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MAX5944ESE+

P1-P3P4-P6P7-P9P10-P12P13-P15
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
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
INA
SENSEA
GATE1A
GATE2A
OUTA
GND
FAULTB
ONB
INB
TOP VIEW
MAX5944
SO
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
MAX5944
Dual FireWire Current Limiter and Low-Drop
ORing Switch Controller
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
IN
= 7.5V to 37V, GND = 0V, and T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
IN_
= 12V, T
A
= +25°C.)
(Note 1)
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.
(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_ ..................................................-0.3V to +8V
GATE2_ to OUT_ ......................................................-0.3V to +8V
FAULT_...................................................................-0.3V to +85V
ON_ONQ1 ...................................................................-0.3V to +85V
Continuous Power Dissipation (T
A
= +70°C)
16-Pin SO (derate 9.1mW/°C above +70°C)................728mW
Operating Temperature Range ...........................-40°C to +85°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range .............................-60°C to +150°C
ESD Rating (Human Body Model)......................................2000V
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
SUPPLIES
Supply Voltage Range V
IN_
7.5 37 V
Supply Current I
IN
V
ON_
= 3V, no load, per channel 1.3 2.3 mA
Shutdown Current I
SD
V
ON_
= 0.4V, per channel 5 10 µA
IN_ Default Undervoltage
Lockout
V
UVLO
V
IN_
rising, ON_ = IN_ 6.2 6.5 6.8 V
IN_ Default Undervoltage-
Lockout Hysteresis
0.35
V
ON_ Undervoltage-Lockout
Threshold
V
ON_REF
V
ON_
rising
1.20 1.24 1.275
V
ON_ Undervoltage-Lockout-
Threshold Hysteresis
70 mV
ON_ Input Bias Current I
ON
1µA
GATE2_ (Current-Limit Control)
GATE2_ Pullup Current (Note 2) I
G2U
36 45 54 µA
7.5V ≤ V
IN
≤ 8V
4.25
5.5
6.50
GATE2_ High Voltage V
G2
V
GATE2_
- V
OUT_
8V ≤ V
IN
≤ 37V 4.5 5.5 6.5
V
Current-Limit Threshold Voltage V
TH
V
IN_
- V
SENSE_
47.5
50
52.5
mV
Fast Pulldown Current-Limit
Threshold Voltage (Note 3)
V
THF
V
IN_
- V
SENSE_
70 75 80 mV
GATE2_ Pulldown Current I
G2D
V
TH
< (V
IN_
- V
SENSE_
) < V
THF
335 435 535
µA
GATE2_ Fast Pulldown Current
(Note 3)
I
G2DF
(V
IN_
- V
SENSE_
) > V
THF
,
V
GATE2_
= (V
OUT_
+ 4.5V)
80
125 200
mA
MAX5944
Dual FireWire Current Limiter and Low-Drop
ORing Switch Controller
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 7.5V to 37V, GND = 0V, and T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at V
IN_
= 12V, T
A
= +25°C.)
(Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
GATE2_ Peak Pulldown Current
I
G2DP
(V
IN_
- V
SENSE_
) = 1V 1.0 A
GATE2_ Pulldown Current During
Any GATE2_ Turn-Off Condition
(Note 4)
I
G2OFF
V
GATE2_
= (V
OUT_
+ 4.5V) 80
125 200
mA
GATE1_ (ORing Control)
ORing Switch Turn-On-Current
Threshold Voltage
V
OR
(V
IN_
- V
SENSE_
) rising 3 5 7 mV
ORing Switch Turn-On-Current
Threshold Voltage Hysteresis
(V
IN_
-
V
SENSE_
) falling 0.5 mV
GATE1_ Pullup Current (Note 5) I
G1U
36 45 54 µA
7.5V ≤ V
IN
≤ 8V
4.25
5.5
6.50
GATE1_ High Voltage V
G1
V
GATE_
- V
SENSE_
8V ≤ V
IN
≤ 37V 4.5 5.5 6.5
V
GATE1_ Turn-Off Switch On-
Resistance
R
G1PD
Measured between GATE1_ and SENSE_
when (V
IN_
- V
SENSE_
) < V
OR
23Ω
LOGIC INPUTS
ONQ1 Input-Logic Low Voltage V
IL
V
ON_
> V
ON_REF
0.7 V
ONQ1 Input-Logic High Voltage V
IH
V
ON_
> V
ON_REF
1.8 V
ONQ1 Input Current I
IH
1µA
FAULT_ Output Low Voltage V
OL
Low-impedance state, I
FAULT_
= 5mA
0.12 0.25
V
FAULT_ Output High Leakage
Current
I
OH
High-impedance state, V
FAULT_
= 37V 1 µA
OUT_ Input Current I
OUT
V
ON_
= GND 1 µA
P1-P3P4-P6P7-P9P10-P12P13-P15

MAX5944ESE+

Mfr. #:
Buy MAX5944ESE+
Manufacturer:
Maxim Integrated
Description:
Hot Swap Voltage Controllers Dual FireWire Current Limiter
Lifecycle:
New from this manufacturer.
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