19-2254; Rev 1; 12/02
1A Current-Limited Switch for 2 USB Ports
General Description
The MAX1922 current-limited 70mΩ switch with built-in
fault blanking provides an accurate, preset 1.4A to 2.1A
current limit, making it ideal for dual USB applications.
Its low quiescent supply current (16µA) and standby
current (1µA) conserve battery power in portable appli-
cations. The MAX1922 operates with inputs from 2.7V
to 5.5V, making it ideal for both 3V and 5V systems.
An overcurrent signal (OC) notifies the microprocessor
that the internal current limit has been reached. A 10ms
overcurrent-blanking 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 blanking also prevents
an
OC
signal from being issued when the device is
powering up.
The MAX1922 has several safety features to ensure that
the USB port is protected. Built-in thermal-overload pro-
tection limits power dissipation and junction tempera-
ture. The device also has accurate internal current-
limiting circuitry to protect the input supply against
overload.
The MAX1922 is offered in a space-saving 8-pin SO
package and operates over the extended (-40°C to
+85°C) temperature range.
♦
10ms Internal
OC
Blanking Timeout
♦
OC
Blanking During Power-Up
♦
125mΩ max High-Side MOSFET
♦
Short-Circuit and Thermal Protection with
Overcurrent Logic Output
♦
Undervoltage Lockout
♦
16µA Quiescent Supply Current
♦
1µA (max) Standby Supply Current
♦
2.7V to 5.5V Supply Range
♦
UL Recognized: UL# E211935
Features
♦
Accurate Current Limit (1.4A min, 2.1A max)
MAX1922
Ordering Information
PART
MAX1922ESA
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
8 SO
Applications
Notebook Computers
USB Ports
USB Hubs
Docking Stations
Pin Configuration
TOP VIEW
INPUT
2.7V TO 5.5V
Typical Operating Circuit
IN
GND
IN
IN
1
2
8
7
OUT
OUT
OUT
OC
ON
OFF
EN
GND
OC
OUT
OUTPUT
MAX1922
MAX1922
3
6
5
EN
4
SO
________________________________________________________________
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.
1A Current-Limited Switch for 2 USB Ports
MAX1922
ABSOLUTE MAXIMUM RATINGS
IN,
EN, OC
to GND...................................................-0.3V to +6V
OUT to GND ................................................-0.3V to (V
IN
+ 0.3V)
Maximum Switch Current.........................2.3A (internally limited)
OUT Short-Circuit to GND ..........................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
Operating Temperature Range (extended) .........-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 CONDITION
Input Voltage
POWER SWITCH
Switch Static Drain-Source On-
State Resistance
Switch Turn-On Time
Switch Turn-Off Time
ENABLE INPUT (EN)
EN
High-Level Input Voltage
EN
Low-Level Input Voltage
EN
Input Current
Startup Time
CURRENT LIMIT
Overload Output Current
Short-Circuit Output Current
SUPPLY CURRENT
Supply Current, Low-Level Input
Supply Current, High-Level
Input
Supply-Leakage Current
UNDERVOLTAGE LOCKOUT
Undervoltage Lockout
OVERCURRENT (OC)
OC
Threshold
OC
Output Low Voltage
V
OL
I
SINK
= 1mA, V
IN
= 3V
1.1
0.4
A
V
UVLO
Rising edge, 100mV hysteresis
2.0
2.4
2.6
V
I
Q
V
EN
= V
IN
= V
OUT
= 5.5V
V
EN
= 0, I
OUT
= 0
V
EN
= V
IN
= 5.5V,
V
OUT
= 0
Timer not running
Timer running
T
A
= +25°C
T
A
= 0°C to +85°C
0.002
16
35
0.01
2
15
1
25
µA
µA
µA
I
LIMIT
I
SC
Force V
OUT
to 4.5V
OUT shorted to GND
1.4
1.75
1
2.1
1.4
A
A
V
IH
V
IL
V
IN
= 2.7V to 3.6V
V
IN
= 3.7V to 5.5V
V
IN
= 2.7V to 5.5V
V
EN
= V
IN
or GND
V
IN
= 5V, C
OUT
= 150µF from
EN
driven low
to 50% full V
OUT
-1
1
2.0
2.4
0.8
1
V
V
µA
ms
T
A
= +25°C
R
DS(ON)
t
ON
t
OFF
T
A
= 0°C to +85°C
I
LOAD
= 400mA
I
LOAD
= 400mA
3
V
IN
= 4.4V to 5.5V
V
IN
= 4.4V to 5.5V
V
IN
= 3V
72
80
6
70
100
125
150
200
20
µs
µs
mΩ
V
IN
2.7
5.5
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
1A Current-Limited Switch for 2 USB Ports
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 5V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
OC
Off-State Current
OC
Blanking Timeout Period
THERMAL SHUTDOWN
Thermal Shutdown Threshold
165
°C
t
BL
SYMBOL
CONDITIONS
V
IN
= V
OC
= 5V
From overcurrent condition to
OC
assertion
6
10
MIN
TYP
MAX
1
13
UNITS
µA
ms
MAX1922
ELECTRICAL CHARACTERISTICS
(V
IN
= 5V,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
OPERATING CONDITION
Input Voltage
POWER SWITCH
Switch Static Drain-Source
On-State Resistance
Switch Turn-On Time
Switch Turn-Off Time
ENABLE INPUT (EN)
EN
High-Level Input Voltage
EN
Low-Level Input Voltage
EN
Input Current
CURRENT LIMIT
Overload Output Current
Short-Circuit Output Current
SUPPLY CURRENT
Supply Current, Low-Level Input
Supply Current, High-Level
Input
Supply Leakage Current
UNDERVOLTAGE LOCKOUT
Undervoltage Lockout
OVERCURRENT (OC)
OC
Threshold
OC
Output Low Voltage
OC
Off-State Current
OC
Blanking Timeout Period
t
BL
V
OL
I
SINK
= 1mA, V
IN
= 3V
V
IN
= V
OC
= 5V
From overcurrent condition to
OC
assertion
6
1.1
0.4
1
14
A
V
µA
ms
UVLO
Rising edge, 100mV hysteresis
2.0
2.9
V
I
Q
V
EN
= V
IN
= V
OUT
= 5.5V
V
EN
= GND, I
OUT
= 0, timer not running
V
EN
= V
IN
= 5.5V, V
OUT
= GND
2
25
15
µA
µA
µA
I
LIMIT
I
SC
Force V
OUT
to 4.5V
OUT shorted to GND
1.2
2.3
1.5
A
A
V
IH
V
IL
V
IN
= 3.0V to 3.6V
V
IN
= 3.7V to 5.5V
V
IN
= 3.0V to 5.5V
V
EN
= V
IN
or GND
-1
2.0
2.4
0.8
1
V
V
µA
R
DS(ON)
t
ON
t
OFF
V
IN
= 4.4V to 5.5V
V
IN
= 3V
I
LOAD
= 400mA
I
LOAD
= 400mA
1
125
150
200
20
mΩ
µs
µs
V
IN
3.0
5.5
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1:
Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
3
1A Current-Limited Switch for 2 USB Ports
MAX1922
Typical Operating Characteristics
(Circuit of Figure 2, V
IN
= 5V, T
A
= +25°C, unless otherwise noted.)
QUIESCENT CURRENT vs. INPUT VOLTAGE
MAX1922 toc01
QUIESCENT CURRENT vs. TEMPERATURE
MAX1922 toc02
OFF SUPPLY CURRENT
vs. TEMPERATURE
EN = IN
OUT = OPEN
OFF SUPPLY CURRENT (nA)
10
MAX1922 toc03
20
18
QUIESCENT CURRENT (µA)
16
14
12
10
8
6
4
2
0
V
EN
= 0
I
OUT
= 0
18.0
I
OUT
= 0
17.5
QUIESCENT CURRENT (µA)
17.0
16.5
16.0
15.5
15.0
14.5
14.0
V
IN
= 3V
V
IN
= 5V
100
1
0.1
0.01
-40
-15
10
35
60
85
-40
-15
TEMPERATURE (°C)
10
35
TEMPERATURE (°C)
60
85
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
OFF SWITCH CURRENT
vs. TEMPERATURE
MAX1922 toc04
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
MAX1922 toc05
NORMALIZED OUTPUT CURRENT
vs. OUTPUT VOLTAGE
I
LIMIT
(1.75A)
MAX1922 toc06
1000
EN = IN
V
OUT
= 0
OFF SWITCH CURRENT (nA)
100
1.4
1.3
1.2
NORMALIZED R
ON
1.1
1.0
0.9
0.8
0.7
I
OUT
= 850mA
1.2
NORMALIZED OUTPUT CURRENT
1.0
0.8
0.6
10
1
SHORT-CIRCUIT CURRENT
0.4
0.2
0
0.1
0.6
0.5
0.01
-40
-15
10
35
TEMPERATURE (°C)
60
85
0.4
-40
-15
10
35
60
85
TEMPERATURE (°C)
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OUTPUT VOLTAGE (V)
TURN-ON TIME vs. TEMPERATURE
140
120
TURN-ON TIME (µs)
V
IN
= 3V
100
80
60
40
20
0
-40
-15
10
35
60
85
TEMPERATURE (°C)
V
IN
= 5V
I
OUT
= 850mA
C
OUT
= 0.1µF
MAX1922 toc07
TURN-OFF TIME vs. TEMPERATURE
MAX1922 toc08
OC BLANKING TIMEOUT
vs. TEMPERATURE
14
OC BLANKING TIMEOUT (ms)
13
12
11
10
9
8
7
6
5
V
IN
= 3V OR 5V
I
OUT
= 1.75A
MAX1922 toc09
160
9.0
8.5
8.0
TURN-OFF TIME (µs)
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
-40
-15
10
35
60
V
IN
= 3V
V
IN
= 5V
I
OUT
= 850mA
C
OUT
= 0.1µF
15
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
1A Current-Limited Switch for 2 USB Ports
Typical Operating Characteristics (continued)
(Circuit of Figure 2, V
IN
= 5V, T
A
= +25°C, unless otherwise noted.)
MAX1922
CURRENT-LIMIT AND OC RESPONSE
MAX1922 toc10
CURRENT-LIMIT RESPONSE
MAX1922 toc11
5V
5V
V
IN
AC-COUPLED
100mV/div
V
OUT
, 5V/div
0
V
OC
, 5V/div
0
I
OUT
, 1A/div
0
2ms/div
0
4µs/div
I
OUT
, 2A/div
0
5V
V
OUT
, 5V/div
V
OC
, 5V/div
V
IN
AC-COUPLED
500mV/div
SWITCH TURN-ON TIME
MAX1922 toc12
SWITCH TURN-OFF TIME
MAX1922 toc13
V
OUT
, 5V/div
0
V
EN
, 5V/div
0
5V
V
OC
, 5V/div
V
OUT
, 5V/div
0
V
EN
, 5V/div
0
5V
V
OC
, 5V/div
I
OUT
,
500mA/div
0
1µs/div
I
OUT
,
500mA/div
0
20µs/div
STARTUP TIME
(TYPICAL USB APPLICATION)
MAX1922 toc14
0
FULL CURRENT LIMIT CHARGES CAPACITOR
V
OUT
5V/div
V
EN
5V/div
0
RESISTOR LOAD CURRENT
0
5V
1ms/div
SHORT-CIRCUIT
CURRENT LIMIT
I
IN
1A/div
V
OC
5A/div
_______________________________________________________________________________________
5
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