19-2631; Rev 0; 7/03 KIT ATION EVALU E L B A AVAIL Programmable 4A USB Current-Limited Switches with Autoreset and Fault Blanking 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 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 Ordering Information PART TEMP RANGE 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 Typical Operating Circuit IN INPUT 4V TO 5.5V FAULT IN Desktop Computers USB Ports and Hubs PDAs and Palmtop Computers Docking Stations PIN-PACKAGE ON ACTIVE-HIGH/ACTIVE-LOW SELECTABLE SEL MAX1562 MAX1562H MAX1563 MAX1563 ONLY ISET OUT USB PORT OUT GND Pin Configurations appear at end of data sheet. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX1562/MAX1562H/MAX1563 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. MAX1562/MAX1562H/MAX1563 Programmable 4A USB Current-Limited Switches with Autoreset and Fault Blanking ABSOLUTE MAXIMUM RATINGS IN, ON, ON, ISET, SEL, OUT to GND .......................-0.3V to +6V FAULT to GND .............................................-0.3V to (VIN + 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 Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = +5V, CIN = 1µF, COUT = 4.7µF, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL Supply Voltage Range VIN Switch On-Resistance RON Standby Supply Current CONDITIONS MIN TYP 4.0 MAX UNITS 5.5 V 26 50 mΩ Switch disabled 3 10 µA Quiescent Supply Current IIN Switch enabled, IOUT = 0 40 80 µA OUT Off-Leakage Current ILKG Switch disabled, VOUT = 0 0.02 10 µA VUVLO Rising edge, 3% hysteresis 3.4 3.8 V Undervoltage-Lockout Threshold Continuous Current-Limit Adjust Range Continuous Current Limit ILIM 2.9 MAX1563 1 4 MAX1562/MAX1562H 1 3 VIN - VOUT = 0.5V RISET = 4.22kΩ (MAX1563 only) 3.2 4 4.8 RISET = 5.76kΩ 2.4 3 3.6 RISET = 8kΩ 1.7 2.1 2.6 RISET = 12kΩ 1.1 1.4 1.7 4.9 RISET = 4.22kΩ (MAX1563 only) Short-Circuit Current Limit ILIM VOUT = 0, RISET = 5.76kΩ IOUT pulsing RISET = 12kΩ 3.6 1.2 1.7 A A(peak) 1.6 2.5 A A(RMS) 4.7 A(peak) 2.3 A(peak) 1.4 A(RMS) 0.4 A(RMS) 1 V Short-Circuit Detect Threshold (Note 1) Continuous Current-Limit Blanking Timeout Period From continuous current-limit condition to FAULT asserted 10 20 35 ms Short-Circuit Blanking Timeout Period From short-circuit current-limit condition to FAULT asserted 7.5 18 35 ms 0.5 1.2 4.0 ms Turn-On Delay tON ROUT = 2Ω, COUT = 4.7µF (from ON to 10% of VOUT) Output Rise Time tRISE ROUT = 2Ω, COUT = 4.7µF (from 10% to 90% of VOUT) 2.5 Turn-Off Delay tOFF ROUT = 2Ω, COUT = 4.7µF (from ON to 90% of VOUT) 0.1 2 _______________________________________________________________________________________ ms 3 ms Programmable 4A USB Current-Limited Switches with Autoreset and Fault Blanking MAX1562/MAX1562H/MAX1563 ELECTRICAL CHARACTERISTICS (continued) (VIN = +5V, CIN = 1µF, COUT = 4.7µF, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Output Fall Time SYMBOL tFALL Thermal-Shutdown Threshold CONDITIONS MIN ROUT = 2Ω, COUT = 4.7µF (from 90% to10% of VOUT) 15°C hysteresis ON, ON, SEL Input High Level VIH VIN = +4V to +5.5V ON, ON, SEL Input Low Level VIL VIN = +4V to +5.5V ON, ON, SEL Input Leakage Current TYP VOL FAULT Output High Leakage Current ms +160 °C 2 V ISINK = 1mA, VIN = +4V VIN = V FAULT = +5.5V OUT Autoreset Current In latched-off state, VOUT = 0 OUT Autoreset Threshold In latched-off state, OUT rising OUT Autoreset Blanking Time In latched-off state, VOUT > 0.5V UNITS 0.8 -1 FAULT Output Low Voltage MAX 0.8 V +1 µA 0.4 V 1 µA 10 25 45 mA 0.35 0.5 0.65 V 10 20 35 ms MIN TYP MAX UNITS 5.5 V 50 mΩ ELECTRICAL CHARACTERISTICS (VIN = +5V, CIN = 1µF, COUT = 4.7µF, TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER SYMBOL Supply Voltage Range VIN Switch On-Resistance RON Standby Supply Current Quiescent Supply Current OUT Off-Leakage Current UVLO Threshold Short-Circuit Current Limit 4.0 Switch disabled 10 µA IIN Switch enabled, IOUT = 0 80 µA ILKG Switch disabled, VOUT = 0 VUVLO Rising edge, 3% hysteresis Continuous Current-Limit Adjust Range Continuous Current Limit CONDITIONS 10 µA 2.9 3.8 V MAX1563 1 4 MAX1562/MAX1562H 1 3 RISET = 4.22kΩ (MAX1563 only) 3.1 4.9 RISET = 5.76kΩ 2.3 3.7 RISET = 8kΩ 1.6 2.7 RISET = 12kΩ 1.0 1.8 2.4 4.8 1.1 2.4 ILIM VIN - VOUT = 0.5V ILIM RISET = 5.76kΩ VOUT = 0, IOUT pulsing RISET = 12kΩ A A A(peak) Continuous Current-Limit Blanking Timeout Period From continuous current-limit condition to FAULT asserted 10 35 ms Short-Circuit Blanking Timeout Period From short-circuit current-limit condition to FAULT asserted 7.5 35 ms _______________________________________________________________________________________ 3 ELECTRICAL CHARACTERISTICS (continued) (VIN = +5V, CIN = 1µF, COUT = 4.7µF, TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS Turn-On Delay tON ROUT = 2Ω, COUT = 4.7µF (from ON to 10% of VOUT) Turn-Off Delay tOFF ROUT = 2Ω, COUT = 4.7µF (from ON to 90% of VOUT) ON, ON, SEL Input High Level VIH VIN = +4V to +5.5V ON, ON, SEL Input Low Level VIL VIN = +4V to +5.5V MIN TYP 0.5 VOL FAULT Output High Leakage Current UNITS 4.0 ms 3 ms V -1 FAULT Output Low Voltage MAX 2 ON, ON, SEL Input Leakage Current ISINK = 1mA, VIN = +4V VIN = V FAULT = +5.5V OUT Autoreset Current In latched-off state, VOUT = 0 OUT Autoreset Threshold In latched-off state, OUT rising OUT Autoreset Blanking Time In latched-off state, VOUT > 0.5V 0.8 V +1 µA 0.4 V 1 µA mA 10 45 0.35 0.65 V 10 35 ms 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. Typical Operating Characteristics (VIN = +5V, CIN = 1µF, COUT = 4.7µF, TA = +25°C, unless otherwise noted.) TEMP = -40°C 30 TEMP = +25°C 20 TEMP = +85°C 15 2.5 2.0 TEMP = +25°C TEMP = +85°C 1.5 1.0 10 0.5 5 0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 4 5.0 5.5 100 10 1 0.1 0.01 0.001 0 3.0 MAX1562 toc03 3.0 1000 SWITCH-OFF LEAKAGE CURRENT (nA) 35 MAX1562 toc02 40 TEMP = -40°C VON = 5V SHUTDOWN CURRENT (µA) 45 25 3.5 MAX1562 toc01 50 SWITCH-OFF LEAKAGE CURRENT vs. TEMPERATURE SHUTDOWN CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT (µA) MAX1562/MAX1562H/MAX1563 Programmable 4A USB Current-Limited Switches with Autoreset and Fault Blanking 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 5.5 -40 -15 10 35 TEMPERATURE (°C) _______________________________________________________________________________________ 60 85 Programmable 4A USB Current-Limited Switches with Autoreset and Fault Blanking NORMALIZED CONTINUOUS CURRENT LIMIT vs. TEMPERATURE 1.0 0.9 0.8 0.7 MAX1562 toc05 1.01 1.00 0.99 0.98 -15 10 35 60 2.0 1.5 1.0 0.5 0.97 85 RLOAD = 2Ω 2.5 0.96 0 -40 -15 10 35 60 85 -40 -15 10 35 60 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) TURN-OFF TIME vs. TEMPERATURE (tOFF + tFALL) FAULT-BLANKING TIME vs. TEMPERATURE AUTORESET CURRENT vs. TEMPERATURE 2.5 2.0 1.5 1.0 22.0 21.8 21.6 21.4 21.2 21.0 20.8 20.6 40 20.4 0.5 85 MAX1562 toc09 RLOAD = 2Ω AUTORESET CURRENT (mA) MAX1562 toc07 3.0 FAULT-BLANKING TIME (ms) -40 TURN-OFF TIME (ms) 1.02 TURN-ON TIME (ms) 1.1 3.0 MAX1562 toc08 NORMALIZED RON 1.2 TURN-ON TIME vs. TEMPERATURE 1.03 NORMALIZED CONTINUOUS CURRENT LIMIT MAX1562 toc04 1.3 MAX1562 toc06 NORMALIZED RON vs. TEMPERATURE 30 20 MAX1562/MAX1562H/MAX1563 Typical Operating Characteristics (continued) (VIN = +5V, CIN = 1µF, COUT = 4.7µF, TA = +25°C, unless otherwise noted.) 10 20.2 0 20.0 -40 -15 10 35 60 0 -40 -15 10 35 60 TEMPERATURE (°C) TEMPERATURE (°C) AUTORESET CURRENT vs. VCC OVERLOAD RESPONSE INTO 1.4Ω 35 85 -40 -15 10 35 VIN 60 85 TEMPERATURE (°C) SHORT-CIRCUIT RESPONSE INTO 0Ω MAX1562 toc12 MAX1562 toc11 MAX1562 toc10 40 AUTORESET CURRENT (mA) 85 5V/div VIN 5V/div VOUT 5V/div VFAULT 5V/div 30 25 VOUT 20 5V/div 15 FAULT 10 5V/div IOUT 5 IOUT 0 10A/div 2A/div 4.0 4.3 4.6 4.9 5.2 5.5 20ms/div TIME (10ms/div) VCC (V) _______________________________________________________________________________________ 5 MAX1562/MAX1562H/MAX1563 Programmable 4A USB Current-Limited Switches with Autoreset and Fault Blanking Typical Operating Characteristics (continued) (VIN = +5V, CIN = 1µF, COUT = 4.7µF, TA = +25°C, unless otherwise noted.) SWITCH TURN-OFF TIME SWITCH TURN-ON TIME MAX1562 toc14 MAX1562 toc13 ROUT = 2Ω ROUT = 2Ω VON (MAX1562) VON (MAX1562) 2V/div 2V/div VON (MAX1562H) VON (MAX1562H) 2V/div VOUT 2V/div 2V/div VOUT 2V/div 1ms/div 400µs/div STARTUP TIME (ROUT = 2Ω, COUT = 4.7µF) STARTUP TIME (ROUT = 2Ω, COUT = 100µF) MAX1562 toc15 MAX1562 toc16 VON 5V/div VON 5V/div VOUT 2V/div VOUT 2V/div FAULT 5V 0V FAULT 5V 0V IOUT 1A/div IOUT 1A/div 1ms/div 1ms/div STARTUP TIME (ROUT = 2Ω, COUT = 330µF) ULVO RESPONSE MAX1562 toc17 MAX1562 toc18 ROUT = 1kΩ VON 5V/div VOUT 2V/div VFAULT 2V/div 2V/div FAULT 5V 0V 0V IOUT 1A/div 1ms/div 6 VIN 2V/div VOUT 10ms/div _______________________________________________________________________________________ Programmable 4A USB Current-Limited Switches with Autoreset and Fault Blanking PIN MAX1562 MAX1562H MAX1563 1 4 NAME FUNCTION ON (ON) 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. 2 5 FAULT 3 6 GND Ground 4 7 ISET Current-Limit Input. Connect an external resistor from ISET to GND to set current limit, where ILIM = 17120 / RISET. 5, 7 9, 12 IN 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. 6, 8 1, 10 OUT 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. — 2, 8, 11 N.C. No Connection. Internally unconnected. Leave unconnected or use with other traces to simplify PC board layout. — 3 SEL Polarity Control Input for ON. Drive SEL high for active-high enable. Drive SEL low for active-low enable. 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-RON NMOS 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 RISET based on the following equation: ILIM = 17120 / RISET Choose RISET with resistor values between 4.22kΩ to 16kΩ. Resistor values greater than 16kΩ significantly degrade current-limit accuracy. For the MAX1562/ MAX1562H, the minimum RISET value is 5.76kΩ. This corresponds to a 3A current limit, which is limited by the 8-pin SO’s maximum power dissipation. _______________________________________________________________________________________ 7 MAX1562/MAX1562H/MAX1563 Pin Description MAX1562/MAX1562H/MAX1563 Programmable 4A USB Current-Limited Switches with Autoreset and Fault Blanking For the MAX1563, the minimum RISET 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 VOUT greater than 1V or short-circuit current limiting for VOUT less than 1V. When VOUT 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 VOUT 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. Table 1. On/Off Control SEL GND VIN 8 ON OUT BEHAVIOR GND ON VIN OFF GND OFF VIN ON 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 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 CONDITION MAX1562/MAX1562H/MAX1563 BEHAVIOR Output Short-Circuit (VOUT < +1V) • 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 ILIM RMS. If the short 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. Output Overload Current (VOUT > +1V) • If an overload occurs, output current regulates at ILIM and the blanking timer turns on. FAULT remains high during the blanking timeout period. • Continuous current at ILIM persists until either the 20ms blanking period expires or a thermal 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). Thermal Fault (TJ > +160°C) • A junction temperature of +160oC immediately asserts FAULT low (the blanking timeout period 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. 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 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. _______________________________________________________________________________________ 9 MAX1562/MAX1562H/MAX1563 Table 2. Current Limiting and Fault Behavior MAX1562/MAX1562H/MAX1563 Programmable 4A USB Current-Limited Switches with Autoreset and Fault Blanking 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 = (IOUT)2 x RON At a 3A operating current and the maximum on-resistance of the switch (50mΩ), the power dissipation is: 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 Typical Application Circuit 100kΩ IN P = (3A)2 x 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: FAULT INPUT +4V TO +5.5V 1µF IN MAX1563 OFF ON ON ISET OUT GND 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. MAX1563 Functional Diagram *USB APPLICATIONS MAY REQUIRE ADDITIONAL BULK CAPACITANCE. Pin Configurations TOP VIEW IN ON (ON) 1 ON CHARGE PUMP SEL FAULT 2 GND IN FAULT USB PORT 4.7µF* OUT SEL P = ILIM x (VIN - VOUT) For a +5V input and +1V output, the maximum power dissipation is: P = 3A x (5V - 1V) = 12W 3 MAX1562 MAX1562H ISET 4 8 OUT 7 IN OUT 1 6 OUT N.C. 2 5 IN SEL 3 IN N.C. OUT 12 11 10 MAX1563 9 IN 8 N.C. 7 ISET SO () FOR MAX1562H. ILIM THERMAL SHUTDOWN OUT 4 5 6 ON FAULT GND QFN 25mA MAX1563 FAULT LOGIC 20ms TIMERS ULVO OSC 25kHz GND 10 Chip Information BIAS REF TRANSISTOR COUNT: 1833 PROCESS: BiCMOS ______________________________________________________________________________________ Programmable 4A USB Current-Limited Switches with Autoreset and Fault Blanking 12,16,20, 24L QFN.EPS PACKAGE OUTLINE 12,16,20,24L QFN, 4x4x0.90 MM 21-0106 E 1 2 PACKAGE OUTLINE 12,16,20,24L QFN, 4x4x0.90 MM 21-0106 E 2 2 ______________________________________________________________________________________ 11 MAX1562/MAX1562H/MAX1563 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.) 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.) DIM A A1 B C e E H L N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS MAX1562/MAX1562H/MAX1563 Programmable 4A USB Current-Limited Switches with Autoreset and Fault Blanking 1.27 VARIATIONS: 1 INCHES TOP VIEW DIM D D D MIN 0.189 0.337 0.386 MAX 0.197 0.344 0.394 MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC D C A B e 0 -8 A1 L FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, .150" SOIC APPROVAL DOCUMENT CONTROL NO. 21-0041 REV. B 1 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. 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.