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19-1988; Rev 1; 4/02
-100V SOT23 Simple Swapper Hot-Swap Controllers MAX5900/MAX5901
General Description
The MAX5900/MAX5901 are SOT23 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 -100V and provide the simplest hot-swap solution by eliminating all external components except an external N-channel MOSFET. The MAX5900/MAX5901 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 MAX5900/MAX5901 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 MAX5900/MAX5901 provide overcurrent protection by monitoring the voltage drop across the external MOSFET's on-resistance. The MAX5900/MAX5901 include an undervoltage lockout (UVLO) function, ON/OFF control input, and a power-good status output, PGOOD (MAX5900) or PGOOD (MAX5901). A built-in thermal shutdown feature is also included to protect the external MOSFET in case of overheating. The MAX5900/MAX5901 offer latched or auto-retry fault management and are available with 200mV, 300mV or 400mV circuit breaker thresholds. Both the MAX5900 and MAX5901 are available in small SOT23 packages, and are specified for the extended -40C to +85C temperature range. For specific ordering information refer to the Selector Guide at the end of the data sheet. o Wide -9V to -100V Operation o Requires No External Sense Resistor o Drives External N-Channel MOSFET o Limits Inrush Current o Circuit Breaker Function o Less than 1mA Quiescent Current o ON/OFF Input Permits Load Power-Supply Control and Sequencing o Adjustable Undervoltage Lockout o Power-Good Output with 100V Rating o Latching or Automatic Retry Fault Management o Thermal Shutdown Helps Protect the External MOSFET o Space-Saving SOT23-6 Package
Features
Ordering Information
PART MAX5900_ _EUT* MAX5901_ _EUT* TEMP. RANGE -40C to +85C -40C to +85C PIN-PACKAGE 6 SOT23 6 SOT23
*For specific part numbers see Selector Guide at end of data sheet.
Applications
Telecom Line Cards Network Routers Base Station Line Cards Network Switches Servers
TOP VIEW
VEE 1
Pin Configuration
6
ON/OFF
Typical Operating Circuits
BACKPLANE GND HOT-SWAP CONTROLLER VI+ MAX5900 GND ON/OFF VEE PGOOD DRAIN GATE VILUCENT JW050A1 ON/OFF CIRCUIT CARD 50W ISOLATED POWER SUPPLY
DRAIN 2
MAX5900 MAX5901
5
PGOOD (PGOOD)
GATE 3
4
GND
SOT23-6 ( ) ARE FOR MAX5901 ONLY.
Typical Operating Circuits continued at end of data sheet.
-48V FUSE IRF540NS
Simple Swapper is a trademark of Maxim Integrated Products Inc. 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.
-100V SOT23 Simple Swapper Hot-Swap Controllers MAX5900/MAX5901
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND unless otherwise noted) VEE, DRAIN, PGOOD, PGOOD ............................-120V to +0.3V ON/OFF to VEE .........................................................-0.3V to +4V GATE to VEE ...........................................................-0.3V to +12V Current into any Pin ............................................................3mA Continuous Power Dissipation at TA = +70C 6-Pin SOT23 (derate 9.1mW/C above +70C)..........727mW Maximum Junction Temperature .....................................+150C Storage Temperature Range .............................-60C to +150C Lead Temperature .............................................................Note 1
Note 1: This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device can be exposed to during board level solder attach and rework. This limit permits only the use of solder profiles recommended in the industry standard specification, JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and convection reflow. Preheating is required. Hand or wave soldering is not allowed.
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
(VEE = -9V to -100V, GND = 0, ON/OFF open circuit, TA = -40C to +85C, unless otherwise noted. Typical values are at VEE = -48V and TA = +25C.) (Notes 2, 3)
PARAMETER Supply Voltage Supply Current External Gate Drive Load Voltage Slew Rate Magnitude Default UVLO UVLO Hysteresis ON/OFF Input Resistance DRAIN to VEE Resistance ON/OFF Reference Threshold ON/OFF Hysteresis Start Delay (Note 4) ON/OFF Off Delay (Note 5) Circuit Breaker Threshold tON tOFF VCB VGATE - VEE < 1V MAX590_ _AEUT VDRAIN - VEE MAX590_ _BEUT MAX590_ _CEUT Circuit Breaker Delay (Note 6) Restart Delay (Note 4) tCB tRS (VDRAIN - VEE) > VCB until (VGATE - VEE ) < 1V, 200mV overdrive step CGATE = 1nF CGATE = 4.7nF CGATE = 10nF 150 150 9 170 265 365 RON/OFF RDVEE VON/OFF (VON/OFF - VEE) increasing 1.14 20 SYMBOL VEE IGND VGS Measured at GND VEE = -36V to -72V VGATE - VEE VEE = -100V VEE = -9V SR VUVLO | dVDRAIN/dt |, CLOAD = 10F, VEE = -9V to -36V 7.5 8 6 4.5 -34.5 CONDITIONS MIN -100 0.5 9.5 10 7 10 -31.5 3.5 32 466 1.26 140 300 20 200 300 400 1.5 2.5 4 300 500 32 240 345 455 3 4.5 6 500 ms s mV 1.38 50 17 -28.5 V/ms V V k k V mV ms ms TYP MAX -9 1.3 11.6 11.6 V UNITS V mA
|VEE| increasing
After circuit breaker event, MAX590_ A_EUT only
2
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-100V SOT23 Simple Swapper Hot-Swap Controllers
ELECTRICAL CHARACTERISTICS (continued)
(VEE = -9V to -100V, GND = 0, ON/OFF open circuit, TA = -40C to +85C, unless otherwise noted. Typical values are at VEE = -48V and TA = +25C.) (Notes 2, 3)
PARAMETER PGOOD (PGOOD) Assertion Threshold (Note 7) PGOOD (PGOOD) Output Low Voltage Power-Good Output OpenDrain Leakage Current Thermal Shutdown Temperature Thermal Shutdown Hysteresis SYMBOL VPG CONDITIONS VDRAIN - VEE; MAX590_A, MAX590_L only MAX5900 V PGOOD - VEE, IOL = 1mA; MAX5901 VPGOOD - VEE, IOL = 1mA V PGOOD - VEE = 100V (MAX5900) VPGOOD - VEE = 100V (MAX5901) Junction temperature MIN TYP 0.75 VCB MAX UNITS mV
MAX5900/MAX5901
VOL IOH TSD THY
0.6 0.2 +125 15
1.65 10
V A C C
Note 2: 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 3: All specifications are 100% tested at TA = +25C. Specifications over -40C to +85C are guaranteed by characterization. Note 4: 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 5: 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 6: Guaranteed by design, not production tested. Note 7: For a detailed description see the Power-Good Output section of the data sheet.
Typical Operating Characteristics
(VEE = -48V, GND = 0, and TA = +25C, unless otherwise noted. See Figure 6 for test circuits.)
SUPPLY CURRENT vs.INPUT VOLTAGE
100k FROM ON/OFF TO GND 1.0 SUPPLY CURRENT (mA) 0.9 0.8 0.7 0.6 0.5 -100 -80 -60 -40 -20 0 INPUT VOLTAGE (V)
MAX5900/01 toc01
SUPPLY CURRENT vs. TEMPERATURE
VEE = -72V 0.85 SUPPLY CURRENT (mA) 0.80 0.75 0.70 0.65 0.60 0.55 -50 -25 0 25 50 75 100 125 TEMPERATURE (C) VEE = -12V
MAX5900/01 toc02
DEFAULT UNDERVOLTAGE LOCKOUT vs. TEMPERATURE
-25.5 -26.5 -27.5 -28.5 -29.5 -30.5 -31.5 -32.5 -33.5 -34.5 -35.5 -36.5 -37.5 -50 DECREASING |VEE|
MAX9500/01 toc03
1.1
0.90
VEE = -48V VUVLO (V)
INCREASING |VEE|
-25
0
25
50
75
100
125
TEMPERATURE (C)
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3
-100V SOT23 Simple Swapper Hot-Swap Controllers MAX5900/MAX5901
Typical Operating Characteristics (continued)
(VEE = -48V, GND = 0, and TA = +25C, unless otherwise noted. See Figure 6 for test circuits.)
GATE DRIVE VOLTAGE vs. INPUT VOLTAGE
MAX 5900/01 toc04
RESTART DELAY vs. TEMPERATURE
MAX5900/01 toc05
STARTUP WAVEFORMS RL = 90, CL = 100F
MAX5900/01 toc06
11.0 10.5 10.0 VGS (V) 9.5 9.0 8.5 8.0 7.5 7.0 -100 -80 -60 -40 -20 0 INPUT VOLTAGE (V)
450 400 350 tRS (ms) 300 250
A 0 0 B 0 C 0
200 150 -50 -25 0 25 50 75 100 125 TEMPERATURE (C)
D
A: VGS, 5V/div B: IIN, 1A/div
40ms/div
C: VEE, 50V/div D: VDRAIN, 40V/div
STARTUP WAVEFORMS RL = OPEN, CL = 10F
MAX5900/01 toc07
STARTUP WAVEFORMS RL = 40, CL = 10F
MAX5900/01 toc08
STARTUP WAVEFORMS RL = 40, CL = 100F
A 0 0 B
MAX5900/01 toc09
A 0 0 B
A 0 0 B 0 C 0 D
0 C 0 D A: VGS, 10V/div B: IIN, 200mA/div C:VOUT, 50V/div D: PGOOD, 50V/div 5ms/div
0 C 0 D A: VGS, 10V/div B: IIN, 1A/div C:VOUT, 50V/div D: PGOOD, 50V/div 5ms/div A: VGS, 10V/div B: IIN, 1A/div C:VOUT, 50V/div D: PGOOD, 50V/div 5ms/div
CIRCUIT BREAKER EVENT (CGATE = 1000pF, VOVERDRIVE = 20mV)
MAX5900/01 toc10
CIRCUIT BREAKER EVENT (CGATE = 1000pF, VOVERDRIVE = 200mV)
MAX5900/01 toc11
SLEW RATE vs. VEE
TA = +120C 11 SLEW RATE (V/ms) 10 9 TA = +25C 8 TA = -40C 7
MAX5900/01 toc12
12
A 0
A 0
B 0 0 C
B 0 C 0
A: PGOOD, 50V/div B:VDS, 0.5V/div C:VGS, 10V/div
2s/div
2s/div A: PGOOD, 50V/div B:VDS, 0.5V/div C:VGS, 10V/div
6 -100 -80 -60 -40 -20 0 VEE (V)
4
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-100V SOT23 Simple Swapper Hot-Swap Controllers
Pin Description
PIN MAX5900 1 MAX5901 1 NAME VEE FUNCTION Negative Supply Voltage Input and External N-Channel MOSFET Source Connection Drain Sense Input for External N-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 MAX5900/MAX5901 and the MOSFET. See Layout Guidelines. Gate Drive Output for External N-Channel MOSFET Ground Connection Power-Good Output. PGOOD is an N-channel, open-drain, active-low output, referenced to VEE. Power-Good Output. PGOOD is an N-channel, open-drain, active-high output, referenced to VEE. ON/OFF Control Input. ON/OFF is referenced to VEE. 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 undervoltage lockout (UVLO) threshold. See Undervoltage Lockout in the Applications section of this data sheet. Internally clamped to nominally 3V through a 1k resistor (see Figure 1).
MAX5900/MAX5901
2
2
DRAIN
3 4 5 --
3 4 -- 5
GATE GND PGOOD PGOOD
6
6
ON/OFF
Detailed Description
The MAX5900/MAX5901 are integrated hot-swap controller ICs contained in 6-pin SOT23 packages. They allow a board to be safely hot-plugged into a live backplane without causing a glitch on the power-supply rail. They are well suited for -48V telecom power systems allowing cost-effective, simple, and compact design. The MAX5900/MAX5901 operate from -9V to -100V to cover the standard telecom voltage range, and to serve more generalized applications. These devices require only an external N-channel power MOSFET to provide hot-swap control. Figure 1 shows a functional diagram of the MAX5900/MAX5901. The MAX5900/MAX5901 control an external N-channel power MOSFET placed in the negative power-supply pathway. When power is first applied, the MAX5900/ MAX5901 keep the MOSFET turned off. The MAX5900/MAX5901 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 300ms (typ), the MAX5900/MAX5901 begin to gradually turn on the MOSFET. During this turn-on phase, the MAX5900/MAX5901 slowly enhance the MOSFET, allowing the voltage on the load, i.e. the drain of the
MAX5900 MAX5901 GND 828k*
ON/OFF 1k* 34.5k* 3V
CONTROL LOGIC PGOOD (PGOOD) N
VEE VEE 466k* GATE DRAIN VEE
( ) ARE FOR THE MAX5901 ONLY * RELATIVE TOLERANCE 1%, ABSOLUTE TOLERANCE 20% TYPICAL
Figure 1. Functional Diagram
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5
-100V SOT23 Simple Swapper Hot-Swap Controllers
MOSFET, to fall no faster than 10V/ms (typ). The inrush current to the load is thus limited to a level proportional to the load capacitance, and the constant load voltage slew rate. After the MOSFET is fully enhanced, and the load voltage is settled to its final value, the MAX5900A/ MAX5901A and MAX5900L/MAX5901L monitor the voltage drop from the MOSFET's drain-to-source (VDS). If the voltage drop exceeds 75% of the circuit breaker threshold the MAX5900A/MAX5901A or MAX5900L/ MAX5901L turn off the MOSFET, disconnecting the load immediately. Because the circuit breaker function is not activated until the MOSFET is fully enhanced, it takes approximately 10ms for the MAX5900A/ MAX5901A or MAX5900L/MAX5901L to react to an output short circuit at startup. If no circuit breaker fault exists, the power-good output is asserted. Then, if any of four conditions exist, the power-good output deasserts and the MOSFET is turned off . The four conditions are: the voltage across the MOSFET exceeds the circuit breaker threshold; the supply voltage magnitude falls below the undervoltage lockout level; the die temperature exceeds +125C; or ON/OFF is forced low. After a circuit breaker fault, the MAX5900L/MAX5901L keep the MOSFET off until the power is cycled, or the part is reset by toggling ON/OFF low for at least 20ms (typ). After a circuit breaker fault, the MAX5900A/ MAX5901A automatically restart in 300ms (typ). All versions automatically restart after a thermal fault, or an undervoltage shutdown, if the fault condition goes away for at least 300ms (typ). ON/OFF offers external control of the MAX5900/ MAX5901, facilitating power-supply sequencing, and may also be used to change the undervoltage lockout level. Undervoltage lockout keeps the external MOSFET switched off as long as the magnitude of the input voltage is below the desired level. A power-good output, PGOOD (MAX5900) or PGOOD (MAX5901), asserts when the external MOSFET is fully enhanced and the drain-source voltage is at least 25% below the circuit breaker threshold. PGOOD and PGOOD are open-drain outputs referenced to VEE, and can withstand up to 100V above VEE. A thermal shutdown feature protects the external MOSFET by turning it off if the die temperature of the MAX5900/MAX5901 exceeds +125C. The MAX5900/ MAX5901 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, VDS, and turns off the MOSFET if VDS exceeds the circuit breaker threshold, VCB. The circuit breaker function is enabled after the MOSFET is
6
MAX5900/MAX5901
fully enhanced. Three threshold voltage options are available--200mV, 300mV, and 400mV. One version is available with no circuit breaker function. Circuit breaker fault management for the MAX5900/MAX5901 is offered with two different configurations--latched and automatic retry.
Latched Circuit Breaker
After a circuit breaker trip event, the latched versions (MAX5900L/MAX5901L) drive GATE to V EE, 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 20ms, or by cycling the power supply, VEE.
Automatic Retry Circuit Breaker
After a circuit breaker trip event the automatic retry versions (MAX5900A/MAX5901A) drive GATE to VEE, turning off the external MOSFET, and PGOOD (PGOOD) is deasserted. If the start conditions are met for a full 300ms (tRS) the start sequence is 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.
No Circuit Breaker
For the versions without a circuit breaker, MAX5900N (MAX5901N), PGOOD (PGOOD) is asserted when the MOSFET is fully enhanced. Once powered up, the MAX5900N/MAX5901N ignore the MOSFET drain-tosource voltage (VDS) for applications where a circuit breaker function is not desired.
Applications Information
ON/OFF Control Input
The ON/OFF control input provides three hot-swap functions: external ON/OFF control; setting of the UVLO level; and resetting after a circuit breaker event has caused the MAX5900L/MAX5901L to turn off the external MOSFET. Pulling ON/OFF to VEE for at least 20ms (t OFF) forces the MAX5900/MAX5901 to turn off the external MOSFET (see Figure 2 for a circuit example). To reset the MAX5900L/MAX5901L after a circuit breaker event, toggle ON/OFF to VEE for at least 20ms (tOFF). ON/OFF can be used to sequence power supplies. Connecting a capacitor from ON/OFF to VEE will delay the rise of ON/OFF proportional to the capacitance and input impedance of ON/OFF, typically 32k (Figure 3).
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-100V SOT23 Simple Swapper Hot-Swap Controllers
HOT-SWAP CONTROLLER GND OPTIONAL ON/OFF R2 47k MAX5900 MAX5901 GND ON/OFF DGND -48V R1 3k VEE
Thermal Shutdown
A thermal shutdown feature helps protect the external MOSFET. If the die temperature of the MAX5900/ MAX5901 exceeds +125C, the MOSFET is turned off. For accurate performance the MAX5900/MAX5901 must be in close thermal contact with the external MOSFET. See Layout Guidelines for information. Due to the low power dissipation of the MAX5900/MAX5901, the junction temperature will typically be within a few degrees of the MOSFET. All versions of the MAX5900/ MAX5901 automatically restart from a temperature fault when the junction temperature drops below +110C.
MAX5900/MAX5901
Figure 2. Programmed -20V Lockout, with Optional Optocoupler On/Off Control
Undervoltage Lockout
HOT-SWAP CONTROLLER #1 GND MAX5900 MAX5901 GND ON/OFF C VEE
HOT-SWAP CONTROLLER #2 MAX5900 MAX5901 GND ON/OFF 2C VEE
The MAX5900/MAX5901 turn off the external MOSFET if the magnitude of the input voltage is below the level set by ON/OFF for longer than 20ms (tOFF). If ON/OFF is left unconnected, the lockout voltage (VUVLO) 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 and -100V use a resistor-divider connected between GND and VEE, with the center node of the divider connected to ON/OFF. For example, use a 3k resistor (R1 in Figure 2) from ON/OFF to VEE and calculate the other resistor, R2, using: |V | R2 = R1 x UVLO - 1 1.26 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 2 shows an example circuit with VUVLO set for -20V. To defeat the UVLO simply connect a single 100k resistor between ON/OFF and GND, as shown in Figure 4.
VEE
Figure 3. Power-Supply Sequencing
Turn-On and Turn-Off Delays
After power is applied, or ON/OFF is released, there is a 300ms 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 2s. An undervoltage condition must exist for at least 20ms (tOFF) before the MAX5900/MAX5901 turn off the external MOSFET. ON/OFF must be held low for at least 20ms (tOFF) before the MAX5900/MAX5901 turn 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 (MAX5900L/MAX5901L).
HOT-SWAP CONTROLLER GND 100k GND ON/OFF VEE -48V MAX5900 MAX5901
Figure 4. Defeating Undervoltage Lockout _______________________________________________________________________________________ 7
-100V SOT23 Simple Swapper Hot-Swap Controllers MAX5900/MAX5901
Power-Good Output
The power-good output, PGOOD (PGOOD), is opendrain and asserts when the external MOSFET is fully enhanced and VDS is less than VPG (75% of the circuit breaker threshold, VCB). For versions without the circuit breaker function (MAX5900N/MAX5901N), PGOOD (PGOOD) asserts when the external MOSFET is fully enhanced. PGOOD (PGOOD) deasserts within 2s when a circuit breaker event occurs or if the die temperature exceeds +125C. PGOOD (PGOOD) deasserts if |VEE| < |VUVLO| for longer than 20ms or ON/OFF is held low for longer than 20ms. The MAX5900 PGOOD is active-low and the MAX5901 PGOOD is active-high. Both are open-drain N-channel MOSFETs with their sources connected to VEE, and can withstand up to 100V. 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 gross overcurrent condition occurs. See Table 1 for MOSFET suggestions. The MAX5900N/MAX5901N have no circuit breaker function. For these parts choose an external MOSFET that meets the load requirements.
Determining Inrush Current
Determining a circuit's inrush current is necessary to help choose the proper MOSFET. The MAX5900/ MAX5901 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
Selecting a Circuit Breaker Threshold
The MAX5900A/MAX5901A and the MAX5900L/ MAX5901L 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, VDS, is generated from drain to source due to the MOSFET's on-resistance, R DS(ON) . The MAX5900A/MAX5901A and MAX5900L/MAX5901L monitor VDS when the external MOSFET is fully enhanced. If VDS 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 MAX5900/MAX5901 are available with circuit breaker threshold voltages of 200mV, 300mV, and 400mV. The circuit breaker function is intended to disconnect the load if a gross overcurrent or short-circuit condition occurs. For calculating the circuit breaker threshold use the MOSFET's RON at the worst possible operating condition, and add a 25% overcurrent margin to the maximum circuit current. For instance, if a MOSFET has an RON of 0.06 at TA = +25C, and a normalized onresistance factor of 1.75 at T A = +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 25% margin, the current for calculation is (2A) x (1.25) = 2.5A. The resulting minimum circuit breaker threshold is then the product of these two results, or (0.105) x (2.5A) = 0.263V. The next highest minimum available threshold is 0.265V of the MAX590_ _BEUT, which is an ideal choice given these
8
where C is the load capacitance, and SR is the MAX5900/MAX5901 Load Voltage Slew Rate Magnitude from the Electrical Characteristics table. For example, assuming a load capacitance of 100F, and using the typical value of 10V/ms for the slew rate, the inrush current is 1A typical. If the maximum possible Load Voltage Slew Rate is used, the maximum inrush current calculates to 1.7A. Choose a MOSFET with a maximum pulsed current specification that exceeds the maximum inrush current.
Suggested External MOSFETs
MAXIMUM ILOAD (A) 0.25 0.5 1 2 3 4 SUGGESTED EXTERNAL MOSFET IRFL110 IRFL4310 IRFR3910 IRF540NS IRF1310NS IRF1310NS SUGGESTED MAXIM PART MAX590_ _CEUT MAX590_ _BEUT MAX590_ _CEUT MAX590_ _BEUT MAX590_ _BEUT MAX590_ _CEUT
VIN = -9V to -90V
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-100V SOT23 Simple Swapper Hot-Swap Controllers
Layout Guidelines
GROUND U1 SOT23-6 POWER IN M1 SOT-223 SDG POWER OUT
MAX5900/MAX5901
MAX5900/MAX5901
Good thermal contact between the MAX5900/ MAX5901 and the external MOSFET is essential for the thermal shutdown feature to operate effectively. Place the MAX5900/MAX5901 as close as possible to the drain of the external MOSFET, and use wide circuit board traces for good heat transfer. See Figure 5 for an example of a PC board layout.
Chip Information
TRANSISTOR COUNT: 678 PROCESS TECHNOLOGY: BiCMOS
Figure 5. Circuit Board Layout Example.
100k VIN + V
GND 100F
GND VIN + -
MAX5900 ON/OFF MAX5901 PGOOD (PGOOD)
VEE GATE DRAIN
V
ON/OFF MAX5901 PGOOD (PGOOD) VEE GATE DRAIN
MAX5900
50k
V
(a) SUPPLY CURRENT
(b) VUVLO
GND 100k VIN + V GND 48V + -
MAX5900 ON/OFF MAX5901 PGOOD (PGOOD)
VEE GATE DRAIN
ON/OFF MAX5901A PGOOD (PGOOD) VEE GATE DRAIN SCOPE
MAX5900A
V 50k
SCOPE
(c) GATE DRIVE VOLTAGE
(d) RETRY TIMEOUT
GND 48V + -
GND 50k RL 50k CL SCOPE 48V + -
ON/OFF MAX5901 PGOOD (PGOOD) VEE GATE DRAIN
MAX5900
MAX5900 ON/OFF MAX5901 PGOOD (PGOOD)
VEE GATE DRAIN SCOPE SCOPE
SCOPE SCOPE SCOPE SCOPE
SCOPE 50k
(e) TURN-ON WAVEFORMS
(f) CIRCUIT BREAKER EVENT
Figure 6. Test Circuits _______________________________________________________________________________________ 9
-100V SOT23 Simple Swapper Hot-Swap Controllers MAX5900/MAX5901
Selector Guide
PART MAX5900NNEUT* MAX5900AAEUT* MAX5900ABEUT* MAX5900ACEUT* MAX5900LAEUT* MAX5900LBEUT* MAX5900LCEUT* MAX5901NNEUT* MAX5901AAEUT* MAX5901ABEUT* MAX5901ACEUT* MAX5901LAEUT* MAX5901LBEUT* MAX5901LCEUT* CIRCUIT BREAKER FUNCTION None Auto Retry Auto Retry Auto Retry Latched Latched Latched None Auto Retry Auto Retry Auto Retry Latched Latched Latched CIRCUIT BREAKER THRESHOLD None 200mV 300mV 400mV 200mV 300mV 400mV None 200mV 300mV 400mV 200mV 300mV 400mV 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 AAQV AAQJ AAQK AAQL AAQM AAQN AAQO AAQW AAQP AAQQ AAQR AAQS AAQT AAQU
*Requires special solder temperature profile described in the Absolute Maximum Ratings section. Future product--contact factory for availability.
Typical Operating Circuits (Continued)
BACKPLANE GND HOT-SWAP CONTROLLER V+ MAX5901 GND ON/OFF VEE PGOOD DRAIN GATE 39k GND 1M CIRCUIT CARD 50W ISOLATED POWER SUPPLY
MAX5003*
INDIV
-48V FUSE
IRF540NS
* MAX5003 IS A 110V PWM CONTROLLER
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-100V SOT23 Simple Swapper Hot-Swap Controllers MAX5900/MAX5901
Package Information
6LSOT.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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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