MAX1922ETB+TC3B [MAXIM]
Power Supply Support Circuit;
| 型号： | MAX1922ETB+TC3B |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Power Supply Support Circuit |
| 文件： | 总9页 (文件大小：180K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-2254; Rev 3; 4/09
1A Current-Limited Switch for 2 USB Ports
MAX192
General Description
Features
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.
o Accurate Current Limit (1.4A min, 2.1A max)
o 10ms Internal OC Blanking Timeout
o OC Blanking During Power-Up
o 125mΩ (max) High-Side MOSFET
o Short-Circuit and Thermal Protection with
Overcurrent Logic Output
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.
o Undervoltage Lockout
o 16µA Quiescent Supply Current
o 1µA (max) Standby Supply Current
o 2.7V to 5.5V Supply Range
o UL Recognized: UL# E211395
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.
Ordering Information
TOP
MARK
PIN-
PACKAGE
The MAX1922 is offered in a space-saving 8-pin SO
package and a 10-pin TDFN package and operates over
the extended (-40°C to +85°C) temperature range.
PART
TEMP RANGE
—
MAX1922ESA+
MAX1922ETB+
-40°C to +85°C 8 SO
-40°C to +85°C 10 TDFN-EP*
AQQ
Applications
*EP = Exposed paddle.
+Denotes a lead(Pb)-free/RoHS-compliant package.
Notebook Computers
USB Ports
USB Hubs
Docking Stations
Pin Configurations
Typical Operating Circuit
TOP VIEW
INPUT
2.7V TO 5.5V
IN
OUT
OUTPUT
GND
IN
1
2
3
4
8
7
6
5
OUT
OUT
OUT
OC
MAX1922
MAX1922
IN
OC
EN
EN
OFF
ON
SO
GND
Pin Configurations continued at end of data sheet.
________________________________________________________________ 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.
1A Current-Limited Switch for 2 USB Ports
ABSOLUTE MAXIMUM RATINGS
IN, EN, OC to GND...................................................-0.3V to +6V
Continuous Power Dissipation (T = +70°C)
A
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
10-Pin TDFN (derate 18.5mW/°C above +70°C) .......1481mW
Operating Temperature Range (extended).........-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
OUT to GND ................................................-0.3V to (V + 0.3V)
Maximum Switch Current.........................2.3A (internally limited)
OUT Short-Circuit to GND..........................................Continuous
IN
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.
MAX192
ELECTRICAL CHARACTERISTICS
(V = 5V, T = 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.)
IN
A
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
OPERATING CONDITION
Input Voltage
V
2.7
5.5
V
IN
POWER SWITCH
T
T
= +25°C
V
V
V
= 4.4V to 5.5V
= 4.4V to 5.5V
= 3V
70
100
125
150
200
20
A
IN
IN
IN
Switch Static Drain-Source On-
State Resistance
R
mΩ
DS(ON)
= 0°C to +85°C
A
72
80
6
Switch Turn-On Time
Switch Turn-Off Time
ENABLE INPUT (EN)
t
I
I
= 400mA
= 400mA
µs
µs
ON
LOAD
t
3
OFF
LOAD
V
V
V
V
V
= 2.7V to 3.6V
= 3.7V to 5.5V
= 2.7V to 5.5V
2.0
2.4
IN
IN
IN
EN
IN
EN High-Level Input Voltage
V
V
IH
EN Low-Level Input Voltage
EN Input Current
V
0.8
1
V
IL
= V or GND
-1
µA
IN
= 5V, C
= 150µF from EN driven low
OUT
Startup Time
1
ms
to 50% full V
OUT
CURRENT LIMIT
Overload Output Current
Short-Circuit Output Current
SUPPLY CURRENT
I
Force V
to 4.5V
OUT
1.4
1.75
1
2.1
1.4
A
A
LIMIT
I
OUT shorted to GND
SC
Supply Current, Low-Level Input
V
V
= V = V
= 5.5V
0.002
16
1
µA
µA
EN
EN
IN
OUT
= 0
Timer not running
Timer running
25
Supply Current, High-Level
Input
I
= 0, I
OUT
Q
35
T
= +25°C
0.01
2
A
A
V
V
= V = 5.5V,
IN
EN
Supply-Leakage Current
µA
V
= 0
OUT
T
= 0°C to +85°C
15
UNDERVOLTAGE LOCKOUT
Undervoltage Lockout
OVERCURRENT (OC)
OC Threshold
UVLO
Rising edge, 100mV hysteresis
2.0
1.1
2.4
2.6
0.4
A
V
OC Output Low Voltage
V
I
= 1mA, V = 3V
OL
SINK IN
2
_______________________________________________________________________________________
1A Current-Limited Switch for 2 USB Ports
MAX192
ELECTRICAL CHARACTERISTICS (continued)
(V = 5V, T = 0°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.)
IN
A
A
PARAMETER
SYMBOL
CONDITIONS
= 5V
MIN
TYP
10
MAX
1
UNITS
µA
OC Off-State Current
V
= V
IN OC
OC Blanking Timeout Period
THERMAL SHUTDOWN
Thermal Shutdown Threshold
t
From overcurrent condition to OC assertion
6
13
ms
BL
165
°C
ELECTRICAL CHARACTERISTICS
(V = 5V, T = -40°C to +85°C, unless otherwise noted.) (Note 1)
IN
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
OPERATING CONDITION
Input Voltage
V
3.0
5.5
V
IN
POWER SWITCH
V
V
= 4.4V to 5.5V
125
150
200
20
IN
IN
Switch Static Drain-Source
On-State Resistance
R
mΩ
DS(ON)
= 3V
Switch Turn-On Time
Switch Turn-Off Time
ENABLE INPUT (EN)
t
I
I
= 400mA
= 400mA
µs
µs
ON
LOAD
LOAD
t
1
OFF
V
V
V
V
= 3.0V to 3.6V
= 3.7V to 5.5V
= 3.0V to 5.5V
2.0
2.4
IN
IN
IN
EN
EN High-Level Input Voltage
V
V
IH
EN Low-Level Input Voltage
EN Input Current
V
0.8
1
V
IL
= V or GND
-1
µA
IN
CURRENT LIMIT
Overload Output Current
Short-Circuit Output Current
SUPPLY CURRENT
I
Force V
to 4.5V
OUT
1.2
2.3
1.5
A
A
LIMIT
I
OUT shorted to GND
SC
Supply Current, Low-Level Input
V
V
V
= V = V
= 5.5V
2
µA
µA
µA
EN
EN
EN
IN
OUT
Supply Current, High-Level
Input
I
= GND, I
= 0, timer not running
25
15
Q
OUT
Supply Leakage Current
UNDERVOLTAGE LOCKOUT
Undervoltage Lockout
OVERCURRENT (OC)
OC Threshold
= V = 5.5V, V
= GND
IN
OUT
UVLO
Rising edge, 100mV hysteresis
2.0
1.1
2.9
V
A
V
OC Output Low Voltage
OC Off-State Current
V
I
= 1mA, V = 3V
0.4
1
OL
SINK
IN
V
= V
= 5V
OC
µA
ms
IN
OC Blanking Timeout Period
t
From overcurrent condition to OC assertion
6
14
BL
Note 1: Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
3
1A Current-Limited Switch for 2 USB Ports
Typical Operating Characteristics
(Circuit of Figure 2, V = 5V, T = +25°C, unless otherwise noted.)
IN
A
OFF SUPPLY CURRENT
vs. TEMPERATURE
QUIESCENT CURRENT vs. INPUT VOLTAGE
QUIESCENT CURRENT vs. TEMPERATURE
100
10
20
18
16
14
12
10
8
18.0
17.5
V
= 0
= 0
EN
EN = IN
OUT = OPEN
I
= 0
OUT
I
OUT
17.0
16.5
MAX192
1
16.0
15.5
15.0
14.5
14.0
V = 5V
IN
V
= 3V
6
IN
0.1
0.01
4
2
0
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)
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
OFF SWITCH CURRENT
vs. TEMPERATURE
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
NORMALIZED OUTPUT CURRENT
vs. OUTPUT VOLTAGE
1000
100
10
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
1.2
1.0
0.8
0.6
0.4
0.2
0
I (1.75A)
LIMIT
EN = IN
I
= 850mA
OUT
V
= 0
OUT
SHORT-CIRCUIT CURRENT
1
0.1
0.01
-40
-15
10
35
60
85
-40
-15
10
35
60
85
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
OUTPUT VOLTAGE (V)
TEMPERATURE (°C)
TEMPERATURE (°C)
OC BLANKING TIMEOUT
vs. TEMPERATURE
TURN-OFF TIME vs. TEMPERATURE
TURN-ON TIME vs. TEMPERATURE
9.0
8.5
8.0
7.5
7.0
6.5
6.0
5.5
15
14
13
12
11
160
140
120
100
80
I
C
= 850mA
I
= 850mA
OUT
OUT
V
OUT
= 3V OR 5V
= 1.75A
IN
= 0.1μF
C
= 0.1μF
OUT
OUT
I
V
= 3V
IN
V
= 5V
IN
10
9
60
V
= 5V
IN
V
= 3V
IN
8
40
5.0
4.5
4.0
7
6
20
5
0
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
1A Current-Limited Switch for 2 USB Ports
MAX192
Typical Operating Characteristics (continued)
(Circuit of Figure 2, V = 5V, T = +25°C, unless otherwise noted.)
IN
A
CURRENT-LIMIT RESPONSE
CURRENT-LIMIT AND OC RESPONSE
MAX1922 toc11
MAX1922 toc10
5V
V
AC-COUPLED
V
AC-COUPLED
IN
IN
5V
500mV/div
100mV/div
V
, 5V/div
OUT
V
V
, 5V/div
0
OUT
0
0
0
5V
, 5V/div
V
, 5V/div
OC
OC
I
, 2A/div
I
, 1A/div
OUT
OUT
0
4μs/div
2ms/div
SWITCH TURN-ON TIME
SWITCH TURN-OFF TIME
MAX1922 toc12
MAX1922 toc13
V
, 5V/div
V
, 5V/div
OUT
OUT
0
0
V
V
, 5V/div
EN
V
V
, 5V/div
EN
0
0
5V
, 5V/div
5V
OC
, 5V/div
OC
I
,
I
,
OUT
OUT
500mA/div
500mA/div
0
0
20μs/div
1μs/div
STARTUP TIME
(TYPICAL USB APPLICATION)
MAX1922 toc14
V
V
5V/div
OUT
0
0
FULL CURRENT LIMIT CHARGES CAPACITOR
RESISTOR LOAD CURRENT
5V/div
EN
0
SHORT-CIRCUIT
CURRENT LIMIT
I
1A/div
IN
5V
V
5A/div
OC
1ms/div
_______________________________________________________________________________________
5
1A Current-Limited Switch for 2 USB Ports
Pin Description
PACKAGE
TDFN
NAME
FUNCTION
SO
6
1, 3, 9
5
1
2, 3
4
GND
IN
Ground
Input. p-channel MOSFET source—connect all IN pins together and bypass with a 1µF capacitor ground.
Active-Low Switch Enable Input. A logic-low turns on the switch.
EN
Overcurrent-Indicator Output. This open-drain output goes low when the device is in thermal shutdown
or undervoltage lockout, or during a sustained (10ms) current-limit condition.
MAX192
7
5
OC
OUT
EP
2, 4,
8, 10
6, 7,
8
Switch Output. p-channel MOSFET drain—connect all OUT pins together and bypass with a 0.1µF
capacitor to ground.
—
TDFN Only. Exposed paddle. Connect to the GND plane for optimum thermal dissipation. This does not
remove the requirement for a proper ground.
—
Continuous Short-Circuit Protection
The MAX1922 is a short-circuit-protected switch. In the
P
IN
OUT
event of an output short-circuit condition, the current
through the switch is foldback-current-limited to 1A
continuous.
MAX1922
OC
P
Thermal Shutdown
The MAX1922 has a thermal shutdown feature. The
REPLICA
AMPLIFIER
N
switch turns off and the OC output goes low immediate-
ly (no overcurrent blanking) when the junction tempera-
ture exceeds +165°C. When the MAX1922 cools 20°C,
the switch turns back on. If the fault short-circuit condi-
tion is not removed, the switch cycles on and off, result-
ing in a pulsed output.
ON
P
ON
CURRENT-LIMIT
AMPLIFIER
OC Indicator
The MAX1922 provides an overcurrent output (OC). A
100kΩ pullup resistor from OC to IN provides a logic
control signal. This open-drain output goes low when
any of the following conditions occur:
1.24V
10ms
TIMER
HOT
GND
• The input voltage is below the 2.4V undervoltage
CONTROL
CIRCUITRY
EN
lockout (UVLO) threshold.
• The die temperature exceeds the thermal shutdown
temperature limit of +165°C.
Figure 1. Functional Diagram
• The device is in current limit for greater than 10ms.
OC Blanking
The MAX1922 features 10ms overcurrent blanking.
Blanking allows brief current-limit faults, including
momentary short-circuit faults that occur when hot-
swapping a capacitive load, and ensures that no OC is
issued during power-up. When a load transient causes
the device to enter current limit, an internal counter
starts. If the load fault persists beyond the 10ms over-
current blanking timeout, the OC output asserts low.
Ensure that the MAX1922 input is adequately bypassed
to prevent input glitches from triggering spurious OC
Detailed Description
The MAX1922 p-channel MOSFET power switch limits
output current to 1.4A min and 2.1A max. When the out-
put current increases beyond the current limit (I
),
LIMIT
the current also increases through the replica switch
(I / 13000). The current-limit error amplifier com-
OUT
pares the voltage to the internal 1.24V reference and
regulates the current back to the I (Figure 1).
LIMIT
These switches are not bidirectional; therefore, the
input voltage must be higher than the output voltage.
6
_______________________________________________________________________________________
1A Current-Limited Switch for 2 USB Ports
MAX192
outputs. Input voltage glitches less than 150mV do not
cause a spurious OC output. Load-transient faults less
than 10ms (typ) will not cause an OC output assertion.
Layout and Thermal Dissipation
Important: Optimize the switch response time to output
short-circuit conditions by keeping all traces as short
as possible to reduce the effect of undesirable parasitic
inductance. Place input and output capacitors as close
as possible to the device (no more than 5mm away). All
IN and OUT pins must be connected with short traces
to the power bus. Wide power-bus planes provide
superior heat dissipation through the MAX1922’s IN
and OUT pins. Under normal operating conditions, the
package can dissipate and channel heat away.
Calculate the maximum power dissipation as follows:
Only current-limit faults are blanked. Die overtempera-
ture faults and input voltage droops below the UVLO
threshold will cause an immediate OC output.
Applications Information
Input Capacitor
To limit the input voltage drop during momentary output
short-circuit conditions, connect a capacitor from IN to
GND. A 1µF ceramic capacitor is adequate for most
applications; however, higher capacitor values further
reduce the voltage drop at the input (Figure 2).
2
ꢀ
P = (I
)
R
ON
LIMIT
where I
ON
is the preset current limit (2.1A max) and
LIMIT
R
is the on-resistance of the switch (125mΩ max).
When the output is short circuited, foldback-current lim-
iting activates and the voltage drop across the switch
equals the input supply voltage. The power dissipated
across the switch increases, as does the die tempera-
ture. If the fault condition is not removed, the thermal-
overload protection circuitry activates (see Thermal
Shutdown section). Wide power-bus planes connected
to IN and OUT and a ground plane in contact with the
device help dissipate additional heat.
INPUT
IN
OUT
OUTPUT
*
0.1μF
1μF
MAX1922
100kΩ
OVERCURRENT
OUTPUT
OC
EN
OFF
Driving Inductive Loads
A wide variety of devices (mice, keyboards, cameras,
and printers) can load the USB port. These devices
commonly connect to the port with cables, which can
add an inductive component to the load. This induc-
tance causes the output voltage at the USB port to ring
during a load step. The MAX1922 is capable of driving
inductive loads, but avoid exceeding the device’s
absolute maximum ratings. Usually the load inductance
is relatively small, and the MAX1922 input includes a
substantial bulk capacitance from an upstream regula-
tor as well as local bypass capacitors, limiting over-
shoot. If severe ringing occurs due to large load
inductance, clamp the MAX1922 output below 6V and
above -0.3V.
ON
GND
*
USB SPECIFICATIONS REQUIRE
A HIGHER VALUE CAPACITOR.
Figure 2. Typical Application Circuit
Output Capacitor
Connect a 0.1µF capacitor from OUT to GND. This
capacitor helps to prevent inductive parasitics from
pulling OUT negative during turn-off.
_______________________________________________________________________________________
7
1A Current-Limited Switch for 2 USB Ports
Pin Configurations (continued)
Chip Information
PROCESS: BiCMOS
TOP VIEW
10
9
8
7
6
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages.
MAX192
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
MAX1922
8 SO
S8-5
21-0041
21-0137
10 TDFN-EP
T1033-1
+
1
2
3
4
5
TDFN
8
_______________________________________________________________________________________
1A Current-Limited Switch for 2 USB Ports
MAX192
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
DESCRIPTION
3
4/09
Fixed typo in UL #
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9
© 2009 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
相关型号：
MAX1924VEEE+T
Power Supply Support Circuit, Fixed, 1 Channel, PDSO16, 0.150 INCH, 0.025 INCH PITCH, QSOP-16
MAXIM
MAX1924VEEE-T
Power Supply Support Circuit, Fixed, 1 Channel, PDSO16, 0.150 INCH, 0.025 INCH PITCH, QSOP-16
MAXIM
MAX1924XEEE+T
Power Supply Support Circuit, Fixed, 1 Channel, PDSO16, 0.150 INCH, 0.025 INCH PITCH, QSOP-16
MAXIM
MAX1924XEEE-T
Power Supply Support Circuit, Fixed, 1 Channel, PDSO16, 0.150 INCH, 0.025 INCH PITCH, QSOP-16
MAXIM
©2020 ICPDF网 联系我们和版权申明