......1454mW Junction to Case Thermal Resistance, JC (TDFN) ..............................8.5C/W Maximum Junction Temperature .....................................+150C Storage Temperature Range .............................-60C 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
(VS = +9V to +72V, GND = 0V, ON/OFF open circuit, TA = -40C to +85C, unless otherwise noted. Typical values are at VS = +48V and TA = +25C.) (Notes 1, 2)
PARAMETER Supply Voltage Supply Current External Gate Drive Load Voltage Slew-Rate Magnitude Default Undervoltage Lockout Undervoltage Lockout Hysteresis ON/OFF Pin Input Resistance DRAIN to GND Resistance DRAIN to VS Resistance ON/OFF Reference Threshold ON/OFF Hysteresis Start Delay (Note 3) ON/OFF Off Delay (Note 4) Circuit-Breaker Threshold tON tOFF VCB VS - VGATE < 1V MAX590_ _AEUT VS - VDRAIN (VS - VDRAIN) > VCB until (VS - VGATE) < 1V, 200mV overdrive step MAX590_ _BEUT MAX590_ _CEUT CGATE = 1nF CGATE = 4.7nF CGATE = 10nF 80 Circuit-Breaker Delay (Note 5) tCB 80 5 200 280 400 RON/OFF RDGND RDS VON/OFF VON/OFF Increasing 1.14 19 SYMBOL VS IGND VGS SR VUVLO CONDITIONS Measured out of GND, PGOOD or PGOOD open circuit, DRAIN = VS VS - VGATE | dVDRAIN/dt | CL = 10F VS increasing VS = +36V to +72V VS = +9V VS = +36V to +72V VS = +9V 9 8 5 3 28.5 MIN 9 TYP MAX 72 2 11 18 11 34.5 UNITS V mA V V/ms V V 52 k k k 1.38 280 18 460 540 660 6.5 11 17 280 0.6 ms V s mV V mV ms ms
1 10 8.5 9 6 31.5 3.5 32 900 650 1.26 140 150 10 300 400 500 2 4 7 150 0.3
Restart Delay (Note 3) Power-Good Output Low Voltage
tRS VOL
After circuit breaker event, MAX590_ A_EUT only IOL = 1mA
2
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+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers
ELECTRICAL CHARACTERISTICS (continued)
(VS = +9V to +72V, GND = 0V, ON/OFF open circuit, TA = -40C to +85C, unless otherwise noted. Typical values are at VS = +48V and TA = +25C.) (Notes 1, 2)
PARAMETER Power-Good Output Open-Drain Leakage Current Thermal Shutdown Temperature Thermal Shutdown Hysteresis SYMBOL IOH TSD THY CONDITIONS V PGOOD = 72V (MAX5902) V PGOOD = 72V (MAX5903) Junction temperature +125 15 MIN TYP MAX 10 UNITS A C C
MAX5902/MAX5903
Note 1: All currents into device pins are positive, all currents out of device pins are negative, and all voltages are referenced to GND, unless otherwise noted. Note 2: All specifications are 100% tested at TA = +25C, unless otherwise noted. Specifications over -40C to +85C are guaranteed by characterization. Note 3: This is the delay time from a valid on condition until VGS begins rising. Valid on conditions are: the device is not in undervoltage lockout; ON/OFF is not driven low; and the device is not in thermal shutdown. Note 4: This is the delay from a valid low on ON/OFF until VGS falls. Pulses on ON/OFF less than tOFF are ignored, offering glitch immunity. Note 5: Guaranteed by characterization, not production tested. CGATE is a capacitor from GATE to VS.
Typical Operating Characteristics
(VS = +48V, GND = 0V, and TA = +25C, unless otherwise noted. See Figure 2 for test circuits.)
SUPPLY CURRENT vs. INPUT VOLTAGE
MAX5902 toc01
SUPPLY CURRENT vs. TEMPERATURE
MAX5902 toc02
VUVLO THRESHOLD vs. TEMPERATURE
34 33 LOCKOUT VOLTAGE (V) 32 31 30 29 28 27 26 DECREASING VIN INCREASING VIN
MAX5902 toc03
1.2
1.2 VIN = +70V
35
1.1 SUPPLY CURRENT (mA)
1.1 SUPPLY CURRENT (mA)
1.0
1.0
VIN = +48V
0.9
0.9 VIN = +12V 0.8
0.8
0.7 0 15 30 45 60 75 INPUT VOLTAGE (V)
0.7 -40 -15 10 35 60 85 TEMPERATURE (C)
25 -40 -15 10 35 60 85 TEMPERATURE (C)
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+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers MAX5902/MAX5903
Typical Operating Characteristics (continued)
(VS = +48V, GND = 0V, and TA = +25C, unless otherwise noted. See Figure 2 for test circuits.) GATE DRIVE VOLTAGE RETRY TIMEOUT vs. INPUT VOLTAGE vs. TEMPERATURE
MAX5902 toc04 MAX5902 toc05
TURN-ON WAVEFORMS RL = 60, CL = 100F
0
15
225 200 TIMEOUT PERIOD (ms) 175 150
MAX5902 toc06
A
13 GATE DRIVE (V)
B 0
11
9
C 125 100 75 D 0 t = 20ms/div 0
7
5 0 15 30 45 60 75 INPUT VOLTAGE (V)
-40
-15
10
35
60
85
TEMPERATURE (C)
A : VOUT, 50V/div B : IIN, 1A/div C : VGATE, 50V/div D : VIN, 50V/div
TURN-ON WAVEFORMS RL = OPEN, CL = 100F
MAX5902 toc07
TURN-ON WAVEFORMS RL = 60, CL = 10F MAX5902 toc08
A 0 0
TURN-ON WAVEFORMS RL = 60, CL = 100F MAX5902 toc09
A 0
A
B 0
B 0
B 0
C 0 t = 2ms/div A : VOUT, 50V/div B : IIN, 1A/div C : VGATE, 20V/div
C 0 t = 2ms/div A : VOUT, 50V/div B : IIN, 0.5A/div C : VGATE, 20V/div
C 0 t = 2ms/div A : VOUT, 50V/div B : IIN, 1A/div C : VGATE, 20V/div
CIRCUIT-BREAKER EVENT VOVERDRIVE = 20mV, CGATE = 1000pF
0 A
MAX5902 toc10
CIRCUIT-BREAKER EVENT VOVERDRIVE = 200mV, CGATE = 1000pF
MAX5902 toc11
0 A
B
0 B
0
0 C C
0
t = 1s/div A : VDS, 0.5V/div B : VGS, 10V/div C : VPGOOD TO VS, 50V/div
t = 1s/div A : VDS, 0.5V/div B : VGS, 10V/div C : VPGOOD TO VS, 50V/div
4
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+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers
Pin Description
PIN NAME MAX5902 1 2 3 4 5 -- MAX5903 1 2 3 4 -- 5 VS DRAIN GATE GND PGOOD PGOOD Positive Supply Voltage Input and External p-Channel MOSFET Source Connection Drain Sense Input for External p-Channel MOSFET. Connect DRAIN as close as possible to the MOSFET's drain and use wide circuit traces to assure good thermal coupling between the MAX5902/MAX5903 and the MOSFET. See Layout Guidelines Section. Gate Drive Output for External p-Channel MOSFET Ground Connection Power-Good Output. PGOOD is an n-channel, open-drain, active-low output, referenced to GND. Power-Good Output. PGOOD is an n-channel, open-drain, active-high output, referenced to GND. ON/OFF Control Input. ON/OFF is referenced to GND. Drive ON/OFF above 1.38V or leave unconnected to enable the device. Drive ON/OFF below 1V to disable the device. ON/OFF is also used to adjust the UVLO threshold. Internally clamped to nominally 3V through a 1k resistor (See Figure 1). (See the Undervoltage Lockout section in the Applications Information.) Exposed Pad (TDFN only). Connect to GND. FUNCTION
MAX5902/MAX5903
6
6
ON/OFF
--
--
EP
Detailed Description
The MAX5902/MAX5903 are integrated hot-swap controller ICs contained in 6-pin SOT23 and TDFN packages. They allow a board to be safely hot-plugged into a live backplane without causing a glitch on the powersupply rail. They are well suited for +48V power systems allowing cost-effective, simple, and compact design. The MAX5902/MAX5903 operate from +9V to +72V to cover a wide range of end equipment hot-swap needs. They require only an external p-channel power MOSFET to provide hot-swap control. Figure 1 shows a functional block diagram of the MAX5902/MAX5903. The MAX5902/MAX5903 controls an external p-channel power MOSFET placed in the positive power-supply pathway. When power is first applied, the MAX5902/ MAX5903 keep the MOSFET turned off. The MAX5902/MAX5903 hold the MOSFET off indefinitely if ON/OFF is held low, if the supply voltage is below the undervoltage lockout level, or if the die temperature exceeds +125C. If none of these conditions exist for 150ms (typ), the MAX5902/MAX5903 begin to gradually turn on the MOSFET. During this turn-on phase, the MAX5902/MAX5903 slowly enhance the MOSFET, allowing the voltage on the load, i.e. the drain of the MOSFET, to rise at a rate of 9V/ms (typ). The inrush current to the load is thus limited to a level proportional to the load capacitance, and the constant slew rate. After
MAX5902 MAX5903 VS * 828k
ON/OFF
1k * 34.5k 3V
CONTROL LOGIC
PGOOD (PGOOD)
GND GND *900k *650k GND
DRAIN GATE ( ) ARE FOR THE MAX5903 ONLY * RELATIVE TOLERANCE 1%, ABSOLUTE TOLERANCE 50% (TYP)
Figure 1. Functional Block Diagram
the MOSFET is fully enhanced, and the load voltage is settled to its final value, the MAX5902A/ MAX5903A and MAX5902L/MAX5903L monitor the voltage drop across the MOSFET. If the voltage drop exceeds the circuitbreaker threshold the MAX5902A/MAX5903A and
5
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+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers MAX5902/MAX5903
MAX5902L/MAX5903L turn off the MOSFET, disconnecting the load immediately. If no circuit-breaker fault exists, the MAX5902/MAX5903 assert the power-good output. Then, if any of four conditions exist, the powergood output deasserts and the MAX5902/MAX5903 turn off the MOSFET. The four conditions are: the voltage across the MOSFET exceeds the circuit-breaker threshold; the supply voltage falls below the undervoltage lockout level; the die temperature exceeds +125C; or ON/OFF is forced low. After a circuit-breaker fault, the MAX5902L/MAX5903L keep the MOSFET off until the power is cycled, or the part is reset by toggling ON/OFF low for 10ms (typ). After a circuit-breaker fault, the MAX5902A/MAX5903A automatically restarts in 150ms (typ). All versions automatically restart after a thermal fault, or an undervoltage shutdown, if the fault condition goes away for at least 150ms (typ). ON/OFF offers external control of the MAX5902/ MAX5903, facilitating power-supply sequencing, and may also be used to change the undervoltage lockout (UVL) level. UVLO keeps the external MOSFET switched off as long as the input voltage is below the desired level. A power-good output, PGOOD (MAX5902) or PGOOD (MAX5903), asserts when the external MOSFET is fully enhanced and the source-drain voltage is below the circuit-breaker threshold. PGOOD and PGOOD are open-drain outputs referenced to GND, and can withstand up to +72V.
VS VIN V
GATE MAX5902
DRAIN 48V PGOOD VS
50k GATE MAX5902A ON/OFF GND PGOOD DRAIN 0 TO 0.5V
SCOPE SCOPE
ON/OFF I
GND
(a) SUPPLY CURRENT
(d) RETRY TIMEOUT SCOPE SCOPE SCOPE SCOPE 50k 48V VS GATE MAX5902 V ON/OFF GND PGOOD DRAIN RL CL
IRFR5410
VS V VIN
GATE MAX5902
DRAIN
ON/OFF
GND
PGOOD
(b) VUVLO
(d) STARTUP WAVEFORMS
SCOPE 50 VS V VIN GATE MAX5902 ON/OFF GND PGOOD ON/OFF DRAIN V 48V VS GATE MAX5902 GND PGOOD DRAIN 50k SCOPE SCOPE
(b) GATE DRIVE VOLTAGE
(d) CIRCUIT-BREAKER EVENT
Figure 2. Test Circuits 6 _______________________________________________________________________________________
+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers
No Circuit Breaker
HOT-SWAP CONTROLLER +24V OPTIONAL ON/OFF R2 40.2k VS MAX5902 MAX5903
MAX5902/MAX5903
For the versions without a circuit breaker, MAX5902N (MAX5903N), PGOOD (PGOOD) are asserted when the MOSFET is fully enhanced. Once powered up the MAX5902N/MAX5903N ignore the MOSFET drain-tosource voltage for applications where a circuit-breaker function is not desired.
ON/OFF DGND GND R1 3.01k GND
Applications Information
ON/OFF Control Input
The ON/OFF control input provides three functions: external ON/OFF control; setting of the UVLO level; and resetting after a circuit-breaker event has caused the MAX5902L/MAX5903L to turn off the external MOSFET. Pulling ON/OFF to GND for at least 10ms (tOFF) forces the MAX5902/MAX5903 to turn off the external MOSFET (see Figure 3 for a circuit example). To reset the MAX5902L/MAX5903L after a circuit-breaker event, toggle ON/OFF to GND for at least 10ms (tOFF). ON/OFF can be used to sequence power supplies. Connecting a capacitor from ON/OFF to GND will delay the rise of ON/OFF proportional to the capacitance and input impedance of ON/OFF, typically 33k (Figure 4). The MAX5902/MAX5903 can be controlled by logiclevel signals. Logic-level signals of 3.3V or 1.8V may be directly connected to ON/OFF. For 5V logic level control, insert a series 47k resistor as shown in Figure 5.
Figure 3. Programmed +18V Lockout, with Optional Optocoupler On/Off Control.
A thermal shutdown feature protects the external MOSFET by turning it off if the die temperature of the MAX5902/MAX5903 exceeds +125C. The MAX5902/ MAX5903 must be in good thermal contact with the external MOSFET. See Layout Guidelines in the Applications section of the data sheet. A circuit-breaker function monitors the voltage across the external MOSFET, VSD, and turns off the MOSFET if VSD exceeds the circuit-breaker threshold, VCB. The circuit-breaker function is enabled after the MOSFET is fully enhanced. Three threshold voltage options are available--300mV, 400mV, and 500mV. One version is available with no circuit-breaker function. Fault management for the MAX5902/MAX5903 is offered with two different configurations; latched and automatic retry.
HOT-SWAP CONTROLLER #1 VS VS C MAX5902 MAX5903
Latched Circuit Breaker
After a circuit-breaker trip event, the latched versions (MAX5902L/MAX5903L) drive GATE to V S , turning off the external MOSFET, and PGOOD (PGOOD) is deasserted. A latched off condition needs to be reset by toggling ON/OFF low for at least 10ms, or by cycling the power supply, VS.
ON/OFF GND
HOT-SWAP CONTROLLER #2 MAX5902 MAX5903
Automatic Retry Circuit Breaker
After a circuit-breaker trip event, the automatic retry versions (MAX5902A/MAX5903A) drive GATE to VS, turning off the external MOSFET, and PGOOD (PGOOD) is deasserted. If the start conditions are met for a full 150ms (tRS) the start sequence is re-initiated. The start conditions are: the device is not in UVLO; ON/OFF is not driven low; and the device is not in thermal shutdown.
VS
ON/OFF 2C GND
GND
Figure 4. Power-Supply Sequencing
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+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers MAX5902/MAX5903
HOT-SWAP CONTROLLER MAX5902 MAX5903 47k 5V LOGIC GND ON/OFF GND +9V TO +72V 100k VS ON/OFF GND LOGIC CONTROL OF 3.3V OR LESS MAY BE CONNECTED DIRECTLY TO THE MAX5902/MAX5903. FOR 5V LOGIC CONTROL INSERT A SERIES 47k RESISTOR AS SHOWN. GND HOT-SWAP CONTROLLER MAX5902
Figure 5. Logic Control
Figure 6. Defeating Undervoltage Lockout
Turn-On and Turn-Off Delays
After power is applied, or ON/OFF is released, there is a 150ms delay (tON) before the gate ramp is started. This delay is also the automatic restart time delay. In the event of a circuit-breaker condition or an overtemperature fault condition, the turn-off delay is less than 4s. An undervoltage condition must exist for at least 10ms (tOFF) before the MAX5902/MAX5903 turns off the external MOSFET. ON/OFF must be held low for at least 10ms (t OFF) before the MAX5902/MAX5903 turns off the external MOSFET. Turn-off delay minimizes spurious shutdowns due to noisy signals or momentary voltage spikes, as well as preventing accidental resetting of the circuit-breaker latch (MAX5902L/MAX5903L).
and +72V use a resistor divider connected between VS and GND, with the center node of the divider connected to ON/OFF. For example, use a 3k resistor (R1 in Figure 3) from ON/OFF to GND and calculate the other resistor, R2, using: V R2 = R1 x UVLO - 1 VON / OFF where V UVLO is the desired lockout voltage, and VON/OFF is the ON/OFF reference threshold specified in the Electrical Characteristics table (typically 1.26V). Figure 3 shows an example circuit with VUVLO set for +18V. To defeat the UVLO simply connect a single 100k resistor between ON/OFF and VS, as shown in Figure 6.
Thermal Shutdown
A thermal shutdown feature helps protect the external MOSFET. If the die temperature of the MAX5902/ MAX5903 exceeds +125C, the MOSFET is turned off. For accurate performance the MAX5902/MAX5903 must be in close thermal contact with the external MOSFET. See the Layout Guidelines section for information. Due to the low power dissipation of the MAX5902/MAX5903, its junction temperature will typically be within a few degrees of the MOSFET. All versions of the MAX5902/MAX5903 automatically restart from a temperature fault when the junction temperature drops below +110C.
The Power-Good Output
The power-good output, PGOOD (PGOOD), is opendrain and asserts when the external MOSFET is fully enhanced and V SD is less than the circuit-breaker threshold (VCB). For versions without the circuit-breaker function (MAX5902N/MAX5903N), PGOOD (PGOOD) asserts when the external MOSFET is fully enhanced. PGOOD (PGOOD) deasserts within 4s when a circuitbreaker event occurs or if the die temperature exceeds +125C. PGOOD (PGOOD) deasserts if VS < VUVLO for longer than 10ms or ON/OFF is held low for longer than 10ms. The MAX5902 PGOOD is active-low and the MAX5903 PGOOD is active-high. Both are open-drain n-channel MOSFETs with their sources connected to GND, and can withstand up to +72V.
Undervoltage Lockout
The MAX5902/MAX5903 turns off the external MOSFET if the magnitude of the input voltage is below the level set by ON/OFF for longer than 10ms (tOFF). If ON/OFF is left unconnected, the lockout voltage (V UVLO ) defaults to 31.5V. VUVLO may also be set to any value within the power-supply range by using external resistors. To set the lockout voltage to a value between +9V
8
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+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers
Selecting a Circuit-Breaker Threshold
The MAX5902A/MAX5903A and the MAX5902L/ MAX5903L offer a circuit-breaker function to protect the external MOSFET and the load from the potentially damaging effects of excessive current. As load current flows through the external MOSFET, a voltage, VSD, is generated from source to drain due to the MOSFET's on-resistance, R DS(ON). The MAX5902A/MAX5903A and MAX5902L/MAX5903L monitor VSD when the external MOSFET is fully enhanced. If V SD exceeds the circuit-breaker threshold the external MOSFET is turned off, and PGOOD (PGOOD) is deasserted. To accommodate different MOSFETs and different load currents the MAX5902/MAX5903 are available with circuit-breaker threshold voltages of 300mV, 400mV, and 500mV. To determine the proper circuit-breaker threshold for an application use: VCB > (RDS(ON)) (IOUT(MAX)) where RDS(ON) is the on-resistance of the MOSFET and IOUT(MAX) is the maximum expected output current. The MAX5902N/MAX5903N have no circuit-breaker function. For these parts choose an external MOSFET which meets the load requirements. The circuit-breaker function is intended to protect against gross overcurrent or short-circuit conditions. During a gross overcurrent or short-circuit condition, the MAX5902/MAX5903 disconnect the load by disabling the external MOSFET. For calculating the circuitbreaker threshold use the MOSFET's RON at the worst possible operating condition, and add a 20% overcurrent margin to the maximum circuit current. For instance, if a MOSFET has an RON of 0.06 at TA = +25C, and a normalized on-resistance factor of 1.75 at TA = +130C (from the MOSFET data sheet), the RON used for calculation is the product of these two numbers, or (0.06) x (1.75) = 0.105. Then, if the maximum current is expected to be 2A, using a 20% margin, the current for calculation is (2A) x (1.2) = 2.4A. The resulting minimum circuit-breaker threshold is then a product of these two results, or (0.105) x (2.4A) = 0.252V. The next highest minimum available threshold is 0.280V of the MAX5902ABEUT, which is an ideal choice given these parameters. Using this method to choose a circuit-breaker threshold allows the circuit to operate under worst case conditions without causing a circuit-breaker fault, but the circuit-breaker function will still operate if a short circuit, or a gross overcurrent condition exists.
GROUND U1 SOT23-6 POWER IN M1 SOT-223 SDG POWER OUT
MAX5902/MAX5903
MAX5902/MAX5903
Figure 7. Circuit Board Layout Example.
Determining Inrush Current
Determining a circuit's inrush current is necessary to help choose the proper MOSFET. The MAX5902/ MAX5903 regulate the inrush current by means of controlling the load voltage slew rate, but inrush current is also a function of load capacitance. Determine inrush current using: I=C dV = C x SR dt
where C is the load capacitance, and SR is the MAX5902/MAX5903 Load Voltage Slew-Rate Magnitude from the Electrical Characteristics table. For example, assuming a load capacitance of 100F, and using the typical value of 9V/ms for the slew rate, the inrush current is 0.9A typical. If the maximum possible Load Voltage Slew Rate is used, the maximum inrush current calculates to 1.8A. Choose a MOSFET with a maximum pulsed current specification that exceeds the maximum inrush current.
MAXIMUM ILOAD (A) 0.5 1 2 3
SUGGESTED EXTERNAL MOSFET IRF9540NS IRF9540NS IRF5210S IRF5210S
SUGGESTED MAXIM PART MAX5902AAEUT MAX5902ABEUT MAX5902ABEUT MAX5902ACEUT
VIN = +9V to +72V
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9
+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers MAX5902/MAX5903
Suggested External MOSFETs Layout Guidelines
Good thermal contact between the MAX5902/ MAX5903 and the external MOSFET is essential for the thermal shutdown feature to operate effectively. Place the MAX5902/MAX5903 as close as possible to the drain of the external MOSFET, and use wide circuit board traces for good heat transfer. See Figure 7 for an example of a PC board layout.
Chip Information
TRANSISTOR COUNT: 658 PROCESS TECHNOLOGY: BiCMOS
10
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+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers
Selector Guide
SOT23
PART MAX5902NNEUT+ MAX5902AAEUT+ MAX5902ABEUT+ MAX5902ACEUT+ MAX5902LAEUT+ MAX5902LBEUT+ MAX5902LCEUT+ MAX5903NNEUT+ MAX5903AAEUT+ MAX5903ABEUT+ MAX5903ACEUT+ MAX5903LAEUT+ MAX5903LBEUT+ MAX5903LCEUT+ CIRCUIT-BREAKER FUNCTION None Autoretry Autoretry Autoretry Latched Latched Latched None Autoretry Autoretry Autoretry Latched Latched Latched CIRCUIT-BREAKER THRESHOLD (mV) None 300 400 500 300 400 500 None 300 400 500 300 400 500 POWER-GOOD OUTPUT LOGIC Active-Low Active-Low Active-Low Active-Low Active-Low Active-Low Active-Low Active-High Active-High Active-High Active-High Active-High Active-High Active-High TOP MARK AASM AASA AASB AASC AASD AASE AASF AASN AASG AASH AASI AASJ AASK AASL
MAX5902/MAX5903
TDFN
PART MAX5902NNETT+ MAX5902AAETT+ MAX5902ABETT+ MAX5902ACETT+ MAX5902LAETT+ MAX5902LBETT+ MAX5902LCETT+ MAX5903NNETT+ MAX5903AAETT+ MAX5903ABETT+ MAX5903ACETT+ MAX5903LAETT+ MAX5903LBETT+ MAX5903LCETT+ CIRCUIT-BREAKER FUNCTION None Autoretry Autoretry Autoretry Latched Latched Latched None Autoretry Autoretry Autoretry Latched Latched Latched CIRCUIT-BREAKER THRESHOLD (mV) None 300 400 500 300 400 500 None 300 400 500 300 400 500 POWER-GOOD OUTPUT LOGIC Active-Low Active-Low Active-Low Active-Low Active-Low Active-Low Active-Low Active-High Active-High Active-High Active-High Active-High Active-High Active-High TOP MARK AKH AKI AKJ AKK AKL AKM AKN AKO AKP AKQ AKR AKS AKT AKU
+Denotes lead-free package.
______________________________________________________________________________________
11
+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers MAX5902/MAX5903
Typical Operating Circuits (continued)
BACKPLANE CIRCUIT CARD +48V IRFR5410 HOT-SWAP CONTROLLER V+ MAX5903 VS ON/OFF GND GND *THE MAX5003 IS A 110V PWM CONTROLLER GATE DRAIN PGOOD 39k GND 1M MAX5003* INDIV 50W ISOLATED POWER SUPPLY
Pin Configurations (continued)
TOP VIEW
VS DRAIN GATE
1 2 3
6 5 4
ON/OFF PGOOD (PGOOD) GND
MAX5902 MAX5903
* EXPOSED PAD
TDFN 3mm x 3mm
( ) ARE FOR MAX5903 ONLY. * EXPOSED PAD CONNECTED TO GND.
12
______________________________________________________________________________________
+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers
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.)
6LSOT.EPS
MAX5902/MAX5903
______________________________________________________________________________________
13
+72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers MAX5902/MAX5903
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.)
6, 8, &10L, DFN THIN.EPS
PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm
21-0137
H
1 2
COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 2.90 2.90 0.00 0.20 MAX. 0.80 3.10 3.10 0.05 0.40
PACKAGE VARIATIONS PKG. CODE T633-1 T633-2 T833-1 T833-2 T833-3 T1033-1 T1033-2 T1433-1 T1433-2 N 6 6 8 8 8 10 10 14 14 D2 1.500.10 1.500.10 1.500.10 1.500.10 1.500.10 1.500.10 1.500.10 1.700.10 1.700.10 E2 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 e 0.95 BSC 0.95 BSC 0.65 BSC 0.65 BSC 0.65 BSC 0.50 BSC 0.50 BSC 0.40 BSC 0.40 BSC JEDEC SPEC MO229 / WEEA MO229 / WEEA MO229 / WEEC MO229 / WEEC MO229 / WEEC MO229 / WEED-3 MO229 / WEED-3 ------b 0.400.05 0.400.05 0.300.05 0.300.05 0.300.05 0.250.05 0.250.05 0.200.05 0.200.05 [(N/2)-1] x e 1.90 REF 1.90 REF 1.95 REF 1.95 REF 1.95 REF 2.00 REF 2.00 REF 2.40 REF 2.40 REF
0.25 MIN. 0.20 REF.
PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm
-DRAWING NOT TO SCALE-
21-0137
H
2 2
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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