MIC29311 3A Fast-Response LDO Regulator for USB General Description Features The MIC29311 is a 3A, fast response, low-dropout (LDO) voltage regulator. Using Micrel’s proprietary Super βeta PNP™ process, the MIC29311 offers exceptional dropout (600mV at 3A) and low ground current (60mA at 3A). Fast transient response allows it to recover quickly from large load changes while maintaining a steady output. The device can be sent into a “zero-current” off mode when the TTL compatible enable is brought low. Designed specifically for Universal Serial Bus (USB) applications, the MIC29311 works with USB power switches to provide an economical solution for selfpowered hubs. The 5.1V output voltage is optimized to work with lower-cost high on-resistance USB power switches (300mΩ) to provide a minimum of 4.75V at 500mA to downstream ports. Used with MIC2527 quad USB power switches, the MIC29311 can power up to 6 downstream ports. Features of the MIC29311 include thermal shutdown, current limit, reversed-battery and reversed-lead insertion protection. An overvoltage clamp is available to maintain a safe output when the input voltage exceeds 8V. An error flag is also available to indicate of the output falls out of regulation, or when an overcurrent condition occurs. The MIC29311 is available in a 5-pin TO-220 or TO-263 package with a fixed 5.1V output voltage. For other high current, low-dropout voltage regulators, please see the MIC29150/300/500/750 and the MIC29310, MIC29510, MIC29710. Data sheets and support documentation can be found on Micrel’s web site at: www.micrel.com. • • • • • • • • • • Fast transient response 3A output current over full temperature range 600mV dropout voltage at full load Low ground current 3% total accuracy “Zero” off-mode current Thermal Shutdown Current Limiting Reversed battery protection Fixed 5.1V Output Applications • • • • Self-powered USB hubs USB power switching High-efficiency linear power supplies High-efficiency switching supply post-regulator Ordering Information Part Number Standard RoHS Compliant* MIC29311-5.1BT MIC29311-5.1WT Voltage Temperature Range Package 5.1V 0° to +125°C TO-220-5 * RoHs compliant with ‘high-melting solder’ exemption. Super ßeta PNP is a trademarks of Micrel, Inc. Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com September 2007 M9999-090507 Micrel, Inc. MIC29311 Typical Application Simple USB Stand-Alone 6-Port Self-Powered Hub Pin Configuration TO-220-5 (T) Pin Description Pin Number Pin Name 1 EN Pin Function Enable (Input): Logic-level high enable/logic-level low shutdown control. 2 IN 3, TAB GND Ground: Ground pin and TAB are internally connected. 4 OUT Regulator Output 5 ERR Error Flag (Output): Open-collector (active-low) output. Active low indicates overcurrent or undervoltage output conditions. September 2007 Unregulated Input: +16V maximum supply. 2 M9999-090507 Micrel, Inc. MIC29311 Absolute Maximum Ratings(1) Operating Ratings(2) Input Voltage (VIN) .......................................... –20V to +12V Enable Voltage (VEN)...................................... –20V to +12V Error Output Voltage (VERR) ............................... 0V to +12V Lead Temperature (soldering, 5 sec.)........................ 260°C EDS Rating(3) Input voltage (VIN) ..........................................................+8V Maximum Power Dissipation (PD(max))(4) Junction Temperature (TJ) ............................ 0°C to +125°C Package Thermal Resistance TO-220-5 (θJA) ...................................................55°C/W TO-220-5 (θJC).....................................................2°C/W Electrical Characteristics TA = 25°C, bold values indicate 0°C < TJ < +125°C, unless noted. Parameter Condition Min Typ Max Units Output Tolerance 10mA ≤ IOUT < 3A, (VOUT + 1V) ≤ VIN ≤ 8V +3 % Line Regulation IOUT = 10mA, (VOUT + 1V ≤ VIN ≤ 8V 0.06 0.5 % Load Regulation VIN = VOUT + 1V, 10mA ≤ IOUT 3A 0.2 1 % Output Voltage Temperature Coefficient Note 5 20 100 ppm/°C Dropout Voltage, Note 6 IOUT = 100mA 80 200 mV Ground Current, Note 7 –3 IOUT = 750mA 220 mV IOUT = 1.5A 330 mV IOUT = 3A 600 1000 mV 5 20 mA VIN = 6.1V, IOUT = 750mA VIN = 6.1V, IOUT = 1.5A 15 VIN = 6.1V, IOUT = 3A 60 150 mA Dropout Ground Current VIN = 6.1V, IOUT = 10mA 2 3 mA Current Limit VIN = 3V, VOUT + 0V 10 mA 3.0 Minimum Load Current Output Noise Voltage mA 3.8 7 A CLOAD = 10µF 400 µV(rms) CLOAD = 33µF 260 µV(rms) Output Leakage Current VIN = 6.1V, VERR = 8V 0.1 1 2 µA µA Output Low Voltage VIN = 4.1V, IERR = 250µA 220 300 400 mV mV Error Flag Output September 2007 3 M9999-090507 Micrel, Inc. Parameter MIC29311 Condition Min Typ Max Units 0.8 V 30 75 µA µA 2 4 µA µA 20 µA Enable Input Logic Low Voltage Regulator shutdown Logic High Voltage Regulator enable Enable Input Current VEN = VIN 2.4 15 VEN = 0.8V Regulator Output Current VIN = ≤8V, VEN ≤ 0.8V (shutdown), VOUT = 0, Note 8 10 Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Devices are ESD sensitive. Handling precautions recommended. 4. PD(max) = TJ(max) – TA) / θJA, where θJA depends upon the pointed circuit board layout. See “Applications Information.” 5. Output voltage temperature coefficient is defined as the ∆VOUT(worst case) / (TJ(max) – TJ(min)) where TJ(max) is +125°C and TJ(min) is 0°C. 6. VDO = VIN – VOUT when VOUT decreases to 99% of its nominal output voltage with VIN = VOUT + 1V. 7. IGND is the quiescent current. IIN = IGND + IOUT. 8. VEN ≤ 0.8V and VIN ≤ 8V, VOUT = 0. September 2007 4 M9999-090507 Micrel, Inc. MIC29311 Typical Characteristics 200 Ground Current vs. Input Voltage IOUT = 3A 150 100 50 0 0 20 2 4 6 8 INPUT VOLTAGE (V) 10 Ground Current vs. Temperature 100 80 15 10 Ground Current vs. Temperature IOUT = 3A 60 IOUT = 1.5A 40 5 0 0 20 30 60 90 120 TEMPERATURE °C) ( Ground Current vs. Output Current 150 0 0 40 30 60 90 120 TEMPERATURE °C) ( 150 Enable Current vs. Temperaure 35 30 25 20 VEN = 5V 15 10 VEN = 2V 5 0 0 September 2007 30 60 90 120 TEMPERATURE °C) ( 5 150 M9999-090507 Micrel, Inc. MIC29311 Functional Characteristics Load Transcient Response Test Circuit September 2007 6 M9999-090507 Micrel, Inc. MIC29311 Functional Diagram September 2007 7 M9999-090507 Micrel, Inc. MIC29311 First, calculate the power dissipation of the regulator from these numbers and the device parameters from this datasheet. PD = IOUT(1.02VIN – VOUT) Where the ground current is approximated by 2% of IOUT. Then the heat sink thermal resistance is determined by: Application Information The MIC29311 is a high-performance low-dropout voltage regulator suitable for all moderate to high-current voltage regulator applications. The 600mV dropout voltage at full load makes it especially valuable in battery-powered systems and as high-efficiency noise filters in “post-regulator” applications. Its unique output voltage makes the MIC39311 ideal for Universal Serial Bus (USB) power switching applications. Unlike older NPN-pass transistor designs, where the minimum dropout voltage is limited by the base-emitter voltage drop and collector-emitter saturation voltage, dropout performance of the PNP output of these devices is limited merely by the low VCE saturation voltage. A trade-off for the low dropout voltage is a varying base drive requirement. But Micrel’s Super βeta PNP™ process reduces this drive requirement to merely 1% to 5% of the load current. The MIC29311 regulator is fully protected from damage due to fault conditions. Current limiting is provided. This limiting is linear; output current under overload conditions is constant. Thermal shutdown disables the device when the die temperature exceeds the maximum safe operating temperature. Transient protection allows device (and load) survival even when the input voltage spikes above and below nominal. The output structure of these regulators allows voltages in excess of the desired output voltage to be applied without reverse current flow. The MIC29311 version offers a logic level on-off control: when disabled, the device draws nearly zero current. θ SA = PD − θ JC + θ CS Where TJ(max) ≤ 125°C and θCS is between 0 and 2°C/W. The heat sink may be significantly reduced in applications where the minimum input voltage is known and is large compared with the dropout voltage. Use a series input resistor to drop excessive voltage and distribute the heat between this resistor and the regulator. The low dropout properties of Micrel Super ßeta PNP regulators allow very significant reductions in regulator power dissipation and the associated heat sink without compromising performance. When this technique is employed, a capacitor of at least 1µF is needed directly between the input and regulator ground. Please refer to Application Note 9 for further details and examples on thermal design and heat sink specification. Capacitor Requirements For stability and minimum output noise, a capacitor on the regulator output is necessary. The value of this capacitor is dependent upon the output current; lower currents allow smaller capacitors. The MIC29311 regulator is stable with a minimum capacitor value of 10µF at full load. This capacitor need not be an expensive low ESR type: aluminum electrolytics are adequate. In fact, extremely low ESR capacitors may contribute to instability. Tantalum capacitors are recommended for systems where fast load transient response is important. Where the regulator is powered from a source with high AC impedance, a 0.1µF capacitor connected between Input and GND is recommended. This capacitor should have good characteristics to above 250kHz. When the regulator is located more than 3 inches from the ac bulk supply capacitors, a 1µF or greater input capacitor is recommended. Figure 1. Input and Output Capacitors Thermal Design Linear regulators are simple to use. The most complicated design parameters to consider are thermal characteristics. Thermal design requires the following application-specific parameters: Maximum ambient temperature, TA Output Current, IOUT Output Voltage, VOUT Input Voltage, VIN September 2007 TJ(max) − TA Minimum Load Current The MIC29311 regulator is specified between finite loads. If the output current is too small, leakage currents dominate and the output voltage rises. A 10mA minimum load current is necessary for proper regulation. 8 M9999-090507 Micrel, Inc. MIC29311 In Figure 2, the MIC29311 provides power to the MIC2527 quad power switches. The MIC2527 provides power switching to four independently controlled downstream ports. Two MIC2527’s can be used to provide a 6-port, self-powered hub in conjunction with the MIC29311. The 5.1V output of the MIC29311 is optimized to ensure that under maximum load condition, the output voltage of each channel of the MIC2527 remains above 4.75V. This is the minimum voltage requirement for self-powered USB hubs. The output voltage is a function of the minimum output voltage of the power supply, the PCB trace resistance and the onresistance of the switch. Table 1 shows the maximum allowable on-resistance for a 5.1V power supply in a self-powered hub, assuming 30mV of voltage drop due to PCB trace resistance. The 5.1V of the MIC29311 and the 300mΩ on-resistance of each MIC2527 switch provide an economical solution to power management of self-powered hubs. Enable Input The MIC29311 version features an enable (EN) input that allows on-off control of the device. Special design allows “zero” current drain when the device is disabled— only micro-amperes of leakage current flows. The EN input has TTL/CMOS compatible thresholds for simple interfacing with logic, or may be directly tied to VIN. Enabling the regulator requires approximately 20µA of current into the EN pin. Error Flag The MIC29311 features an error flag which looks at the output voltage and signals an error condition when this voltage drops 5% below its expected value. The error flag is an open-collector output that pulls low under fault conditions. It may sink 10mA. Low output voltage signifies a number of possible problems, including an overcurrent fault (the device is incurrent limit) and low input voltage. The flag output is inoperative during overtemperature shutdown conditions. Nominal Voltage USB Applications The main application of the MIC29311 is to control power distribution in a self-powered Universal Serial Bus hub. For self-powered hubs, the MIC29311 provides 5.1V ±3% to downstream ports from an unregulated supply voltage (see “Typical Application”). USB requires that the downstream voltage supplied to peripherals from a self-powered hub is between 4.75V and 5.25V. The MIC29311 provides regulation with this requirement. The enable pin input controls ganged power for up to seven downstream ports, each drawing up to 500mA. The device has an output current limiting circuit that linearly decreases the output voltage as the output current exceeds 3A. When the part is out of regulation by 5%, the error flag goes low and signals a fault condition to the microcontroller, allowing the system to be disabled. This provides the overcurrent protection that is required by USB. September 2007 5.10V Supply Tolerance Minimum Voltage Maximum Voltage Maximum RON 1% 5.05V 5.15V 540mΩ 2% 5V 5.2V 440 mΩ 3% 4.95V 5.25V 340 mΩ 4% 4.9V 5.3V – 5% 4.85V 5.38V – Table 1. Max. Allowable On-Resistance For further information concerning USB power management, refer to Application Note 17 and Application Hint 30. 9 M9999-090507 Micrel, Inc. MIC29311 Figure 2. 4-Port Self-Powered Hub September 2007 10 M9999-090507 Micrel, Inc. MIC29311 Package Information 5-Pin TO-220 (T) MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http:/www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 1998 Micrel, Incorporated. September 2007 11 M9999-090507