Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - OR controller, electrical elements n-channel SOIC 16 N+1 OR controller

General Description

The MAX5944 is a dual, current limiter/low-drop ORing,

switch controller power-management IC for FireWire

applications. Each independent channel controls two

external power MOSFETs to regulate current from the

input power supply to the load and performs low-voltage-

drop power-supply ORing. The MAX5944 operates over

the 7.5V to 37V input range and provides inrush and out-

put current limit in addition to diode ORing functions suit-

able for FireWire applications.

The MAX5944 allows the safe insertion and removal of

FireWire peripherals into a live FireWire port by providing

inrush current control and output current-limiting func-

tions. The MAX5944 features a current-limit function that

actively limits the current drawn by the load with a 2ms

timeout. Its autoretry function then automatically restarts

after the 259ms autoretry delay time.

The ORing feature provides a very efficient way to pro-

tect the FireWire port when connected to another

FireWire peripheral that sources a higher voltage. By

turning off the external MOSFETS, the MAX5944 provides

a true bidirectional load disconnect. Each channel has

an independent ON/OFF control that results in less than

10µA supply current per channel.

The MAX5944 operates over the -40°C to +85°C

extended temperature range and is available in a

16-pin SO package.

Applications

FireWire Desktop/Notebook Port

FireWire Peripheral Device Current Limit

FireWire Hub

Hot Swap

Features

♦ Provides Safe Hot-Swap for 7.5V to 37V Power

Supplies

♦ Dual-Channel Hot-Swap

♦ Low-Drop Power ORing with Ultra-Fast Turn-Off

♦ Active Current Limit

♦ ±5% Current-Limit Sensing Accuracy

♦ 2ms Current-Limit Timeout

♦ Fast Current-Limit Response to Output

Short-Circuit Conditions

♦ Drives External n-Channel Power MOSFETs

♦ Independent Overcurrent Fault Status Outputs

♦ 259ms Autoretry Period

♦ 10µA (Per Channel) Shutdown Current

♦ Independent ON/OFF Control Allows

Undervoltage Lockout Programming

♦ Fast Load Disconnect Control Through

ON/OFF Inputs

♦ Bidirectional Load Disconnect

♦ Power Routing from One Port to Another

MAX5944

Dual FireWire Current Limiter and Low-Drop

ORing Switch Controller

________________________________________________________________ Maxim Integrated Products 1

INA

SENSEA

GATE1A

GATE2A

OUTA

GND

FAULTB

ONB

INB

TOP VIEW

MAX5944

ONA

FAULTA

GATE2B

ONQ1

OUTB

GATE1B

SENSEB

Pin Configuration

Ordering Information

19-3426; Rev 0; 10/04

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.

EVALUATION KIT

AVAILABLE

Typical Operating Circuit appears at end of data sheet.

FireWire is a registered trademark of Apple Computer, Inc.

PART TEMP RANGE PIN-PACKAGE

MAX5944ESE -40°C to +85°C 16 SO

Summary of content (15 pages)

PAGE 1
9-3426; Rev 0; 10/04 KIT ATION EVALU E L B A IL AVA Dual FireWire Current Limiter and Low-Drop ORing Switch Controller The MAX5944 is a dual, current limiter/low-drop ORing, switch controller power-management IC for FireWire ® applications. Each independent channel controls two external power MOSFETs to regulate current from the input power supply to the load and performs low-voltagedrop power-supply ORing. The MAX5944 operates over the 7.
PAGE 2
MAX5944 Dual FireWire Current Limiter and Low-Drop ORing Switch Controller ABSOLUTE MAXIMUM RATINGS (Voltages referenced to GND, unless otherwise noted.) IN_ ..........................................................................-0.3V to +80V OUT_ ......................................................................-0.3V to +80V SENSE_ to IN_ ..........................................................-1V to +0.3V GATE1_ to SENSE_ ..................................................-0.
PAGE 3
Dual FireWire Current Limiter and Low-Drop ORing Switch Controller (VIN = 7.5V to 37V, GND = 0V, and TA = -40°C to +85°C, unless otherwise noted. Typical values are at VIN_ = 12V, TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX 1.0 UNITS GATE2_ Peak Pulldown Current IG2DP (VIN_ - VSENSE_) = 1V A GATE2_ Pulldown Current During Any GATE2_ Turn-Off Condition (Note 4) IG2OFF VGATE2_ = (VOUT_ + 4.
PAGE 4
ELECTRICAL CHARACTERISTICS (continued) (VIN = 7.5V to 37V, GND = 0V, and TA = -40°C to +85°C, unless otherwise noted. Typical values are at VIN_ = 12V, TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 1.78 2.02 2.
PAGE 5
Dual FireWire Current Limiter and Low-Drop ORing Switch Controller 2.15 2.10 2.05 5.4 5.3 46.5 GATE CURRENTS (µA) 2.20 47.0 MAX5944 toc05 2.25 GATE CURRENTS vs. TEMPERATURE 5.5 ORing THRESHOLD VOLTAGE (mV) MAX5944 toc04 CURRENT-LIMIT TIMEOUT (ms) 2.30 ORing THRESHOLD VOLTAGE vs. TEMPERATURE MAX5944 toc06 CURRENT-LIMIT TIMEOUT vs. TEMPERATURE 5.2 5.1 5.0 4.9 4.8 GATE1 46.0 45.5 45.0 GATE2 4.7 44.5 4.6 4.5 -15 10 35 60 44.0 -40 -15 10 35 TEMPERATURE (°C) GATE1 DRIVE VOLTAGE vs.
PAGE 6
MAX5944 Dual FireWire Current Limiter and Low-Drop ORing Switch Controller Typical Operating Characteristics (continued) (VIN_ = +12V, TA = +25°C, unless otherwise noted.
PAGE 7
Dual FireWire Current Limiter and Low-Drop ORing Switch Controller ORing SWITCHOVER WAVEFORM (VINB RISING ABOVE VINA) ORing SWITCHOVER WAVEFORM MAX5944 toc19 MAX5944 toc18 VINA = 12V VINB = 12.
PAGE 8
Dual FireWire Current Limiter and Low-Drop ORing Switch Controller MAX5944 Pin Description 8 PIN NAME FUNCTION 1 INA Channel A Input Power and Current-Sense Positive Input. Connect INA to the other end of the currentsense resistor and to the power source (see the Typical Operating Circuit). 2 ONA Channel A On/Off Control Input. ONA sets the undervoltage lockout threshold and resets the part after a fault latch. Drive ONA high to enable the device. Drive ON_ low to disable the device.
PAGE 9
Dual FireWire Current Limiter and Low-Drop ORing Switch Controller Q1 Q2 SENSEA GATE1A INA MAX5944 RSENSEA BATTERY SOURCE GATE2A OUTA ONQ1 OR COMPARATOR SENSEA GATE1A INA - 5mV OUTA GATE2A DRIVE CURRENT-LIMIT COMPARATOR MAX5944 2.02ms FAULT TIMEOUT INA - 50mV CP1A FAST CURRENT-LIMIT COMPARATOR UVLO COMPARATOR GATE2A GATE1A DRIVE CP2A x128 GATE CHARGE PUMPS 259ms AUTORETRY PERIOD INA - 75mV 6.5V FAULTA ONA COMPARATOR ONA 1.24V SHUTDOWN MODE 0.4V GND SHUTDOWN MODE 1.
PAGE 10
MAX5944 Dual FireWire Current Limiter and Low-Drop ORing Switch Controller Detailed Description The MAX5944 dual-channel controller IC performs hotswapping, power-supply ORing, and current limiting for FireWire power-supply applications. The MAX5944 incorporates four MOSFET drivers (GATE1_ and GATE2_) to control external n-channel power MOSFETs to perform low-voltage-drop power-supply ORing (GATE1_), hot-swapping, and current limiting (GATE2_) from the input power supply to the load.
PAGE 11
Dual FireWire Current Limiter and Low-Drop ORing Switch Controller VIN MAX5944 TO FireWire PORT RSENSE VFAULT Q1A Q2A ILIMIT tILIM ON_ IN_ SENSE_ IOUT GATE1_ GATE2_ OUT_ MAX5944 GND VIN ONQ1 VGATE1 Figure 3.
PAGE 12
MAX5944 Dual FireWire Current Limiter and Low-Drop ORing Switch Controller VINA ONQ1 IINA ONB ONA INB INA 30mΩ 30mΩ MAX5944 IINB VOUT SENSEB SENSEA GATE1B GATE1A Q1 GATE2B GATE2A Q2 OUTB OUTA GND PORT 2 VINB PORT 1 VINB > VINA Figure 5. MAX5944 Power Switch Over ORing Timing Diagram Undervoltage Lockout The MAX5944 dual-channel, independent current-limit switches have independent ON/OFF control. Both channels operate from 7.5V to 37V and have default 6.
PAGE 13
Dual FireWire Current Limiter and Low-Drop ORing Switch Controller IN_ R1 MAX5944 ON_ R2 GND Figure 7. Setting the MAX5944 Turn-On Voltage to 1/129 under continuous fault conditions. FAULT_ deasserts every time a restart attempt is made. Applications Information Startup Considerations Set the appropriate current-limit threshold for a successful MAX5944 startup. A successful startup is dependent on the MAX5944 current-limit threshold and timeout period.
PAGE 14
MAX5944 Dual FireWire Current Limiter and Low-Drop ORing Switch Controller FB VIN BST ON CPA SENSE MAX5035 PHY POWER OUT LX IN4148 IN4148 VD GND SGND IN4148 15mΩ CABLE POWER SOURCE INA IRF7478 30mΩ IRF7478 SENSEA GATE1A GATE2A OUTA INA ONA IRF7478 SENSEA GATE1A IRF7478 PORT 0 GATE2A OUTA ONA ONQ1 ONQ1 FAULTA GND MAX5944 FAULTA GND FAULTB ONB MAX5944 FAULTB ONB INB SENSEB GATE1B BATTERY-POWER SOURCE GATE2B OUTB IRF7478 15mΩ INB IRF7478 CABLE NOT ON SLEEP SENSEB G
PAGE 15
Dual FireWire Current Limiter and Low-Drop ORing Switch Controller N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS DIM A A1 B C e E H L 1.27 VARIATIONS: 1 INCHES TOP VIEW DIM D D D MIN 0.189 0.337 0.386 MAX 0.197 0.344 0.394 MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.