19-2497; Rev 1; 2/10
Triple USB Switch with Autoreset and
Fault Blanking
General Description
The MAX1940 triple current-limited switch with auto-
reset supplies a guaranteed 500mA load per channel in
accordance with USB specifications. The MAX1940
operates from a 4V to 5.5V input supply and consumes
only 60µA of quiescent current when operating and only
3µA in standby. Selectable active-high/active-low con-
trol logic and independent shutdown controls for each
channel provide additional flexibility. An autoreset fea-
ture latches the switch off in the event of a short circuit,
saving system power. The switch reactivates upon
removal of the shorted condition.
The MAX1940 provides several safety features to pro-
tect the USB port. Built-in thermal-overload protection
turns off the switch when the die temperature exceeds
+160°C. Accurate internal current-limiting circuitry pro-
tects the input supply against both overload and short-
circuit conditions. Independent open-drain fault signals
(FAULTA,
FAULTB,
and
FAULTC)
notify the micro-
processor when a thermal-overload, current-limit,
undervoltage lockout (UVLO), or short-circuit fault
occurs. A 20ms fault-blanking feature enables the cir-
cuit to ignore momentary faults, such as those caused
when hot-swapping a capacitive load, preventing false
alarms to the host system. The fault-blanking feature
also prevents fault signals from being issued when the
device powers up the load.
The MAX1940 is available in a space-saving 16-pin
QSOP package and operates over the extended (-40°C
to +85°C) temperature range.
Features
o
Triple USB Switch in Tiny 16-Pin QSOP Package
o
Autoreset Feature Saves System Power
o
Guaranteed 500mA Load Current per Channel
o
Built-In 20ms Fault-Blanking Circuitry
o
Active-High/Active-Low Control Logic
o
Fully Compliant to USB Specifications
o
4V to 5.5V Input Voltage Range
o
Independent Shutdown Control
o
Independent Fault Indicator Outputs
o
Thermal-Overload Protection
o
3µA Standby Current
MAX1940
Ordering Information
PART
MAX1940EEE
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
16 QSOP
Applications
USB Ports
USB Hubs
Notebook Computers
Desktop Computers
PDAs and Palmtop
Computers
Docking Stations
Typical Operating Circuit
MAX1940
IN1
FAULTA
FAULTB
FAULTC
Pin Configuration
TOP VIEW
ONA 1
IN1 2
IN2 3
IN3 4
ONB 5
IN4 6
IN5 7
ONC 8
16 FAULTA
15 OUTA
14 GND
INPUT
4V TO 5.5V
IN2
IN3
IN4
IN5
ONA
ONB
ONC
SEL
GND
OUTA
USB
PORT A
MAX1940
13 OUTB
OUTB
12 FAULTB
11 SEL
10 OUTC
9
FAULTC
ACTIVE-HIGH/ACTIVE-LOW
SELECTABLE
USB
PORT B
OUTC
USB
PORT C
QSOP
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Triple USB Switch with Autoreset and
Fault Blanking
MAX1940
ABSOLUTE MAXIMUM RATINGS
IN_, ON_, OUT_, SEL,
FAULT_,
to GND...................-0.3V to +6V
IN1, IN2 to OUTA......................................................-0.3V to +6V
IN2, IN3 to OUTB......................................................-0.3V to +6V
IN4, IN5 to OUTC .....................................................-0.3V to +6V
OUT_ Continuous Switch Current
(per channel, internally limited).........................................1.4A
FAULT_
DC Current ............................................................20mA
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C)...........667mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°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, C
IN_
= 0.1µF, C
OUT_
= 1µF,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Supply Voltage Range
Switch On-Resistance
Standby Supply Current
Quiescent Supply Current
I
IN_
SYMBOL
V
IN_
R
ON
T
A
= 0°C to +85°C, each switch
All switches disabled
One switch enabled, I
OUT_
= 0
Two switches enabled, I
OUT_
= 0
All switches enabled, I
OUT_
= 0
OUT_ Off-Leakage Current
Undervoltage Lockout Threshold
Continuous Load Current
Continuous Current Limit
Short-Circuit Current Limit
Short-Circuit Detect Threshold
Continuous Current-Limit
Blanking Timeout Period
Short-Circuit Blanking Timeout
Period
Turn-On Delay
Output Rise Time
Turn-Off Delay
Output Fall Time
Thermal-Shutdown Threshold
ON_, SEL Input High Level
ON_, SEL Input Low Level
ON_, SEL Input Leakage Current
V
IH
V
IL
t
ON
t
RISE
t
OFF
t
FALL
I
LIM
I
SC
V
IN_
- V
OUT_
= 0.5V
V
OUT_
= 0 (I
OUT_
pulsing)
(Note 1)
From continuous current-limit condition to
FAULT_
asserted
From short-circuit current-limit condition to
FAULT_
asserted
R
OUT_
= 10Ω, does not include rise time
(from ON_ to 10% of V
OUT_
)
R
OUT_
= 10Ω, from 10% to 90% of V
OUT_
R
OUT_
= 10Ω, does not include fall time
(from ON_ to 90% of V
OUT_
)
R
OUT_
= 10Ω, from 90% to 10% of V
OUT_
15°C hysteresis
V
IN_
= 4V to 5.5V
V
IN_
= 4V to 5.5V
V
ON_
= 0 or V
IN_
-1
2
0.8
+1
10
7.5
0.5
I
LKG
V
ULVO
All switches disabled, V
OUT_
= 0,
T
A
= 0°C to +85°C
Rising edge, 3% hysteresis
3.0
500
0.7
0.9
0.9
1.2
0.35
1
20
18
1.2
2.5
0.8
2.5
160
3
35
35.0
4.0
1.2
1.6
CONDITIONS
MIN
4.0
85
3
47
55
63
0.02
3.4
TYP
MAX
5.5
135
10
75
90
100
10
3.8
µA
V
mA
A
A
PK
A
RMS
V
ms
ms
ms
ms
ms
ms
°C
V
V
µA
µA
UNITS
V
mΩ
µA
2
_______________________________________________________________________________________
Triple USB Switch with Autoreset and
Fault Blanking
ELECTRICAL CHARACTERISTICS (continued)
(V
IN_
= 5V, C
IN_
= 0.1µF, C
OUT_
= 1µF,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
FAULT_
Output Low Voltage
FAULT_
Output High Leakage
Current
OUT_ Autoreset Current
OUT_ Autoreset Threshold
OUT_ Autoreset Blanking Time
SYMBOL
V
OL
CONDITIONS
I
SINK
= 1mA, V
IN_
= 4V
V
IN_
= V
FAULT_
= 5.5V
In latched off state, V
OUT_
= 0
In latched off state, OUT_ rising
In latched off state, V
OUT_
> 0.5V
10
0.4
10
25
0.5
20
MIN
TYP
MAX
0.4
1
45
0.6
35
UNITS
V
µA
mA
V
ms
MAX1940
ELECTRICAL CHARACTERISTICS
(V
IN_
= 5V, C
IN_
= 0.1µF, C
OUT_
= 1µF,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 2)
PARAMETER
Supply Voltage Range
Switch On-Resistance
Standby Supply Current
Quiescent Supply Current
OUT_ Off-Leakage Current
Undervoltage Lockout Threshold
Continuous Load Current
Continuous Current Limit
Short-Circuit Current Limit
Continuous Current-Limit
Blanking Timeout Period
Short-Circuit Blanking Timeout
Period
Turn-On Delay
Turn-Off Delay
ON_, SEL Input High Level
ON_, SEL Input Low Level
ON_, SEL Input Leakage Current
FAULT_
Output Low Voltage
FAULT_
Output High Leakage
Current
OUT_ Autoreset Current
OUT_ Autoreset Threshold
OUT_ Autoreset Blanking Time
V
OL
t
ON
t
OFF
V
IH
V
IL
I
LIM
I
SC
V
IN_
- V
OUT_
= 0.5V
V
OUT_
= 0 (I
OUT_
pulsing)
From continuous current-limit condition to
FAULT_
asserted
From short-circuit current-limit condition to
FAULT_
asserted
R
OUT_
= 10Ω, does not include rise time
(from ON_ to 10% of V
OUT_
)
R
OUT_
= 10Ω, does not include fall time
(from ON_ to 90% of V
OUT_
)
V
IN_
= 4V to 5.5V
V
IN_
= 4V to 5.5V
V
ON_
= 0 or V
IN_
I
SINK
= 1mA, V
IN_
= 4V
V
IN_
= V
FAULT_
= 5.5V
In latched off state, V
OUT_
= 0
In latched off state, OUT_ rising
In latched off state, V
OUT_
> 0.5V
10
0.4
10
-1
2
0.8
+1
0.4
1
50
0.6
35
I
IN_
I
LKG
V
ULVO
SYMBOL
V
IN_
R
ON
Each switch
All switches disabled
One switch enabled, I
OUT_
= 0
Two switches enabled, I
OUT_
= 0
All switches enabled, I
OUT_
= 0
All switches disabled, V
OUT_
= 0
Rising edge, 3% hysteresis
3.0
500
0.7
0.9
10
7.5
0.5
1.2
1.6
35
35.0
4.0
3
CONDITIONS
MIN
4.0
MAX
5.5
135
10
75
90
100
10
3.8
µA
V
mA
A
A
PK
ms
ms
ms
ms
V
V
µA
V
µA
mA
V
ms
µA
UNITS
V
mΩ
µA
Note 1:
Short-circuit detect threshold is the output voltage at which the device transitions from short-circuit current limit to
continuous current limit.
Note 2:
Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
3
Triple USB Switch with Autoreset and
Fault Blanking
MAX1940
Typical Operating Characteristics
(Circuit of Figure 2, V
IN_
= 5V, C
IN_
= 0.1µF, C
OUT_
= 1µF, ON_ = SEL, T
A
= +25°C, unless otherwise noted.)
QUIESCENT SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX1940 toc01
QUIESCENT SUPPLY CURRENT
vs. TEMPERATURE
SHUTDOWN SUPPLY CURRENT (µA)
69
68
67
66
65
64
63
62
61
60
2.5
-40
-15
10
35
60
85
-40
V
IN_
= 4.5V
V
IN_
= 5V
ALL SWITCHES ACTIVE
V
IN_
= 5.5V
MAX1940 toc02
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
ON_ = GND, V
SEL
= 5V
2.9
MAX1940 toc03
70
ALL SWITCHES ACTIVE
QUIESCENT SUPPLY CURRENT (µA)
60
50
40
30
20
10
0
70
QUIESCENT SUPPLY CURRENT (µA)
3.0
2.8
2.7
2.6
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)
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
SWITCH OFF-LEAKAGE (ONE SWITCH)
vs. TEMPERATURE
MAX1940 toc04
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
CONTINUOUS CURRENT-LIMIT THRESHOLD (mA)
MAX1940 toc05
CONTINUOUS CURRENT-LIMIT THRESHOLD
vs. TEMPERATURE
MAX1940 toc06
1000
ON_ = OUT_, V
SEL
= 5V
SWITCH OFF-LEAKAGE (nA)
100
1.3
1.2
1.1
1.0
0.9
0.8
0.7
920
NORMALIZED ON-RESISTANCE
916
V
IN_
= 5.0V
V
IN_
= 5.5V
10
912
1
908
0.1
904
V
IN_
= 4.5V
0.01
-40
-15
10
35
60
85
TEMPERATURE (°C)
900
-40
-15
10
35
60
85
TEMPERATURE (°C)
-40
-15
10
35
60
85
TEMPERATURE (°C)
TURN-ON TIME (t
ON
+ t
RISE
)
vs. TEMPERATURE
R
OUT_
= 10Ω
3.4
TURN-ON TIME (ms)
V
IN_
= 5V
V
IN_
= 4.5V
MAX1940 toc07
TURN-OFF TIME (t
OFF
+ t
FALL
)
vs. TEMPERATURE
R
OUT_
= 10Ω
3.2
TURN-OFF TIME (ms)
3.1
3.0
2.9
2.8
2.7
2.6
V
IN_
= 4.5V
-40
-15
10
35
60
85
V
IN_
= 5V
V
IN_
= 5.5V
MAX1940 toc08
FAULT-BLANKING TIME
vs. TEMPERATURE
MAX1940 toc09
3.5
3.3
22.0
21.5
21.0
20.5
20.0
19.5
19.0
-40
-15
10
35
60
V
IN_
= 5.5V
V
IN_
= 4.5V
3.3
3.2
FAULT-BLANKING TIME (ms)
V
IN_
= 5V
3.1
V
IN_
= 5.5V
3.0
-40
-15
10
35
60
85
TEMPERATURE (°C)
85
TEMPERATURE (°C)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
Triple USB Switch with Autoreset and
Fault Blanking
Typical Operating Characteristics (continued)
(Circuit of Figure 2, V
IN_
= 5V, C
IN_
= 0.1µF, C
OUT_
= 1µF, ON_ = SEL, T
A
= +25°C, unless otherwise noted.)
FAULT OUTPUT LOW VOLTAGE
vs. TEMPERATURE
250
240
230
220
210
200
190
180
170
160
150
140
130
120
110
100
MAX1940 toc10
MAX1940
AUTORESET CURRENT
vs. TEMPERATURE
36
AUTORESET CURRENT (mA)
34
32
30
28
26
24
22
20
18
V
IN_
= 4.5V
-40
-15
10
35
60
85
V
IN_
= 5.5V
V
IN_
= 5V
MAX1940 toc11
AUTORESET CURRENT
vs. INPUT VOLTAGE
35
AUTORESET CURRENT (mA)
30
25
20
15
T
A
= +85°C
10
5
0
3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5
INPUT VOLTAGE (V)
T
A
= -40°C
MAX1940 toc12
MAX1940 toc15
R
PU
= 4.7kΩ
V
IN_
= 5V
V
IN_
= 5.5V
38
40
T
A
= +25°C
FAULT OUTPUT LOW VOLTAGE (mV)
V
IN_
= 4.5V
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
OVERLOAD RESPONSE INTO 2.5Ω
MAX1940 toc13
OVERLOAD RESPONSE INTO 2.5Ω
(EXPANDED TIME SCALE)
MAX1940 toc14
SHORT-CIRCUIT RESPONSE INTO 0Ω
5V
A
5V
A
5V
A
5V
B
0
B
0
C
C
0
D
0
A: V
IN_
5V/div
B: V
OUT_
5V/div
10ms/div
C: V
FAULT_
5V/div
D: I
OUT_
1A/div
A: V
IN_
5V/div
B: V
OUT_
5V/div
400µs/div
C: V
FAULT_
5V/div
D: I
OUT_
1A/div
D
0
A: V
IN_
5V/div
B: V
OUT_
5V/div
10ms/div
C: V
FAULT_
5V/div
D: I
OUT_
1A/div
D
0
5V
C
5V
B
SHORT-CIRCUIT RESPONSE INTO 0Ω
(EXPANDED TIME SCALE)
MAX1940 toc16
SWITCH TURN-ON TIME (t
ON
+ t
RISE
)
5V
A
V
SEL
= 5V
R
OUT_
= 10Ω
C
OUT_
= 1µF
MAX1940 toc17
SWITCH TURN-ON TIME (t
ON
+ t
FALL
)
V
SEL
= 5V
R
OUT_
= 10Ω
C
OUT_
= 1µF
5V
A
MAX1940 toc18
A
5V
B
C
0
5V
5V
B
B
0
D
0
A: V
IN_
5V/div
B: V
OUT_
5V/div
400µs/div
C: V
FAULT_
5V/div
D: I
IN_
2A/div
1ms/div
A: V
ON_
5V/div
B: V
OUT_
2V/div
A: V
ON_
5V/div
B: V
OUT_
2V/div
1ms/div
_______________________________________________________________________________________
5
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