Rainbow Electronics MAX1563 User Manual

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) 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
Programmable Current Limit (1A to 4A) with
Resistor
Autoreset Feature Saves System Power
20ms Fault-Blanking Circuitry
Active-High/Low Control Logic
Fault-Indicator Output
Thermal-Overload Protection
Smaller 4mm x 4mm QFN Package (MAX1563)
3µA Shutdown Current
UL Certification Pending
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
19-2631; Rev 0; 7/03
For pricing, delivery, and ordering information, please contact Maxim/Dallas 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
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 QFN 4mm x 4mm
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 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
Switch disabled, V
Rising edge, 3% hysteresis 2.9 3.4 3.8 V
MAX1563 1 4
MAX1562/MAX1562H 1 3
R
ISET
R
LIM
LIM
VIN - V = 0.5V
V
OUT
I
OUT
OUT
= 0,
pulsing
R
R
R
R
R
ISET
ISET
ISET
ISET
ISET
ISET
From continuous current-limit condition to FAULT asserted
From short-circuit current-limit condition to FAULT asserted
R
= 2, C
ON
RISE
OFF
OUT
(from ON to 10% of V
R
OUT
(from 10% to 90% of V
R
OUT
(from ON to 90% of V
= 2, C
= 2, C
OUT
OUT
OUT
4.0 5.5 V
26 50 m
= 0 40 80 µA
OUT
= 0 0.02 10 µA
OUT
= 4.22k (MAX1563 only) 3.2 4 4.8
= 5.76k 2.4 3 3.6
= 8k 1.7 2.1 2.6
= 12k 1.1 1.4 1.7
= 4.22k (MAX1563 only)
= 5.76k
= 12k
2.5 3.6 4.7 A(peak)
1.2 1.7 2.3 A(peak)
4.9 A(peak)
1.6 A(RMS)
1.4 A(RMS)
0.4 A(RMS)
10 20 35 ms
7.5 18 35 ms
= 4.7µF
OUT
= 4.7µF
OUT
= 4.7µF
OUT
)
)
)
0.5 1.2 4.0 ms
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)
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
PARAMETER SYM B O L CONDITIONS MIN TYP MAX UNITS
R
FALL
IH
IL
OL
= 2, 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
IN
FAULT
= 4.7µF
OUT
= +5.5V 1 µA
)
OUT
-1 +1 µA
= 0 10 25 45 mA
OUT
> 0.5V 10 20 35 ms
OUT
0.8 ms
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
PARAMETER SYM B O L CONDITIONS MIN TYP MAX UNITS
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
= 0,
OUT
pulsing
I
OUT
From continuous current-limit condition to FAULT asserted
From short-circuit current-limit condition to FAULT asserted
= 0 80 µA
OUT
= 0 10 µA
OUT
R
= 4.22k (MAX1563 only) 3.1 4.9
ISET
R
= 5.76k 2.3 3.7
ISET
R
= 8k 1.6 2.7
ISET
R
= 12k 1.0 1.8
ISET
R
= 5.76k 2.4 4.8
ISET
R
= 12k 1.1 2.4
ISET
4.0 5.5 V
50 m
A(peak)
10 35 ms
7.5 35 ms
A
A
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
= 2, C
ON
OFF
IH
IL
OLISINK
OUT
(from ON to 10% of V
R
= 2, 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
= 0 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
OFF
3.0 R
= 2
LOAD
2.5
2.0
1.5
1.0
TURN-OFF TIME (ms)
0.5
0
-40 85
FALL
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
603510-15
)
6035-15 10
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)
TURN-ON TIME vs. TEMPERATURE
3.0
R
= 2
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 1.4
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
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
= 2
SWITCH TURN-OFF TIME
MAX1562 toc14
400µs/div
2V/div
2V/div
R
OUT
= 2
2V/div
V
ON
(MAX1562H)
V
OUT
V
ON
(MAX1562)
STARTUP TIME
(R
OUT
= 2, 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
= 2, 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
= 2, 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
= 1k
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
following equation:
I
LIM
= 17120 / R
ISET
Choose R
ISET
with resistor values between 4.22kΩ to 16k. Resistor values greater than 16ksignificantly degrade current-limit accuracy. For the MAX1562/ MAX1562H, the minimum R
ISET
value is 5.76k. This corresponds to a 3A current limit, which is limited by the 8-pin SOs maximum power dissipation.
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
_______________________________________________________________________________________ 7
Pin Description
PIN
MAX1562
MAX1562H
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
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
.
MAX1562/MAX1562H/MAX1563
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 100kpullup 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 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.
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
GND OFF
V
IN
IN
OFF
ON
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 outputs 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 devices 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 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.
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 1.4 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
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 (50m), the power dissipation is:
P = (3A)2x 0.05= 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
Chip Information
TRANSISTOR COUNT: 1833
PROCESS: BiCMOS
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
SEL
IN
MAX1563
CHARGE
PUMP
THERMAL
SHUTDOWN
FAULT LOGIC
20ms TIMERS
ULVO
OSC
25kHz
GND
25mA
REFBIAS
IN
FAULT
ILIM
OUT
TOP VIEW
ON (ON)
GND
() FOR MAX1562H.
IN
IN
1µF
FAULT
MAX1563
OFF
ON
ON
SEL
ISET
*USB APPLICATIONS MAY REQUIRE ADDITIONAL BULK CAPACITANCE.
OUT
OUT
GND
100k
USB PORT
4.7µF*
N.C.10OUT
1
2
3
4
MAX1562
MAX1562H
SO
87OUT
INFAULT
OUT
6
INISET
5
12IN11
1OUT
MAX1563
2N.C.
3SEL
4ON5
FAULT6GND
QFN
9 IN
8 N.C.
7 ISET
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited
Switches with Autoreset and Fault Blanking
______________________________________________________________________________________ 11
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
.)
12,16,20, 24L QFN.EPS
PACKAGE OUTLINE 12,16,20,24L QFN, 4x4x0.90 MM
21-0106
1
E
2
PACKAGE OUTLINE 12,16,20,24L QFN, 4x4x0.90 MM
21-0106
2
E
2
MAX1562/MAX1562H/MAX1563
Programmable 4A USB Current-Limited Switches with Autoreset and 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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
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
.)
N
HE
1
TOP VIEW
D
C
0-8
L
SIDE VIEW
e
FRONT VIEW
A
B
A1
INCHES
DIM
MIN
0.053A
0.004
A1
0.014
B
0.007
C e 0.050 BSC 1.27 BSC
0.150
E H 0.2440.228 5.80 6.20
0.016L
VARIATIONS:
INCHES
MINDIM
D
0.189 0.197 AA5.004.80 8
0.337 0.344 AB8.758.55 14
D
PROPRIETARY INFORMATION
TITLE:
MAX
0.069
0.010
0.019
0.010
0.157
0.050
MAX
0.3940.386D
MILLIMETERS
MIN
1.35
1.75
0.10
0.25
0.35
0.49
0.19
0.25
3.80 4.00
0.40 1.27
MILLIMETERS
MAX
MIN
9.80 10.00
PACKAGE OUTLINE, .150" SOIC
21-0041
MAX
N MS012
16
AC
REV.DOCUMENT CONTROL NO.APPROVAL
B
1
SOICN .EPS
1
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