Maxim MAX1694EUB Usb current-limited switches with fault blanking Datasheet

19-1518; Rev 0; 9/99
USB Current-Limited Switches
with Fault Blanking
Features
♦ Accurate Current Limit (0.7A min, 1.0A max)
♦ Guaranteed 0.75A Short-Circuit Protection
♦ 10ms Internal Fault-Blanking Timeout
♦ No Fault Signal During Power-Up
♦ Latched FAULT Output Turns Off Power Switch
(MAX1694)
♦ Thermal Shutdown Protection
♦ +2.7V to +5.5V Supply Range
♦ 14µA Supply Current
♦ Small 10-Pin µMAX Package
♦ UL Recognition Pending
Applications
USB Ports and Hubs
Notebook Computers
Portable Equipment
Docking Stations
Hot Plug-In Power Supplies
Battery-Charger Circuits
Ordering Information
PART
TEMP. RANGE
PIN-PACKAGE
MAX1693EUB
MAX1694EUB
-40°C to +85°C
-40°C to +85°C
10 µMAX
10 µMAX
Typical Operating Circuit
Pin Configuration
INPUT
+2.7V TO +5.5V
IN
OUT
OUTPUT
TOP VIEW
IN 1
MAX1693
MAX1694
10 OUT
OUT
2
IN
3
OUT
4
7
FAULT
ON
5
6
GND
MAX1693
MAX1694
µMAX
9
IN
8
OUT
FAULT
OFF
ON
ON
GND
________________________________________________________________ Maxim Integrated Products
1
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MAX1693/MAX1694
General Description
The MAX1693/MAX1694 are current-limited, 60mΩ
switches with built-in fault blanking. Their accurate preset current limit of 0.7A to 1.0A makes them ideally suited for USB applications. Their low quiescent supply
current (14µA) and shutdown current (1µA) conserve
battery power in portable applications. The MAX1693/
MAX1694 operate with inputs from +2.7V to +5.5V,
making them ideal for both +3V and +5V systems.
A fault signal notifies the microprocessor that the internal current limit has been reached. A 10ms fault-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 fault blanking also prevents a fault signal
from being issued when the device is powering up.
In the MAX1693, an output overcurrent condition causes the switch to current limit at 0.7A to 1.0A and FAULT
to go low after the 10ms blanking period. When the
overcurrent condition is removed, FAULT returns to its
high-impedance state. In the MAX1694, any overcurrent longer than 10ms will latch the switch open and set
FAULT low. The latch is cleared by cycling the ON
input or by powering up the device again. This feature
saves power by preventing the device from thermally
cycling on and off in case of a persistent short-circuit
condition.
The MAX1693/MAX1694 have several safety features to
ensure that the USB port is protected. Built-in thermaloverload protection limits power dissipation and junction temperatures. Both devices have accurate internal
current-limiting circuitry to protect the input supply
against overload. They are available in space-saving
10-pin µMAX packages.
MAX1693/MAX1694
USB Current-Limited Switches
with Fault Blanking
ABSOLUTE MAXIMUM RATINGS
IN, ON, FAULT to GND.............................................-0.3V to +6V
OUT to GND ................................................-0.3V to (VIN + 0.3V)
Maximum Continuous Switch Current .....1.2A (internally limited)
OUT Short Circuit to GND ..........................................Continuous
Continuous Power Dissipation (TA = +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C) ............444mW
Operating Temperature Range
MAX1693EUB/MAX1694EUB ..........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec) .............................+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
(VIN = +5V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
Operating Voltage
Quiescent Current
SYMBOL
VIN
IQ
Off-Supply Current
Undervoltage Lockout
Current Limit
RON
ILIMIT
2.7
V ON = GND, IOUT = 0
14
Timer running
35
Rising edge, 100mV hysteresis
V ON = VIN,
VIN = 5.5V,
VOUT = GND
TA = +25°C
TA = +25°C
VIN = 4.4V to 5.5V
TA = 0°C to +85°C
(Note 1)
VIN = 2.7V to 5.5V
FAULT Output High Leakage
Current
Fault-Blanking Timeout Period
tFB
700
VIN = 2.7V to 3.6V
2
VIN = 3.7V to 5.5V
2.4
V
25
µA
1
µA
2.6
V
2
90
mΩ
72
150
850
1000
mA
500
700
mA
0.8
V
V
V ON = VIN or GND
±1
µA
ISINK = 1mA, VIN = 3V
0.4
V
1
µA
13
ms
From overcurrent condition to FAULT assertion
7
10
VIN = 5V, COUT = 150µF, RL = 15Ω,
from ON driven low to 50% full VOUT
1
80
200
6
20
Switch Turn-On Time
tON
ILOAD = 400mA
Switch Turn-Off Time
tOFF
ILOAD = 400mA
2
5.5
125
VIN = V FAULT = 5.5V
Start-Up Time
Thermal Shutdown Threshold
60
VIN = 3V
VIL
VOL
UNITS
15
VIN = 4.4V to 5.5V
ON Input Logic Low Voltage
FAULT Output Logic Low
Voltage
0.01
MAX
µA
OUT shorted to GND, MAX1693 only (Note 2)
ON Input Leakage
0.001
2.0
TA = 0°C to +85°C
ISC
VIH
TYP
Timer not running
Continuous Short-Circuit
Current Limit
ON Input Logic High Voltage
MIN
V ON = VIN = VOUT = 5.5V
UVLO
Off-Switch Leakage
On-Resistance
CONDITIONS
3
165
_______________________________________________________________________________________
ms
µs
µs
°C
USB Current-Limited Switches
with Fault Blanking
MAX1693/MAX1694
ELECTRICAL CHARACTERISTICS
(VIN = +5V, TA = -40°C to +85°C, unless otherwise noted.) (Note 3)
PARAMETER
SYMBOL
Operating Voltage
VIN
Quiescent Current
IQ
Off-Supply Current
Undervoltage Lockout
UVLO
Off-Switch Leakage
On-Resistance
RON
Current Limit
ILIMIT
Continuous Short-Circuit
Current Limit
ON Input Logic Low Voltage
ON Input Logic High Voltage
VIL
VIH
VOL
FAULT Output High Leakage
Current
MAX
UNITS
5.5
V
V ON = GND, IOUT = 0, timer not running
25
µA
V ON = VIN = VOUT = 5.5V
2
µA
2.9
V
V ON = VIN = 5.5V, VOUT = GND
15
µA
VIN = 4.4V to 5.5V
125
VIN = 3V
150
3
Rising edge, 100mV hysteresis
(Note 1)
2.0
640
VIN = 3V to 5.5V
VIN = 3V to 3.6V
VIN = 3.7V to 5.5V
TYP
mΩ
1060
mA
750
mA
0.8
V
2
V
2.4
V ON = VIN or GND
±1
µA
ISINK = 1mA, VIN = 3V
0.4
V
1
µA
14
ms
200
µs
20
µs
VIN = V FAULT = 5.5V
tFB
From overcurrent condition to FAULT assertion
Switch Turn-On Time
tON
ILOAD = 400mA
Switch Turn-Off Time
tOFF
ILOAD = 400mA
Fault-Blanking Timeout Period
MIN
OUT shorted to GND, MAX1693 only (Note 2)
ON Input Leakage
FAULT Output Logic Low
Voltage
CONDITIONS
6
1
Note 1: MAX1693’s current limit is tested by forcing VOUT to 4.5V. The MAX1694’s current limit is tested by increasing the output current until the switch is latched off.
Note 2: This specification applies to the MAX1693 only. The MAX1694 latches the switch off under a sustained (>10ms) shortcircuit condition.
Note 3: Specifications to -40°C are guaranteed by design, not production tested.
_______________________________________________________________________________________
3
Typical Operating Characteristics
(VIN = +5V, TA = +25°C, unless otherwise noted.)
10
8
6
4
14
VIN = 3V
13
12
11
100
VON = VIN
10
1
0.1
10
0.01
0
1
2
3
4
5
6
-40
-20
0
20
40
60
80
100
INPUT VOLTAGE (V)
TEMPERATURE (°C)
0
20
40
60
TEMPERATURE (°C)
OFF-SWITCH CURRENT vs. TEMPERATURE
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
NORMALIZED OUTPUT CURRENT
vs. OUTPUT VOLTAGE
1.2
NORMALIZED RON
100
IOUT = 425mA
10
1
1.0
0.8
0.6
0.4
0.1
0.2
0.01
0
-20
0
20
40
60
80
100
0.8
SHORT-CIRCUIT CURRENT
0.6
0.4
0.2
-20
0
20
40
60
80
100
0
1
2
3
4
5
OUTPUT VOLTAGE (V)
TURN-ON TIME vs. TEMPERATURE
TURN-OFF TIME vs. TEMPERATURE
FAULT-BLANKING TIMEOUT
vs. TEMPERATURE
ILOAD = 425mA
VIN = 5V
6
100
80
VIN = 5V
60
tOFF (µs)
5
4
VIN = 3V
3
2
40
1
20
0
0
20
40
60
TEMPERATURE (°C)
80
100
10
8
6
4
2
IOUT = 850mA
VIN = 3V OR 5V
0
0
-20
12
6
MAX1693/4 toc09
VIN = 3V
120
7
FAULT-BLANKING TIMEOUT (ms)
ILOAD = 425mA
MAX1693/4 toc08
TEMPERATURE (°C)
140
100
ILIMIT
1.0
TEMPERATURE (°C)
160
-40
80
0
-40
MAX1693/4 toc07
-40
-20
1.2
NORMALIZED OUTPUT CURRENT
V0N = VIN
MAX1693/4 toc05
1.4
MAX1693/4 toc04
1000
-40
MAX1693/4 toc06
9
0
4
MAX1693/4 toc03
15
2
OFF-SWITCH CURRENT (nA)
MAX1693/4 toc02
VIN = 5V
OFF-SUPPLY CURRENT (nA)
12
16
QUIESCENT CURRENT (µA)
VON = GND
IOUT = O
14
QUIESCENT CURRENT (µA)
MAX1693/4 toc01
16
OFF-SUPPLY CURRENT
vs. TEMPERATURE
QUIESCENT CURRENT vs. TEMPERATURE
QUIESCENT CURRENT vs. INPUT VOLTAGE
tON (µs)
MAX1693/MAX1694
USB Current-Limited Switches
with Fault Blanking
-40
-20
0
20
40
60
TEMPERATURE (°C)
80
100
-40
-20
0
20
40
60
TEMPERATURE (°C)
_______________________________________________________________________________________
80
100
USB Current-Limited Switches
with Fault Blanking
MAX1693
CURRENT-LIMIT AND FAULT RESPONSE
1
2
2
3
3
4
4
2ms/div
10µs/div
CH1 = VIN, 200mV/div, AC-COUPLED; CH2 = VOUT,
5V/div; CH3 = VFAULT, 5V/div; CH4 = IOUT, 500mA/div
CH1 = VIN, 200mV/div, AC-COUPLED; CH2 = VOUT,
5V/div; CH3 = VFAULT, 5V/div; CH4 = IOUT, 1A/div
MAX1693
SWITCH TURN-OFF TIME
MAX1693/4 toc14
MAX1693/4 toc13
MAX1693
SWITCH TURN-ON TIME
1
1
2
2
3
3
4
4
1µs/div
20µs/div
CH1 = VOUT, 5V/div; CH2 = VON, 5V/div;
CH3 = VFAULT, 5V/div; CH4 = IOUT, 200mA/div
CH1 = VOUT, 5V/div; CH2 = VON, 5V/div;
CH3 = VFAULT, 5V/div; CH4 = IOUT, 200mA/div
MAX1694
OVERCURRENT TO FAULT
AND SWITCH LATCHED OFF
MAX1693/4 toc15
MAX1693
START-UP TIME
(TYPICAL USB APPLICATION)
1
1
CL = 150µF
RL = 15Ω
MAX1693/4 toc16
1
MAX1693/4 toc11
MAX1693/4 toc10
MAX1693
CURRENT-LIMIT RESPONSE
2
2
FULL-CURRENT LIMIT CHARGES CAPACITOR
3
FOLDBACKCURRENT LIMIT
RESISTOR
LOAD
CURRENT
3
4
2ms/div
CH1 = VFAULT, 5V/div; CH2 = IOUT, 5V/div;
CH3 = IOUT, 1A/div
1ms/div
CH1 = VOUT, 5V/div; CH2 = VON, 5V/div;
CH3 = IOUT, 500mA/div; CH4 = VFAULT, 5V/div
_______________________________________________________________________________________
5
MAX1693/MAX1694
Typical Operating Characteristics (continued)
(VIN = +5V, TA = +25°C, unless otherwise noted.)
USB Current-Limited Switches
with Fault Blanking
MAX1693/MAX1694
Pin Description
PIN
NAME
FUNCTION
Input. P-channel MOSFET source. Connect all IN pins together and bypass with a 1µF
ceramic capacitor to ground.
1, 3, 9
IN
2, 4, 8, 10
OUT
Switch Output. P-channel MOSFET drain. Connect all OUT pins together and bypass with a
0.1µF capacitor to ground.
5
ON
Active-Low Switch On Input. A logic low turns the switch on.
6
GND
Ground
Fault-Indicator Output. This open-drain output goes low when the device is in thermal shutdown or undervoltage lockout or on a sustained (>10ms) current-limit condition. For the
MAX1694 only, this output latches low when asserted, and the power switch is turned off
until the latch is reset.
FAULT
7
These switches are not bidirectional; therefore, the
input voltage must be higher than the output voltage.
P
IN
OUT
MAX1693
P
FAULT
N
REPLICA
AMPLIFIER
ON
Thermal Shutdown
P
ON
10ms
TIMER
The MAX1693/MAX1694 feature thermal shutdown. The
switch turns off and the FAULT output goes low immediately (no fault blanking) when the junction temperature exceeds +165°C. The MAX1694 remains latched
with the switch off and the FAULT output low. When the
MAX1693 cools 20°C, the switch turns back on. If the
fault short-circuit condition is not removed, the switch
will cycle on and off, resulting in a pulsed output.
CURRENT-LIMIT
AMPLIFIER
1.24V
HOT
ON
CONTROL
CIRCUITRY
GND
Figure 1. MAX1693 Functional Diagram
_______________Detailed Description
The MAX1693/MAX1694 P-channel MOSFET power
switches limit output current to 0.7A min to 1.0A max.
When the output current is increased beyond the current limit (ILIMIT), the current also increases through the
replica switch (IOUT/6500). The current-limit error amplifier compares the voltage to the internal 1.24V reference and regulates the current back to the ILIMIT.
6
Continuous Short-Circuit Protection
The MAX1693/MAX1694 are foldback short circuit-protected switches. In the event of an output short-circuit
or current-overload condition, the current through the
switch is foldback-current limited to 500mA continuous
for the MAX1693. For the MAX1694, if the short circuit
lasts longer than 10ms, the switch is latched off.
FAULT Indicator
The MAX1693/MAX1694 provide a fault output
(FAULT). A 100kΩ pull-up resistor from FAULT to IN
provides a logic control signal. This open-drain output
goes low when any of the following conditions occur:
• The input voltage is below the undervoltage-lockout
(UVLO) threshold.
• The die temperature exceeds the thermal shutdown
temperature limit of +165°C.
• The device is in current limit and the 10ms faultblanking period is exceeded.
Fault Blanking
The MAX1693/MAX1694 feature 10ms fault blanking.
Fault blanking allows current-limit faults, including
_______________________________________________________________________________________
USB Current-Limited Switches
with Fault Blanking
Only current-limit faults are blanked. Die overtemperature faults and input voltage droops below the UVLO
threshold will cause an immediate fault output.
Fault Latching (MAX1694 Only)
The MAX1694 features a latched FAULT output.
Whenever the FAULT output is activated, it latches the
FAULT output low and also turns the switch off. To clear
the latch, either cycle the ON input or cycle the input
voltage below UVLO.
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 will be adequate for most
applications; however, higher capacitor values will further reduce the voltage drop at the input. See Figure 2.
Output Capacitor
Connect a 0.1µF capacitor from OUT to GND. This capacitor helps prevent inductive parasitics from pulling
OUT negative during turn-off.
INPUT
+2.7V TO +5.5V
IN
OUT
1µF
Layout and Thermal Dissipation
To optimize the switch-response time to output shortcircuit conditions, it is very important to keep all traces
as short as possible to reduce the effect of undesirable
parasitic inductance. Place input and output capacitors
as close to the device as possible (no more than 5mm).
All IN and all OUT pins must be connected with short
traces to the power bus. Wide power bus planes will
provide superior heat dissipation through the switch IN
and OUT pins. Figure 3 shows suggested pin connections for a single-layer board.
Under normal operating conditions, the package can
dissipate and channel heat away. Calculate the maximum power dissipation as follows:
P = (ILIMIT)2 · RON
where ILIMIT is the preset current limit (1.0A max) and
RON is the on-resistance of the switch (125mΩ max).
When the output is short-circuited, foldback-current limiting activates and the voltage drop across the switch
equals the input supply. The power dissipated across
the switch increases, as does the die temperature. If the
fault condition is not removed, the thermal-overload-protection circuitry activates (see the Thermal Shutdown
section). Wide power-bus planes connected to IN and
OUT and a ground plane in contact with the device will
help dissipate additional heat.
Chip Information
TRANSISTOR COUNT: 715
OUTPUT
MAX1693
MAX1694
0.1µF*
MAX1693
MAX1694
100k
FAULT
OFF
ON
ON
GND
1
IN
2
OUT
3
IN
4
OUT
5
ON
OUT
10
IN
9
OUT
8
FAULT
7
GND
6
*USB SPECIFICATIONS REQUIRE A LARGER CAPACITOR
Figure 2. Typical Application Circuit
Figure 3. IN and OUT Cross Connections for a Single-Layer
Board
_______________________________________________________________________________________
7
MAX1693/MAX1694
momentary short-circuit faults that occur when hotswapping a capacitive load, and also ensures that no
fault 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 fault-blanking timeout, the FAULT output asserts
low. Ensure that the MAX1693/MAX1694’s input is adequately bypassed to prevent input glitches from triggering spurious FAULT outputs. Input voltage glitches less
than 150mV will not cause a spurious FAULT output.
Load-transient faults less than 10ms (typ) will not cause
a FAULT output assertion.
USB Current-Limited Switches
with Fault Blanking
10LUMAX.EPS
MAX1693/MAX1694
Package Information
Note: Neither the MAX1693 nor MAX1694 has an exposed pad.
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1999 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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