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MAX5902/MAX5903

+72V , SOT23/TDFN, Simple Swapper Hot-Swap

Controllers

________________________________________________________________Maxim Integrated Products

19-1988; Rev 3; 1/07

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-sup-ply 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 cur-rent by gradually turning on the external MOSFET. Once the external MOSFET is fully enhanced, the circuit-break-er function is enabled and the MAX5902/MAX5903 pro-vide overcurrent protection by monitoring the voltage drop across the external MOSFET’s on-resistance.

The MAX5902/MAX5903 include an undervoltage lock-out (UVLO) function, ON/OFF control input, and a power-good status output, PGOOD (MAX5902) or PGOOD (MAX5903). A built-in thermal shutdown fea-ture 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 pack-ages, 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 Servers Network Switches RAID

Base Station Line Industrial Systems

Cards

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

Pin Configurations

Typical Operating Circuits

Simple Swapper is a trademark of Maxim Integrated Products, Inc.

For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at https://www.wendangku.net/doc/7416508058.html,.

M A X 5902/M A X 5903

Controllers 2_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V S = +9V to +72V, GND = 0V, ON/OFF open circuit, T A = -40°C to +85°C, unless otherwise noted. Typical values are at V S = +48V and T

= +25°C.) (Notes 1, 2)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.

Terminal Voltage (with respect to GND unless otherwise noted)V S , DRAIN, PGOOD, PGOOD ................................-0.3V to +76V ON/OFF ....................................................................-0.3V to +4V GATE to V S ............................................................-12V to +0.3V Current into any Pin............................................................±3mA

Continuous Power Dissipation (T A = +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

MAX5902/MAX5903

Controllers

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GND, unless otherwise noted.

Note 2:All specifications are 100% tested at T A = +25°C, unless otherwise noted. Specifications over -40°C to +85°C are guaran-teed by characterization.

Note 3:This is the delay time from a valid on condition until V GS begins rising. Valid on conditions are: the device is not in undervolt-age 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 V GS falls. Pulses on ON/OFF less than t OFF are ignored, offering glitch

immunity.

Note 5:Guaranteed by characterization, not production tested. C GATE is a capacitor from GATE to V S .

ELECTRICAL CHARACTERISTICS (continued)

(V S = +9V to +72V, GND = 0V, ON/OFF open circuit, T A = -40°C to +85°C, unless otherwise noted. Typical values are at V S = +48V and T A = +25°C.) (Notes 1, 2)

Typical Operating Characteristics

(V S = +48V, GND = 0V, and T A = +25°C, unless otherwise noted. See Figure 2 for test circuits.)

0.7

0.8

1.00.91.11.20

SUPPLY CURRENT vs. INPUT VOLTAGE

INPUT VOLTAGE (V)

S U P P L Y C U R R E N T (m A )

0.70.8

1.0

0.9

1.11.2

-40

-15

SUPPLY CURRENT vs. TEMPERATURE

TEMPERATURE (°C)

S U P P L Y C U R R E N T (m A )

25282726

29303132333435

-40

-15

V UVLO THRESHOLD vs. TEMPERATURE

TEMPERATURE (°C)

L O C K O U T V O L T A G E (V )

Typical Operating Characteristics (continued)

(V S = +48V, GND = 0V, and T A = +25°C, unless otherwise noted. See Figure 2 for test circuits.)

M A X 5902/M A X 5903

Controllers 4

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13150

GATE DRIVE VOLTAGE vs. INPUT VOLTAGE

INPUT VOLTAGE (V)

G A T E D R I V E (V )

125100175150200225-4010-15356085

RETRY TIMEOUT vs. TEMPERATURE

M A X 5902 t o c 05

TEMPERATURE (°C)

T I M E O U T P E R I O D (m s )

t = 20ms/div

TURN-ON WAVEFORMS R L = 60?, C L = 100μF

A : V OUT , 50V/div

B : I IN , 1A/div

C : V GATE , 50V/div

D : V IN , 50V/div

A B D

MAX5902 toc06

000

t = 2ms/div

TURN-ON WAVEFORMS R L = OPEN, C L = 100μF

A : V OUT , 50V/div

B : I IN , 1A/div

C : V GATE , 20V/div

A B C MAX5902 toc07

t = 1μs/div

CIRCUIT-BREAKER EVENT

V OVERDRIVE = 20mV, C GATE = 1000pF

MAX5902 toc10

A : V DS , 0.5V/div

B : V GS , 10V/div

C : V PGOO

D TO V S , 50V/div t = 2ms/div

TURN-ON WAVEFORMS

R L = 60?, C L = 10μF A : V OUT , 50V/div B : I IN , 0.5A/div C : V GATE , 20V/div A

B C MAX5902 toc08

t = 1μs/div

CIRCUIT-BREAKER EVENT

V OVERDRIVE = 200mV, C GATE = 1000pF

MAX5902 toc11

0A : V DS , 0.5V/div B : V GS , 10V/div

C : V TO V S , 50V/div

t = 2ms/div

TURN-ON WAVEFORMS

R L = 60?, C L = 100μF A : V OUT , 50V/div B : I IN , 1A/div C : V GATE , 20V/div

B C MAX5902 toc09

MAX5902/MAX5903Controllers

M A X 5902/M A X 5903

Controllers

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MAX5902L/MAX5903L turn off the MOSFE T, discon-necting 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 power-good output deasserts and the MAX5902/MAX5903turn off the MOSFET. The four conditions are: the volt-age across the MOSFE T exceeds the circuit-breaker threshold; the supply voltage falls below the undervolt-age lockout level; the die temperature exceeds +125°C; or ON/OFF is forced low. After a circuit-break-er fault, the MAX5902L/MAX5903L keep the MOSFE T off until the power is cycled, or the part is reset by tog-gling 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 MOSFE T 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 with-stand up to +72V.

Figure 2. Test Circuits

MAX5902/MAX5903

Controllers

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A thermal shutdown feature protects the external MOS-FE T 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 MOSFE T. See Layout Guidelines in the Appli-cations section of the data sheet.

A circuit-breaker function monitors the voltage across the external MOSFET, V SD , and turns off the MOSFET if V SD exceeds the circuit-breaker threshold, V C

B . 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 man-agement for the MAX5902/MAX5903 is offered with two different configurations; latched and automatic retry.

Latched Circuit Breaker

After a circuit-breaker trip event, the latched versions (MAX5902L/MAX5903L) drive GATE to V S , turning off the external MOSFE T, 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, V S .

Automatic Retry Circuit Breaker

After a circuit-breaker trip event, the automatic retry versions (MAX5902A/MAX5903A) drive GATE to V S ,turning off the external MOSFE T, and PGOOD (PGOOD) is deasserted. If the start conditions are met for a full 150ms (t RS ) 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 ther-mal shutdown.

No Circuit Breaker

For the versions without a circuit breaker, MAX5902N (MAX5903N), PGOOD (PGOOD) are asserted when the MOSFE T is fully enhanced. Once powered up the MAX5902N/MAX5903N ignore the MOSFE T drain-to-source voltage for applications where a circuit-breaker function is not desired.

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 (t OFF ) 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 (t OFF ).

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 logic-level 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 4. Power-Supply Sequencing

Figure 3. Programmed +18V Lockout, with Optional Optocoupler On/Off Control.

Turn-On and Turn-Off Delays

After power is applied, or ON/OFF is released, there is a 150ms delay (t ON ) 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 over-temperature fault condition, the turn-off delay is less than 4μs. An undervoltage condition must exist for at least 10ms (t OFF ) before the MAX5902/MAX5903 turns off the external MOSFET. ON/OFF must be held low for at least 10ms (t OFF ) before the MAX5902/MAX5903turns off the external MOSFET. Turn-off delay minimizes spurious shutdowns due to noisy signals or momentary voltage spikes, as well as preventing accidental reset-ting of the circuit-breaker latch (MAX5902L/MAX5903L).

Thermal Shutdown

A thermal shutdown feature helps protect the external MOSFE T. If the die temperature of the MAX5902/MAX5903 exceeds +125°C, the MOSFET is turned off.For accurate performance the MAX5902/MAX5903must be in close thermal contact with the external MOS-FET. See the Layout Guidelines section for information.Due to the low power dissipation of the MAX5902/MAX5903, its junction temperature will typi-cally be within a few degrees of the MOSFE T. All ver-sions 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 (t OFF ). If ON/OFF is left unconnected, the lockout voltage (V UVLO )defaults to 31.5V. V UVLO may also be set to any value within the power-supply range by using external resis-tors. To set the lockout voltage to a value between +9V

and +72V use a resistor divider connected between V S and GND, with the center node of the divider connect-ed to ON/OFF . For example, use a 3k ?resistor (R1 in Figure 3) from ON/OFF to GND and calculate the other

where V UVLO is the desired lockout voltage, and V ON/OFF is the ON/OFF reference threshold specified in the Electrical Characteristics table (typically 1.26V).Figure 3 shows an example circuit with V UVLO set for +18V. To defeat the UVLO simply connect a single 100k ?resistor between ON/OFF and V S , as shown in Figure 6.

The Power-Good Output

The power-good output, PGOOD (PGOOD), is open-drain and asserts when the external MOSFE T is fully enhanced and V SD is less than the circuit-breaker threshold (V CB ). 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 circuit-breaker event occurs or if the die temperature exceeds +125°C. PGOOD (PGOOD) deasserts if V S < V UVLO for longer than 10ms or ON/OFF is held low for longer than 10ms.

The MAX5902 PGOOD is active-low and the MAX5903PGOOD is active-high. Both are open-drain n-channel MOSFE Ts with their sources connected to GND, and can withstand up to +72V.

M A X 590

2/M A X 5903

Controllers 8

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Figure 6. Defeating Undervoltage Lockout

Figure 5. Logic Control

MAX5902/MAX5903

Controllers

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Selecting a Circuit-Breaker Threshold

The MAX5902A/MAX5903A and the MAX5902L/MAX5903L offer a circuit-breaker function to protect the external MOSFE T and the load from the potentially damaging effects of excessive current. As load current flows through the external MOSFET, a voltage, V SD , is generated from source to drain due to the MOSFE T’s on-resistance, R DS(ON). The MAX5902A/MAX5903A and MAX5902L/MAX5903L monitor V SD when the exter-nal MOSFE T is fully enhanced. If V SD exceeds the circuit-breaker threshold the external MOSFET is turned off, and PGOOD (PGOOD) is deasserted. To accom-modate different MOSFE Ts and different load currents the MAX5902/MAX5903 are available with circuit-break-er threshold voltages of 300mV, 400mV, and 500mV. To determine the proper circuit-breaker threshold for an application use:

V CB > (R DS(ON)) ? (I OUT(MAX))

where R DS(ON)is the on-resistance of the MOSFET and I OUT (MAX) is the maximum expected output current.The MAX5902N/MAX5903N have no circuit-breaker function. For these parts choose an external MOSFE T 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 dis-abling the external MOSFET. For calculating the circuit-breaker threshold use the MOSFET’s R ON at the worst possible operating condition, and add a 20% overcur-rent margin to the maximum circuit current. For instance, if a MOSFE T has an R ON of 0.06?at T A =+25°C, and a normalized on-resistance factor of 1.75 at T A = +130°C (from the MOSFE T data sheet), the R ON used for calculation is the product of these two num-bers, or (0.06?) x (1.75) = 0.105?. Then, if the maxi-mum 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 MAX5902ABE UT, 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.

Determining Inrush Current

Determining a circuit’s inrush current is necessary to help choose the proper MOSFE T. The MAX5902/MAX5903 regulate the inrush current by means of con-trolling the load voltage slew rate, but inrush current is also a function of load capacitance. Determine inrush current using:

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 MOSFE T with a maximum pulsed current

specification that exceeds the maximum inrush current.

Figure 7. Circuit Board Layout Example.

V IN = +9V to +72V

M A X 5902/M A X 5903

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 MOSFE T, 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

Controllers 10______________________________________________________________________________________

MAX5902/MAX5903

Controllers

______________________________________________________________________________________11

Selector Guide

TDFN

+Denotes lead-free package.

M A X 5902/M A X 5903

Controllers 12______________________________________________________________________________________

Typical Operating Circuits (continued)

Pin Configurations (continued)

MAX5902/MAX5903

Controllers

______________________________________________________________________________________13

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 https://www.wendangku.net/doc/7416508058.html,/packages .)

M A X 5902/M A X 5903

Controllers 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.

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 https://www.wendangku.net/doc/7416508058.html,/packages .)