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MAX5917BESE中文资料

General Description

The MAX5910/MAX5917 are fully integrated hot-swap switches for positive supply rails. These devices allow the safe insertion and removal of circuit cards into live backplanes or ports without causing glitches on the backplane power-supply rail. They also monitor various circuit parameters and disconnect the load if a fault condition occurs, alerting the host with a logic-level IFAULT output. The MAX5910/MAX5917 operate over a +10V to +65V input voltage range. They are designed to permit hot plugging of an internet appliance such as an IP phone but are not limited to that application.

During startup, an internal power FET regulates the cur-rent between the backplane power source and the load to 280mA for the MAX5910, 567mA for the MAX5917A,and 420mA for the MAX5917B. After startup, the FET is fully enhanced to reduce its on-resistance. To ensure robust operation, the MAX5910/MAX5917 contain built-in safety features that prevent damage to the internal FET. They include an enable input, which responds to positive logic signals (+3.3V or +5V), allowing the host system to disconnect the load.

The MAX5910/MAX5917 Simple Swapper? hot-swap ICs monitor four parameters for fault conditions: undervoltage lockout (UVLO), power-not-good, zero-current detection,and thermal shutdown. These devices are available in the extended temperature range, -40°C to +85°C. The MAX5910 comes in an 8-pin SO package and the MAX5917A/B is available in a 16-pin SO package.

Applications

IP Phones

Power-Over-LAN Power-Over-MDI

Remote Power Distribution Network Routers Network Switches Internet Appliances

Features

o Provides Safe Hot Swap for +10V to +65V Power Supplies o IEEE 802.3af Compliant (MAX5917A)o Startup into 500μF Load (MAX5917A)o 280mA Current Limit for MAX5910

o 567mA Current Limit for MAX5917A

o 420mA Current Limit for MAX5917B o Zero-Current Load Detection o Integrated 2.2?Power FET

o Status Output Reports Fault Conditions o Internal Switch-Protection Circuitry o Built-In Thermal Shutdown

MAX5910/MAX5917

+65V Simple Swapper Hot-Swap Switches

________________________________________________________________Maxim Integrated Products 1

Typical Operating Circuit

Ordering Information

19-1706; Rev 0; 7/01

*Future product—contact factory for availability.

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/a29784125.html,.

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

Pin Configurations appear at end of data sheet.

M A X 5910/M A X 5917

+65V Simple Swapper Hot-Swap Switches 2_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

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.

V IN , V OUT to GND................................................-0.3V to +70.0V ENABLE to GND..................................................-0.3V to +12.0V PGOOD, IFAULT to GND ....................................-0.3V to +12.0V UVLO to GND..............................................-0.3V to (V IN + 0.3V)PGOOD, IFAULT Sink Current............................................10mA Continuous Power Dissipation (T A = +70°C)

8-Pin SO (derate 5.9mW/°C above +70°C)..................470mW 16-Pin SO (derate 12.9mW/°C above +70°C)............1039mW

Operating Temperature Range ...........................-40°C to +85°C Maximum Junction Temperature.....................................+150°C Storage Temperature Range.............................-60°C to +150°C Lead Temperature (soldering 10s)..................................+300°C

MAX5910/MAX5917

+65V Simple Swapper Hot-Swap Switches

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ELECTRICAL CHARACTERISTICS (continued)

(V IN = +42V, GND = 0, UVLO = open circuit, V ENABLE = +3.3V, and T A = -40°C to +85°C, unless otherwise noted. Typical values are Figure 1. IFAULT Delay

Figure 2. Power-Good Delay

M A X 5910/M A X 5917

+65V Simple Swapper Hot-Swap Switches 4_______________________________________________________________________________________

Typical Operating Characteristics

(V IN = +42V, GND = 0, UVLO = open circuit, V ENABLE = 3.3V, R L = 1.8k ?, T A = +25°C, unless otherwise noted).

2ms/div

MAX5910 TURN-ON WAVEFORMS

(R L = 1.8k ?, C L = 0)

A: ENABLE, 5V/div B: V OUT , 20V/div C: PGOOD, 5V/div

A 0

C B

MAX5910 toc04

2ms/div

MAX5910 TURN-OFF WAVEFORMS

(R L = 1.8k ?, C L = 0)

A: ENABLE, 5V/div B: V OUT , 20V/div C: PGOOD, 5V/div

MAX5910 toc05

A 0C B

2ms/div

MAX5910 TURN-ON WAVEFORMS

(R L = 1.8k ?, C L = 47μF)

A: ENABLE, 5V/div B: V OUT , 20V/div C: PGOOD, 5V/div

MAX5910 toc06

A 0C B

SUPPLY CURRENT vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

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

0.4

0.801.62.01.2-15

-40

SUPPLY CURRENT vs. TEMPERATURE

TEMPERATURE (°C)

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

0.4

0.8

01.62.0

1.2

-15

-40

ON-RESISTANCE vs. TEMPERATURE

TEMPERATURE (°C)

O N -R E S I S T A N C E (?)

1.4

1.8

1.0

2.6

3.0

2.2

2ms/div

MAX5917B TURN-ON WAVEFORMS

(R L = 1.8k ?, C L = 0)

A: ENABLE, 5V/div B: V OUT , 20V/div C: PGOOD, 5V/div

MAX5910 toc10

A 0

C B 0

2ms/div

MAX5917B TURN-OFF WAVEFORMS

(R L = 1.8k ?, C L = 0)

A: ENABLE, 5V/div B: V OUT , 20V/div C: PGOOD, 5V/div

MAX5910 toc11

A 0

C B 00

2ms/div

MAX5917B TURN-ON WAVEFORMS

(R L = 1?, C L = 47μF)

A: ENABLE, 5V/div B: V OUT , 20V/div C: PGOOD, 5V/div

MAX5910 toc12

A 0

C B 00

MAX5910/MAX5917

+65V Simple Swapper Hot-Swap Switches

_______________________________________________________________________________________5

Typical Operating Characteristics (continued)

(V IN = +42V, GND = 0, UVLO = open circuit, V ENABLE = 3.3V, R L = 1.8k ?, T A = +25°C, unless otherwise noted).

20ms/div

MAX5910 TURN-OFF WAVEFORMS

(R L = 1.8k ?, C L = 47μF)

A: ENABLE, 5V/div B: V OUT , 20V/div C: PGOOD, 5V/div

MAX5910 toc07

A 0

C B

2ms/div

MAX5910 ZERO-CURRENT RESPONSE

A: I OUT , 100mA/div B: IFAULT, 5V/div C: V OUT , 20V/div

00B

MAX5910 toc08

40ms/div

MAX5910 OVER-CURRENT RESPONSE

A: I OUT , 200mA/div B: IFAULT, 5V/div

C: V OUT , 20V/div (SHORTED TO GND)

MAX5910 toc09

B C 0

M A X 5910/M A X 5917

+65V Simple Swapper Hot-Swap Switches 6

_______________________________________________________________________________________

40ms/div

MAX5917B OVER-CURRENT RESPONSE

A: I OUT , 200mA/div B: IFAULT, 5V/div

C: V OUT , 20V/div (SHORTED TO GND)

MAX5910 toc17

B C 0

250

260

280

270

290

300

-40

-15

MAX5910 I OUT vs. TEMPERATURE

TEMPERATURE (°C)

I O U T (m A )

2ms/div

MAX5917B ZERO-CURRENT RESPONSE

A: I OUT , 100mA/div B: IFAULT, 5V/div C: V OUT , 20V/div

MAX5910 toc16

Typical Operating Characteristics (continued)

(V IN = +42V, GND = 0, UVLO = open circuit, V ENABLE = 3.3V, R L = 1.8k ?, T A = +25°C, unless otherwise noted).

20ms/div

MAX5917B TURN-OFF WAVEFORMS

(R L = 1.8k ?, C L = 47μF)

A: ENABLE, 5V/div B: V OUT , 20V/div C: PGOOD, 5V/div

MAX5910 toc13

A 0

C B 00

10ms/div

MAX5917B TURN-ON WAVEFORMS

(R L = 300?, C L = 500μF)

A: ENABLE, 5V/div B: V OUT , 20V/div C: PGOOD, 5V/div

MAX5910 toc14

A 0C

B 0

100ms/div

MAX5917B TURN-OFF WAVEFORMS

(R L = 300?, C L = 500μF)

A: ENABLE, 5V/div B: V OUT , 20V/div C: PGOOD, 5V/div

MAX5910 toc15

A 0C B

MAX5910/MAX5917

+65V Simple Swapper Hot-Swap Switches

_______________________________________________________________________________________7

530

550

540570560590580

600-40

-15

MAX5917A I OUT vs. TEMPERATURE

M A X 5910 t o c 20

TEMPERATURE (°C)

I O U T (m A )

10050200150300250350

00.80.4 1.2 1.6 2.0

MAX5910 I OUT vs. (V IN - V OUT )

M A X 5910 t o c 21

V IN - V OUT (V)

I O U T (m A )

350

370

410

390

430

450

-40

-15

MAX5917B I OUT vs. TEMPERATURE

TEMPERATURE (°C)

I O U T (m A )

100

300

200

400

5000

0.8

0.4

1.2

1.6

2.0

MAX5917B I OUT vs. (V IN

- V OUT )

V IN - V OUT (V)

I O U T (m A )

200

100400

3005006000

0.8

0.4

1.2

1.6

2.0

MAX5917A I OUT vs. (V IN - V OUT )

M A X 5910 t o c 23

V IN - V OUT (V)

I O U T (m A )

Typical Operating Characteristics (continued)

(V IN = +42V, GND = 0, UVLO = open circuit, V ENABLE = 3.3V, R L = 1.8k ?, T A = +25°C, unless otherwise noted).

M A X 5910/M A X 5917

+65V Simple Swapper Hot-Swap Switches 8_______________________________________________________________________________________

Detailed Description

The MAX5910/MAX5917 are fully integrated hot-swap switches for positive power-supply rails. The devices allow safe insertion and removal of circuit cards into live backplanes or ports without causing glitches on the backplane power-supply rail. During startup these devices act as current regulators using their on-board FET to limit the amount of current drawn by the load to 280mA for MAX5910, 567mA for MAX5917A, and 420mA for MAX5917B. If the required load current exceeds that current limit, the internal switch behaves like a constant current source.

The MAX5910/MAX5917 monitor the input voltage, the output voltage, the output current, and the die tempera-ture. They assert IFAULT and PGOOD accordingly if they detect an error condition.

A zero-current load detection feature activates if the load current drops below IF TH for over 12ms. The MAX5910/MAX5917 also include an ENABLE input allowing the host system to turn the FET on or off.

Normal Operation

Startup

When power is first applied with ENABLE high, or when ENABLE is asserted, the MAX5910/MAX5917A/MAX5917B limit the current to the load to 280mA/567mA/420mA. PGOOD is asserted high 12ms after the output voltage exceeds the power-good threshold.PGOOD is pulled low if V OUT is less than 70% V IN .

Zero-Current Load Fault

A zero-current load detection feature activates if the load current drops below IF TH for more than 12ms. The MAX5910/MAX5917 flag the zero-current condition but do not disconnect the load. IFAULT is deasserted whenever the load current exceeds the IF TH + IF HYS zero-current detection threshold.

Undervoltage Lockout Fault

If V IN ≤UVLO, where UVLO is the desired voltage at which the UVLO fault occurs, the internal FET is turned off and IFAULT and PGOOD are pulled low. The default UVLO voltage is 26.5V, but it can be adjusted using an external resistive-divider (see the Changing the Undervoltage Lockout Setting section).

MAX5910/MAX5917

+65V Simple Swapper Hot-Swap Switches

_______________________________________________________________________________________

Thermal Shutdown Fault

The MAX5910/MAX5917 monitor their internal die tem-perature. If the temperature of the die exceeds +140°C,the internal FET is turned off and IFAULT and PGOOD are pulled low. The output is enabled again only when the die temperature is below the thermal shutdown tem-perature by 3.5°C typically.

Power-Good (PGOOD)

Power-good (PGOOD) logic output signals when the output has exceeded the PGOOD threshold. When the output voltage is below 70% of the input voltage,PGOOD is pulled low. When the output voltage is larger than 80% of the input voltage for more than 12ms,PGOOD is asserted.

Applications Information

Choosing a Device

The MAX5910 can output 280mA, the MAX5917B can output 420mA, and the MAX5917A can output up to 567mA. In applications where high power is expected,use the MAX5917 for its superior heat dissipation prop-erties, and always solder all of its GND pins to a large section of circuit board copper.

Logic Control

The enable input (ENABLE) responds to 3.3V logic sig-nals and will force the internal FET off if ENABLE is pulled low. This feature allows the host to disconnect the load from the power bus if required. Drive ENABLE high to enable V OUT .

Changing the Undervoltage Lockout

Setting

The undervoltage lockout (UVLO) value defaults to 26.5V if the UVLO pin is left open circuit (Figure 3).Connect UVLO to V IN to set the undervoltage lockout to a minimum of 7.5V (Figure 4). This lockout voltage can also be changed with a resistive-divider from V IN to GND. The center node of the divider is connected to the UVLO pin (Figure 5). The values of R1 and R2 must satisfy the condition R1//R2 << 260k ?and R2 <<1.65M ?. R2 can be calculated as follows:

R2 = R1 ?[(V UVLO / 7.5V) - 1]

where V IN (UVLO)is the desired lockout voltage.

Figure 3. UVLO is Set Internally to its +26.5V Default Value

Figure 4. Minimum +7.5V UVLO Configuration

Figure 5. Adjusting UVLO with an External Resistive-Divider

M A X 5910/M A X 5917

+65V Simple Swapper Hot-Swap Switches 10______________________________________________________________________________________

Functional Diagram

Pin Configurations

MAX5910/MAX5917

+65V Simple Swapper Hot-Swap Switches

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?2001 Maxim Integrated Products

Printed USA

is a registered trademark of Maxim Integrated Products.

Package Information

Chip Information

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