General Description
The MAX1562/MAX1562H/MAX1563 single currentlimited switches provide up to 4A to power up to eight
USB ports. They operate from a 4V to 5.5V input
supply and consume only 40µA of quiescent current
when operating and only 3µA in shutdown.
The MAX1562/MAX1562H/MAX1563s’ autoreset feature
latches the switch off if the output is shorted, thereby
saving system power. When the short is removed, the
switch is reactivated. A fault-blanking feature enables the
circuit to ignore momentary faults, such as those caused
when hot swapping a capacitive load, preventing false
alarms to the host system. Fault blanking also prevents
fault signals from being issued when the device powers
up the load.
The MAX1562/MAX1562H/MAX1563 provide several
safety features to protect the USB port. Built-in thermaloverload protection turns off the switch when the die
temperature exceeds +160°C. Accurate internal current-limiting circuitry protects the input supply against
both overload and short-circuit conditions. An opendrain fault signal (FAULT) notifies the microprocessor
when a thermal-overload, current-limit, undervoltage
lockout (UVLO), or short-circuit fault occurs.
The MAX1562 has an active-low ON, and the
MAX1562H has an active-high ON enable input. The
MAX1563 has a selectable active-high or active-low
logic-controlled enable. The current limit is programmed from 1A to 4A using a resistor.
The MAX1562/MAX1562H are available in 8-pin SO
packages and are pin-compatible upgrades to the
MIC2545A/MIC2549A. The MAX1563 provides the
same features and higher current performance in a
smaller 12-pin (4mm x 4mm) Thin QFN package. These
devices operate over an extended temperature range
(-40°C to +85°C). An evaluation kit is available to speed
designs.
Applications
Notebook Computers
Desktop Computers
USB Ports and Hubs
PDAs and Palmtop Computers
Docking Stations
Features
o Programmable Current Limit (1A to 4A) with
Resistor
o Autoreset Feature Saves System Power
o 20ms Fault-Blanking Circuitry
o Active-High/Low Control Logic
o Fault-Indicator Output
o Thermal-Overload Protection
o Smaller 4mm x 4mm Thin QFN Package (MAX1563)
o 3µA Shutdown Current
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
________________________________________________________________
Maxim Integrated Products
1
Ordering Information
19-2631; Rev 2; 2/10
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.
EVALUATION KIT
AVAILABLE
Pin Configurations appear at end of data sheet.
Typical Operating Circuit
+
Denotes a lead(Pb)-free/RoHS-compliant package.
*
EP = Exposed pad.
PART TEMP RANGE PIN-PACKAGE
MAX1562ESA+ -40°C to +85°C 8 SO
MAX1562HESA+ -40°C to +85°C 8 SO
MAX1563ETC+ -40°C to +85°C 12 TQFN-EP*
IN
GND
FAULT
OUT
OUT
USB
PORT
INPUT
4V TO 5.5V
ACTIVE-HIGH/ACTIVE-LOW
SELECTABLE
IN
ON
SEL
ISET
MAX1562
MAX1562H
MAX1563
MAX1563
ONLY
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN= +5V, CIN= 1µF, C
OUT
= 4.7µF, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +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, ON, ISET, SEL, OUT to GND .......................-0.3V to +6V
FAULT to GND.............................................-0.3V to (V
IN
+ 0.3V)
IN to OUT..................................................................-0.3V to +6V
OUT Maximum Continuous Switch Current ............................5A
FAULT DC Current ..............................................................10mA
Continuous Power Dissipation
8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW
12-Pin Thin QFN (4mm x 4mm)
(derate 16.9mW/°C above +70°C).............................1350mW
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
PARAMETER SYM B O L CONDITIONS MIN TYP MAX UNITS
Supply Voltage Range V
Switch On-Resistance R
Standby Supply Current Switch disabled 3 10 µA
Quiescent Supply Current I
OUT Off-Leakage Current I
Undervoltage-Lockout Threshold V
Continuous Current-Limit Adjust
Range
Continuous Current Limit I
Short-Circuit Current Limit I
Short-Circuit Detect Threshold (Note 1) 1 V
Continuous Current-Limit
Blanking Timeout Period
Short-Circuit Blanking Timeout
Period
Turn-On Delay t
Output Rise Time t
Turn-Off Delay t
IN
ON
Switch enabled, I
IN
LKG
UVLO
RISE
OFF
Switch disabled, V
Rising edge, 3% hysteresis 2.9 3.4 3.8 V
MAX1563 1 4
MAX1562/MAX1562H 1 3
R
OUT
R
R
R
R
R
R
OUT
OUT
OUT
VIN - V
LIM
= 0.5V
V
= 0V,
LIM
ON
OUT
pulsing
I
OUT
From continuous current-limit condition to
FAULT asserted
From short-circuit current-limit condition to
FAULT asserted
R
= 2Ω, C
OUT
(from ON to 10% of V
R
= 2Ω, C
OUT
(from 10% to 90% of V
R
= 2Ω, C
OUT
(from ON to 90% of V
4.0 5.5 V
26 50 mΩ
= 0A 40 80 µA
OUT
= 0V 0.02 10 µA
OUT
= 4.22kΩ (MAX1563 only) 3.2 4 4.8
ISET
= 5.76kΩ 2.4 3 3.6
ISET
= 8kΩ 1.7 2.1 2.6
ISET
= 12kΩ 1.1 1.4 1.7
ISET
= 4.22kΩ (MAX1563 only)
ISET
= 5.76kΩ
ISET
= 12kΩ
ISET
= 4.7µF
)
OUT
= 4.7µF
)
OUT
= 4.7µF
)
OUT
2.5 3.6 4.7 A(peak)
1.2 1.7 2.3 A(peak)
10 20 35 ms
7.5 18 35 ms
0.5 1.2 4.0 ms
4.9 A(peak)
1.6 A(RMS)
1.4 A(RMS)
0.4 A(RMS)
2.5 ms
0.1 3 ms
A
A
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VIN= +5V, CIN= 1µF, C
OUT
= 4.7µF, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
ELECTRICAL CHARACTERISTICS
(VIN= +5V, CIN= 1µF, C
OUT
= 4.7µF, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER SYM B O L CONDITIONS MIN TYP MAX UNITS
Output Fall Time t
Thermal-Shutdown Threshold 15°C hysteresis +160 °C
ON, ON, SEL Input High Level V
ON, ON, SEL Input Low Level V
ON, ON, SEL Input
Leakage Current
FAULT Output Low Voltage V
FAULT Output
High Leakage Current
OUT Autoreset Current In latched-off state, V
OUT Autoreset Threshold In latched-off state, OUT rising 0.35 0.5 0.65 V
OUT Autoreset Blanking Time In latched-off state, V
R
FALL
IH
IL
OL
= 2Ω, C
OUT
(from 90% to10% of V
VIN = +4V to +5.5V 2 V
VIN = +4V to +5.5V 0.8 V
I
= 1mA, VIN = +4V 0.4 V
SINK
V
= V
FAULT
IN
= 4.7µF
OUT
= +5.5V 1 µA
)
OUT
-1 +1 µA
= 0V 10 25 45 mA
OUT
> 0.5V 10 20 35 ms
OUT
0.8 ms
PARAMETER SYM B O L CONDITIONS MIN TYP MAX UNITS
Supply Voltage Range V
Switch On-Resistance R
Standby Supply Current Switch disabled 10 µA
Quiescent Supply Current I
OUT Off-Leakage Current I
UVLO Threshold V
Continuous Current-Limit Adjust
Range
Continuous Current Limit I
Short-Circuit Current Limit I
Continuous Current-Limit
Blanking Timeout Period
Short-Circuit Blanking Timeout
Period
IN
ON
IN
LKG
UVLO
LIM
LIM
Switch enabled, I
Switch disabled, V
Rising edge, 3% hysteresis 2.9 3.8 V
MAX1563 1 4
MAX1562/MAX1562H 1 3
VIN - V
OUT
= 0.5V
V
= 0V,
OUT
pulsing
I
OUT
From continuous current-limit condition to
FAULT asserted
From short-circuit current-limit condition to
FAULT asserted
= 0A 80 µA
OUT
= 0V 10 µA
OUT
R
= 4.22kΩ (MAX1563 only) 3.1 4.9
ISET
R
= 5.76kΩ 2.3 3.7
ISET
R
= 8kΩ 1.6 2.7
ISET
R
= 12kΩ 1.0 1.8
ISET
R
= 5.76kΩ 2.4 4.8
ISET
= 12kΩ 1.1 2.4
R
ISET
4.0 5.5 V
50 mΩ
10 35 ms
7.5 35 ms
A
A
A(peak)
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VIN= +5V, CIN= 1µF, C
OUT
= 4.7µF, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)
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.
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX1562 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
5.04.54.03.5
5
10
15
20
25
30
35
40
45
50
0
3.0 5.5
TEMP = +25°C
TEMP = -40°C
TEMP = +85°C
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
MAX1562 toc02
SUPPLY VOLTAGE (V)
SHUTDOWN CURRENT (µA)
5.04.54.03.5
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
3.0 5.5
TEMP = +25°C
TEMP = -40°C
TEMP = +85°C
VON = 5V
SWITCH-OFF LEAKAGE CURRENT
vs. TEMPERATURE
MAX1562 toc03
TEMPERATURE (°C)
SWITCH-OFF LEAKAGE CURRENT (nA)
603510-15
0.01
0.1
1
10
100
1000
0.001
-40 85
Typical Operating Characteristics
(VIN= +5V, CIN= 1µF, C
OUT
= 4.7µF, TA= +25°C, unless otherwise noted.)
PARAMETER SYM B O L CONDITIONS MIN TYP MAX UNITS
Turn-On Delay t
Turn-Off Delay t
ON, ON, SEL Input High Level V
ON, ON, SEL Input Low Level V
ON, ON, SEL Input
Leakage Current
FAULT Output Low Voltage V
FAULT Output
High Leakage Current
OUT Autoreset Current In latched-off state, V
OUT Autoreset Threshold In latched-off state, OUT rising 0.35 0.65 V
OUT Autoreset Blanking Time In latched-off state, V
R
= 2Ω, C
ON
OFF
IH
IL
OLISINK
OUT
(from ON to 10% of V
R
= 2Ω, C
OUT
(from ON to 90% of V
VIN = +4V to +5.5V 2 V
VIN = +4V to +5.5V 0.8 V
= 1mA, VIN = +4V 0.4 V
= V
V
IN
FAULT
= 4.7µF
OUT
OUT
OUT
= 4.7µF
OUT
)
)
= +5.5V 1 µA
= 0V 10 45 mA
OUT
> 0.5V 10 35 ms
OUT
0.5 4.0 ms
3ms
-1 +1 µA
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
_______________________________________________________________________________________
5
Typical Operating Characteristics (continued)
(VIN= +5V, CIN= 1µF, C
OUT
= 4.7µF, TA= +25°C, unless otherwise noted.)
NORMALIZED RON vs. TEMPERATURE
1.3
1.2
ON
1.1
1.0
NORMALIZED R
0.9
0.8
0.7
-40 85
TEMPERATURE (°C)
TURN-OFF TIME vs. TEMPERATURE
(t
+ t
3.0
R
LOAD
2.5
2.0
1.5
1.0
TURN-OFF TIME (ms)
0.5
0
-40 85
OFF
= 2Ω
TEMPERATURE (°C)
NORMALIZED CONTINUOUS
CURRENT LIMIT vs. TEMPERATURE
1.03
1.02
MAX1562 toc04
1.01
1.00
0.99
0.98
0.97
NORMALIZED CONTINUOUS CURRENT LIMIT
0.96
-40 85
22.0
21.8
MAX1562 toc07
21.6
21.4
21.2
21.0
20.8
20.6
FAULT-BLANKING TIME (ms)
20.4
20.2
20.0
-40 85
TEMPERATURE (°C)
FAULT-BLANKING TIME
vs. TEMPERATURE
TEMPERATURE (°C)
FALL
603510-15
)
6035-15 10
TURN-ON TIME vs. TEMPERATURE
3.0
R
= 2Ω
LOAD
2.5
MAX1562 toc05
2.0
1.5
1.0
TURN-ON TIME (ms)
0.5
603510-15
0
-40 85
TEMPERATURE (°C)
603510-15
AUTORESET CURRENT
vs. TEMPERATURE
40
MAX1562 toc08
30
20
AUTORESET CURRENT (mA)
10
603510-15
0
-40 85
TEMPERATURE (°C)
603510-15
MAX1562 toc06
MAX1562 toc09
AUTORESET CURRENT vs. V
40
35
30
25
20
15
AUTORESET CURRENT (mA)
10
5
0
4.0 5.5
VCC (V)
CC
MAX1562 toc10
5.24.94.3 4.6
OVERLOAD RESPONSE INTO 1.4Ω
V
IN
V
OUT
FAULT
I
OUT
20ms/div
MAX1562 toc11
5V/div
5V/div
5V/div
2A/div
SHORT-CIRCUIT RESPONSE INTO 0
V
IN
V
OUT
V
FAULT
I
OUT
TIME (10ms/div)
MAX1562 toc12
Ω
5V/div
5V/div
5V/div
10A/div
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VIN= +5V, CIN= 1µF, C
OUT
= 4.7µF, TA= +25°C, unless otherwise noted.)
SWITCH TURN-ON TIME
MAX1562 toc13
1ms/div
V
ON
(MAX1562H)
V
ON
(MAX1562)
2V/div
2V/div
V
OUT
2V/div
R
OUT
= 2Ω
SWITCH TURN-OFF TIME
MAX1562 toc14
400µs/div
2V/div
2V/div
R
OUT
= 2Ω
2V/div
V
ON
(MAX1562H)
V
OUT
V
ON
(MAX1562)
STARTUP TIME
(R
OUT
= 2Ω, C
OUT
= 4.7µF)
MAX1562 toc15
FAULT
V
ON
2V/div
5V/div
V
OUT
1A/div
I
OUT
5V
0V
1ms/div
STARTUP TIME
(R
OUT
= 2Ω, C
OUT
= 100µF)
MAX1562 toc16
FAULT
V
ON
2V/div
5V/div
V
OUT
1A/div
I
OUT
5V
0V
1ms/div
STARTUP TIME
(R
OUT
= 2Ω, C
OUT
= 330µF)
MAX1562 toc17
FAULT
V
ON
2V/div
5V/div
V
OUT
1A/div
I
OUT
5V
0V
1ms/div
ULVO RESPONSE
MAX1562 toc18
10ms/div
V
FAULT
V
IN
V
OUT
2V/div
2V/div
2V/div
R
OUT
= 1kΩ
0V
Detailed Description
The MAX1562/MAX1562H/MAX1563 family comprises a
programmable current-limited switch designed for USB
and hot-swap applications. The MAX1563 can be programmed for loads up to 4A, and the MAX1562/
MAX1562H can be programmed for loads up to 3A. The
current limit is programmed using a single resistor. A fault
output notifies the host when the current-limit, short-circuit, UVLO, or thermal-shutdown threshold is exceeded.
A built-in current limit protects the load and the source
in the event of an overload condition. In addition, a
built-in short-circuit detection circuit pulses the output if
the output is less than 1V (typ), resulting in a lower RMS
output current and reduced power dissipation in the
device. Thermal shutdown protects the device in the
event of a prolonged overload or short-circuit condition.
An internal micropower charge pump generates the
high-side supply needed for driving the gate of the
internal low-RONNMOS switch.
Fault blanking allows the MAX1562/MAX1562H/
MAX1563 family to handle USB loads that may not be
fully compliant with USB specifications. USB loads with
additional bypass capacitance or large startup currents
can be successfully powered while protecting the
upstream power source. If the switch brings up the
load within the blanking period (20ms typ), FAULT is
not asserted. In the event of a current-limit event, current through the switch is regulated at the current-limit
target. Below approximately 1V, the short-circuit current
limit is 30% higher than the programmed current limit.
Current-Limit Programming
The MAX1562/MAX1562H/MAX1563 continuous current
limit is set by selecting the value of R
ISET
based on the
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
_______________________________________________________________________________________ 7
Pin Description
PIN
MAX1562
MAX1562H
SO
1 4 ON (ON)
25FAULT
3 6 GND Ground
4 7 ISET
5, 7 9, 12 IN
6, 8 1, 10 OUT
— 2, 8, 11 N.C.
— 3 SEL
MAX1563
(TQFN-EP)
NAME FUNCTION
Switch On/Off Control Input. The active polarity of ON is low for the MAX1562 and high
for the MAX1562H. For the MAX1563, the active polarity of ON is set by SEL.
Fault Indicator Output. FAULT is an open-drain output that asserts low when the switch
enters a sustained (>20ms) current limit. FAULT goes low immediately during thermal
shutdown or an undervoltage input. Note that during severe short conditions, FAULT
goes low immediately since there is typically also a brief undervoltage transient.
Current-Limit Input. Connect an external resistor from ISET to GND to set current limit,
where I
Power Input for Switch. Connect both IN inputs together and bypass with a 1µF
ceramic capacitor to GND. Load conditions might require additional bulk capacitance
to prevent fluctuation on the input source.
Power Output for Switch. Bypass OUT to GND with a 4.7µF ceramic capacitor. Load
conditions might require additional bulk capacitance. When disabled, OUT goes into
a high-impedance state.
No Connection. Internally unconnected. Leave unconnected or use with other traces
to simplify PC board layout.
Polarity Control Input for ON. Drive SEL high for active-high enable. Drive SEL low for
active-low enable.
= 17120 / R
LIM
ISET
.
Exposed Pad. Internally connected to GND. Connect to a large ground plane with
——EP
multiple vias to manage thermal performance. Not intended as an electrical
connection point.
MAX1562/MAX1562H/MAX1563
following equation:
I
LIM
= 17120 / R
ISET
Choose R
ISET
with resistor values between 4.22kΩ to
16kΩ. Resistor values greater than 16kΩ significantly
degrade current-limit accuracy. For the MAX1562/
MAX1562H, the minimum R
ISET
value is 5.76kΩ. This
corresponds to a 3A current limit, which is limited by
the 8-pin SO’s maximum power dissipation. For the
MAX1563, the minimum R
ISET
value is 4.22kΩ, corresponding to a 4A current limit. Set the continuous current-limit value 20% to 30% higher than the expected
load current to ensure that normal conditions do not
trigger nuisance fault outputs. The short-circuit current
limit is internally set to 1.3 times the continuous currentlimit setting.
On/Off Control and UVLO
The MAX1562 has an active-low ON polarity and the
MAX1562H has an active-high ON polarity. SEL sets the
active polarity of the MAX1563. Connect ON to the same
voltage as SEL to enable OUT. Connect ON to the
opposite voltage as SEL to disable OUT (see Table 1).
The MAX1562/MAX1562H/MAX1563 include a UVLO
circuit to prevent erroneous switch operation when the
input voltage goes low during startup and brownout
conditions. Input voltages of less than +3.4V inhibit
operation of the device. FAULT asserts low during a
UVLO condition.
Output Fault Protection and Autoreset
The MAX1562/MAX1562H/MAX1563 sense the switch
output voltage and select continuous current limiting for
V
OUT
greater than 1V or short-circuit current limiting for
V
OUT
less than 1V. When V
OUT
is greater than 1V, the
device operates in a continuous current-limit mode that
limits output current to the programmed current limit
(1A to 4A). When V
OUT
is less than 1V, the device operates in short-circuit current-limit mode, sourcing a
pulsed current to the load. The pulse current depends
on the programmed current-limit value, typically 30%
higher than the programmed current limit.
When either fault condition persists for 20ms, the output
turns off and the fault flag asserts. The output automatically restarts when the short or overload is removed. Note
that during severe short conditions, FAULT does not wait
20ms but goes low immediately since there is typically
also an undervoltage transient during a severe short.
The MAX1562/MAX1562H/MAX1563 detect short-circuit
removal by sourcing 25mA from the output and monitoring the output voltage. When the voltage at the output
exceeds +0.5V for 20ms, the fault flag resets, the output
turns back on, and the 25mA current source turns off.
Thermal Shutdown
When the MAX1562/MAX1562H/MAX1563 die temperature exceeds +160°C, the switch turns off and FAULT
goes low. Thermal shutdown does not utilize the 20ms
fault-blanking timeout period. When the junction temperature cools by 15°C, the switch turns on again and
FAULT returns high. The switch cycles on and off if an
overload condition persists, resulting in a pulsed output
that reduces the average system load.
Fault Indicators
The MAX1562/MAX1562H/MAX1563 provide an opendrain fault output, FAULT. Connect FAULT to IN through
a 100kΩ pullup resistor for most applications. FAULT
asserts 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 currentlimit mode for more than 20ms.
The FAULT output deasserts after a 20ms delay once the
fault condition is removed. Ensure that the MAX1562/
MAX1562H/MAX1563 input bypass capacitance is sufficiently large to prevent load glitches from triggering the
FAULT output. Limit the input-voltage slew rate to
0.2V/µs to prevent erroneous FAULT indications.
To differentiate large capacitive loads from short circuits
or sustained overloads, the switches have a fault-blanking circuit. When a load transient causes the device to
enter current limit, an internal counter monitors the duration of the fault. For load faults exceeding the 20ms
fault-blanking time, the switch turns off, FAULT asserts
low, and the device enters autoreset mode (see the
Output Fault Protection and Autoreset
section). Only
current-limit and short-circuit faults are blanked. If thermal-overload faults or the input voltage drops below the
UVLO threshold, the switch turns off and asserts FAULT
low immediately. Note that during severe short conditions, FAULT goes low immediately since there is typically also a brief undervoltage transient.
Fault blanking allows the MAX1562/MAX1562H/
MAX1563 to handle USB loads that might not be fully
compliant with the USB specifications. These switches
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
8 _______________________________________________________________________________________
Table 1. On/Off Control
SEL ON OUT BEHAVIOR
GND
V
IN
GND ON
V
IN
GND OFF
V
IN
OFF
ON
successfully power USB loads with additional bypass
capacitance and/or large startup currents while protecting the upstream power source. No fault is reported
if the switch brings up the load within the 20ms blanking period. See Table 2 for a summary of current-limit
and fault behavior.
Applications Information
Input Power Supply and Capacitance
Connect both IN inputs together externally. IN powers
the internal control circuitry and charge pump for the
switch, allowing a decreased RON. Bypass IN to GND
with a 1µF ceramic capacitor. When driving inductive
loads or operating from inductive sources, which may
occur when the device is powered by long leads or PC
traces, larger input bypass capacitance is required to
prevent voltage spikes from exceeding the absolute
maximum ratings during short-circuit events.
Output Capacitor
Bypass OUT to GND with a 4.7µF ceramic capacitor for
local decoupling. Additional bulk capacitance (up to
470µF) reduces output-voltage transients under dynamic load conditions. Using output capacitors greater than
470µF might assert FAULT if the current limit cannot
charge the output capacitor within the 20ms faultblanking period. In addition to bulk capacitance, smallvalue (0.1µF or greater) ceramic capacitors improve the
output’s resilience to electrostatic discharge (ESD).
Driving Inductive Loads
A wide variety of devices (mice, keyboards, cameras,
and printers) typically connect to the USB port with
cables, which might add an inductive component to the
load. This inductance causes the output voltage at the
USB port to oscillate during a load step. The
MAX1562/MAX1562H/MAX1563 drive inductive loads,
but avoid exceeding the device’s absolute maximum
ratings. The load inductance is usually relatively small,
and the MAX1562/MAX1562H/MAX1563s’ input
includes a substantial bulk capacitance from an
upstream regulator, as well as local bypass capacitors,
limiting overshoot. If severe ringing occurs because of
large-load inductance, clamp the MAX1562/MAX1562H/
MAX1563 outputs below +6V and above -0.3V.
Turn-On and Turn-Off Behavior
When turned on, the MAX1562/MAX1562H/MAX1563 output ramps up over 2.5ms to eliminate load transients on
the upstream power source. When turned off, the output
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
_______________________________________________________________________________________ 9
Table 2. Current Limiting and Fault Behavior
CONDITION MAX1562/MAX1562H/MAX1563 BEHAVIOR
• If a short is detected at the output, the channel turns off, and the blanking timer begins. FAULT
remains high during the blanking timeout period.
• If the short persists during the fault-blanking period, the output pulses at 0.30 x I
Output Short-Circuit
< +1V)
(V
OUT
Output Overload Current
> +1V)
(V
OUT
Thermal Fault
> +160°C)
(T
J
is removed before the 20ms short-circuit blanking timeout period, the next ramped current pulse softstarts the output. FAULT remains high.
• If the short-circuit persists after the fault-blanking period. FAULT goes low, autoreset mode begins,
and the output sources 25mA.
• If the output voltage rises above 0.5V for 20ms, the channel resets, the output turns on, and FAULT
goes high.
• If an overload occurs, output current regulates at I
high during the blanking timeout period.
• Continuous current at I
fault occurs.
• If overcurrent persists after 20ms, FAULT goes low, autoreset mode is enabled, and the output
sources 25mA.
• If the output voltage rises above 0.5V for 20ms, the channel resets, the output turns on, and
FAULT goes high (see the Overload Response into 1.4Ω graph in the Typical Operating
Characteristics section).
• A junction temperature of +160
does not apply for thermal faults) and turns off the switch. When the junction cools by 15°C, the
thermal fault is cleared and FAULT goes high. Note that if other fault conditions are present when
a thermal fault clears, those fault states take effect.
persists until either the 20ms blanking period expires or a thermal
LIM
o
C immediately asserts FAULT low (the blanking timeout period
and the blanking timer turns on. FAULT remains
LIM
RMS. If the short
LIM
MAX1562/MAX1562H/MAX1563
ramps down for 800µs. Under fault conditions, the output
of the switches turns off rapidly to provide maximum safety for the upstream power source and downstream
devices. Internal blocks shut down to minimize supply
current when the switch is off.
Layout and Thermal Dissipation
Keep all traces as short as possible to reduce the effect
of undesirable parasitic inductance and optimize the
switch response time to output short-circuit conditions.
Place the input and output capacitors no more than
5mm from the device leads. Connect IN and OUT to the
power bus with short traces. Wide power bus planes at
IN and OUT provide superior heat dissipation.
Calculate the power dissipation for a normal loaded
condition as follows:
P = (I
OUT
)2x R
ON
At a 3A operating current and the maximum on-resistance of the switch (50mΩ), the power dissipation is:
P = (3A)2x 0.05Ω = 450mW
The worst-case power dissipation occurs when the output current is just below the current-limit threshold (set
to 3A in this example) with an output voltage greater
than +1V. In this case, the power dissipated in the
switch is the voltage drop across the switch multiplied
by the current limit:
P = I
LIM
x (VIN- V
OUT
)
For a +5V input and +1V output, the maximum power
dissipation is:
P = 3A x (5V - 1V) = 12W
Because the package power dissipation is 471mW for
the MAX1562/MAX1562H and 1.35W for the MAX1563,
the devices’ die temperature exceeds the +160°C thermal-shutdown threshold, and the switch output shuts
down until the junction temperature cools by 15°C. The
duty cycle and period are strong functions of the ambient temperature and the PC board layout.
If the output current exceeds the current-limit threshold,
or the output voltage is pulled below the short-circuit
detect threshold, the MAX1562/MAX1562H/MAX1563
enter a fault state for 20ms, after which autoreset mode
is enabled and 25mA is sourced by the output. For a
+5V input, OUT short-circuited to GND, and autoreset
mode active, the power dissipation is as follows:
P = 0.025A x 5V = 0.125W
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
10 ______________________________________________________________________________________
Typical Application Circuit
MAX1563 Functional Diagram
Pin Configurations
INPUT
+4V TO +5.5V
ON
IN
ON
SEL
IN
MAX1563
CHARGE
PUMP
THERMAL
SHUTDOWN
FAULT LOGIC
20ms TIMERS
ULVO
OSC
25kHz
GND
25mA
FAULT
ILIM
OUT
REFBIAS
TOP VIEW
ON (ON)
GND
() FOR MAX1562H.
100kΩ
USB
PORT
4.7µF*
1µF
OFF
IN
IN
FAULT
MAX1563
ON
SEL
ISET
*USB APPLICATIONS MAY REQUIRE
ADDITIONAL BULK CAPACITANCE.
OUT
OUT
GND
IN N.C. OUT
12 11 10
+
1
2
3
MAX1563
456
ON FAULT GND
THIN QFN
4 mm x 4 mm
1
2
3
4
+
MAX1562H
MAX1562
SO
87OUT
6
5
INFAULT
OUT
OUT
N.C.
INISET
SEL
IN
9
N.C.
8
7
ISET
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
______________________________________________________________________________________ 11
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
8 SO S8-2
21-0041
12 TQFN-EP T1244-4
21-0139
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
Chip Information
TRANSISTOR COUNT: 1833
PROCESS: BiCMOS
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
12 ______________________________________________________________________________________
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
24L QFN THIN.EPS
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
______________________________________________________________________________________ 13
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
Revision History
REVISION
NUMBER
0 7/03 Initial release —
1 7/09
2 2/10 Removed UL Certification Pending bullet from the Features section 1
REVISION
DATE
DESCRIPTION
Changed package reference, package drawing, added lead-free designation,
corrected Pin Description
PAGES
CHANGED
1, 2, 10, 11
MAX1562/MAX1562H/MAX1563
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
© 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
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