MIC2529 Micrel MIC2529 Single-Channel USB Power Controller Advance Information General Description Features The MIC2529 is a high-side power switch optimized for selfpowered (individual port switching) and bus-powered (ganged port switching) Universal Serial Bus (USB) hub applications. An on-board voltage regulator provides the 3.3V supply voltage needed for many USB microcontrollers reducing board component count. The MIC2529 satisfies the following USB requirements: it supplies up to 500mA as required by USB downstream devices; the switch’s low on-resistance meets USB voltage drop requirements; fault current is limited to typically 750mA, well below the UL 25VA safety requirement; and a flag output is available to indicate fault conditions to the local USB controller. Soft start eliminates the momentary voltage drop on the upstream port that may occur when the switch is enabled in bus-powered applications. • • • • • • • • • • • • • Compliant to USB specifications UL Recognized Component On-board 3.3V, 100mA low-dropout regulator 500mA minimum continuous switch load current 160mΩ maximum on-resistance 750mA typical current limit Open-drain fault flag pin for switch Output can be forced higher than input (off-state) Thermal shutdown 1ms turn-on (soft-start) and fast turnoff Available with active-high or active-low switch enable Active-high enable on 3.3V regulated output 8-pin SOIC package Applications • USB self-powered hubs • USB bus-powered hubs • USB keyboard hubs A low-dropout (LDO) regulator provides 3.3V at loads up to 100mA and includes an enable pin for low current shutdown. Both enable inputs are compatible with 3.3V and 5V logic. Thermal shutdown prevents catastrophic failure from highcurrent loads. The MIC2529 is available in an 8-pin SOIC package with active-high or active-low enable circuitry on switch. Typical Applications Upstream VBUS Ferrite Bead 4.40V to 5.25V D+ D– 4.7 µF GND VBUS 0.1 µF 3.3V USB Controller V+ D+ MIC2529 8 ON/OFF OVERCURRENT D– 10k 1 6 0.1µF GND 5 EN IN FLG OUT 3VEN OUT GND 10k 3VOUT 0.01µF 3 D– GND 2 VBUS 4 D+ 33µF† 0.01µF D– GND Bold lines indicate 0.1" wide, 1-oz. copper high-current traces. Downstream USB Port 2 100mA max. VBUS D+ 33µF† 0.01µF D– GND * Speed sense termination resistor. Must be connected between V3VOUT and D+ to indicate high speed operation. † Downstream USB Port 1 100mA max. 7 1.5k* 5% 1µF D+ 33µF† 33µF tantalum or 100µF electrolytics are recommended. Downstream USB Port 3 100mA max. VBUS D+ 33µF† 0.01µF D– GND Downstream USB Port 4 100mA max. 4-Port Ganged Bus-Powered Hub UL Recognized Component June 1999 1 MIC2529 MIC2529 Micrel Ordering Information Part Number Switch Enable Temperature Range Package MIC2529-1BM Active High –40°C to +85°C 8-Pin SOIC MIC2529-2BM Active Low –40°C to +85°C 8-Pin SOIC Pin Configuration MIC2529 FLG 1 8 EN OUT 2 7 OUT IN 3 6 3VEN 3VOUT 4 5 GND 8-Pin SOIC (M) Pin Description Pin Number Pin Name 1 FLG Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent and thermal shutdown switch conditions. 2, 7 OUT Switch Output: Output MOSFET source. Typically connected to switched side of load. Pin 2 and 7 must be connected together externally. 3 IN Supply Voltage Input. Supply to switch and regulator. Connect to positive supply. 4 3VOUT 3.3V Regulator Output 5 GND Ground: Supply return. 6 3VEN Regulator Enable (Input): Logic-compatible input. Logic high = enable, logic low or open = shutdown. Do not float. 8 EN Switch Enable (Input): Logic-compatible enable input. High input = 2.1V typical. Low input = 1.9V typical. (-1 active high, -2 active low) Do not float. MIC2529 Pin Function 2 June 1999 MIC2529 Micrel Absolute Maximum Ratings (Note 1) Operating Ratings (Note 2) Supply Voltage (VIN) ..................................................... +6V Fault Flag Voltage (VFLG) .............................................. +6V Fault Flag Current (IFLG) ............................................ 50mA Switch Output Voltage (OUT) ........................................ +6V Switch Output Current (IOUT) ................... Internally Limited Switch Control Input (VEN) ........................... –0.3V to +12V Regulator Control Input (V3VEN) .................... –20V to +20V Storage Temperature (TS) ....................... –65°C to +150°C Lead Temperature (soldering 5 sec.) ........................ 260°C Supply Voltage (VIN) ...................................... +3V to +5.5V Ambient Temperature (TA) ......................... –40°C to +85°C Thermal Resistance SOIC (θJA) ......................................................... 160°C/W Electrical Characteristics VIN = +5V; TA = 25°C; unless noted. Parameter Condition Supply Current EN Input Threshold Min Typ Max Units V3VEN = high, switch EN off, Note 3 80 150 µA V3VEN = high, switch EN on, OUT = open, Note 3 160 300 µA 2.1 1.9 2.4 V V low to high transition high to low transition, Note 3 0.8 0.01 µA 1 pF VIN = 5V; IOUT = 500mA 120 mΩ VIN = 3.3V; IOUT = 500mA 160 mΩ Output Turn-On Delay RL = 10Ω 0.25 ms Output Turn-On Rise Time RL = 10Ω 3 ms Output Turnoff Delay RL = 10Ω 1 20 µs Output Turnoff Fall Time RL = 10Ω 1 20 µs 10 µA Enable Input Current VEN = 0 - 5.5V Enable Input Capacitance Switch Resistance Output Leakage Current Continuous Load Current FLG not active 0.5 Short Circuit Current Limit enabled into load, VOUT = 0V 0.5 Current-Limit Threshold A 0.75 1.25 A ramped load applied to enabled output, VOUT = 0V, Note 4 0.95 1.50 A Overtemperature Shutdown Threshold TJ increasing TJ decreasing 135 125 °C °C Error Flag Output Resistance VIN = 5V, IL = 10mA 20 Ω VIN = 3.3V, IL = 10mA 30 Ω Error-Flag Off Current VFLAG = 5V 0.01 3VEN Input Threshold enable input logic-low voltage (regulator shutdown) enable input logic-high voltage (regulator enabled) 3VEN Input Current June 1999 1 µA 0.4 V 2.0 V VIL ≤ 0.4V 0.01 –1 µA VIH ≥ 2.0V 5 20 µA 3 MIC2529 MIC2529 Micrel Parameter Condition Min Typ Max Units Regulator Output Voltage VIN = 4.0V to 5.25V, IL = 100mA 3.14 3.3 3.47 V Regulator Output Voltage Temperature Coefficient Note 5 50 ppm/°C Regulator Line Regulation VIN = 4.0V to 5.25V 0.3 mV Regulator Load Regulation IL = 0.1mA to 100mA 3 mV Regulator Dropout Voltage IL = 100mA, Note 6 Regulator Current Limit 3VOUT = 0V mV 320 mA Note 1. Exceeding the absolute maximum rating may damage the device. Devices are ESD sensitive. Handling precautions recommended. Note 2. The device is not guaranteed to function outside its operating rating. Note 3. Off is ≤ 0.8V and on is ≥ 2.4V for the MIC2529-1 switch. Off is ≥ 2.4V and on is ≤ 0.8V for the MIC2529-2 switch. The enable input has approximately 200mV of hysteresis. See control threshold charts. Limits do not include 3VOUT load current of 100µA during test. Note 4. See “Functional Characteristics: Current-Limit Response” photo. Note 5. Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range. Note 6. Dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1V differential. Typical Characteristics 140 ON-RESISTANCE (mΩ) 120 Awaiting Further Characterization Data 100 RL = 44Ω 120 100 VIN = 5V 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) 5.5 On-State Supply Current vs. Temperature Awaiting Further Characterization Data 60 40 VIN = 5V 20 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) MIC2529 Awaiting Further Characterization Data 0.5 TA = 25°C 0 2 3 4 5 SUPPLY VOLTAGE (V) 4 6 Awaiting Further Characterization Data 40 TA = 25°C 2.0 1.5 1.0 80 0 Off-State Supply Current vs. Supply Voltage SUPPLY CURRENT (µA) 100 80 120 2.0 180 160 140 120 160 60 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) 200 SUPPLY CURRENT (µA) RL = 44Ω 80 T = 25°C 80 3.0 200 SUPPLY CURRENT (µA) OUTPUT RESISTANCE (mΩ) 140 On-State Supply Current vs. Supply Voltage Output On-Resistance vs. Temperature SUPPLY CURRENT (µA) Output On-Resistance vs. Supply Voltage 2 3 4 5 SUPPLY VOLTAGE (V) 6 Off-State Supply Current vs. Temperature 1.5 1.0 Awaiting Further Characterization Data 0.5 VIN = 5V 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) June 1999 Micrel 1.5 1.0 3.0 50 TA = 25°C 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) 5.5 TIME (µs) 30 20 VEN FALLING 1.5 10 Threshold Trip Current vs. Supply Voltage 2.5 RISING FALLING 2.0 1.5 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) June 1999 Short Circuit Output Current vs. Temperature 3 Awaiting Further Characterization Data 1 1000 DROPOUT VOLTAGE (V) THRESHOLD VOLTAGE (V) 3.0 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) 2 0 UVLO Threshold Voltage vs. Temperature 2 VIN = 5V 1.0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) VIN = 5V 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) Awaiting Further Characterization Data 1 3 Awaiting Further Characterization Data 3 VIN = 5V Output Fall Time vs. Temperature 40 4 VEN RISING 2.0 TIME (ms) VEN FALLING Output Rise Time vs. Temperature 5 SWITCH OUTPUT (A) VEN RISING 2.0 Switch Enable Threshold vs. Temperature 2.5 1 2 3 4 SUPPLY VOLTAGE (V) 2 1 5 Regulator Dropout Voltage vs. Output Current Regulator Dropout Voltage vs. Temperature 400 100 Awaiting Further Characterization Data 10 1 0.01 Awaiting Further Characterization Data VIN = 5V 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) TA = 25°C 0 0.1 1 10 100 OUTPUT CURRENT (mA) 5 DROPOUT VOLTAGE (V) SWITCH ENABLE VOLTAGE (V) 2.5 Switch Enable Threshold vs. Supply Voltage SWITCH OUTPUT (A) SWITCH ENABLE VOLTAGE (V) MIC2529 350 300 250 200 150 Awaiting Further Characterization Data 100 50 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) MIC2529 MIC2529 Micrel Functional Characteristics Short Circuit Transient Response Short Applied to Output VOUT (2V/div.) VOUT (2V/div.) VFLG (5V/div.) VFLG (5V/div.) Short-Circuit Response Short Applied to Output IOUT (0.5A/div.) IOUT (500mA/div.) Thermal Shutdown VIN = 5V RL = 0.3Ω TIME (100µs/div.) Short Circuit Response Enabled into Short Circuit Current Limit Response VOUT (2V/div.) VOUT (2V/div.) VFLG (5V/div.) VFLG VEN (5V/div.) (5V/div.) TIME (100ms/div.) IOUT (500mA/div.) IOUT (500mA/div.) (Regulator Disabled) VIN = 5V Turn-On and Turnoff Characteristics Turn-On and Turnoff Characteristics on VFLG VEN (5V/div.) (5V/div.) TIME (5ms/div.) off off on off 100µs VOUT (2V/div.) off VIN = 5V TIME (100ms/div.) IOUT (500mA/div.) IOUT (100mA/div.) VOUT (2V/div.) VFLG VEN (5V/div.) (5V/div.) 1.24A Current Limit Threshold Thermal Shutdown VIN = 5V RL =40Ω CL = 10µF TIME (1ms/div.) MIC2529 VIN = 5V VIN = 5V RL = 40Ω CL = 150µF TIME (5ms/div.) 6 June 1999 MIC2529 Micrel Test Circuit IIN 5V 0.1µF 10k MIC2529 VEN EN VFLG FLG OUT 3VEN OUT V3VEN GND IN 3VOUT IOUT CL Ferrite Bead 0.1µF RL VOUT Functional Characteristics Test Circuit Block Diagram 3.3V LDO REG 3VEN 3VOUT EN OSC. THERMAL SHUTDOWN 1.2V REFERENCE CHARGE PUMP GATE CONTROL IN CURRENT LIMIT OUT FLG MIC2529-x GND June 1999 7 MIC2529 MIC2529 Micrel Switch Current Sensing and Limiting The current limit threshold is preset internally. The preset level prevents damage to the switch output MOSFET and external load but allows a minimum current of 0.5A through the switch output MOSFET. The current limit circuit senses a portion of the output switch (FET) current. The current sense resistor shown in the block diagram is virtual and has no voltage drop. The reaction to an overcurrent varies with three scenarios: Functional Description The MIC2529-1 and MIC2529-2 are high-side power switches with on-board voltage regulators. Switch fault conditions turn off or inhibit turn-on of the output transistor, depending upon the type of fault, and activate the open-drain error flag transistor, making it sink current to ground. Input and Output IN (input) is the power supply connection to the logic circuitry, drain of the output MOSFET, and the voltage regulator input. 3VOUT is the regulated 3.3V output. OUT (output) is the source of the MOSFET switch. In a typical circuit current flows through the switch from IN to OUT toward the load. Both OUT pins must be connected together externally. If VOUT is greater than VIN when a switch is disabled, current will flow from OUT to IN when the switch is enabled since the switch is bidirectional when enabled. Switch Enabled into Short Circuit If the switch is powered on or enabled into an excessive load or short circuit, the switch current ramps up to a constant current. The fault flag goes low until the load is reduced. See the “Functional Characteristic: Short Circuit Response, Enabled into Short Circuit” photo. Short Circuit Applied to Outputs When a heavy load or short circuit is applied to an enabled switch, a large transient current will flow until the current limit circuitry responds. Once this occurs, the device limits current to less than the short circuit current specification. See “Functional Characteristic: Short Circuit Response, Short Applied to Output” graph. Current-Limit Response The MIC2529 current-limit profile exhibits a small foldback effect of approximately 200mA. Once this current-limit threshold is exceeded the device enters constant-current mode. This constant current is specified as the short circuit current limit in the “Electrical Characteristics” table. It is important to note that the MIC2529 will deliver load current up to the current-limit threshold. Refer to “Functional Characteristics: Current-Limit Response” photo for details. Fault Flag FLG is an open-drain N-channel MOSFET output. The fault flag is active (low) for one or more of the following switch conditions: current limit or thermal shutdown. The flag output MOSFET is capable of sinking a 10mA load to typically 100mV above ground. The flag does not indicate faults in the LDO regulator. The output MOSFET and driver circuitry are also designed to allow the MOSFET source to be externally forced to a higher voltage than the drain (VOUT > VIN) when the output is off. Thermal Shutdown Thermal shutdown shuts off the switch and activates the flag if the die temperature exceeds 135°C. 10°C of hysteresis prevents the switch from turning on until the die temperature drops to 125°C. Switch overtemperature detection functions only when the switch is enabled. The internal LDO regulator has a similar shutdown without flag output. When an excessive load is applied to the switch output, the MIC2529 will enter a thermal shutdown condition. As shown in the “Electrical Characteristics” short-circuit response graphs, the thermal time constant is about 640ms for the initial condition. If the channel is not shut off, the output will go into thermal oscillation with a frequency of about 20Hz. While this will not damage the device, it is recommended that the port is shut down prior to this occurring. MIC2529 8 June 1999 MIC2529 Micrel “Functional Characteristics: Switch Turn-On and Turnoff Characteristics” for details. During the charging time, the device enters into constant-current mode and the flag is activated. As the capacitance is charged, the current decreases below the short circuit current-limit threshold and the flag will be deasserted. Applications Information Supply Filtering A 0.1µF to 1µF bypass capacitor from IN to GND, located at the device, is strongly recommended to control supply transients. See Figure 1. Without a bypass capacitor, an output short may cause sufficient ringing on the input (from supply lead inductance) to damage internal control circuitry. Input or output transients must not exceed the absolute maximum supply voltage (VIN(max) = 6V) even for a short duration. 4.0V to 5.5V USB Controller OVERCURRENT ON/OFF MIC2529 1 2 3 0.1µF to 1µF V+ 4 FLG OUT IN 3VOUT EN OUT 3VEN GND 0.1µF MIC2529 1 2 8 3 7 4 FLG EN OUT OUT IN 3VEN 3VOUT GND 8 7 6 5 6 5 Figure 2. Transient Filter 1µF In USB applications it is required that output bulk capacitance, shown in “Typical Application,” is utilized to meet transient regulation requirements during hot-plug events. When the MIC2529 is enabled into this capacitive load, the flag may go active for about 200µs. Additionally, during hotplug events, inrush currents will also cause the flag to go active for approximately 30µs. Since these conditions are not valid overcurrent faults, the USB controller must ignore the flag during these events. To prevent this erroneous overcurrent reporting, a 1ms RC filter must be used (see Figure 2). Figure 1. Supply Bypassing Regulator Output Capacitor A 1µF output capacitor is required between 3VOUT and GND to prevent oscillation. Larger values improve the regulator’s transient response. The output capacitor value may be increased without limit. The output capacitor should have an ESR (effective series resistance) of about 5Ω or less and a resonant frequency above 1MHz. Most tantalum or aluminum electrolytic capacitors are adequate. Film types will work but are more expensive. Since many aluminum electrolytics have electrolytes that freeze at about –30°C, solid tantalums are recommended for operation below –25°C. Bus-Powered Hub Applications The MIC2529 was designed for self-powered or bus-powered hubs. The integrated regulator reduces cost and space in applications using a 3.3V USB controller. For self-powered hubs, the MIC2529 will support 1 downstream port. For buspowered hubs, the MIC2529 will support up to four ganged downstream ports. Bus-Powered Hub Port Switching The USB Specification requires that bus-powered hubs implement port switching on either a ganged or individual basis. The specific implementation must be reported via the Hub Descriptor Status Register. Individual port switching does have some advantages in that a fault on one port will not prevent the other ports from operating correctly. In addition, a soft-start circuit must be included in order to reduce inrush currents when the switch is enabled. To meet this requirement, the MIC2529 has been designed to slowly ramp its output. The regulator will remain stable and in regulation with no load other than the internal voltage divider, unlike many other voltage regulators. Switch Enable Input EN must be driven logic high or logic low for a clearly defined input. Floating the input may cause unpredictable operation. EN should not be allowed to go negative with respect to GND. Regulator Enable Input Forcing 3VEN (regulator enable/shutdown) high enables the regulator. Like EN, 3VEN is compatible with CMOS logic gates. If the enable/shutdown feature is not required, connect 3VEN to IN. Transient Overcurrent Fault-Flag Filter When the MIC2529 is enabled, large values of capacitance at the output of the device may cause inrush currents to flow that exceed the short circuit current-limit threshold of the device and cause the flag to activate. The duration of this time depends on the size of the output capacitance. Refer to June 1999 10k 10k The USB Specification does not require bus-powered hubs to report overcurrent conditions to the host since the hub is already current-limited at the upstream port. However, if it is desired to report overcurrent, the Hub Descriptor Status Register must be programmed to indicate this. The MIC2529 provides a flag output for this application. 9 MIC2529 MIC2529 Micrel The 500µA worst-case suspend current must be further divided among the data port termination resistors and internal functions. The termination resistors will consume 3.6V ÷ (16.5kΩ – 5%) = 230µA worst case. This leaves only 270µA for internal functions. Assuming 100µA as the maximum USB controller suspend current, 170µA remains for the rest of the system. The MIC2529 will consume 150µA maximum, leaving a margin of 20µA. USB Voltage Regulation USB specifications require a minimum downstream voltage supply of 4.40V from a bus-powered hub port (see Application Note 17 for details). The USB specification allows for a 100mV drop across the hub, leaving 250mV for PCB, upstream cable, and connector resistance. Therefore, the onresistance of the switch for each port, not including PCB resistance, must be about 100mV ÷ 100mA = 1Ω. For a 4-port ganged hub, this resistance reduces to 250mΩ. The MIC2529 easily satisfies this requirement. Suspend Current Universal Serial Bus Specification places a maximum suspend current requirement of 500µA on devices. For hubs, Universal Serial Bus Specification Revision 1.1 clarifies this issue. Revision 1.1, section 7.2.3, stipulates that the maximum suspend current for a configured hub is 2.5mA. This number is derived by allocating 500µA for up to four downstream ports plus 500µA for the hub’s internal functions. A nonconfigured hub is considered a low-power device and cannot consume more than 500µA. In a nonconfigured state all downstream devices will be switched off. In most cases, a nonconfigured hub is not a practical state for the system. Therefore, the 2.5mA specification is the applicable target specification for the suspend state. In a bus-powered hub with less than 4 ports, the hub may use the additional current for internal functions. MIC2529 10 June 1999 MIC2529 Micrel Package Information 0.026 (0.65) MAX) PIN 1 0.157 (3.99) 0.150 (3.81) DIMENSIONS: INCHES (MM) 0.050 (1.27) TYP 0.064 (1.63) 0.045 (1.14) 0.197 (5.0) 0.189 (4.8) 0.020 (0.51) 0.013 (0.33) 0.0098 (0.249) 0.0040 (0.102) 0°–8° SEATING PLANE 45° 0.010 (0.25) 0.007 (0.18) 0.050 (1.27) 0.016 (0.40) 0.244 (6.20) 0.228 (5.79) 8-Pin SOIC (M) June 1999 11 MIC2529