View MIC29311-51WT_341846.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

MIC29311
3A Fast-Response LDO Regulator for USB
General Description
The MIC29311 is a 3A, fast response, low-dropout (LDO) voltage regulator. Using Micrel's proprietary Super eta PNPTM 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 (300m) 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.
Features
* * * * * * * * * * 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 MIC29311-5.1BT RoHS Compliant* MIC29311-5.1WT Voltage 5.1V Temperature Range 0 to +125C Package TO-220-5
* RoHs compliant with `high-melting solder' exemption.
Super eta 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 1 2 3, TAB 4 5 Pin Name EN IN GND OUT ERR Pin Function Enable (Input): Logic-level high enable/logic-level low shutdown control. Unregulated Input: +16V maximum supply. Ground: Ground pin and TAB are internally connected. Regulator Output Error Flag (Output): Open-collector (active-low) output. Active low indicates overcurrent or undervoltage output conditions.
September 2007
2
M9999-090507
Micrel, Inc.
MIC29311
Absolute Maximum Ratings(1)
Input Voltage (VIN) .......................................... -20V to +12V Enable Voltage (VEN)...................................... -20V to +12V Error Output Voltage (VERR) ............................... 0V to +12V Lead Temperature (soldering, 5 sec.)........................ 260C EDS Rating(3)
Operating Ratings(2)
Input voltage (VIN) ..........................................................+8V Maximum Power Dissipation (PD(max))(4) Junction Temperature (TJ) ............................ 0C to +125C Package Thermal Resistance TO-220-5 (JA) ...................................................55C/W TO-220-5 (JC).....................................................2C/W
Electrical Characteristics
TA = 25C, bold values indicate 0C < TJ < +125C, unless noted.
Parameter Output Tolerance Line Regulation Load Regulation Output Voltage Temperature Coefficient Dropout Voltage, Note 6 Condition 10mA IOUT < 3A, (VOUT + 1V) VIN 8V IOUT = 10mA, (VOUT + 1V VIN 8V VIN = VOUT + 1V, 10mA IOUT 3A Note 5 IOUT = 100mA IOUT = 750mA IOUT = 1.5A IOUT = 3A Ground Current, Note 7 VIN = 6.1V, IOUT = 750mA VIN = 6.1V, IOUT = 1.5A VIN = 6.1V, IOUT = 3A Dropout Ground Current Current Limit Minimum Load Current Output Noise Voltage Error Flag Output Output Leakage Current Output Low Voltage VIN = 6.1V, VERR = 8V VIN = 4.1V, IERR = 250A 0.1 220 1 2 300 400 A A mV mV CLOAD = 10F CLOAD = 33F VIN = 6.1V, IOUT = 10mA VIN = 3V, VOUT + 0V 3.0 Min -3 0.06 0.2 20 80 220 330 600 5 15 60 2 3.8 7 400 260 10 150 3 1000 20 Typ Max +3 0.5 1 100 200 Units % % % ppm/C mV mV mV mV mA mA mA mA A mA V(rms) V(rms)
September 2007
3
M9999-090507
Micrel, Inc.
MIC29311
Parameter Enable Input Logic Low Voltage Logic High Voltage Enable Input Current
Condition Regulator shutdown Regulator enable VEN = VIN VEN = 0.8V
Min
Typ
Max 0.8
Units V A A A A A
2.4 15 30 75 2 4 10 20
Regulator Output Current
Notes:
VIN = 8V, VEN 0.8V (shutdown), VOUT = 0, Note 8
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) / JA, where JA 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 +125C and TJ(min) is 0C. 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
200 150 100 50 0
Ground Current vs. Input Voltage
IOUT = 3A
0
2 4 6 8 INPUT VOLTAGE (V)
10
20 15 10 5 0 0
Ground Current vs. Temperature
100 80
Ground Current vs. Temperature
IOUT = 3A IOUT = 1.5A 60 40 20 30 60 90 120 TEMPERATURE C) ( 150 0 0 30 60 90 120 TEMPERATURE C) ( 150
Ground Current vs. Output Current
40 35 30 25 20 15 10 5 0 0
Enable Current vs. Temperaure
VEN = 5V VEN = 2V
30 60 90 120 TEMPERATURE C) (
150
September 2007
5
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:
SA = TJ(max) - TA PD - JC + CS
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 eta PNPTM 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.
Where TJ(max) 125C and CS is between 0 and 2C/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 eta 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 1F 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 10F 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 0.1F 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 1F or greater input capacitor is recommended. 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.
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
8
M9999-090507
Micrel, Inc.
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 20A 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. 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.
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 300m on-resistance of each MIC2527 switch provide an economical solution to power management of self-powered hubs.
Nominal Voltage Supply Tolerance 1% 2% 5.10V 3% 4% 5% Minimum Voltage 5.05V 5V 4.95V 4.9V 4.85V Maximum Voltage 5.15V 5.2V 5.25V 5.3V 5.38V Maximum RON 540m 440 m 340 m - -
Table 1. Max. Allowable On-Resistance
For further information concerning USB power management, refer to Application Note 17 and Application Hint 30.
September 2007
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. (c) 1998 Micrel, Incorporated.
September 2007
11
M9999-090507

▲Up To Search▲

Price & Availability of MIC29311-51WT

	To Download MIC29311-51WT Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .