19-3128; Rev 2; 3/08
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
The MAX1558/MAX1558H are dual, current-limited
switches with autoreset for USB applications. Autoreset
latches the switch off if it is shorted for more than 20ms,
saving system power. The shorted output is then tested
to determine when the short is removed to automatically
restart the channel. Each channel delivers up to 1.2A
and meets all IEC specifications for USB ports. Low
quiescent supply current (45µA) and standby current
(3µA) conserve battery power in portable applications.
The MAX1558/MAX1558H safety features ensure that the
USB port is protected. Built-in thermal-overload protection
limits power dissipation and junction temperature.
Accurate, programmable current-limiting circuitry protects the input supply against both overload and short-circuit conditions. 20ms fault blanking enables the circuit to
ignore transient faults, such as those caused when hot
swapping a capacitive load, preventing false alarms to
the host system. The MAX1558/MAX1558H also feature
reverse-current protection circuitry to block current flow
from the output to the input when the switches are off.
The MAX1558/MAX1558H are available in space-saving 3mm x 3mm, 10-pin TDFN packages. The MAX1558
is enabled with an active-low signal, and the
MAX1558H is enabled with an active-high signal.
Features
♦ 55mΩ Switch Resistance
♦ Tiny 10-Pin, 3mm x 3mm TDFN Package
♦ 14% Accurate Current Limit
♦ Autorestart when Fault is Removed
♦ Programmable Current Up to 1.2A
♦ Thermal-Overload Protection
♦ Built-In 20ms Fault Blanking
♦ Compliant to All USB Specifications
♦ 2.7V to 5.5V Supply Range
♦ Independent-Output Fault Indicators
♦ Block Reverse Current when Disabled
♦ 15kV ESD Protection (with Capacitor)
♦ UL Recognized: UL# E211395
Ordering Information
TEMP RANGE
PINPACKAGE
MAX1558ETB+
-40°C to +85°C
10 TDFN
(3mm x 3mm)
AAR
USB Ports and Hubs
MAX1558HETB+
-40°C to +85°C
10 TDFN
(3mm x 3mm)
AAS
Notebook Computers and Desktops
+Denotes a lead-free package.
PART
Applications
TOP
MARK
Typical Operating Circuit
PDAs and Palmtop Computers
Docking Stations
FLTA
GND
FLTB
OUTB
TOP VIEW
OUTA
Pin Configuration
10
9
8
7
6
INPUT
2.7V TO 5.5V
INA
ONA
ONA
INB
ONB
ONB
OUTA
USB
PORT A
OUTB
USB
PORT B
MAX1558
FLTA
MAX1558
(MAX1558H)
5
INB
4
ONB (ONB)
3
ISET
2
ONA (ONA)
INA
+ 1
FLTB
ISET
GND
TDFN
3mm x 3mm
________________________________________________________________ Maxim Integrated Products
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.
1
MAX1558/MAX1558H
General Description
MAX1558/MAX1558H
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
ABSOLUTE MAXIMUM RATINGS
IN_, ON_, OUT_, ISET, FLT_ to GND........................-0.3V to +6V
IN_ to OUT_ (when disabled) (Note 1) ........................-6V to +6V
IN_ to OUT_ (when enabled) (Note 2) ............-1.6A to +1.6ARMS
FLT_ Sink Current................................................................20mA
Continuous Power Dissipation (TA = +70°C)
10-Pin TDFN 3mm x 3mm
(derate 24.4mW/°C above +70°C) .............................1952mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+160°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1: Reverse current (current from OUT_ to IN_) is blocked when disabled.
Note 2: Forward current (current from IN_ to OUT_) is internally limited. Reverse current, from OUT_ to IN_, is not limited when the
device is enabled and must be kept below 1.5ARMS to prevent permanent device damage. When the MAX1558/MAX1558H
are disabled, the switch turns off and reverse current is internally blocked.
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
(VINA = VINB = 5V, V ONA = V ONB = 0V (MAX1558), VONA = VONB = 5V (MAX1558H), RISET = 26kΩ to GND, TA = 0°C to +85°C,
unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
Supply Voltage Range
Switch On-Resistance
MIN
TYP
2.75
RON
VIN_ = 5V, TA = +25°C
55
VIN_ = 3.3V, TA = +25°C
64
VIN_ = 4.4V, TA = 0°C to +85°C
MAX
UNITS
5.50
V
75
mΩ
105
Standby Supply Current
Both switches disabled
3
6
µA
Quiescent Supply Current
Both switches enabled
45
75
µA
OUT_ Off-Leakage Current
Switches disabled
VOUTA = VOUTB = 0V
0.03
10
VOUTA = VOUTB = 5V
0.03
Reverse Leakage Current
VIN_ = 0V, VOUTA = VOUTB = 5V, both
switches disabled
Undervoltage-Lockout Threshold
Rising edge, 3% hysteresis
2.3
Continuous Load Current
RISET = 26kΩ
1.2
Current-Limit Threshold
VIN_ - VOUT_ =
0.5V
Peak Short-Circuit Current Limit
RMS Short-Circuit Current Limit
VUVLO
0.03
ISHORT
ISHORT
VOUT_ = 0V
(IOUT_ pulsing)
VOUT_ = 0V
(IOUT_ pulsing)
2.5
µA
µA
2.7
V
A
RISET = 26kΩ
1.20
1.4
RISET = 39kΩ
0.80
0.925
1.05
RISET = 60kΩ
0.50
0.6
0.70
RISET = 26kΩ
1.45
2.0
2.60
RISET = 39kΩ
1.40
RISET = 60kΩ
0.90
RISET = 26kΩ
0.55
RISET = 39kΩ
0.37
RISET = 60kΩ
0.23
1.60
A
A(PEAK)
ARMS
Short-Circuit Continuous CurrentLimit Transition Threshold
(Note 4)
Fault-Blanking Timeout Period
From ILIMIT condition to 50% of V FLT_
8
20
40
ms
ROUT_ = 10Ω, COUT_ = 1µF, does not
include rise time (from ON asserted to
VOUT_ = 10% VIN_)
0.5
1.4
4.0
ms
Turn-On Delay
2
tON
1
_______________________________________________________________________________________
V
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
(VINA = VINB = 5V, V ONA = V ONB = 0V (MAX1558), VONA = VONB = 5V (MAX1558H), RISET = 26kΩ to GND, TA = 0°C to +85°C,
unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Output Rise Time
tRISE
COUT_ = 1µF, ROUT_ = 10Ω, (from 10% to
90% of VOUT_)
4
Turn-Off Delay from ON
tOFF
ROUT_ = 10Ω, COUT_ = 1µF, does not
include rise time (from ON deasserted to
VOUT_ = 90% VIN_)
100
Output Fall Time
tFALL
COUT_ = 1µF, ROUT_ = 10Ω (from 90% to
10% of VOUT_)
3
ms
+160
°C
Thermal-Shutdown Threshold
10°C hysteresis
ONA/ONB Logic Input High
Voltage
VIH
ONA/ONB Logic Input Low
Voltage
VIL
VIN_ = 2.7V to 4.0V
1.6
VIN_ = 4.0V to 5.5V
2.0
ms
1000
µs
V
VIN_ = 2.7V to 4.0V
0.6
VIN_ = 4.0V to 5.5V
0.8
Logic Input Current
VON_ = 0V or VIN_
FLT_ Output Low Voltage
ISINK = 1mA
-1
FLT_ Output High Leakage
Current
VIN_ = V FLT_ = 5.5V
Autorestart Current
In latched-off state, VOUT_ = 0V
10
Autorestart Threshold
In latched-off state, rising
0.4
Autorestart Delay
In latched-off state, VOUT_ > 1V
8
20
V
+1
µA
0.4
V
1
µA
25
50
mA
0.5
0.6
V
40
ms
ELECTRICAL CHARACTERISTICS
(VINA = VINB = 5V, V ONA = V ONB = 0V (MAX1558), VONA = VONB = 5V (MAX1558H), RISET = 26kΩ to GND, TA = -40°C to +85°C,
unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
Supply Voltage Range
Switch On-Resistance
MIN
2.7
RON
TYP
MAX
UNITS
5.5
V
VIN_ = 5V, TA = +25°C
75
VIN_ = 4.4V, TA = 0°C to +85°C
105
mΩ
Standby Supply Current
Both switches disabled
6
µA
Quiescent Supply Current
Both switches enabled
75
µA
OUT_ Off-Leakage Current
Switches disabled, VOUTA = VOUTB = 0V
10
µA
Undervoltage-Lockout Threshold
Rising edge, 3% hysteresis
2.3
Continuous Load Current
RISET = 26kΩ
1.2
Current-Limit Threshold
VIN_ - VOUT_ = 0.5V
Peak Short-Circuit Current Limit
Fault-Blanking Timeout Period
VUVLO
ISHORT
VOUT_ = 0V
(IOUT_ pulsing)
2.7
V
A
RISET = 26kΩ
1.20
1.60
RISET = 39kΩ
0.80
1.05
RISET = 60kΩ
0.50
0.70
RISET = 26kΩ
1.45
2.60
A(PEAK)
8
40
ms
From ILIMIT condition to 50% of V FLT_
A
_______________________________________________________________________________________
3
MAX1558/MAX1558H
ELECTRICAL CHARACTERISTICS (continued)
ELECTRICAL CHARACTERISTICS (continued)
(VINA = VINB = 5V, V ONA = V ONB = 0V (MAX1558), VONA = VONB = 5V (MAX1558H), RISET = 26kΩ to GND, TA = -40°C to +85°C,
unless otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
Turn-On Delay
tON
ROUT_ = 10Ω, COUT_ = 1µF, does not
include rise time (from ON asserted to
VOUT_ = 10% VIN_)
Turn-Off Delay from ON
tOFF
ROUT_ = 10Ω, COUT_ = 1µF, does not
include rise time (from ON deasserted to
VOUT_ = 90% VIN_)
ONA/ONB Logic Input High
Voltage
VIH
ONA/ONB Logic Input Low
Voltage
VIL
TYP
0.5
VIN_ = 2.7V to 4.0V
1.6
VIN_ = 4.0V to 5.5V
2.0
MAX
UNITS
4.0
ms
1000
µs
V
VIN_ = 2.7V to 4.0V
0.6
VIN_ = 4.0V to 5.5V
0.8
Logic Input Current
VON_ = 0V or VIN_
FLT_ Output Low Voltage
ISINK = 1mA
FLT_ Output High Leakage
Current
VIN_ = V FLT_ = 5.5V
Autorestart Current
In latched-off state, VOUT_ = 0V
Autorestart Threshold
In latched-off state, rising
Autorestart Delay
In latched-off state, VOUT_ > 1V
8
-1
V
+1
µA
0.4
V
1
µA
10
50
mA
0.4
0.6
V
40
ms
Note 3: Specifications from 0°C to -40°C are guaranteed by design but not 100% tested.
Note 4: The output voltage at which the device transitions from short-circuit current limit to continuous current limit. See the OutputCurrent Fault Protection section.
Typical Operating Characteristics
(VINA = VINB = 5V, V ONA = V ONB = 0V (MAX1558), VONA = VONB= 5V (MAX1558H), RISET = 26kΩ to GND. Typical values are at TA =
+25°C, unless otherwise noted.)
QUIESCENT SUPPLY CURRENT
vs. SUPPLY VOLTAGE
1.3
1.2
1.1
1.0
0.9
0.8
0.7
60
50
40
30
20
50
MAX1558/58H toc03
1.4
QUIESCENT CURRENT vs. TEMPERATURE
MAX1558/58H toc02
1.5
QUIESCENT CURRENT (μA)
MAX1558/58H toc01
1.6
VIN_ = 5.5V
QUIESCENT CURRENT (μA)
CURRENT-LIMIT PROGRAM vs. RISET
CURRENT LIMIT (A)
MAX1558/MAX1558H
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
45
VIN_ = 5V
40
VIN_ = 4.5V
35
10
0.6
0.5
24
28
32
36
40
44
RISET (kΩ)
4
48
52
56
60
30
0
0
1
2
3
4
SUPPLY VOLTAGE (V)
5
6
-40
-15
10
35
TEMPERATURE (°C)
_______________________________________________________________________________________
60
85
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
SWITCH OFF-LEAKAGE CURRENT
vs. TEMPERATURE
2.5
2.0
1.5
1.0
0.5
-15
10
35
60
10
1
0.1
-40
-15
10
35
60
0
1
2
3
4
5
NORMALIZED ON-RESISTANCE
vs. TEMPERATURE
CONTINUOUS CURRENT-LIMIT THRESHOLD
vs. TEMPERATURE
TURN-ON TIME
vs. TEMPERATURE (tON + tRISE)
1.44
8
1.43
7
TURN-ON TIME (ms)
1.42
1.41
1.40
1.39
1.38
-15
10
35
60
VIN_ = 4.5V
6
5
VIN_ = 5.5V
VIN_ = 5V
4
1.37
1.36
1.35
0.50
3
-40
85
-15
10
35
85
60
-40
-15
10
35
60
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
TURN-OFF TIME
vs. TEMPERATURE (tOFF + tFALL)
FAULT-BLANKING TIME
vs. TEMPERATURE
FAULT OUTPUT LOW VOLTAGE
vs. TEMPERATURE
3.25
3.00
VIN_ = 5V
VIN_ = 4.5V
2.50
VIN_ = 4.5V
23
22
VIN_ = 5V
21
VIN_ = 5.5V
2.25
-15
10
35
TEMPERATURE (°C)
60
85
VIN_ = 4.5V
200
VIN_ = 5V
175
VIN_ = 5.5V
150
125
100
20
2.00
250
225
85
MAX1558/58H toc12
3.50
24
275
FAULT OUTPUT LOW VOLTAGE (mV)
VIN_ = 5.5V
25
MAX1558/58H toc11
MAX1558/58H toc10
4.00
6
MAX1558/58H toc09
1.45
MAX1558/58H toc08
MAX1558/58H toc07
0.75
-40
0.1
85
OUTPUT VOLTAGE (V)
1.00
2.75
1
TEMPERATURE (°C)
1.25
3.75
10
TEMPERATURE (°C)
1.50
-40
100
MAX1558/58H toc06
100
85
CONTINUOUS CURRENT-LIMIT THRESHOLD (A)
-40
NORMALIZED RON (Ω)
ON_ = IN_ (MAX1558)
ON_ = GND
(MAX1558H)
0.01
0
TURN-OFF TIME (ms)
MAX1558/58H toc05
3.0
1000
SWITCH OFF-LEAKAGE CURRENT (nA)
ON_ = VIN_ (MAX1558)
ON_ = GND (MAX1558H)
FAULT-BLANKING TIME (ms)
SHUTDOWN CURRENT (μA)
3.5
MAX1558/58H toc04
4.0
OFF REVERSE-BLOCKING LEAKAGE
CURRENT vs. OUTPUT VOLTAGE
OFF REVERSE-BLOCKING LEAKAGE CURRRENT (nA)
SHUTDOWN CURRENT vs. TEMPERATURE
-40 -25 -10
5
20
35
50
TEMPERATURE (°C)
65
80
-40
-15
10
35
60
85
TEMPERATURE (°C)
_______________________________________________________________________________________
5
MAX1558/MAX1558H
Typical Operating Characteristics (continued)
(VINA = VINB = 5V, V ONA = V ONB = 0V (MAX1558), VONA = VONB= 5V (MAX1558H), RISET = 26kΩ to GND. Typical values are at TA =
+25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VINA = VINB = 5V, V ONA = V ONB = 0V (MAX1558), VONA = VONB= 5V (MAX1558H), RISET = 26kΩ to GND. Typical values are at TA =
+25°C, unless otherwise noted.)
AUTORESET CURRENT
vs. INPUT VOLTAGE
AUTORESET CURRENT
vs. TEMPERATURE
34
32
30
28
VIN_ = 5V
VIN_ = 4.5V
26
24
MAX1558/58H toc14
VIN_ = 5.5V
36
AUTORESET CURRENT (mA)
38
40
MAX1558/58H toc13
40
AUTORESET CURRENT (mA)
MAX1558/MAX1558H
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
TA = -40°C
35
30
TA = +85°C
25
TA = +25°C
22
20
20
-40
-15
10
35
60
3.0
85
3.5
4.0
4.5
5.0
5.5
6.0
VIN (V)
TEMPERATURE (°C)
OVERLOAD RESPONSE INTO 2.5Ω
SHORT-CIRCUIT RESPONSE INTO 0Ω
MAX1558/58H toc15
VIN
MAX1558/58H toc16
5V
VIN
SWITCH ON
5V/div
SHORT
APPLIED
OUT_
0
VOUT
5V/div
0
FLT_
SHORT
REMOVED
5V/div
0
AUTORESTART
5V/div
0
5A/div
0
FLTA_
IOUT_
1A/div
0
5V/div
0
IOUT_
20ms/div
20ms/div
SWITCH TURN-OFF TIME
SWITCH TURN-ON TIME
MAX1558/58H toc18
MAX1558/58H toc17
2V/div
ON_
2V/div
ON_
0
0
2V/div
OUT_
0
2V/div
OUT_
0
2.0ms/div
6
1.0ms/div
_______________________________________________________________________________________
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
PIN
NAME
FUNCTION
1
INA
2
ONA
*(ONA)
Control Input for Switch A. Can be driven higher than IN_ without damage. A logic low turns switch A on
for the MAX1558. A logic high turns switch A on for the MAX1558H.
3
ISET
Current-Limit Adjust for Both Channels. Connect a resistor between 26kΩ to 60kΩ from ISET to ground to
program the current limit. See Setting the Current Limit in the Applications Information section.
4
ONB
*(ONB)
Control Input for Switch B. Can be driven higher than IN_ without damage. A logic low turns switch B on
for the MAX1558. A logic high turns switch B on for the MAX1558H.
5
INB
6
OUTB
Power Output for Switch B. Connect a 1µF capacitor from OUTB to ground. The load condition may
require additional bulk capacitance.
7
FLTB
Fault Indicator Output for Switch B. This open-drain output goes low when switch B is in thermal
shutdown or UVLO or in a sustained (>20ms) current-limit or short-circuit condition.
8
GND
Ground
9
FLTA
Fault Indicator Output for Switch A. This open-drain output goes low when switch A is in thermal
shutdown or UVLO or in a sustained (>20ms) current-limit or short-circuit condition.
10
OUTA
Power Output for Switch A. Connect a 1µF capacitor from OUTA to ground. The load condition may
require additional bulk capacitance.
—
PAD
Power Input for OUTA. Connect INA and INB together and bypass with a 0.1µF capacitor to ground.
Load conditions may require additional bulk capacitance to prevent the input from being pulled down.
Power Input for OUTB. Connect INB and INA together and bypass with a 0.1µF capacitor to ground.
Load conditions may require additional bulk capacitance to prevent the input from being pulled down.
Exposed Pad, Internally Connected to GND. Connect exposed pad to a large copper trace for maximum
power dissipation.
*( ) are for the MAX1558H only.
Detailed Description
The MAX1558/MAX1558H are dual current-limited
switches designed for USB applications. They have two
independent switches, each with its own enable control
input and autoreset function. Each switch has an errorflag output to notify the USB controller when currentlimit, short-circuit, undervoltage-lockout, or thermalshutdown conditions occur (Figure 2). The MAX1558/
MAX1558H operate from a 2.7V to 5.5V supply. Each
output can supply up to 1.2A. Current limit for both
channels is set with one external resistor.
The MAX1558/MAX1558H have independent thermal
shutdown for each switch in the event of a prolonged
overload. An autoreset function monitors the output and
automatically turns the switch on when the overload is
removed. Separate current limiting and thermal-shutdown circuits permit each switch to operate independently, improving system robustness.
0.1μF
INPUT
2.7V TO 5.5V
INA
ONA
ONA
INB
ONB
ONB
OUTA
100kΩ
1μF*
USB
PORT A
MAX1558
FLTA
OUTB
100kΩ
1μF*
USB
PORT B
FLTB
ISET
GND
*USB APPLICATIONS MAY REQUIRE ADDITIONAL
BULK CAPACITANCE
Figure 1. Typical Application Circuit
_______________________________________________________________________________________
7
MAX1558/MAX1558H
Pin Description
MAX1558/MAX1558H
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
INA
FLTA
INA
ONA
CHARGE
PUMP
ONA
ILIMA
BIAS
OUTA
THERMAL
SHUTDOWN
UVLO
30mA
FAULT
LOGIC
REF
GND
30mA
OSC
25kHz
TIMER
20ms
OUTB
ONB
CHARGE
PUMP
ONB
ILIMB
INB
INB
0.6V
PROGRAM ILIMA
PROGRAM ILIMB
FLTB
MAX1558
ISET
Figure 2. Functional Diagram
8
_______________________________________________________________________________________
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
The MAX1558/MAX1558H include a UVLO circuit to
prevent erroneous switch operation when the input voltage is low during startup and brownout conditions.
Operation is inhibited when VIN_ is less than 2.5V.
Output-Current Fault Protection
The current limit for both switch outputs is programmed
by a resistor between 26kΩ and 60kΩ connected from
ISET to ground. See the Current-Limit Program vs. RISET
curve in the Typical Operating Characteristics and Setting
the Current Limit in the Applications Information section.
The MAX1558 reduces the gate drive to the MOSFET
switch when the programmed current-limit value is
reached. If the current-limit program value is reached, the
part reduces gate drive to regulate at the current limit. If
the current limit persists for 20ms (typ), the output turns
off and the fault flag is set until the fault is removed, as
detected by the autoreset circuit.
When the the output drops below 1V (typ), the current
limit is set 30% above the programmed level and
pulsed. This lowers the RMS current for a short-circuit
condition, which reduces system load current and
power dissipation. If a short circuit persists for 20ms,
the output turns off and the fault flag is set. The autoreset circuit automatically restarts the part if the fault is
removed.
Fault Blanking
The MAX1558/MAX1558H switches can reach current
limit in normal operation when powering up or driving
heavy capacitive loads. To differentiate these conditions
from short circuits or sustained overloads, the
MAX1558/MAX1558H have independent fault-blanking
circuits in each switch. When a load transient causes
the device to enter the current limit, an internal counter
monitors the duration of the fault. For load faults exceeding the 20ms fault-blanking time, the offending switch
turns off, the corresponding FLT_ signal asserts low,
and that channel enters autoreset mode (see the
Autoreset Mode section). Only current-limit and shortcircuit faults are blanked. Thermal-overload faults and
input-voltage drops below the UVLO threshold immediately cause the switch to turn off and FLT_ to assert low.
Fault blanking allows the MAX1558 to handle USB
loads that may not be fully compliant with USB specifications. USB loads with additional bypass capacitance
and/or large startup currents can be successfully powered even while protecting the upstream power source.
No fault is indicated if the switch is able to bring up the
load within the 20ms blanking period.
Autoreset Mode
If an output fault is detected for more than the 20ms
blanking time, the output latches off and the FLT_ output goes low. The MAX1558/MAX1558H then source
30mA to the faulted output and monitor the output voltage to determine when the overload is removed. If the
voltage on the output rises above 0.5V for more than
20ms, the fault resets and the output turns on. The
MAX1558 can also be reset from fault manually by toggling ON_ (ON_ for the MAX1558H) for that channel.
Reverse Current Blocking
The USB specification does not allow an output device
to source current back into the USB port. However, the
MAX1558/MAX1558H are designed to safely power
noncompliant devices. When disabled, each output is
switched to a high-impedance state, blocking reversecurrent flow from the output back to the input. However,
during normal operation with the device enabled, the
MAX1558/MAX1558H are bidirectional switches.
Thermal Shutdown
The MAX1558/MAX1558H feature independent thermal
shutdown for each switch channel, allowing one switch
to deliver power even if the other switch has a fault condition. When the junction temperature exceeds +160°C,
the switch turns off and the FLT_ output goes low immediately; fault blanking does not occur during thermal
limit. When the junction cools by 10°C, the switch turns
on again. If the fault-overload condition continues, the
switch cycles on and off, resulting in a pulsed output,
saving battery power.
Fault Indicators
The MAX1558/MAX1558H provide an open-drain fault
output (FLT_) for each switch. For most applications, connect FLT_ to IN_ through a 100kΩ pullup resistor. FLT_
goes low when any of the following conditions occur:
• The input voltage is below the UVLO threshold.
• The switch junction temperature exceeds the +160°C
thermal-shutdown temperature limit.
• The switch is in current-limit or short-circuit limit mode
after the 20ms fault-blanking period is exceeded.
• The switch is in autoreset mode.
After the fault condition is removed, the FLT_ output
deasserts after a 20ms delay. Ensure that the
MAX1558/MAX1558H have adequate input bypass
capacitance to prevent glitches from triggering FLT_ outputs. Glitches that cause the input supply to drop below
2.5V may cause the undervoltage lockout to trigger, turning the outputs off and asserting the FLT signals.
_______________________________________________________________________________________
9
MAX1558/MAX1558H
Undervoltage Lockout and
Input Voltage Requirements
MAX1558/MAX1558H
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
Applications Information
Setting the Current Limit
A resistor from ISET to ground programs the currentlimit value for both outputs. Use a resistor between
26kΩ and 86kΩ to set the current limit according to
the formula:
ILIM(TYPICAL) = 36400 / RISET (Amps)
Do not use RISET values below 26kΩ because the maximum current rating of the device may be exceeded.
RISET values larger than 60kΩ are not recommended
and do not provide a lower limit current than 500mA.
If the output drops below 1V (typ), the MAX1558 shifts
to a short-circuit current-limit threshold that is 30%
above the programmed level given by the ILIM(TYPICAL)
formula. If the short-circuit threshold is exceeded, the
switch shuts off immediately (no 20ms delay) and
ramps the current back up in approximately 3ms. If the
short persists and the current ramps all the way up to
the short-circuit limit again, the switch again turns off. If
the short still persists, the output pulses this way for
20ms, at which time the switch turns off and autoreset
mode begins.
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 inductance causes the output voltage at the USB port to ring during a
load step. The MAX1558/MAX1558H are capable of driving inductive loads, but avoid exceeding the devices’
absolute maximum ratings. Usually the load inductance
is relatively small, and the MAX1558/MAX1558Hs’
input includes a substantial bulk capacitance from an
upstream regulator as well as local bypass capacitors,
limiting overshoot. If severe ringing occurs due to large
load inductance, clamp the MAX1558/MAX1558Hs’ output below +6V and above -0.3V.
Turn-On and Turn-Off Behavior
In the absence of faults, the MAX1558/MAX1558Hs’
internal switches turn on and off slowly under the control
of the ON_ inputs. Transition times for both edges are
approximately 4ms. The slow charge-pump switch drive
minimizes load transients on the upstream power source.
Under thermal fault and UVLO, the power device turns
off rapidly (100ns) to protect the power device.
Input Capacitor
Layout and Thermal Dissipation
INA and INB provide the power for all control and
charge-pump circuitry and must be connected together
externally. Connect a capacitor from IN_ to ground to
limit the input-voltage drop during momentary output
short-circuit conditions. A 0.1µF ceramic capacitor is
required for local decoupling; higher capacitor values
further reduce the voltage drop at the input. When driving inductive loads, a larger capacitance prevents
voltage spikes from exceeding the MAX1558/
MAX1558Hs’ absolute maximum ratings.
To optimize the switch response time to output shortcircuit conditions, keep all traces as short as possible
to reduce the effect of undesirable parasitic inductance. Place input and output capacitors no more than
5mm from device leads. 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 switch IN_ and OUT_ pins. While the
switches are on, power dissipation is small and the
package temperature change is minimal. Calculate the
power dissipation for this condition as follows:
Output Capacitor
Place a 1µF or greater capacitor at each output for
noise immunity. When starting up into very large capacitive loads, the switch may pulse the output current at
the short-circuit current-limit program level until the output voltage rises above 1V. Then, the capacitor continues to charge at the full, continuous current-limit
program level. There is no limit to the output capacitor
size, but to prevent a startup fault assertion, the capacitor must charge up within the fault-blanking delay period. Typically, starting up into a 500µF or smaller
capacitor does not trigger a fault output. In addition to
bulk capacitance, small-value (0.1µF or greater) ceramic capacitors improve the output’s resilience to electrostatic discharge (ESD).
10
P = (IOUT_)2 RON
For the maximum operating current (IOUT_ = 1.2A) and
the maximum on-resistance of the switch (125mΩ), the
power dissipation is:
P = (1.2A)2 x 0.125Ω = 180mW per switch
The worst-case power dissipation occurs when the
switch is in current limit and the output is greater than
1V. The instantaneous power dissipated in each switch
is the voltage drop across the switch multiplied by the
current limit. The fault-blanking circuit turns the output
off if the fault persists for 20ms, while the autoreset circuit can turn it back on after 20ms in the off state. Thus,
the average worst-case power is approximately 50% of
the instantaneous value.
P = 0.5 x (ILIM) x (VIN_ - VOUT_)
______________________________________________________________________________________
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
P = 0.5 x (1.5A) x (5V - 1V) = 3W
Since the package power dissipation is limited to
1952mW, the MAX1558/MAX1558H die temperature
exceeds the thermal-shutdown threshold and the
switch turns off. After the die temperature cools by
10°C, the switch turns on again. If the fault-overload
condition continues, the switch cycles on and off with a
duty cycle and period that is a function of the ambient
temperature and PC board layout.
A short across the output for more than 20ms places
the part in autoreset mode. With V IN_ = 5V and an
autoreset test current of 30mA, the power dissipation
for a short-circuited output is given by:
P = (30mA) x 5V = 0.15W
Chip Information
TRANSISTOR COUNT: 2932
PROCESS: BiCMOS
______________________________________________________________________________________
11
MAX1558/MAX1558H
For a 5V input and 1V output, the maximum possible
power dissipation per switch is:
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
6, 8, &10L, DFN THIN.EPS
MAX1558/MAX1558H
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
12
______________________________________________________________________________________
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
COMMON DIMENSIONS
PACKAGE VARIATIONS
SYMBOL
MIN.
MAX.
PKG. CODE
N
D2
E2
e
JEDEC SPEC
b
[(N/2)-1] x e
A
0.70
0.80
T633-2
6
1.50±0.10
2.30±0.10
0.95 BSC
MO229 / WEEA
0.40±0.05
1.90 REF
D
2.90
3.10
T833-2
8
1.50±0.10
2.30±0.10
0.65 BSC
MO229 / WEEC
0.30±0.05
1.95 REF
E
2.90
3.10
T833-3
8
1.50±0.10
2.30±0.10
0.65 BSC
MO229 / WEEC
0.30±0.05
1.95 REF
A1
0.00
0.05
T1033-1
10
1.50±0.10
2.30±0.10
0.50 BSC
MO229 / WEED-3
0.25±0.05
2.00 REF
L
0.20
0.40
T1033-2
10
1.50±0.10
2.30±0.10
0.50 BSC
MO229 / WEED-3
0.25±0.05
2.00 REF
k
0.25 MIN.
T1433-1
14
1.70±0.10
2.30±0.10
0.40 BSC
----
0.20±0.05
2.40 REF
A2
0.20 REF.
T1433-2
14
1.70±0.10
2.30±0.10
0.40 BSC
----
0.20±0.05
2.40 REF
______________________________________________________________________________________
13
MAX1558/MAX1558H
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX1558/MAX1558H
Dual, 3mm x 3mm, 1.2A/Programmable-Current
USB Switches with Autoreset
Revision History
REVISION
NUMBER
REVISION
DATE
2
3/08
DESCRIPTION
Changed “UL Listing Pending” to “UL Recognized: UL # E211395”
PAGES
CHANGED
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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