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MIC20XX Family Fixed and Adjustable Current Limiting Power Distribution Switches General Description MIC20XX family of switches are current limiting, high-side power switches, designed for general purpose power distribution and control in digital televisions (DTV), printers, set top boxes (STB), PCs, PDAs, and other peripheral devices. See Functionality Table on page 6 and Pin Configuration Drawings on page 7. MIC20XX family's primary functions are current limiting and power switching. They are thermally protected and will shutdown should their internal temperature reach unsafe levels, protecting both the device and the load, under high current or fault conditions Features include fault reporting, fault blanking to eliminate noise-induced false alarms, output slew rate limiting, under voltage detection, automatic-on output, and enable pin with choice of either active low or active high enable. The FET is self-contained, with a fixed or user adjustable current limit. The MIC20XX family is ideal for any system where current limiting and power control are desired. The MIC201X (3 x 9) subfamily offers a unique new patented feature: KICKSTARTTM, which allows momentary high current surges up to the secondary current limit (ILIMIT_2nd) without sacrificing overall system safety. The MIC20XX family is offered, depending on the desired features, in a space saving 5-pin SOT-23, 6-pin SOT-23, (R) and 2mm x 2mm MLF packages. Data sheets and support documentation can be found on Micrel's web site at www.micrel.com. Features * * * * * * * * * * * * * 70m typical on-resistance @ 5V 170m typical on-resistance @ 5V (MIC2005A) Enable active high or active low * 2.5V - 5.5V operating range Pre-set current limit values of 0.5A, 0.8A, and 1.2A * User adjustable current limit from 0.2A to 2.1A * Under voltage lock-out (UVLO) Variable UVLO allows adjustable UVLO thresholds * Automatic load discharge for capacitive loads * Soft start prevents large current inrush Adjustable slew rate allows custom slew rates * Automatic-on output after fault Thermal Protection * Available on some family members Applications * * * * * * * * Digital televisions (DTV) Set top boxes PDAs Printers USB / IEEE 1394 power distribution Desktop and laptop PCs Game consoles Docking stations _________________________________________________________________________________________________________ Typical Application 5V Supply Logic Controller VIN ON/OFF OVERCURRENT/ 1F MIC20X5 VIN GND EN (1,3) VOUT (2,3) VBUS 120F USB Port IADJ FAULT/ Figure 1. Typical Application Circuit Notes: (1) Depending on the family member this pin can function as FAULT/, IADJ, or VUVLO. (2) Depending on the family member this pin can function as IADJ, or CSLEW. (3) See Pin Configuration and Functional Diagram. KICKSTART is a trademark of Micrel, Inc. MLF and MicroLeadFrame are registered trademarks of Amkor Technology, Inc. CableCARD is a trademark of CableLabs. Protected by U.S. Patent No. 7,170,732 Micrel Inc. * 2180 Fortune Drive * San Jose, CA 95131 * USA * tel +1 (408) 944-0800 * fax + 1 (408) 474-1000 * http://www.micrel.com January 2009 M9999-012109-A Micrel, Inc. MIC20XX Family Ordering Information MIC2003/2013 Part Number (1) Marking FD05 FD08 FD12 D05 D08 D12 FL05 FL08 FL12 L05 L09 L12 (2) Current Limit 0.5A 0.8A 1.2A 0.5A 0.8A 1.2A 0.5A 0.8A 1.2A 0.5A 0.8A 1.2A Kickstart Package 5-Pin SOT-23 MIC2003-0.5YM5 MIC2003-0.8YM5 MIC2003-1.2YM5 MIC2003-0.5YML MIC2003-0.8YML MIC2003-1.2YML MIC2013-0.5YM5 MIC2013-0.8YM5 MIC2013-1.2YM5 MIC2013-0.5YML MIC2013-0.8YML MIC2013-1.2YML No 6-Pin 2mm x 2mm MLF (R) 5-Pin SOT-23 Yes 6-Pin 2mm x 2mm MLF (R) MIC2004/2014 Part Number (1) Marking FE05 FE08 FE12 E05 E08 E12 FM05 FM08 FM12 M05 M09 M12 (2) Current Limit 0.5A 0.8A 1.2A 0.5A 0.8A 1.2A 0.5A 0.8A 1.2A 0.5A 0.8A 1.2A Kickstart Package 5-Pin SOT-23 MIC2004-0.5YM5 MIC2004-0.8YM5 MIC2004-1.2YM5 MIC2004-0.5YML MIC2004-0.8YML MIC2004-1.2YML MIC2014-0.5YM5 MIC2014-0.8YM5 MIC2014-1.2YM5 MIC2014-0.5YML MIC2014-0.8YML MIC2014-1.2YML Notes: No 6-Pin 2mm x 2mm MLF (R) 5-Pin SOT-23 Yes 6-Pin 2mm x 2mm MLF (R) 1. All MIC20XX Family parts are RoHS compliant lead free. 2. Over/Under-bar symbol ( / _ ) may not be to scale. On the package the over/under symbol begins above/below the first character of the marking. January 2009 2 M9999-012109-A Micrel, Inc. MIC20XX Family Ordering Information (continued) MIC2005 Part Number (1) Marking FF05 FF08 FF12 F05 F08 F12 (2) Current Limit 0.5A 0.8A 1.2A 0.5A 0.8A 1.2A Enable Active High Active High Active High Active High Active High Active High Kickstart Package 6-Pin SOT-23 MIC2005-0.5YM6 MIC2005-0.8YM6 MIC2005-1.2YM6 MIC2005-0.5YML MIC2005-0.8YML MIC2005-1.2YML No 6-Pin 2mm x 2mm MLF (R) MIC2005L Part Number (1) Marking 5LFF 8LFF 4LFF (2) Current Limit 0.5A 0.8A 1.2A Enable Active Low Active Low Active Low Kickstart No Package 5-Pin SOT-23 MIC2005-0.5LYM5 MIC2005-0.8LYM5 MIC2005-1.2LYM5 MIC2005A Part Number (1) Marking FA51 FA52 FA53 FA54 (2) Current Limit 0.5A 0.5A 0.5A 0.5A Enable Active High Active Low Active High Active Low Kickstart Package 5-Pin SOT-23 MIC2005A-1YM5 MIC2005A-2YM5 MIC2005A-1YM6 MIC2005A-2YM6 No 6-Pin SOT-23 MIC2015 Part Number (1) Marking FN05 FN08 FN12 N05 N08 N12 (2) Current Limit 0.5A 0.8A 1.2A 0.5A 0.8A 1.2A Enable Active High Active High Active High Active High Active High Active High Kickstart Package 6-Pin SOT-23 MIC2015-0.5YM6 MIC2015-0.8YM6 MIC2015-1.2YM6 MIC2015-0.5YML MIC2015-0.8YML MIC2015-1.2YML Notes: Yes 6-Pin 2mm x 2mm MLF (R) 1. All MIC20XX Family parts are RoHS compliant lead free. 2. Over/Under-bar symbol ( / _ ) may not be to scale. On the package the over/under symbol begins above/below the first character of the marking. January 2009 3 M9999-012109-A Micrel, Inc. MIC20XX Family Ordering Information (continued) MIC2006/2016 Part Number (1) Marking FG05 FG08 FG12 G05 G08 G12 FP05 FP08 FP12 P05 P09 P12 (2) Current Limit 0.5A 0.8A 1.2A 0.5A 0.8A 1.2A 0.5A 0.8A 1.2A 0.5A 0.8A 1.2A Kickstart Package 6-Pin SOT-23 MIC2006-0.5YM6 MIC2006-0.8YM6 MIC2006-1.2YM6 MIC2006-0.5YML MIC2006-0.8YML MIC2006-1.2YML MIC2016-0.5YM6 MIC2016-0.8YM6 MIC2016-1.2YM6 MIC2016-0.5YML MIC2016-0.8YML MIC2016-1.2YML Notes: No 6-Pin 2mm x 2mm MLF (R) 6-Pin SOT-23 Yes 6-Pin 2mm x 2mm MLF (R) 1. All MIC20XX Family parts are RoHS compliant lead free. 2. Over/Under-bar symbol ( / _ ) may not be to scale. On the package the over/under symbol begins above/below the first character of the marking. January 2009 4 M9999-012109-A Micrel, Inc. MIC20XX Family Ordering Information (continued) MIC2007/2017 Part Number (1) Marking FHAA HAA FQAA QAA (2) Current Limit Kickstart No Package 6-Pin SOT-23 6-Pin 2mm x 2mm MLF 6-Pin SOT-23 6-Pin 2mm x 2mm MLF (R) (R) MIC2007YM6 MIC2007YML MIC2017YM6 MIC2017YML 0.2A - 2.0A Yes MIC2008/2018 Part Number (1) Marking FJAA JAA FRAA RAA (2) Current Limit Kickstart No Package 6-Pin SOT-23 6-Pin 2mm x 2mm MLF 6-Pin SOT-23 6-Pin 2mm x 2mm MLF (R) (R) MIC2008YM6 MIC2008YML MIC2018YM6 MIC2018YML 0.2A - 2.0A Yes MIC2009/2019 Part Number (1) Marking FKAA KAA FSAA SAA (2) Current Limit Kickstart No Package 6-Pin SOT-23 6-Pin 2mm x 2mm MLF 6-Pin SOT-23 6-Pin 2mm x 2mm MLF (R) (R) MIC2009YM6 MIC2009YML MIC2019YM6 MIC2019YML Notes: 0.2A - 2.0A Yes 1. All MIC20XX Family parts are RoHS compliant lead free. 2. Over/Under-bar symbol ( / _ ) may not be to scale. On the package the over/under symbol begins above/below the first character of the marking. January 2009 5 M9999-012109-A Micrel, Inc. MIC20XX Family MIC20XX Family Member Functionality Part Number Normal Limiting 2003 2004 2005 2005L 2005A-1 2005A-2 2006 2007 2008 2009 Notes: 1. 2. 3. 4. 5. 6. Pin Function (1) Kickstart 2013 2014 2015 (2) (2) (2) I Limit ILIMIT ENABLE High ENABLE Low CSLEW (6) (6) (6) FAULT/ VUVLO (5) Load Discharge Fixed (3) 2016 2017 2018 2019 Adj. (4) Kickstart provides an alternate start-up behavior; however, pin-outs are identical. Kickstart not available. Fixed = Factory programmed current limit. Adj. = User adjustable current limit. VUVLO = Variable UVLO (Previously called DML). CSLEW not available in 5-pin package. MIC20XX Family Member Pin Configuration Table Part Number Normal Limiting 2003 2004 2005 2005L 2005A 2006 2007 2008 2009 Notes: 1. 2. 3. 4. 5. Pin Number I Limit 1 VIN VIN Fixed (2) Kickstart 2013 2014 2015 (1) (1) 2 GND GND GND GND GND GND GND GND GND 3 EN EN EN EN EN EN EN EN 4 FAULT/ FAULT/ FAULT/ VUVLO IADJ IADJ FAULT/ (4) 5 CSLEW CSLEW CSLEW (5) (5) 6 VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VOUT VIN VIN VIN VIN VIN 2016 2017 2018 2019 Adj. (3) CSLEW CSLEW CSLEW IADJ VIN VIN Kickstart not available. Fixed = Factory programmed current limit. Adj. = User adjustable current limit. VUVLO = Variable UVLO (Previously called DLM). CSLEW not available in 5-pin package. January 2009 6 M9999-012109-A Micrel, Inc. MIC20XX Family MIC20XX Family Member Pin Configuration Drawings Fixed Current Limit VIN 1 GND 2 NC 3 5 VOUT VOUT NC 1 2 3 6 5 4 VIN GND NC 4 NC NC (Top View) MIC20X3 VIN 1 GND 2 ENABLE 3 5 VOUT VOUT NC 1 2 3 6 5 4 VIN GND ENABLE 4 NC NC (Top View) MIC20X4 VIN 1 GND 2 ENABLE 3 5 VOUT VIN 1 GND 2 6 VOUT 5 CSLEW 4 FAULT/ VOUT CSLEW FAULT/ 1 2 3 6 5 4 VIN GND ENABLE 4 FAULT/ ENABLE 3 (Top View) MIC2005-X.XL / MIC2005A MIC20X5 MIC20X5 VIN 1 GND 2 ENABLE 3 6 VOUT 5 CSLEW 4 VUVLO VOUT CSLEW VUVLO 1 2 3 6 5 4 VIN GND ENABLE (Top View) MIC20X6 January 2009 7 M9999-012109-A Micrel, Inc. MIC20XX Family MIC20XX Family Member Pin Configuration Drawings (continued) Adjustable Current Limit VIN 1 GND 2 ENABLE 3 6 VOUT 5 CSLEW 4 ILIMIT VOUT CSLEW ILIMIT 1 2 3 6 5 4 VIN GND ENABLE (Top View) MIC20X7 / 20X8 VIN 1 GND 2 ENABLE 3 6 VOUT 5 ILIMIT 4 FAULT/ VOUT ILIMIT FAULT/ 1 2 3 6 5 4 VIN GND ENABLE (Top View) MIC20X9 January 2009 8 M9999-012109-A Micrel, Inc. MIC20XX Family Descriptions These pin and signal descriptions aid in the differentiation of a pin from electrical signals and components connected to that pin. For example, VOUT is the switch's output pin, while VOUT is the electrical signal output voltage present at the VOUT pin. Pin Descriptions Pin Name Type Description VIN GND ENABLE FAULT/ CSLEW VOUT VUVLO ILIMIT Input Input Output Input Output Input Input Supply input. This pin provides power to both the output switch and the switch's internal control circuitry. Ground. Switch Enable (Input): Fault status. A logic LOW on this pin indicates the switch is in current limiting, or has been shut down by the thermal protection circuit. This is an open-drain output allowing logical OR'ing of multiple switches. Slew rate control. Adding a small value capacitor between this pin and VIN slows turn-ON of the power FET. Switch output. The load being driven by the switch is connected to this pin. Variable Under Voltage Lockout (VUVLO): Monitors the input voltage through a resistor divider between VIN and GND. Shuts the switch off if voltage falls below the threshold set by the resistor divider. Previously called VUVLO. Set current limit threshold via a resistor connected from ILIMIT to GND. Signal Descriptions Signal Name Type Description VIN GND VEN VFAULT/ CSLEW VOUT VVUVLO_TH CLOAD IOUT ILIMIT Input Input Output Component Output Internal Component Output Internal Electrical signal input voltage present at the VIN pin. Ground. Electrical signal input voltage present at the ENABLE pin. Electrical signal output voltage present at the FAULT/ pin. Capacitance value connected to the CSLEW pin. Electrical signal output voltage present at the VOUT pin. VUVLO internal reference threshold voltage. This voltage is compared to the VUVLO pin input voltage to determine if the switch should be disabled. Reference threshold voltage has a typical value of 250mV. Capacitance value connected in parallel with the load. Load capacitance. Electrical signal output current present at the VOUT pin. Switch's current limit. Fixed at factory or user adjustable. January 2009 9 M9999-012109-A Micrel, Inc. MIC20XX Family Absolute Maximum Ratings(1) VIN, VOUT.................................................. -0.3V to 6V All other pins ............................................ -0.3V to 5.5V Power Dissipation (PD) .......................Internally Limited Continuous Output Current...................................2.25A Continuous Output Current (MIC2005A) ................0.9A Maximum Junction Temperature (TJ) .................. 150C Storage Temperature (Ts)...................-65C to +150C Operating Ratings(2) Supply Voltage ..............................................2.5V to 5.5V Continuous Output Current Range...................0A to 2.1A Ambient Temperature Range (TA)............ -40C to+85C (3) Package Thermal Resistance SOT-23-5/6 (JA) .......................................... 230C/W 2mm x 2mm MLF-6 (JA)................................ 90C/W 2mm x 2mm MLF-6 (JC) ............................... 45C/W Electrical Characteristics(4) VIN = 5V, TA = 25C unless otherwise specified. Bold indicates -40C to +85C limits; CIN = 1F. Symbol Parameter Condition Min 2.5 Typ Max 5.5 Units VIN Switch Input Voltage Internal Supply Current All except: MIC2005-X.XLYM5 MIC2005A Switch = OFF V A A A A A A VEN = 0V Switch = ON, IOUT = 0A 1 80 8 80 1 8 5 VEN = 1.5V Switch = OFF 330 Internal Supply Current MIC2005-X.XLYM5 IIN VEN = 1.5V Switch = ON, IOUT = 0A 15 300 5 15 VEN = 0V Switch = OFF MIC2005A-1, VEN = 0V Internal Supply Current MIC2005A Switch = OFF MIC2005A-2, VEN = 1.5V Switch = ON MIC2005A-1, VEN = 1.5V MIC2005A-2, VEN = 0V Switch = OFF, VOUT = 0V ILEAK IEN ICSLEW Output Leakage Current Enable Input Current CSLEW Input Current Power Switch Resistance RDS(ON) All except MIC2005A Power Switch Resistance Only MIC2005A RDSCHG Load Discharge Resistance MIC20X4 & MIC20X7 Fixed Current Limit MIC20X3 - MIC20X6 Active Low; ENABLE = 1.5V Active High; ENABLE = 0V 0V VEN 5V 0V VOUT 0.8VIN VIN = 5V, IOUT = 100mA VIN = 5V, IOUT = 100mA VIN = 5V, ISINK = 5mA MIC20XX-0.5, VOUT = 0.8 * VIN MIC20XX-0.8, VOUT = 0.8 * VIN MIC20XX-1.2, VOUT = 0.8 * VIN 70 80 300 A 12 1 0.175 70 170 100 A A A 5 100 125 220 275 m 126 0.7 1.1 1.6 200 0.5 0.8 1.2 0.9 1.5 2.1 M9999-012109-A A ILIMIT January 2009 10 Micrel, Inc. MIC20XX Family Electrical Characteristics (continued) Symbol Parameter Condition Min Typ Max Units CLF Variable Current Limit Factor MIC20X7 - MIC20X9 RSET () = CLF (V) IOUT (A) Secondary current limit MIC201X (All Kickstart parts only) Under Voltage Lock Out Threshold Undervoltage Lock Out Hysteresis Variable UVLO Threshold MIC20X6 ENABLE Input Voltage (5) IOUT = 2A, VOUT = 0.8VIN IOUT = 1A, VOUT = 0.8VIN IOUT = 0.5A, VOUT = 0.8VIN IOUT = 0.2A, VOUT = 0.8VIN VIN = 2.5V VIN Rising VIN Falling 210 190 168 144 2.2 2 1.9 250 243 235 225 4 2.25 2.15 0.1 286 293 298 299 6 2.5 2.4 V ILIMIT_2nd UVLOTHRESHOLD UVLOHysteresis VVUVLO_TH VEN VFAULT OTTHRESHOLD A V V 225 250 275 0.5 mV V V C VIL (MAX) VIH (MIN) IOL = 10mA TJ Increasing TJ Decreasing 1.5 Fault status Output Voltage Over-temperature Threshold 0.25 145 135 0.4 AC Characteristics Symbol Parameter Condition Min Typ Max Units RL = 10 , CLOAD = 1F, tRISE Output Turn-on rise time Delay before asserting or releasing FAULT/ MIC200X tD_FAULT Delay before asserting or releasing FAULT/ MIC201X tD_LIMIT Delay before current limiting MIC201X Delay before resetting Kickstart current limit delay, tD_LIMIT MIC201X tON_DLY Output Turn-on Delay Out of current limit following a current limit event. RL = 43, CL = 120F, VEN = 50% to VOUT = 10% *CSLEW = Open RL = 43, CL = 120F, tOFF_DLY Output Turn-off Delay VEN = 50% to VOUT = 90% *CSLEW = Open Note: * Whenever CSLEW is present. VOUT = 10% to 90% *CSLEW = Open Time from current limiting to FAULT/ state change Time from IOUT continuously exceeding primary current limit condition to FAULT/ state change 500 1000 1500 s 20 32 49 ms 77 128 192 77 128 192 ms tRESET 77 128 192 ms 1000 1500 s 700 s January 2009 11 M9999-012109-A Micrel, Inc. MIC20XX Family Electrical Characteristics (continued) ESD (6) Symbol Parameter Condition Min Typ Max Units VESD_HB Electro Static Discharge Voltage: Human Body Model Electro Static Discharge Voltage; Machine Model VOUT and GND All other pins All pins Machine Model 4 kV 2 200 V VESD_MCHN Notes: 1. Exceeding the absolute maximum rating may damage the device. 2. The device is not guaranteed to function outside its operating rating. 3. Requires proper thermal mounting to achieve this performance 4. Specifications for packaged product only. 5. VIL (MAX) = maximum positive voltage applied to the input which will be accepted by the device as a logic low. VIH (MIN) = minimum positive voltage applied to the input which will be accepted by the device as a logic high. 6. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. Timing Diagrams tRISE 90% 10% 90% 10% tFALL Rise and Fall Times ENABLE 50% tON_DLY 50% tOFF_DLY 90% VOUT 10% Switching Delay Times January 2009 12 M9999-012109-A Micrel, Inc. MIC20XX Family Typical Characteristics 100 SUPPLY CURRENT (A) 80 60 40 20 0 2 Supply Current Output Enabled 25C -40C 85C 16 SUPPLY CURRENT (A) 14 12 10 8 6 4 2 0 2 Supply Current Output Disabled -40C LEAKAGE CURRENT (A) 2.00 1.80 1.60 1.40 1.20 1.00 0.80 0.60 0.40 0.20 Switch Leakage Current OFF 85C 3 4 VIN (V) 5 6 3 4 VIN (V) 5 25C 6 0.00 -50 -30 -10 10 30 50 70 TEMPERATURE (C) 90 ILIMIT vs. Temperature 1.10 1.08 1.06 ILIMIT (A) ILIMIT (A) 1.04 1.02 1.00 0.98 0.96 5V 3V 2.5V ILIMIT vs. Temperature 1.40 1.20 1.00 0.80 0.60 0.40 0.20 90 5V 3V 2.5V ILIMIT vs. Temperature 1.10 1.08 1.06 ILIMIT (A) 1.04 1.02 1.00 0.98 90 5V 2.5V (MIC20xx - 1.2) (MIC20xx - 0.8) (MIC20xx - 0.5) Note: Please note that the 3 plots overlay each 0.94 -50 -30 -10 10 30 50 70 TEMPERATURE (C) 0.00 -50 -30 -10 10 30 50 70 TEMPERATURE (C) 0.96 -50 -30 -10 10 30 50 70 TEMPERATURE (C) 90 2.3 2.25 THRESHOLD (V) 2.2 2.15 2.1 2.05 -50 UVLO Threshold vs. Temperature V RISING RON (mOhm) RON vs. 100 80 60 40 20 0 2 RON (mOhm) RON vs. 120 100 80 5V 60 40 20 Supply Voltage Temperature 3.3V 2.5V V FALLING 0 50 100 TEMPERATURE (C) 150 2.5 3 3.5 4 4.5 VIN (V) 5 5.5 0 -50 -30 -10 10 30 50 70 TEMPERATURE (C) 90 January 2009 13 M9999-012109-A Micrel, Inc. MIC20XX Family Functional Characteristics January 2009 14 M9999-012109-A Micrel, Inc. MIC20XX Family Functional Characteristics (continued) January 2009 15 M9999-012109-A Micrel, Inc. MIC20XX Family Functional Diagram VUVLO MIC20X6 ENABLE MIC20X4 - MIC20X9 FAULT/ MIC20X5 & MIC20X9 VUVLO Under Voltage Detector Control Logic and Delay Timer VIN Current Mirror FET Power FET Gate Control VOUT Thermal Sensor CSLEW MIC20X5 - MIC20X8 Slew Rate Control Load Discharge MIC20X4 & MIC20X7 VREF Current Limit Control Loop GND ILIM Factory Adjusted MIC20X3 - MIC20X6 ILIM User Adjustable MIC20X7 - MIC20X9 Figure 2 MIC20XX Family Functional Diagram January 2009 16 M9999-012109-A Micrel, Inc. MIC20XX Family of Kickstart operation is shown below. Functional Description VIN and VOUT VIN is both the power supply connection for the internal circuitry driving the switch and the input (Source connection) of the power MOSFET switch. VOUT is the Drain connection of the power MOSFET and supplies power to the load. In a typical circuit, current flows from VIN to VOUT toward the load. Since the switch is bidirectional when enabled, if VOUT is greater than VIN, current will flow from VOUT to VIN. When the switch is disabled, current will not flow to the load, except for a small unavoidable leakage current of a few microamps. However, should VOUT exceed VIN by more than a diode drop (~0.6 V), while the switch is disabled, current will flow from output to input via the power MOSFET's body diode. If discharging CLOAD is required by your application, consider using MIC20X4 or MIC20X7; these MIC20XX family members are equipped with a discharge FET to insure complete discharge of CLOAD. Current Sensing and Limiting MIC20XX protects the system power supply and load from damage by continuously monitoring current through the on-chip power MOSFET. Load current is monitored by means of a current mirror in parallel with the power MOSFET switch. Current limiting is invoked when the load exceeds the set over-current threshold. When current limiting is activated the output current is constrained to the limit value, and remains at this level until either the load/fault is removed, the load's current requirement drops below the limiting value, or the switch goes into thermal shutdown. Kickstart 2003 2013 2004 2014 2005 2015 2006 2016 2007 2017 2008 2018 2009 2019 Figure 3. Kickstart Operation Figure 3 Label Key: A) MIC201X is enabled into an excessive load (slew rate limiting not visible at this time scale) The initial current surge is limited by either the overall circuit resistance and power supply compliance, or the secondary current limit, whichever is less. B) RON of the power FET increases due to internal heating (effect exaggerated for emphasis). C) Kickstart period. D) Current limiting initiated. FAULT/ goes LOW. E) VOUT is non-zero (load is heavy, but not a dead short where VOUT = 0V. Limiting response will be the same for dead shorts). F) Thermal shutdown followed by thermal cycling. G) Excessive load released, normal load remains. MIC201X drops out of current limiting. H) FAULT/ delay period followed by FAULT/ going HIGH. Under Voltage Lock Out Under voltage lock-out insures no anomalous operation occurs before the device's minimum input voltage of UVLOTHRESHOLD which is 2V minimum, 2.25V typical, and 2.5V maximum had been achieved. Prior to reaching this voltage, the output switch (power MOSFET) is OFF and no circuit functions, such as FAULT/ or ENABLE, are considered to be valid or operative. Only parts in white boxes have Kickstart. (Not available in 5-pin SOT-23 packages) The MIC201X is designed to allow momentary current surges (Kickstart) before the onset of current limiting, which permits dynamic loads, such as small disk drives or portable printers to draw the energy needed to overcome inertial loads without sacrificing system safety. In this respect, the Kickstart parts (MIC201X) differs markedly from the non-Kickstart parts (MIC200X) which immediately limit load current, potentially starving the motor and causing the appliance to stall or stutter. During this delay period, typically 128ms, a secondary current limit is in effect. If the load demands a current in excess the secondary limit, MIC201X acts immediately to restrict output current to the secondary limit for the duration of the Kickstart period. After this time the MIC201X reverts to its normal current limit. An example January 2009 17 M9999-012109-A Micrel, Inc. Variable Under Voltage Lock Out (VUVLO) 2003 2013 2004 2014 2005 2015 2006 2016 2007 2017 2008 2018 2009 2019 MIC20XX Family Because FAULT/ is an open-drain it must be pulled HIGH with an external resistor and it may be wire-OR'd with other similar outputs, sharing a single pull-up resistor. FAULT/ may be tied to a pull-up voltage source which is higher than VIN, but no greater than 5.5V. Soft-start Control Large capacitive loads can create significant inrush current surges when charged through the switch. For this reason, the MIC20XX family of switches provides a built-in soft-start control to limit the initial inrush currents. Soft-start is accomplished by controlling the power MOSFET when the ENABLE pin enables the switch. CSLEW 2003 2013 2004 2014 2005 2015 2006 2016 2007 2017 2008 2018 2009 2019 Only parts in white boxes have VUVLO. VUVLO functions as an input voltage monitor when the switch in enabled. The VIN pin is monitored for a drop in voltage, indicating excessive loading of the VIN supply. When VIN is less than the VULVO threshold voltage (VVUVLO_TH) for 32ms or more, the MIC20XX disables the switch to protect the supply and allow VIN to recover. After 128ms has elapsed, the MIC20X6 enables switch. This disable and enable cycling will continue as long as VIN deceases below the VUVLO threshold voltage (VVUVLO_TH) which has a typical value of 250mV. The VUVLO voltage is commonly established by a voltage divider from VIN to GND. ENABLE 2003 2013 2004 2014 2005 2015 2006 2016 2007 2017 2008 2018 2009 2019 Only parts in white boxes have CSLEW pin. (Not available in 5-pin SOT-23 packages) Only parts in white boxes have ENABLE pin. ENABLE pin is a logic compatible input which activates the main MOSFET switch thereby providing power to the VOUT pin. ENABLE is either an active HIGH or active LOW control signal. The MIC20XX can operate with logic running from supply voltages as low as 1.8V. ENABLE may be driven higher than VIN, but no higher than 5.5V and not less than -0.3V. FAULT/ 2003 2013 2004 2014 2005 2015 2006 2016 2007 2017 2008 2018 2009 2019 The CSLEW pin is provided to increase control of the output voltage ramp at turn-on. This input allows designers the option of decreasing the output's slew rate (slowing the voltage rise) by adding an external capacitance between the CSLEW and VIN pins. Thermal Shutdown Thermal shutdown is employed to protect the MIC20XX family of switches from damage should the die temperature exceed safe operating levels. Thermal shutdown shuts off the output MOSFET and asserts the FAULT/ output if the die temperature reaches 145C. The switch will automatically resume operation when the die temperature cools down to 135C. If resumed operation results in reheating of the die, another shutdown cycle will occur and the switch will continue cycling between ON and OFF states until the overcurrent condition has been resolved. Depending on PCB layout, package type, ambient temperature, etc., hundreds of milliseconds may elapse from the incidence of a fault to the output MOSFET being shut off. This delay is due to thermal time constants within the system itself. In no event will the device be damaged due to thermal overload because die temperature is monitored continuously by on-chip circuitry. Only parts in white boxes have FAULT/ pin. FAULT/ is an N-channel open-drain output, which is asserted (LOW true) when switch either begins current limiting or enters thermal shutdown. FAULT/ asserts after a brief delay when events occur that may be considered possible faults. This delay insures that FAULT/ is asserted only upon valid, enduring, over-current conditions and that transitory event error reports are filtered out. In MIC200X FAULT/ asserts after a brief delay period, of 32ms typical. After a fault clears, FAULT/ remains asserted for the delay period of 32ms MIC201X's FAULT/ asserts at the end of the Kickstart period which is 128ms typical. This masks initial current surges, such as would be seen by a motor load starting up. If the load current remains above the current limit threshold after the Kickstart has timed out, then the FAULT/ will be asserted. After a fault clears, FAULT/ remains asserted for the delay of 128ms. January 2009 18 M9999-012109-A Micrel, Inc. MIC20XX Family ILIMIT vs. IOUT measured The MIC20XX's current limiting circuitry, during current limiting, is designed to act as a constant current source to the load. As the load tries to pull more than the allotted current, VOUT drops and the input to output voltage differential increases. When VIN - VOUT exceeds 1V, IOUT drops below ILIMIT to reduce the drain of fault current on the system's power supply and to limit internal heating of the switch. When measuring IOUT it is important to bear this voltage dependence in mind, otherwise the measurement data may appear to indicate a problem when none really exists. This voltage dependence is illustrated in Figures 4 and 5. In Figure 4 output current is measured as VOUT is pulled below VIN, with the test terminating when VOUT is 1V below VIN. Observe that once ILIMIT is reached IOUT remains constant throughout the remainder of the test. In Figure 5 this test is repeated but with VIN - VOUT exceeding 1V. When VIN - VOUT > 1V, switch's current limiting circuitry responds by decreasing IOUT, as can be seen in Figure 5. In this demonstration, VOUT is being controlled and IOUT is the measured quantity. In real life applications VOUT is determined in accordance with Ohm's law by the load and the limiting current. Application Information Setting ILIMIT The MIC2009/2019's current limit is user programmable and controlled by a resistor connected between the ILIMIT pin and Ground. The value of this resistor is determined by the following equation: ILIMIT = or R SET = CurrentLim itFactor(CLF) R SET CurrentLim itFactor(V) ILIMIT (A) For example: Set ILIMIT = 1.25 A Looking in the Electrical specifications we will find CLF at ILIMIT = 1 A. Min 190 Typ 243 Max 293 Units V For the sake of this example, we will say the typical value of CLF at an IOUT of 1A is 243V. Applying the equation above: R SET () = 243V = 194.4 1.25A RSET = 196 (the closest standard 1% value) Designers should be aware that variations in the measured ILIMIT for a given RSET resistor, will occur because of small differences between individual ICs (inherent in silicon processing) resulting in a spread of ILIMIT values. In the example above we used the typical value of CLF to calculate RSET. We can determine ILIMIT's spread by using the minimum and maximum values of CLF and the calculated value of RSET. ILIMIT_MIN = ILIMIT_MIN = 190V = 0.97 A 196 260V = 1.5 A 196 Figure 4. IOUT in Current Limiting for VIN - VOUT < 1V Giving us a maximum ILIMIT variation over temperature of: ILIMIT_MIN ILIMIT_TYP ILIMIT_MAX 0.97 A 1.25 A 1.5 A or 1.25 A - 22% and 1.25 A + 20% January 2009 19 M9999-012109-A Micrel, Inc. CSLEW 2003 2013 2004 2014 2005 2015 2006 2016 2007 2017 MIC20XX Family 2008 2018 2009 2019 Only parts in white boxes have CSLEW pin. (Not available in 5-pin SOT-23 packages). The CSLEW pin is provided to increase control of the output voltage ramp at turn-on. This input allows designers the option of decreasing the output's slew rate (slowing the voltage rise) by adding an external capacitance between the CSLEW and VIN pins. This capacitance slows the rate at which the pass FET gate voltage increases and thus, slows both the response to an Enable command as well as VOUT's ascent to its final value. Figure 5. IOUT in Current Limiting for VIN - VOUT > 1V Figure 8 illustrates effect of CSLEW on turn-on delay and output rise time. Typical Turn-on Times Capacitance vs. External C 14 0.014 12 0.012 10 0.01 TIME (mS) 8 0.008 6 0.006 4 0.004 2 0.002 0 0 0.5 1 1.5 0 2.5 0 3.5 0 4.5 0000203040 TRISE SLEW This folding back of ILIMIT can be generalized by plotting ILIMIT as a function of VOUT, as shown below in Figures 6 and 7. The slope of VOUT between IOUT = 0V and IOUT = ILIMIT (where ILIMIT = 1A) is determined by RON of the switch and ILIMIT. Normalized Output Current vs. Output Voltage (5V) TON TDELAY NORMALIZED OUTPUT CURRENT (A) 1.2 1.0 0.8 0.6 0.4 0.2 0 CSLEW (nF) Figure 8. 0 1 2 3 4 5 OUTPUT VOLTAGE (V) 6 Figure 6. NORMALIZED OUTPUT CURRENT (A) 1.2 1.0 0.8 0.6 0.4 0.2 0 Normalized Output Current vs. Output Voltage (2.5V) CSLEW's effect on ILIMIT An unavoidable consequence of adding CSLEW capacitance is a reduction in the MIC20X5 - 20X8's ability to quickly limit current transients or surges. A sufficiently large capacitance can prevent both the primary and secondary current limits from acting in time to prevent damage to the MIC20X5 - 20X8 or the system from a short circuit fault. For this reason, the upper limit on the value of CSLEW is 4nF. Variable Under Voltage Lock Out (VUVLO) 2003 2013 2004 2014 2005 2015 2006 2016 2007 2017 2008 2018 2009 2019 Only parts in white boxes have VUVLO pin and functionality. 0 0.5 1.0 1.5 2.0 2.5 OUTPUT VOLTAGE (V) 3.0 Figure 7. Power conscious systems, such as those implementing ACPI, will remain active even in their low power states and may require the support of external devices through both phases of operation. Under these conditions, the current allowed these external devices may vary according to the system's operating state and as such 20 M9999-012109-A January 2009 Micrel, Inc. require dual current limits on their peripheral ports. The MIC20X6 is designed for systems demanding two primary current limiting levels but without the use of a control signal to select between current limits. To better understand how the MIC20X6 provides this, imagine a system whose main power supply supports heavy loads during normal operation, but in sleep mode is reduced to only few hundred milliamps of output current. In addition, this system has several USB ports which must remain active during sleep. In normal operation, each port can support a 500mA peripheral, but in sleep mode their combined output current is limited to what the power supply can deliver minus whatever the system itself is drawing. If a peripheral device is plugged in which demands more current than is available, the system power supply will sag, or crash. The MIC20X6 prevents this by monitoring both the load current and VIN. During normal operation, when the power supply can source plenty of current, the MIC20X6 will support any load up to its factory programmed current limit. When the weaker, standby supply is in operation, the MIC20X6 monitors VIN and will shut off its output should VIN dip below a predetermined value. This predetermined voltage is user programmable and set by the selection of the resistor divider driving the VUVLO pin. To prevent false triggering of the VUVLO feature, the MIC20X6 includes a delay timer to blank out momentary excursions below the VUVLO trip point. If VIN stays below the VUVLO trip point for longer than 32ms (typical), then the load is disengaged and the MIC20X6 will wait 128ms before reapplying power to the load. If VIN remains below the VUVLO trip point, then the load will be powered for the 32ms blanking period and then again disengaged. This is illustrated in the scope plot below. If VIN remains above the VUVLO trip point MIC20X6 resumes normal operation. MIC20XX Family VUVLO and Kickstart operate independently in the MIC2016. If the high current surge allowed by Kickstart causes VIN to dip below the VUVLO trip point for more than 32ms, VUVLO will disengage the load even though the Kickstart timer has not timed out. IIN_LOAD Input Supply + R1 R2 VUVLO VIN VOUT + Calculating VUVLO resistor divider values Selection of R1 and R2 is driven by the input voltage at which VUVLO should go into effect and the allowed loading of the input supply. The VUVLO pin input voltage is the result of the voltage division of VIN by the voltage divider comprised of R1 and R2. We know VVUVLO_TH = 250 mV, then by choosing a VIN trip voltage (VTRIP) we know the voltage divider ratio formed by R1 and Then an R2.is chosen such that the series resistance R1 + R2 results in a small IIN_LOAD. And then the VUVLO trip voltage as it relates to the comparator threshold and the resistor divider: VVUVLO_TH VTRIP Rearranging these: = R2 =X (R 2 + R1 ) R1 = X *R (1 - X ) 2 Choose an R2 that minimizes the IIN_LOAD current yet at the same time is less than input impedance of the VUVLO pin. The VUVLO pin internally is connected to a comparator with an extremely high input impedance. It is recommended that R2 not exceed 1 M. R2 can then be calculated from the equation above. For example: VTRIP = 4.75V for a 5V supply VVUVLO_TH = 250mV R2 = 750k Substituting these values into the equation above: X= R1 = VVUVLO_TH VTRIP 0.05263 = 4.75 V = 0.05263 0.25 V * 750 k = 41,667k (1 - 0.05263 ) Figure 9. VUVLO Operation R1 = 41,667k 21 M9999-012109-A January 2009 Micrel, Inc. In this example we have used the nominal value of VVUVLO_TH. By substituting in the min and max values of VVUVLO_TH, R1 and R2 the VUVLO trip point window can be established. The VUVLO comparator uses no Hysteresis. This is because the VUVLO blanking timer prevents any chattering that might otherwise occur if VIN varies about the trigger point. The timer is reset by upward crossings of the trip point such that VIN must remain below the trip point for the full 32ms period for load disengagement to occur. In selecting a VTRIP voltage the designer is cautioned to not make this value less than 2.5V. A minimum of 2.5V is required for the MIC20X6's internal circuitry to operate properly. VUVLO trip points below 2.5V will result in erratic or unpredictable operation. Kickstart 2003 2013 2004 2014 2005 2015 2006 2016 2007 2017 2008 2018 2009 2019 MIC20XX Family Figure 10. Kickstart Automatic Load Discharge 2003 2013 2004 2014 2005 2015 2006 2016 2007 2017 2008 2018 2009 2019 Only parts in white boxes have Kickstart. (Not available in 5-pin SOT-23 packages). Only parts in white boxes have automatic load discharge. Kickstart allows brief current surges to pass to the load before the onset of normal current limiting, which permits dynamic loads to draw bursts of energy without sacrificing system safety. Functionally, Kickstart is a forced override of the normal current limiting function provided by the switch. The Kickstart period is governed by an internal timer which allows current to pass up to the secondary current limit (ILIMIT_2nd) to the load for 128ms and then normal (primary) current limiting goes into action. During Kickstart a secondary current limiting circuit is monitoring output current to prevent damage to the switch, as a hard short combined with a robust power supply can result in currents of many tens of amperes. This secondary current limit is nominally set at 4A and reacts immediately and independently of the Kickstart period. Once the Kickstart timer has finished its count the primary current limiting circuit takes over and holds IOUT to its programmed limit for as long as the excessive load persists. Once the switch drops out of current limiting the Kickstart timer initiates a lock-out period of 128ms such that no further bursts of current above the primary current limit, will be allowed until the lock-out period has expired. Kickstart may be over-ridden by the thermal protection circuit and if sufficient internal heating occurs, Kickstart 0A. Upon cooling, if the will be terminated and IOUT ILIMIT, not ILIMIT_2nd. load is still present IOUT Automatic discharge is a valuable feature when it is desirable to quickly remove charge from the VOUT pin. This allows for a quicker power-down of the load. This also prevents any charge from being presented to a device being connected to the VOUT pin, for example, USB, 1394, PCMCIA, and CableCARDTM. Automatic discharge is performed by a shunt MOSFET from VOUT pin to GND. When the switch is disabled, a break before make action is performed turning off the main power MOSFET and then enabling the shunt MOSFET. The total resistance of the MOSFET and internal resistances is typically 126. Supply Filtering A minimum 1F bypass capacitor positioned close to the VIN and GND pins of the switch is both good design practice and required for proper operation of the switch. This will control supply transients and ringing. Without a bypass capacitor, large current surges or a short may cause sufficient ringing on VIN (from supply lead inductance) to cause erratic operation of the switch's control circuitry. For best performance good quality, low ESR capacitors are recommended, preferably ceramic. When bypassing with capacitors of 10F and up, it is good practice to place a smaller value capacitor in parallel with the larger to handle the high frequency components of any line transients. Values in the range of 0.01F to 0.1F are recommended. Again, good quality, low ESR capacitors should be chosen. January 2009 22 M9999-012109-A Micrel, Inc. Power Dissipation Power dissipation depends on several factors such as the load, PCB layout, ambient temperature, and supply voltage. Calculation of power dissipation can be accomplished by the following equation: MIC20XX Family 160 140 120 100 Die Temperature vs. Output Current (T CASE=85C) SOT-23 MLF PD = R DS(ON) x (IOUT ) 2 80 60 40 20 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 OUTPUT CURRENT (A) To relate this to junction temperature, the following equation can be used: TJ = PD x R (J- A) + TA Where: TJ = junction temperature, TA = ambient temperature R(J-A) is the thermal resistance of the package In normal operation the switch's Ron is low enough that 2 no significant I R heating occurs. Device heating is most often caused by a short circuit, or very heavy load, when a significant portion of the input supply voltage appears across the switch's power MOSFET. Under these conditions the heat generated will exceed the package and PCB's ability to cool the device and thermal limiting will be invoked. In Figure 11 die temperature is plotted against IOUT assuming a constant case temperature of 85C. The plots also assume a worst case RON of 140m at a die temperature of 135C. Under these conditions it is clear that an SOT-23 packaged device will be on the verge of thermal shutdown, typically 140C die temperature, when operating at a load current of 1.25A. For this (R) reason we recommend using MLF packaged switch s for any design intending to supply continuous currents of 1A or more. Figure 11. Die Temperature vs. IOUT January 2009 23 M9999-012109-A Micrel, Inc. MIC20XX Family Package Information 5-Pin SOT-23 (M5) 6-Pin SOT-23 (M6) January 2009 24 M9999-012109-A Micrel, Inc. MIC20XX Family 6 Pin 2mm x 2mm MLF (ML) (R) 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) 2008 Micrel, Incorporated. January 2009 25 M9999-012109-A |
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