19-2357; Rev 0; 4/02
Current-Limited Switch for Single USB Port
General Description
The MAX1931 is a current-limited, 60mΩ switch with
built-in fault blanking. Its accurate preset current limit of
0.64A to 1.06A makes it ideally suited for USB applica-
tions. The device’s low quiescent supply current (14µA)
and shutdown current (1µA) conserve battery power in
portable applications. The MAX1931 operates with
inputs from 2.7V to 5.5V, making it ideal for both 3V and
5V systems.
A fault signal notifies the microprocessor that the inter-
nal current limit has been reached. A 10ms fault-blank-
ing feature allows momentary faults (such as those
caused when hot-swapping into a capacitive load) to be
ignored, thus preventing false alarms to the host system.
This fault blanking also prevents a fault signal from
being issued when the device is powering up.
In the MAX1931, an output overcurrent condition causes
the switch to current limit at 0.64A to 1.06A and
FAULT
to go low after the 10ms blanking period. When the
overcurrent condition is removed,
FAULT
returns to its
high-impedance state.
The MAX1931 has several safety features to ensure that
the USB port is protected. Built-in thermal overload
protection limits power dissipation and junction tempera-
tures. The device has an accurate internal current-limit-
ing circuitry to protect the input supply against overload.
The MAX1931 is available in a space-saving 10-pin
µMAX package.
o
0.5A Guaranteed Output Current
o
Guaranteed 0.75A Short-Circuit Protection
o
10ms Internal Fault-Blanking Timeout
o
No Fault Signal During Power-Up
o
Thermal Shutdown Protection
o
2.7V to 5.5V Supply Range
o
14µA Supply Current
o
Small 10-Pin µMAX Package
Features
MAX1931
Ordering Information
PART
MAX1931EUB
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
10µMAX
Pin Configuration
TOP VIEW
IN 1
OUT
IN
OUT
ON
2
3
4
5
10 OUT
9
IN
OUT
FAULT
GND
MAX1931
8
7
6
Applications
USB Ports and Hubs
Notebook Computers
Portable Equipment
Docking Stations
Hot Plug-In Power Supplies
Battery-Charger Circuits
INPUT
2.7V TO 5.5V
µMAX
Typical Operating Circuit
IN
OUT
OUTPUT
MAX1931
FAULT
OFF
ON
ON
GND
_______________________________________________________________
Maxim Integrated Products
1
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.
Current-Limited Switch for Single USB Port
MAX1931
ABSOLUTE MAXIMUM RATINGS
IN,
ON
(ON),
FAULT
to GND....................................-0.3V to +6V
OUT to GND ................................................-0.3V to (V
IN
+ 0.3V)
Maximum Continuous Switch Current .....1.2A (internally limited)
OUT Short Circuit to GND ..........................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C) ............444mW
Operating Temperature Range ............................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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
(V
IN
= 5V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Operating Voltage
Quiescent Current
Off Supply Current
Undervoltage Lockout
Off Switch Leakage
UVLO
SYMBOL
V
IN
I
Q
V
ON
= GND, I
OUT
= 0
Timer not running
Timer running
2.0
0.01
CONDITIONS
MIN
2.7
14
35
0.001
1
2.6
4
µA
T
A
= 0°C to +85°C
V
IN
= 4.4V to 5.5V
V
IN
= 4.4V to 5.5V
V
IN
= 3V
640
72
850
500
60
20
110
150
180
1060
700
0.8
2
2.4
±1
0.4
1
6
10
1
80
3
6
165
200
20
13
mA
mA
V
V
µA
V
µA
ms
ms
µs
µs
°C
mΩ
TYP
MAX
5.5
35
UNITS
V
µA
µA
V
V
ON
= V
IN
= V
OUT
= 5.5V
Rising edge, 100mV hysteresis
V
ON
= V
IN
V
IN
= 5.5V,
V
OUT
= GND
T
A
= +25°C
R
ON
I
LIMIT
I
SC
V
IL
V
IH
T
A
= +25°C
On-Resistance
Current Limit
Continuous Short-Circuit
Current Limit
ON
Input Logic Low Voltage
ON
Input Logic High Voltage
ON
Input Leakage
FAULT
Output Logic
Low Voltage
FAULT
Output High
Leakage Current
Fault-Blanking Timeout Period
Startup Time
Switch Turn-On Time
Switch Turn-Off Time
Thermal Shutdown Threshold
T
A
= 0°C to +85°C
V
OUT
= 4.5V
OUT shorted to GND
V
IN
= 2.7V to 5.5V
V
IN
= 2.7V to 3.6V
V
IN
= 3.7V to 5.5V
V
ON
= V
IN
or GND
V
OL
I
SINK
= 1mA, V
IN
= 3V
V
IN
= V
FAULT
= 5.5V
t
FB
From overcurrent condition to
FAULT
assertion
V
IN
= 5V, C
OUT
= 150µF, R
L
= 15Ω,
from
ON
driven low to 50% full V
OUT
t
ON
t
OFF
I
LOAD
= 400mA
I
LOAD
= 400mA
2
_______________________________________________________________________________________
Current-Limited Switch for Single USB Port
ELECTRICAL CHARACTERISTICS
(V
IN
= 5V,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
Operating Voltage
Quiescent Current
Off Supply Current
Undervoltage Lockout
Off Switch Leakage
On-Resistance
Current Limit
Continuous Short-Circuit
Current Limit
ON
Input Logic Low Voltage
ON
Input Logic High Voltage
ON
Input Leakage
FAULT
Output Logic
Low Voltage
FAULT
Output High
Leakage Current
Fault-Blanking Timeout Period
Switch Turn-On Time
Switch Turn-Off Time
t
FB
t
ON
t
OFF
V
OL
V
IL
V
IH
R
ON
I
LIMIT
UVLO
SYMBOL
V
IN
I
Q
V
ON
= GND, I
OUT
= 0, timer not running
V
ON
= V
IN
= V
OUT
= 5.5V
Rising edge, 100mV hysteresis
V
ON
= V
IN
= 5.5V, V
OUT
= GND
V
IN
= 4.4V to 5.5V
V
IN
= 3V
V
OUT
= 4.5V
OUT shorted to GND
V
IN
= 3V to 5.5V
V
IN
= 3V to 3.6V
V
IN
= 3.7V to 5.5V
V
ON
= V
IN
or GND
I
SINK
= 1mA, V
IN
= 3V
V
IN
= V
FAULT
= 5.5V
From overcurrent condition to
FAULT
assertion
I
LOAD
= 400mA
I
LOAD
= 400mA
1
6
2
2.4
±1
0.4
1
14
200
20
600
2.0
CONDITIONS
MIN
3
TYP
MAX
5.5
35
2
2.9
20
150
180
1100
750
0.8
UNITS
V
µA
µA
V
µA
mΩ
mA
mA
V
V
µA
V
µA
ms
µs
µs
MAX1931
Note 1:
Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
3
Current-Limited Switch for Single USB Port
MAX1931
Typical Operating Characteristics
(V
IN
= 5V, T
A
= +25°C, unless otherwise noted.)
QUIESCENT CURRENT vs. TEMPERATURE
MAX1931 toc02
QUIESCENT CURRENT vs. INPUT VOLTAGE
MAX1931 toc01
OFF SUPPLY CURRENT
vs. TEMPERATURE
V
ON
(ON) = V
IN
(GND)
OFF SUPPLY CURRENT (nA)
10
MAX1931 toc03
16
14
QUIESCENT CURRENT (µA)
12
10
8
6
4
2
0
0
1
2
3
4
5
6
INPUT VOLTAGE (V)
V
ON (ON)
= GND (V
IN
)
I
OUT
= O
16
V
IN
= 5V
15
QUIESCENT CURRENT (µA)
14
13
12
11
10
9
-40
-20
0
20
40
60
80
V
IN
= 3V
100
1
0.1
0.01
100
-40
-20
TEMPERATURE (°C)
0
20
40
60
TEMPERATURE (°C)
80
100
OFF SWITCH CURRENT vs. TEMPERATURE
MAX1931 toc04
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
I
OUT
= 425mA
1.2
NORMALIZED R
ON
1.0
0.8
0.6
0.4
MAX1931 toc05
NORMALIZED OUTPUT CURRENT
vs. OUTPUT VOLTAGE
I
LIMIT
MAX1931 toc06
1000
V
0N (ON)
= V
IN
(GND)
OFF SWITCH CURRENT (nA)
100
1.4
1.2
NORMALIZED OUTPUT CURRENT
1.0
0.8
SHORT-CIRCUIT CURRENT
0.6
0.4
0.2
0
10
1
0.1
0.2
0
-40
-20
0
20
40
60
80
100
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
TEMPERATURE (°C)
0.01
0
1
2
3
4
5
6
OUTPUT VOLTAGE (V)
TURN-ON TIME vs. TEMPERATURE
MAX1931 toc07
TURN-OFF TIME vs. TEMPERATURE
I
LOAD
= 425mA
V
IN
= 5V
MAX1931 toc08
160
I
LOAD
= 425mA
140
120
V
IN
= 3V
7
6
5
t
OFF
(µs)
4
3
2
1
0
100
t
ON
(µs)
80
60
40
20
0
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
V
IN
= 5V
V
IN
= 3V
-40
-20
0
20
40
60
80
100
TEMPERATURE (°C)
4
_______________________________________________________________________________________
Current-Limited Switch for Single USB Port
Typical Operating Characteristics (continued)
(V
IN
= 5V, T
A
= +25°C, unless otherwise noted.)
FAULT-BLANKING TIMEOUT
vs. TEMPERATURE
MAX1931 toc09
MAX1931
CURRENT-LIMIT AND FAULT RESPONSE
MAX1931 toc10
CURRENT-LIMIT RESPONSE
1
MAX1931 toc11
12
FAULT-BLANKING TIMEOUT (ms)
10
8
6
4
2
0
-40
-20
0
20
40
60
80
I
OUT
= 850mA
V
IN
= 3V OR 5V
1
2
2
3
3
4
100
2ms/div
CH1 = V
IN
, 200mV/div, AC-COUPLED; CH2 = V
OUT
,
5V/div; CH3 = V
FAULT
, 5V/div; CH4 = I
OUT
, 500mA/div
4
10µs/div
CH1 = V
IN
, 200mV/div, AC-COUPLED; CH2 = V
OUT
,
5V/div; CH3 = V
FAULT
, 5V/div; CH4 = I
OUT
, 1A/div
TEMPERATURE (°C)
SWITCH TURN-ON TIME
MAX1931 toc12
SWITCH TURN-OFF TIME
MAX1931 toc13
STARTUP TIME
(TYPICAL USB APPLICATION)
1
MAX1931 toc14
1
2
1
2
2
C
L
= 150µF
R
L
= 15Ω
FULL CURRENT LIMIT CHARGES CAPACITOR
RESISTOR
LOAD
CURRENT
3
3
3
FOLDBACK
CURRENT LIMIT
4
20µs/div
CH1 = V
OUT
, 5V/div; CH2 = V
ON
, 5V/div;
CH3 = V
FAULT
, 5V/div; CH4 = I
OUT
, 200mA/div
4
4
1µs/div
CH1 = V
OUT
, 5V/div; CH2 = V
ON
, 5V/div;
CH3 = V
FAULT
, 5V/div; CH4 = I
OUT
, 200mA/div
1ms/div
CH1 = V
OUT
, 5V/div; CH2 = V
ON
, 5V/div;
CH3 = I
OUT
, 500mA/div; CH4 = V
FAULT
, 5V/div
_______________________________________________________________________________________
5
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