19-1988; Rev 3; 1/07 +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers 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 -40°C to +85°C temperature range. For specific ordering information, see the Selector Guide at the end of the data sheet. Applications Network Routers Network Switches Base Station Line Cards Servers RAID Industrial Systems Features ♦ 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 Ordering Information TEMP RANGE PINPACKAGE MAX5902_ _EUT-T+* -40°C to +85°C 6 SOT23-6 U6F+6 MAX5902_ _ETT-T+* 6 TDFN-6 T633+2 MAX5903_ _EUT-T+* -40°C to +85°C 6 SOT23-6 U6F+6 MAX5903_ _ETT-T+* 6 TDFN-6 T633+2 PART -40°C to +85°C -40°C to +85°C *For specific part numbers see the Selector Guide at end of data sheet. +Denotes lead-free package. Typical Operating Circuits Pin Configurations 50W ISOLATED POWER SUPPLY BACKPLANE CIRCUIT CARD +48V TOP VIEW VS 1 6 IRFR5410 HOT-SWAP CONTROLLER ON/OFF MAX5902 DRAIN 2 MAX5902 MAX5903 5 VS PGOOD (PGOOD) ON/OFF GATE 3 4 PKG CODE GND GND VIN (+) LUCENT JW050A1 GATE DRAIN PGOOD ON/OFF VIN (-) GND SOT23-6 ( ) ARE FOR MAX5903 ONLY. Pin Configurations continued at end of data sheet. Typical Operating Circuits continued at end of data sheet. Simple Swapper 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 MAX5902/MAX5903 General Description MAX5902/MAX5903 +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers 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 = +70°C) 6-Pin SOT23 (derate 9.1mW/°C above +70°C)..........727mW 6-Pin TDFN (derate 18.2mW/°C above +70°C) .......1454mW Junction to Case Thermal Resistance, θJC (TDFN) ..............................8.5°C/W Maximum Junction Temperature .....................................+150°C Storage Temperature Range .............................-60°C to +150°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VS = +9V to +72V, GND = 0V, ON/OFF open circuit, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VS = +48V and TA = +25°C.) (Notes 1, 2) PARAMETER Supply Voltage SYMBOL VS CONDITIONS Supply Current IGND Measured out of GND, PGOOD or PGOOD open circuit, DRAIN = VS External Gate Drive VGS VS - VGATE Load Voltage Slew-Rate Magnitude SR | dVDRAIN/dt | CL = 10µF VUVLO VS increasing Default Undervoltage Lockout MIN 9 DRAIN to VS Resistance ON/OFF Reference Threshold 2 UNITS V 1 2 mA 11 9 10 VS = +9V 8 8.5 VS = +36V to +72V 5 9 18 VS = +9V 3 6 11 28.5 31.5 34.5 3.5 RON/OFF 19 32 RDGND 900 RDS 650 VON/OFF VON/OFF Increasing 1.14 1.26 Start Delay (Note 3) tON ON/OFF Off Delay (Note 4) tOFF VS - VGATE < 1V Circuit-Breaker Threshold VCB VS - VDRAIN tCB (VS - VDRAIN) > VCB until (VS - VGATE) < 1V, 200mV overdrive step V V/ms V V 52 kΩ kΩ kΩ 1.38 140 ON/OFF Hysteresis Circuit-Breaker Delay (Note 5) MAX 72 VS = +36V to +72V Undervoltage Lockout Hysteresis ON/OFF Pin Input Resistance DRAIN to GND Resistance TYP V mV 80 150 280 ms 5 10 18 ms MAX590_ _AEUT 200 300 460 MAX590_ _BEUT 280 400 540 MAX590_ _CEUT 400 500 660 CGATE = 1nF 2 6.5 CGATE = 4.7nF 4 11 CGATE = 10nF 7 17 150 280 ms 0.3 0.6 V Restart Delay (Note 3) tRS After circuit breaker event, MAX590_ A_EUT only Power-Good Output Low Voltage VOL IOL = 1mA 80 _______________________________________________________________________________________ mV µs +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers (VS = +9V to +72V, GND = 0V, ON/OFF open circuit, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VS = +48V and TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS Power-Good Output Open-Drain Leakage Current IOH V PGOOD = 72V (MAX5902) V PGOOD = 72V (MAX5903) Thermal Shutdown Temperature TSD Junction temperature Thermal Shutdown Hysteresis THY MIN TYP MAX UNITS 10 µA +125 °C 15 °C 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 = +25°C, unless otherwise noted. Specifications over -40°C to +85°C 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 = +25°C, unless otherwise noted. See Figure 2 for test circuits.) SUPPLY CURRENT vs. INPUT VOLTAGE SUPPLY CURRENT vs. TEMPERATURE 0.9 0.8 1.0 VIN = +48V 0.9 VIN = +12V MAX5902 toc03 MAX5902 toc02 35 34 33 LOCKOUT VOLTAGE (V) 1.0 VIN = +70V 1.1 SUPPLY CURRENT (mA) 1.1 SUPPLY CURRENT (mA) 1.2 MAX5902 toc01 1.2 VUVLO THRESHOLD vs. TEMPERATURE INCREASING VIN 32 31 30 29 DECREASING VIN 28 27 0.8 26 0.7 0.7 0 15 30 45 INPUT VOLTAGE (V) 60 75 25 -40 -15 10 35 TEMPERATURE (°C) 60 85 -40 -15 10 35 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX5902/MAX5903 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VS = +48V, GND = 0V, and TA = +25°C, unless otherwise noted. See Figure 2 for test circuits.) GATE DRIVE VOLTAGE RETRY TIMEOUT vs. INPUT VOLTAGE vs. TEMPERATURE 200 TIMEOUT PERIOD (ms) 13 11 9 7 MAX5902 toc05 225 MAX5902 toc04 15 GATE DRIVE (V) MAX5902/MAX5903 +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers MAX5902 toc06 A 0 B 175 0 150 C 0 125 D 100 0 75 5 0 15 30 45 60 -40 75 -15 10 35 60 85 A : VOUT, 50V/div B : IIN, 1A/div C : VGATE, 50V/div D : VIN, 50V/div TEMPERATURE (°C) INPUT VOLTAGE (V) TURN-ON WAVEFORMS RL = OPEN, CL = 100µF TURN-ON WAVEFORMS RL = 60Ω, CL = 10µF MAX5902 toc08 MAX5902 toc07 TURN-ON WAVEFORMS RL = 60Ω, CL = 100µF MAX5902 toc09 0 0 0 B B B 0 0 C 0 C C 0 0 0 t = 2ms/div t = 2ms/div t = 2ms/div A : VOUT, 50V/div B : IIN, 0.5A/div C : VGATE, 20V/div A : VOUT, 50V/div B : IIN, 1A/div C : VGATE, 20V/div A : VOUT, 50V/div B : IIN, 1A/div C : VGATE, 20V/div CIRCUIT-BREAKER EVENT VOVERDRIVE = 20mV, CGATE = 1000pF CIRCUIT-BREAKER EVENT VOVERDRIVE = 200mV, CGATE = 1000pF MAX5902 toc10 MAX5902 toc11 0 0 A A B t = 20ms/div A A A 0 0 B 0 0 C C t = 1µs/div A : VDS, 0.5V/div B : VGS, 10V/div C : VPGOOD TO VS, 50V/div 4 TURN-ON WAVEFORMS RL = 60Ω, CL = 100µF t = 1µs/div A : VDS, 0.5V/div B : VGS, 10V/div C : VPGOOD TO VS, 50V/div _______________________________________________________________________________________ +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers PIN NAME MAX5902 MAX5903 1 1 VS 2 2 DRAIN 3 3 GATE 4 4 GND FUNCTION 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 5 — PGOOD Power-Good Output. PGOOD is an n-channel, open-drain, active-low output, referenced to GND. — 5 PGOOD 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 1kΩ resistor (See Figure 1). (See the Undervoltage Lockout section in the Applications Information.) 6 6 ON/OFF — — EP Exposed Pad (TDFN only). Connect to GND. 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 +125°C. 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 * 828kΩ ON/OFF 1kΩ * 34.5kΩ 3V PGOOD (PGOOD) CONTROL LOGIC GND GND *900kΩ GND *650kΩ 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 MAX5902/MAX5903 Pin Description MAX5902/MAX5903 +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers 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 +125°C; 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 VS VIN V GATE 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. SCOPE 48V MAX5902 ON/OFF GND SCOPE 50kΩ DRAIN VS GATE DRAIN 0 TO 0.5V MAX5902A PGOOD ON/OFF I (a) SUPPLY CURRENT GND PGOOD (d) RETRY TIMEOUT SCOPE SCOPE IRFR5410 VS DRAIN SCOPE SCOPE 50kΩ VS 48V V VIN GATE MAX5902 ON/OFF GND PGOOD GATE DRAIN RL CL MAX5902 V ON/OFF (b) VUVLO GND PGOOD (d) STARTUP WAVEFORMS SCOPE 50Ω VS V VIN GATE DRAIN MAX5902 ON/OFF GND SCOPE V 48V VS DRAIN 50kΩ PGOOD MAX5902 ON/OFF (b) GATE DRIVE VOLTAGE GATE GND PGOOD SCOPE (d) CIRCUIT-BREAKER EVENT Figure 2. Test Circuits 6 _______________________________________________________________________________________ +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers HOT-SWAP CONTROLLER +24V OPTIONAL ON/OFF R2 40.2kΩ VS MAX5902 MAX5903 ON/OFF DGND R1 3.01kΩ Applications Information GND GND 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 +125°C. 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. 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 33kΩ (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 47kΩ resistor as shown in Figure 5. HOT-SWAP CONTROLLER #1 VS VS Latched Circuit Breaker ON/OFF 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. C GND HOT-SWAP CONTROLLER #2 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. MAX5902 MAX5903 VS MAX5902 MAX5903 ON/OFF 2C GND GND Figure 4. Power-Supply Sequencing _______________________________________________________________________________________ 7 MAX5902/MAX5903 No Circuit Breaker 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. MAX5902/MAX5903 +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers HOT-SWAP CONTROLLER MAX5902 MAX5903 47kΩ GND MAX5902 100kΩ ON/OFF 5V LOGIC HOT-SWAP CONTROLLER +9V TO +72V VS ON/OFF GND GND LOGIC CONTROL OF 3.3V OR LESS MAY BE CONNECTED DIRECTLY TO THE MAX5902/MAX5903. FOR 5V LOGIC CONTROL INSERT A SERIES 47kΩ RESISTOR AS SHOWN. Figure 6. Defeating Undervoltage Lockout Figure 5. Logic Control 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 4µs. 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). Thermal Shutdown A thermal shutdown feature helps protect the external MOSFET. If the die temperature of the MAX5902/ MAX5903 exceeds +125°C, 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 +110°C. 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 GND 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 3kΩ resistor (R1 in Figure 3) from ON/OFF to GND and calculate the other resistor, R2, using: ⎛ V ⎞ R2 = R1 × ⎜ UVLO − 1⎟ V ⎝ ON / 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 100kΩ resistor between ON/OFF and VS, as shown in Figure 6. 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 4µs when a circuitbreaker event occurs or if the die temperature exceeds +125°C. 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. _______________________________________________________________________________________ +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers 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 0.06Ω at TA = +25°C, and a normalized on-resistance factor of 1.75 at TA = +130°C (from the MOSFET data sheet), the RON used for calculation is the product of these two numbers, or (0.06Ω) x (1.75) = 0.105Ω. 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 (0.105Ω) 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 MAX5902/MAX5903 POWER IN M1 SOT-223 S D G POWER OUT 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 × 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 100µF, 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) SUGGESTED EXTERNAL MOSFET SUGGESTED MAXIM PART 0.5 IRF9540NS MAX5902AAEUT 1 IRF9540NS MAX5902ABEUT 2 IRF5210S MAX5902ABEUT 3 IRF5210S MAX5902ACEUT VIN = +9V to +72V _______________________________________________________________________________________ 9 MAX5902/MAX5903 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: MAX5902/MAX5903 +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers 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. 10 Chip Information TRANSISTOR COUNT: 658 PROCESS TECHNOLOGY: BiCMOS ______________________________________________________________________________________ +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers SOT23 CIRCUIT-BREAKER FUNCTION CIRCUIT-BREAKER THRESHOLD (mV) MAX5902NNEUT+ None MAX5902AAEUT+ Autoretry MAX5902ABEUT+ MAX5902ACEUT+ MAX5902LAEUT+ PART POWER-GOOD OUTPUT LOGIC TOP MARK None Active-Low AASM 300 Active-Low AASA Autoretry 400 Active-Low AASB Autoretry 500 Active-Low AASC Latched 300 Active-Low AASD AASE MAX5902LBEUT+ Latched 400 Active-Low MAX5902LCEUT+ Latched 500 Active-Low AASF MAX5903NNEUT+ None None Active-High AASN MAX5903AAEUT+ Autoretry 300 Active-High AASG MAX5903ABEUT+ Autoretry 400 Active-High AASH MAX5903ACEUT+ Autoretry 500 Active-High AASI MAX5903LAEUT+ Latched 300 Active-High AASJ MAX5903LBEUT+ Latched 400 Active-High AASK MAX5903LCEUT+ Latched 500 Active-High AASL TDFN CIRCUIT-BREAKER FUNCTION CIRCUIT-BREAKER THRESHOLD (mV) POWER-GOOD OUTPUT LOGIC TOP MARK MAX5902NNETT+ None None Active-Low AKH MAX5902AAETT+ Autoretry 300 Active-Low AKI MAX5902ABETT+ Autoretry 400 Active-Low AKJ MAX5902ACETT+ Autoretry 500 Active-Low AKK MAX5902LAETT+ Latched 300 Active-Low AKL MAX5902LBETT+ Latched 400 Active-Low AKM MAX5902LCETT+ Latched 500 Active-Low AKN MAX5903NNETT+ None None Active-High AKO MAX5903AAETT+ Autoretry 300 Active-High AKP MAX5903ABETT+ Autoretry 400 Active-High AKQ MAX5903ACETT+ Autoretry 500 Active-High AKR MAX5903LAETT+ Latched 300 Active-High AKS MAX5903LBETT+ Latched 400 Active-High AKT MAX5903LCETT+ Latched 500 Active-High AKU PART +Denotes lead-free package. ______________________________________________________________________________________ 11 MAX5902/MAX5903 Selector Guide +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers MAX5902/MAX5903 Typical Operating Circuits (continued) 50W ISOLATED POWER SUPPLY BACKPLANE CIRCUIT CARD +48V IRFR5410 HOT-SWAP CONTROLLER V+ MAX5903 VS 1MΩ GATE DRAIN ON/OFF GND PGOOD MAX5003* INDIV 39kΩ GND GND *THE MAX5003 IS A 110V PWM CONTROLLER Pin Configurations (continued) TOP VIEW VS 1 DRAIN 2 GATE 3 MAX5902 MAX5903 6 ON/OFF 5 PGOOD (PGOOD) 4 GND * EXPOSED PAD TDFN 3mm x 3mm ( ) ARE FOR MAX5903 ONLY. * EXPOSED PAD CONNECTED TO GND. 12 ______________________________________________________________________________________ +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers 6LSOT.EPS ______________________________________________________________________________________ 13 MAX5902/MAX5903 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.) 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 MAX5902/MAX5903 +72V, SOT23/TDFN, Simple Swapper Hot-Swap Controllers PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm 21-0137 COMMON DIMENSIONS MIN. MAX. PKG. CODE N D2 E2 e JEDEC SPEC b A 0.70 0.80 T633-1 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF D 2.90 3.10 T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF E 2.90 3.10 T833-1 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF 0.00 0.05 T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF L 0.20 0.40 T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF T1033-1 10 1.50±0.10 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 2.00 REF A2 0.20 REF. 2 [(N/2)-1] x e A1 0.25 MIN. 1 PACKAGE VARIATIONS SYMBOL k H T1033-2 10 1.50±0.10 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 2.00 REF T1433-1 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF T1433-2 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 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 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.