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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.
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
MAX1693/MAX1694
USB Current-Limited Switches
with Fault Blanking
________________________________________________________________
Maxim Integrated Products
1
MAX1693
MAX1694
IN OUTPUTOUT
INPUT
+2.7V TO +5.5V
FAULT
ON
ON
OFF
GND
1
2
3
4
5
10
9
8
7
6
OUT
IN
OUT
FAULTOUT
IN
OUT
IN
MAX1693
MAX1694
µMAX
TOP VIEW
GNDON
Typical Operating Circuit
19-1518; Rev 0; 9/99
PART
MAX1693EUB
MAX1694EUB
-40°C to +85°C
-40°C to +85°C
TEMP. RANGE PIN-PACKAGE
10 µMAX
10 µMAX
Pin Configuration
Ordering Information
MAX1693/MAX1694
USB Current-Limited Switches
with Fault Blanking
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
IN
= +5V, TA= 0°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°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.
IN, 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
MAX1693EUB/MAX1694EUB ..........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10sec) .............................+300°C
VON= GND, I
OUT
= 0
I
SINK
= 1mA, VIN= 3V
VON= VINor GND
(Note 1)
VIN= 2.7V to 3.6V
VIN= 2.7V to 5.5V
TA= +25°C
VON= VIN= V
OUT
= 5.5V
Rising edge, 100mV hysteresis
VON= VIN,
V
IN
= 5.5V,
V
OUT
= GND
OUT shorted to GND, MAX1693 only (Note 2)
CONDITIONS
V0.4V
OL
FAULT Output Logic Low
Voltage
µA±1
ON Input Leakage
V
2
V
IH
ON Input Logic High Voltage
V0.8V
IL
ON Input Logic Low Voltage
mA500 700I
SC
Continuous Short-Circuit
Current Limit
µA
35
I
Q
14 25
V2.7 5.5V
IN
Operating Voltage
Quiescent Current
mA700 850 1000I
LIMIT
Current Limit
mΩ
72 150
R
ON
On-Resistance
125
60 90
µA0.001 1Off-Supply Current
V2.0 2.6UVLOUndervoltage Lockout
0.01 2
µA
15
Off-Switch Leakage
UNITSMIN TYP MAXSYMBOLPARAMETER
Timer not running
Timer running
TA= +25°C
TA= 0°C to +85°C
VIN= 4.4V to 5.5V
VIN= 4.4V to 5.5V
VIN= 3V
VIN= V
FAULT
= 5.5V µA1
FAULT Output High Leakage
Current
From overcurrent condition to FAULT assertion
ms71013t
FB
Fault-Blanking Timeout Period
VIN= 5V, C
OUT
= 150µF, R
L
= 15Ω,
from ON driven low to 50% full V
OUT
ms1Start-Up Time
I
LOAD
= 400mA µs3620t
OFF
Switch Turn-Off Time
I
LOAD
= 400mA µs80 200t
ON
Switch Turn-On Time
°C165Thermal Shutdown Threshold
TA= 0°C to +85°C
VIN= 3.7V to 5.5V 2.4
MAX1693/MAX1694
USB Current-Limited Switches
with Fault Blanking
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS
(V
IN
= +5V, TA= -40°C to +85°C, unless otherwise noted.) (Note 3)
VIN= V
FAULT
= 5.5V µA1
VIN= 4.4V to 5.5V
FAULT Output High Leakage
Current
VON= GND, I
OUT
= 0, timer not running
From overcurrent condition to FAULT assertion
I
SINK
= 1mA, VIN= 3V
VON= VINor GND
(Note 1)
VIN= 3V to 3.6V
VIN= 3V to 5.5V
ms
VON= VIN= V
OUT
= 5.5V
Rising edge, 100mV hysteresis
VIN= 3V
VON= V
IN
= 5.5V, V
OUT
= GND
OUT shorted to GND, MAX1693 only (Note 2)
CONDITIONS
614t
FB
Fault-Blanking Timeout Period
I
LOAD
= 400mA µs120t
OFF
Switch Turn-Off Time
I
LOAD
= 400mA µs200t
ON
Switch Turn-On Time
V0.4V
OL
FAULT Output Logic Low
Voltage
µA±1
ON Input Leakage
V
2
V
IH
ON Input Logic High Voltage
V0.8V
IL
ON Input Logic Low Voltage
mA750
Continuous Short-Circuit
Current Limit
µAI
Q
25
V3 5.5V
IN
Operating Voltage
Quiescent Current
mA640 1060I
LIMIT
Current Limit
150
125
µA2Off-Supply Current
V2.0 2.9UVLOUndervoltage Lockout
µA15Off-Switch Leakage
UNITSMIN TYP MAXSYMBOLPARAMETER
R
ON
On-Resistance mΩ
Note 1: MAX1693’s current limit is tested by forcing V
OUT
to 4.5V. The MAX1694’s current limit is tested by increasing the output cur-
rent 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) short-
circuit condition.
Note 3: Specifications to -40°C are guaranteed by design, not production tested.
VIN= 3.7V to 5.5V 2.4
MAX1693/MAX1694
USB Current-Limited Switches
with Fault Blanking
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VIN= +5V, TA= +25°C, unless otherwise noted.)
0
2
4
6
8
10
12
14
16
021 3456
QUIESCENT CURRENT vs. INPUT VOLTAGE
MAX1693/4 toc01
INPUT VOLTAGE (V)
QUIESCENT CURRENT (µA)
I
OUT
= O
VON = GND
9
11
10
13
12
15
14
16
-40 0 20-20 40 60 80 100
QUIESCENT CURRENT vs. TEMPERATURE
MAX1693/4 toc02
TEMPERATURE (°C)
QUIESCENT CURRENT (µA)
VIN = 5V
VIN = 3V
100
0.01
OFF-SUPPLY CURRENT
vs. TEMPERATURE
0.1
1
10
MAX1693/4 toc03
TEMPERATURE (°C)
OFF-SUPPLY CURRENT (nA)
-40 0-20 20 40 60 80 100
VON = V
IN
100
1000
0.01
-40 0-20 40 10080
OFF-SWITCH CURRENT vs. TEMPERATURE
0.1
1
10
MAX1693/4 toc04
TEMPERATURE (°C)
OFF-SWITCH CURRENT (nA)
20 60
V0N = V
IN
-40 0-20 40 10080
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
MAX1693/4 toc05
TEMPERATURE (°C)
NORMALIZED R
ON
20 60
0
0.4
0.2
0.8
0.6
1.2
1.0
1.4
I
OUT
= 425mA
0
0.4
0.2
0.8
0.6
1.0
1.2
0231 456
NORMALIZED OUTPUT CURRENT
vs. OUTPUT VOLTAGE
MAX1693/4 toc06
OUTPUT VOLTAGE (V)
NORMALIZED OUTPUT CURRENT
SHORT-CIRCUIT CURRENT
I
LIMIT
0
40
20
80
60
140
120
100
160
-40 0-20 20 40 60 80 100
TURN-ON TIME vs. TEMPERATURE
MAX1693/4 toc07
TEMPERATURE (°C)
t
ON
(µs)
I
LOAD
= 425mA
VIN = 3V
VIN = 5V
0
2
1
4
3
6
5
7
-40 0 20-20 40 60 80 100
TURN-OFF TIME vs. TEMPERATURE
MAX1693/4 toc08
TEMPERATURE (°C)
t
OFF
(µs)
I
LOAD
= 425mA
VIN = 3V
VIN = 5V
0
2
6
4
10
8
12
-40 0 20-20 40 60 80 100
FAULT-BLANKING TIMEOUT
vs. TEMPERATURE
MAX1693/4 toc09
TEMPERATURE (°C)
FAULT-BLANKING TIMEOUT (ms)
I
OUT
= 850mA
VIN = 3V OR 5V
MAX1693/MAX1694
USB Current-Limited Switches
with Fault Blanking
_______________________________________________________________________________________
5
4
3
1
2
2ms/div
MAX1693/4 toc10
MAX1693
CURRENT-LIMIT AND FAULT RESPONSE
CH1 = VIN, 200mV/div, AC-COUPLED; CH2 = V
OUT
,
5V/div; CH3 = V
FAULT
, 5V/div; CH4 = I
OUT
, 500mA/div
4
10µs/div
3
1
2
MAX1693
CURRENT-LIMIT RESPONSE
MAX1693/4 toc11
CH1 = VIN, 200mV/div, AC-COUPLED; CH2 = V
OUT
,
5V/div; CH3 = V
FAULT
, 5V/div; CH4 = I
OUT
, 1A/div
4
3
2
1
MAX1693
SWITCH TURN-ON TIME
MAX1693/4 toc13
CH1 = V
OUT
, 5V/div; CH2 = VON, 5V/div;
CH3 = V
FAULT
, 5V/div; CH4 = I
OUT
, 200mA/div
20µs/div
4
3
2
1
MAX1693
SWITCH TURN-OFF TIME
MAX1693/4 toc14
CH1 = V
OUT
, 5V/div; CH2 = VON, 5V/div;
CH3 = V
FAULT
, 5V/div; CH4 = I
OUT
, 200mA/div
1µs/div
3
2
1
MAX1693/4 toc15
MAX1694
OVERCURRENT TO FAULT
AND SWITCH LATCHED OFF
CH1 = V
FAULT
, 5V/div; CH2 = I
OUT
, 5V/div;
CH3 = I
OUT
, 1A/div
2ms/div
4
3
2
1
MAX1693
START-UP TIME
(TYPICAL USB APPLICATION)
MAX1693/4 toc16
CH1 = V
OUT
, 5V/div; CH2 = VON, 5V/div;
CH3 = I
OUT
, 500mA/div; CH4 = V
FAULT
, 5V/div
C
L
= 150µF
R
L
= 15Ω
1ms/div
FULL-CURRENT LIMIT CHARGES CAPACITOR
RESISTOR
LOAD
CURRENT
FOLDBACKCURRENT LIMIT
Typical Operating Characteristics (continued)
(VIN= +5V, TA= +25°C, unless otherwise noted.)
_______________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 (I
LIMIT
), the current also increases through the
replica switch (I
OUT
/6500). The current-limit error amplifier compares the voltage to the internal 1.24V reference and regulates the current back to the I
LIMIT
.
These switches are not bidirectional; therefore, the
input voltage must be higher than the output voltage.
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.
Thermal Shutdown
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.
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 fault-
blanking period is exceeded.
Fault Blanking
The MAX1693/MAX1694 feature 10ms fault blanking.
Fault blanking allows current-limit faults, including
MAX1693/MAX1694
USB Current-Limited Switches
with Fault Blanking
6 _______________________________________________________________________________________
Pin Description
NAME FUNCTION
1, 3, 9 IN
Input. P-channel MOSFET source. Connect all IN pins together and bypass with a 1µF
ceramic capacitor to ground.
PIN
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
7
FAULT
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.
MAX1693
P
P
P
OUT
GND
1.24V
N
FAULT
ON
ON
CURRENT-LIMIT
AMPLIFIER
REPLICA
AMPLIFIER
ON
HOT
IN
CONTROL
CIRCUITRY
10ms
TIMER
Figure 1. MAX1693 Functional Diagram
MAX1693/MAX1694
USB Current-Limited Switches
with Fault Blanking
_______________________________________________________________________________________ 7
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.
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.
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 = (I
LIMIT
)
2
· R
ON
where I
LIMIT
is the preset current limit (1.0A max) and
R
ON
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.
1
2
3
4
5
10
9
8
7
6
OUT
IN
OUT
FAULT
OUT
IN
OUT
IN
MAX1693
MAX1694
GND
ON
Figure 3. IN and OUT Cross Connections for a Single-Layer
Board
Figure 2. Typical Application Circuit
Chip Information
TRANSISTOR COUNT: 715
MAX1693
MAX1694
IN OUTPUTOUT
INPUT
+2.7V TO +5.5V
FAULT
ON
ON
OFF
100k
1µF 0.1µF*
*USB SPECIFICATIONS REQUIRE A LARGER CAPACITOR
GND
MAX1693/MAX1694
USB Current-Limited Switches
with Fault Blanking
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.
Package Information
10LUMAX.EPS
Note:
Neither the MAX1693 nor MAX1694 has an exposed pad.
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