MIC2095/MIC2097/MIC2098/MIC2099 Current-Limiting Power Distribution Switches General Description Features The MIC2095/97/98/99 family of switches are selfcontained, current-limiting, high-side power switches, ideal for power-control applications. These switches are useful for general purpose power distribution applications such as digital televisions (DTV), printers, set-top boxes (STB), PCs, PDAs, and other peripheral devices. The current limiting switches feature either a fixed 0.5A/0.9A or resistor programmable output current limit. The family also has fault blanking to eliminate false noiseinduced, over current conditions. After an over-current condition, these devices automatically restart if the enable pin remains active. The MIC2097 switch offers a unique new patented Kickstart feature, which allows momentary high-current surges up to the secondary current limit (ILIMIT_2nd). This is useful for charging loads with high inrush currents, such as capacitors. The MIC2095/97/98/99 family of switches provides undervoltage, over-temperature shutdown, and output fault status reporting. The family also provides either an active low or active high, logic level enable pin. The MIC2095/97/98/99 family is offered in a space saving 1.6mm x 1.6mm Thin MLF® (TMLF) package. Datasheets and support documentation can be found on Micrel’s web site at: www.micrel.com. • MIC2095: 0.5A fixed current limit • MIC2098: 0.9A fixed current limit • MIC2097/99: Resistor programmable current limit – 0.1A to 1.1A • • • • • • • • MIC2097: Kickstart for high peak current loads Under voltage lock-out (UVLO) Soft start prevents large current inrush Automatic-on output after fault Thermal protection Enable active high or active low 170mΩ typical on-resistance @ 5V 2.5V – 5.5V operating range Applications • • • • • • • • • Digital televisions (DTV) Set top boxes PDAs Printers USB / IEEE 1394 power distribution Desktop and laptop PCs Game consoles USB keyboard Docking stations _________________________________________________________________________________________________________________________ Typical Application MIC2095 USB Power Switch MLF and MicroLeadFrame are registered trademarks of Amkor Technology, 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 August 2011 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Ordering Information Output Junction Temperature (1) Range Package 0.5A Yes –40°C to +125°C 6-Pin 1.6mm x 1.6mm TMLF No 0.5A Yes –40°C to +125°C 6-Pin 1.6mm x 1.6mm TMLF Active High Yes 0.1 A – 1.1A Yes –40°C to +125°C 6-Pin 1.6mm x 1.6mm TMLF K2K Active Low Yes 0.1 A – 1.1A Yes –40°C to +125°C 6-Pin 1.6mm x 1.6mm TMLF MIC2098-1YMT H1K Active High No 0.9A Yes –40°C to +125°C 6-Pin 1.6mm x 1.6mm TMLF MIC2098-2YMT H2K Active Low No 0.9A Yes –40°C to +125°C 6-Pin 1.6mm x 1.6mm TMLF MIC2099-1YMT G1K Active High No 0.1 A – 1.1A Yes –40°C to +125°C 6-Pin 1.6mm x 1.6mm TMLF MIC2099-2YMT G2K Active Low No 0.1 A – 1.1A Yes –40°C to +125°C 6-Pin 1.6mm x 1.6mm TMLF Marking ENABLE Logic Kickstart(™) ILIMIT MIC2095-1YMT J1K Active High No MIC2095-2YMT J2K Active Low MIC2097-1YMT K1K MIC2097-2YMT Part Number FAULT/ Pin Configuration August 2011 6-Pin 1.6mm x 1.6mm TMLF (MT) (Top View) MIC2095-1YMT/MIC2098-1YMT 6-Pin 1.6mm x 1.6mm TMLF (MT) (Top View) MIC2095-2YMT/MIC2098-2YMT 6-Pin 1.6mm x 1.6mm TMLF (MT) (Top View) MIC2097-1YMT / MIC2099-1YMT 6-Pin 1.6mm x 1.6mm TMLF (MT) (Top View) MIC2097-2YMT / MIC2099-2YMT 2 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Pin Description Pin Number Pin Name 1 VOUT 2 (MIC2095/MIC2098) NC Pin Function Switch output (Output): The load being driven by the switch is connected to this pin. No Connect; Pin not used. 2 (MIC2097/MIC2099) ILIMIT Current Limit (Input): A resistor from this pin to ground sets the current limit value. See the “setting ILMIIT” section for details on setting the resistor value. 3 FAULT/ Fault status (Output): 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 FAULT/ outputs from multiple devices. ENABLE Switch Enable (Input): Logic high on this pin enables the switch. ENABLE/ Switch Enable (Input): Logic low on this pin enables the switch. 4 (MIC2095-1/MIC2097-1/ MIC2098-1/MIC2099-1) 4 (MIC2095-2/MIC2097-2/ MIC2098-2/MIC2099-2) 5 GND Ground. 6 VIN Power input (Input): This pin provides power to both the output power switch and the internal control circuitry. EP EP Used to remove heat from die. Connect to ground. Use multiple vias to the ground plane to minimize thermal impedance. See Applications Section for additional information. August 2011 3 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VIN) ....................................... −0.3V to 6.0V Output Voltage (VOUT) ....................................... −0.3V to VIN FAULT Pin Voltage (VFAULT) .............................. −0.3V to VIN ENABLE Pin Voltage (VENABLE).......................... −0.3V to VIN ILIMIT Pin Voltage (VILIMIT) ................................ −0.3V to VIN Power Dissipation (PD) ..............................Internally Limited Maximum Junction Temperature (TJ)......................... 150°C Storage Temperature (Ts).........................−65°C to +150°C Lead Temperature (soldering, 10sec.)....................... 260°C ESD HBM Rating (VOUT, GND)(3) ................................. 4kV ESD HBM Rating (FAULT, ENABLE, VIN)(3) ................. 2kV Supply Voltage (VIN)......................................... 2.5V to 5.5V ENABLE Pin Voltage (VENABLE) .............................. 0V to VIN FAULT Pin Voltage (VFAULT) ................................... 0V to VIN Ambient Temperature Range (TA) .............. –40°C to +85°C Package Thermal Resistance(6) 1.6mm × 1.6mm TMLF (θJA) .............................. 93ºC/W Electrical Characteristics(4) VIN = 5V; CIN = 1µF TA = 25°C unless noted, bold values indicate –40°C≤ TA ≤ +85°C. Symbol Parameter Condition Min. Typ. Max. Units 5.5 V Power Input Supply VIN 2.5 Input Voltage Range Quiescent Supply Current(5) IIN Shutdown Current UVLOTHRESHOLD Switch = ON Active Low Enable, VEN = 0V Active High Enable, VEN = 1.5V 80 300 µA Switch = OFF Active Low Enable, VEN = 1.5V 8 15 µA Switch = OFF Active High Enable, VEN = 0.5V 0.1 5 µA VIN Rising 2 2.25 2.5 V VIN Falling 1.9 2.15 2.4 V VIN UVLO Threshold VIN UVLO Hysteresis 100 mV Enable Control VEN ENABLE Logic Level Low(5) ENABLE Logic Level High (5) 0.5 VIL(MAX) 1.5 VIH(MIN) IEN ENABLE Bias Current 0V ≤ VEN ≤ 5V tON_DLY Output Turn-on Delay RL = 43Ω, CL = 120µF VEN = 50% to VOUT = 10% tOFF_DLY Output Turn-off Delay RL = 43Ω, CL = 120µF VEN = 50% to VOUT = 90% tRISE Output Turn-on rise time RL = 100Ω, CLOAD = 1µF VOUT = 10% to 90% 500 V V 0.1 5 µA 1000 1500 µs 700 µs 1500 µs 1000 Thermal Protection OTThreshold August 2011 Over-temperature Shutdown TJ Rising 145 °C TJ Falling 135 °C 4 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Electrical Characteristics (Continued) VIN = 5V; CIN = 1µF TA = 25°C unless noted, bold values indicate –40°C≤ TA ≤ +85°C. Symbol Parameter Condition Min. Typ. Max. Units 170 220 mΩ 275 mΩ 0.1 10 µA Internal Switch RDS(ON) On Resistance VIN = 5V, IOUT = 100mA ILEAK Output Leakage Current Switch = OFF, VOUT = 0V Active Low Enable, VEN = 1.5V Active High Enable, VEN = 0V Output Current Limit (MIC2095) ILIMIT Fixed Current Limit VOUT = 0.8 × VIN 0.5 0.7 0.9 A VOUT = 0.8 × VIN 0.9 1.1 1.5 A IOUT = 1.1A, VOUT = 0.8 × VIN; VIN =2.5V 175 215 263 V IOUT = 0.5A, VOUT = 0.8 × VIN; VIN =2.5V 152 206 263 V IOUT = 0.2A, VOUT = 0.8 × VIN; VIN =2.5V 138 200 263 V IOUT = 0.1A, VOUT = 0.8 × VIN; VIN =2.5V 121 192 263 V Output Current Limit (MIC2098) ILIMIT Fixed Current Limit Output Current Limit (MIC2097, MIC2099) Variable Current Limit Factors CLF Kickstart TM Current Limit (MIC2097) ILIMIT_2nd Secondary Current Limit VIN = 2.5V; VOUT = 0V 1.5 A TM tD_LIMIT Duration of Kickstart Current Limit VIN = 2.5V Fault Flag Output Voltage Fault Flag Off Current 77 105 192 ms IOL = 10mA 0.25 0.4 V VFAULT/ =5V 0.01 1 µA Fault Flag VFAULT/ Fault Delay (MIC2095, MIC2098, MIC2099) tD_FAULT Delay before asserting or releasing FAULT/ Time from current limiting (VOUT = 0.4 x VIN) to FAULT/ state change 20 32 49 ms Time from current limiting (VOUT = 0.8 x VIN) to FAULT/ state change; VIN = 2.5V 77 105 192 ms Fault Delay (MIC2097) tD_FAULT Delay before asserting or releasing FAULT/ 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. Human body model, 1.5k in series with 100pF. 4. Specifications for packaged product only. 5. Check the Ordering Information section to determine which parts are Active High or Active Low. 6. Requires proper thermal mounting to achieve this performance. August 2011 5 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Timing Diagrams tFALL tRISE 90% 90% 10% 10% Rise and Fall Times ENABLE 50% 50% tOFF_DLY tON_DLY 90% VOUT 10% Switching Delay Times August 2011 6 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Typical Characteristics VIN Shutdown Current vs. Input Voltage VIN Shutdown Current vs. Input Voltage 6 8 6 4 -2 Version 2 0 100 4 2 0 -1 Version 3.0 3.5 4.0 4.5 5.0 60 40 20 0 2.5 5.5 3.0 3.5 4.0 4.5 5.0 5.5 2.5 1.2 0.8 RSET = 298Ω, ISET = 0.7A RSET = 508Ω, ISET = 0.4A 0.4 VOUT=0.8*VIN RSET = 1920Ω, ISET=0.1A 0.2 0.8 1.0 0.6 ISC 0.4 0.2 3.0 3.5 4.0 4.5 5.0 5.5 2.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) INPUT VOLTAGE (V) Current Limit vs. Input Voltage MIC2097/MIC2099 Switch On Resistance vs. Input Voltage 1.2 1.0 RESISTANCE (mΩ) ILIMIT 0.8 0.6 ISC 0.4 RSET =195Ω ISET = 1.1A VOUT = 0.8*VIN 0.2 3.0 3.5 4.0 4.5 5.0 ISC 0.4 3.0 35 200 30 180 160 140 4.5 5.0 5.5 25 20 15 CLOAD = 1μF 10 IOUT = 100mA RLOAD = 100Ω 5 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 2.5 3.0 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) Kickstart Current vs. Input Voltage MIC2097 Kickstart Period vs. Input Voltage MIC2097 1.8 140 4.0 Fault Delay vs. Input Voltage MIC2095/MIC2098/MIC2099 220 Fault Delay vs. Input Voltage MIC2097 3.5 INPUT VOLTAGE (V) 40 5.5 VOUT = 0.8*VIN 2.5 5.5 100 2.5 ILIMIT 0.6 240 120 0.0 5.5 0.0 DELAY (ms) 2.5 5.0 0.8 0.2 VOUT = 0.8*VIN 0.0 0.0 4.5 1.2 ILIMIT CURRENT LIMIT (A) CURRENT LIMIT (A) RSET = 200Ω, ISET = 1.08A 4.0 Current Limit vs. Input Voltage MIC2098 1.0 1.0 3.5 INPUT VOLTAGE (V) Current Limit vs. Input Voltage MIC2095 Current Limit vs. Input Voltage MIC2097/MIC2099 0.6 3.0 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 140 1.6 PEAK CURRENT (A) 120 100 80 60 40 CLOAD = 1μF RLOAD = 100Ω 20 120 1.4 100 1.2 1.0 TIME (ms) CURRENT LIMIT (A) 80 -2 2.5 CURRENT LIMIT (A) SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) 10 DELAY (ms) VIN Supply Current vs. Input Voltage 0.8 RSET = 195Ω 0.6 ISET = 1.1A 0.4 20 0.0 2.5 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) August 2011 5.0 5.5 60 40 VOUT = 0.8*VIN 0.2 0 80 2.5 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) 7 5.0 5.5 0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Typical Characteristics (Continued) VIN ShutdownCurrent vs. Temperature 10.0 100 -2 Version 0.8 0.6 0.4 VIN = 3V 0.2 VIN = 5V 0.0 VIN = 5V SUPPLY CURRENT (µA) -1 Version SUPPLY CURRENT (µA) 8.0 VIN = 5V 6.0 4.0 VIN = 3V 2.0 0.0 -40 -15 10 35 60 85 -15 TEMPERATURE (°C) CURRENT LIMIT (A) 0.6 0.4 0.2 ISC VIN = 5.0V VOUT = 4V 1.0 10 35 60 VIN = 3V 40 20 85 -40 60 1.2 ISC VIN = 5.0V 0.2 VOUT = 4V -15 85 10 ILIMIT 0.6 ISC VOUT = 4V RSET =195Ω ISET = 1.1A 35 60 0.0 85 -40 VIN = 5.0V 140 100 60 VIN = 3V 220 180 85 CLOAD = 1μF 600 VIN = 3V 400 CLOAD = 1μF RLOAD =100Ω 0 -15 10 35 60 85 -40 -15 10 35 60 85 TEMPERATURE (°C) TEMPERATURE (°C) VIN UVLO Thresholds vs. Temperature Fault Delay vs. Temperature MIC2095/MIC2099 Kickstart Current vs. Temperature MIC2097 40 1.60 VIN = 5.0V PEAK CURRENT (A) 2.3 2.2 25 VIN = 3V 20 15 10 VIN Falling CLOAD = 1μF RLOAD =100Ω 5 2.0 0 -15 10 35 TEMPERATURE (°C) 60 85 VIN = 3V 1.55 30 VIN Rising August 2011 800 TEMPERATURE (°C) 2.4 -40 85 Output Rise Time vs. Temperature 200 RLOAD =100Ω -40 Delay (ms) VIN ULVO THRESHOLDS (V) 260 35 2.1 60 1000 100 2.5 35 VIN = 5.0V VIN = 5.0V 140 120 35 10 1200 RISE TIME (μs) FALL TIME (μs) RESISTANCE (mΩ) 340 300 10 -15 Output Fall Time vs. Temperature 180 -15 VIN = 5.0V 0.4 TEMPERATURE (°C) 200 -40 85 0.8 0.2 TEMPERATURE (°C) VIN = 3.3V 160 60 1.0 0.6 0.4 35 0.0 RDS(ON) vs. Temperature 220 10 Current Limit vs.Temperature MIC2097/MIC2099 TEMPERATURE (°C) 240 -15 TEMPERATURE (°C) ITHRESHOLD -40 -15 35 0.8 0.0 -40 10 Current Limit vs. Temperature MIC2098 1.2 ILIMIT 0.8 60 TEMPERATURE (°C) Current Limit vs. Temperature MIC2095 1.0 80 0 -40 CURRENT LIMIT (A) SHUTDOWN CURRENT (µA) 1.0 CURRENT LIMIT (A) VIN Supply Current vs.Temperature VIN ShutdownCurrent vs. Temperature 1.50 1.45 VIN = 5.0V 1.40 1.35 1.30 VOUT = 4V 1.25 ISET = 1.1A RSET =195Ω 1.20 -40 -15 10 35 TEMPERATURE (°C) 8 60 85 -40 -15 10 35 60 85 TEMPERATURE (°C) M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Typical Characteristics (Continued) VIN = 5.0V 140 100 ISET (A) TIME (ms) 120 VIN = 3V 80 60 40 20 0 -40 -15 10 35 60 85 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 250 85ºC 200 ISET VIN = 5V Vo=4V TA = 25°C ILIMIT 25ºC 150 -40ºC 100 50 VIN = 5V 0 0 300 600 900 1200 1500 1800 2100 R SET(Ω) TEMPERATURE (°C) VIN - VOUT (VIN = 5.0V) vs. Output Current VIN - VOUT (mV) 160 ILIMIT & ISET vs. RSET MIC2097/MIC2099 Kickstart Period vs. Temperature MIC2097 0.0 0.2 0.4 0.6 0.8 1.0 1.2 OUTPUT CURRENT (A) VIN - VOUT (VIN = 3.0V) vs. Output Current 250 85ºC 25ºC VIN - VOUT (mV) 200 -40ºC 150 100 VIN = 3V 50 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 OUTPUT CURRENT (A) August 2011 9 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Functional Characteristics August 2011 10 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Functional Characteristics (Continued) August 2011 11 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Functional Characteristics (Continued) August 2011 12 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Functional Characteristics (Continued) August 2011 13 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Functional Characteristics (Continued) August 2011 14 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Functional Diagram MIC2095/97/98/99 Functional Diagram August 2011 15 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Functional Description and Application Information Limitations on COUT The part may enter current limit when turning on with a large output capacitance. This is an acceptable condition, however, if the part remains in current limit for a time greater than tD_FAULT, the FAULT pin will assert low. The maximum value of COUT may be approximated by the following equation: 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 micro amps. However, should VOUT exceed VIN by more than a diode drop (~0.6V), while the switch is disabled, current will flow from output to input via the power MOSFET’s body diode. When the switch is enabled, current can flow both ways, from VIN to VOUT, or VOUT to VIN. C OUT _ MAX = VIN _ MAX Eq. 1 Where: ILIMIT_MIN and tD_FAULT_MIN are the minimum specified values listed in the Electrical Characteristic table and VIN_MAX is the maximum input voltage to the switch. Current Sensing and Limiting The current limiting switches protect 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 overcurrent 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. CIN A minimum 1μF bypass capacitor positioned as close as possible 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 sufficient 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 a good quality, low-ESR ceramic capacitor is recommended. An additional 22μF (or greater) capacitor, positioned close to the VIN and GND pins of the switch is necessary if the distance between a larger bulk capacitor and the switch is greater than 3 inches. This additional capacitor limits input voltage transients at the switch caused by fast changing input currents that occur during a fault condition, such as current limit and thermal shutdown. When bypassing with capacitors of 10μF 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 0.1μF to 1μF are recommended. Again, good quality, low-ESR capacitors, preferably ceramic, should be chosen. Kickstart™ The MIC2097 has a Kickstart feature that allows higher momentary current surges before the onset of current limiting. This permits dynamic loads, such as small disk drives or portable printers to draw the inrush current needed to overcome inertial loads without sacrificing system safety. The Kickstart parts differ from the nonKickstart parts which more rapidly limit load current, potentially starving a motor and causing the appliance to stall or stutter. During the Kickstart delay period, (typically 105ms), a secondary current limit (nominally set at 1.5A), is in effect. If the load demands a current in excess the secondary limit, Kickstart parts act immediately to restrict output current to the secondary limit for the duration of the Kickstart period. After this time the Kickstart parts revert to their normal current limit. An example of Kickstart operation is in Figure 1. Kickstart may be over-ridden by the thermal protection circuit and if sufficient internal heating occurs, Kickstart will be terminated and the output switch will be turned off. After the parts cools, if the load is still present IOUT Æ ILIMIT, not ILIMIT_2nd. COUT An output capacitor is recommended to reduce ringing and voltage sag on the output during a transient condition. A value between 1µf and 10µf is recommended, however, larger values can be used. August 2011 ILIMIT _ MIN × t D _ FAULT _ MIN 16 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 pull-up resistor. FAULT/ may be tied to a pull-up voltage source which is less than or equal to VIN. Soft-Start Control Large capacitive loads can create significant inrush current surges when charged through the current limiting switch. When the switch is enabled, the built-in soft-start limits the initial inrush current by slowly turning on the output. Power Dissipation and Thermal Shutdown Thermal shutdown is used to protect the current limiting switch from damage should the die temperature exceed a safe operating temperature. Thermal shutdown shuts off the output MOSFET and asserts the FAULT/ output if the die temperature reaches 145°C (typical). The switch will automatically resume operation when the die temperature cools down to 135°C. 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 reason for the overcurrent condition has been resolved. Depending on PCB layout, package type, ambient temperature, etc., hundreds of milliseconds may elapse from the time a fault occurs to the time the output MOSFET will be shut off. This delay is caused because of the time it takes for the die to heat after the fault condition occurs. 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: Figure 1. MIC2097 Kickstart Operation Figure 1 Label Key: A. The MIC2097 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. 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. MIC2097 drops out of current limiting. H. FAULT/ delay period followed by FAULT/ going HIGH. PD = R DS(ON) × (IOUT ) 2 To relate this to junction temperature, the following equation can be used: Enable Input The ENABLE pin is a logic level compatible input which turns on or off the main MOSFET switch. There are two versions of each device. The −1 version has an active high (ENABLE) and the −2 version has an active low (ENABLE/). TJ = PD × Rθ (J- A) + TA Eq. 3 Where TJ = junction temperature, TA = ambient temperature, and Rθ(J-A) is the thermal resistance of the package. In normal operation, excessive switch heating is most often caused by an output short circuit. If the output is shorted, when the switch is enabled, the switch limits the output current to the maximum value. The heat generated by the power dissipation of the switch continuously limiting the current may exceed the package and PCB’s ability to cool the device and the switch will shut down and signal a fault condition. Please see the Fault Output description in the previous page for more details on the FAULT/ output. After the switch Fault Output The FAULT/ is an N-channel open-drain output, which is asserted (LOW true) when the device either begins current limiting or enters thermal shutdown. The FAULT/ signal asserts after a brief delay period in order to filter out very brief over current conditions. After an overcurrent or over-temperature fault clears, the FAULT/ pin remains asserted (low) for the delay period. The FAULT/output is open-drain and must be pulled HIGH with an external resistor. The FAULT/ signal may be wire-OR’d with other similar outputs, sharing a single August 2011 Eq. 2 17 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 For the sake of this example, the typical value of CLF at an IOUT of 1.1A is 215V. Applying Equation 5: shuts down, and cools, it will re-start itself if the Enable signal retains true (high on the ENABLE parts, low on the ENABLE/ parts). In Figure 2, die temperature is plotted against IOUT assuming a constant ambient temperature of 85°C. The plot also assumes the maximum specified switch resistance at high temperature. DIE TEMPERATURE (°C) 130 R LIMIT (Ω ) = 120 110 100 Tamb=85°C 80 ILIMIT_MIN = 70 0.0 0.2 0.4 0.6 IOUT (A) 0.8 1.0 1.2 Figure 2. Die Temperature vs. IOUT CurrentLim itFactor(CLF) R LIMIT 175V = 0.89 A 196Ω ILIMIT _ MAX = Setting ILIMIT The current limit of the MIC2097 and MIC2099 parts are user programmable and controlled by a resistor connected between the ILIMIT pin and Ground. The value of the current limit resistor is determined by the following equations: ILIMIT = Eq. 6 Choose RLIMIT = 196Ω (the closest standard 1% value) Designers should be aware that variations in the measured ILIMIT for a given RLIMIT 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 RLIMIT. We can determine ILIMIT’s spread by using the minimum and maximum values of CLF and the calculated value of RLIMIT: Die Temperature vs Output Current (Ambient Temperature = 85°C) 90 215V = 195Ω 1.1A Eq. 7 263 V = 1.34 A 196Ω Eq. 8 Giving us a maximum ILIMIT variation of: ILIMIT_MIN 0.89A (-19%) ILIMIT_TYP 1.1A ILIMIT_MAX 1.34A (+22%) For convenience, Table 2 lists the resistance values for the RSET pin, for various current limit values. Eq. 4 or R LIMIT = CurrentLimitFactor(CLF) ILIMIT Nominal Eq. 5 The Current-Limit Factor (CLF) is a number that is characteristic to the MIC2097/9 switches. The CLF is a product of the current-setting resistor value, and the desired current-limit value. Please note that the CLF varies with the current output current, so caution is necessary to use the correct CLF value for the current that you intend to use the part at. For example: If one wishes to set a ILIMIT = 1.1A, looking in the electrical specifications we will find CLF at ILIMIT = 1.1 A, as noted in Table 1. Min. Typ. Max. Units 175 215 263 V RLIMIT ILIMIT_MIN ILIMIT_MAX 0.1A 1920 0.063 0.137 0.2A 1000 0.138 0.263 0.3A 672 0.211 0.391 0.4A 508 0.288 0.517 0.5A 412 0.369 0.638 0.6A 344 0.448 0.764 0.7A 298 0.533 0.884 0.8A 263 0.620 1.002 0.9A 235 0.709 1.118 1.0A 213 0.801 1.233 1.1A 195 0.895 1.346 ILIMIT Table 2. MIC2097 and MIC2099 RLIMIT Table Table 1. CLF at ILIMIT = 1.1A August 2011 18 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 When measuring IOUT it is important to remember voltage dependence, otherwise the measurement data may appear to indicate a problem when none really exists. This voltage dependence is illustrated in Figures 5 and 6. In Figure 5, 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 6 this test is repeated but with (VIN − VOUT) is 4V. NORMALIZED OUTPUT CURRENT (A) ILIMIT vs. IOUT Measured When in current limit, the switches are designed to act as a constant-current source to the load. As the load tries to pull more than the maximum current, VOUT drops and the input-to-output voltage differential increases. As the (VIN − VOUT) voltage differential increases, the IC internal temperature also increases. To limit the IC’s power dissipation, the current limit is reduced as a function of output voltage. This folding back of ILIMIT can be generalized by plotting ILIMIT as a function of VOUT, as shown in Figures 3 and 4. The slope of VOUT between IOUT = 0V and IOUT = ILIMIT (where ILIMIT is a normalized 1A) is determined by RON of the switch and ILIMIT. 1.2 Normalized Output Current vs. Output Voltage (5V) 1.0 0.8 0.6 Figure 5. IOUT in Current Limiting for VOUT = 4V 0.4 0.2 0 0 1 2 3 4 5 OUTPUT VOLTAGE (V) 6 NORMALIZED OUTPUT CURRENT (A) Figure 3. Normalized Output Current vs. Output Voltage 1.2 Normalized Output Current vs. Output Voltage (2.5V) 1.0 Figure 6. IOUT in Current Limiting for VOUT = 1V 0.8 0.6 Under Voltage Lock Out (UVLO) The switches have an Under Voltage Lock Out (UVLO) feature that will shut down the switch in a reproducible manner when the input power supply voltage goes too low. The UVLO circuit disables the output until the supply voltage exceeds the UVLO threshold. Hysteresis in the UVLO circuit prevents noise and finite circuit impedance from causing chatter during turn-on and turnoff. While disable by the UVLO circuit, the output switch (power MOSFET) is OFF and no circuit functions, such as FAULT/ or ENABLE, are considered to be valid or operative. 0.4 0.2 0 0 0.5 1.0 1.5 2.0 2.5 OUTPUT VOLTAGE (V) 3.0 Figure 4. Normalized Output Current vs. Output Voltage August 2011 19 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Typical Application Schematics Figure 7. MIC2095-1 or MIC2098-1 Typical Schematic Note: MIC2095-1 and MIC2098-1; R5=NF; EN pin uses R4 (pull-up resistor to VIN) to enable the output without an external enable signal. MIC2095-2 and MIC2098-2; R4=NF; EN/ pin uses R5 (pull-down resistor to GND) to enable the output without an external enable signal. Figure 8. MIC2097-1 Typical Schematic Note: MIC2097-1; R5=NF; EN pin uses R4 (pull-up resistor to VIN) to enable the output without an external enable signal. MIC2097-2; R4=NF; EN/ pin uses R5 (pull-down resistor to GND) to enable the output without an external enable signal. Figure 9. MIC2099-1 Schematic Note: MIC2099-1; R5=NF; EN pin uses R4 (pull-up resistor to VIN) to enable the output without an external enable signal. MIC2099-2; R4=NF; EN/ pin uses R5 (pull-down resistor to GND) to enable the output without an external enable signal. August 2011 20 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Evaluation Board Schematic Figure 10. Schematic of MIC209X Evaluation Board Notes: 1. Evaluation board is used for all parts. 2. Part numbering scheme is 209X-Y where X is the place holder for the last number (i.e. MIC2095, MIC2097, MIC2098 or MIC2099) and Y is the polarity of the enable signal (-1 indicates active high logic and -2 indicates active low logic). 3. MIC209X-1 EN pin only requires R4 (pull-up resistor to VIN) to enable the output without an external enable signal. 4. MIC209X-2 EN/ pin only requires R3 (pull-down resistor-to-GND) to enable the output without an external enable signal. 5. R1 is NF (no fill) with the MIC2095 (fixed current limit). August 2011 21 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 MIC209x Bill of Materials Item C1 Part Number 08056D106MAT2A Manufacturer Description Qty. (1) Ceramic Capacitor, 10µF, 6.3V, X5R 1 (1) AVX C2 06033D105MAT2A AVX Ceramic Capacitor, 1µF, 25V, X5R 1 C3 0805D226MAT2A AVX(1) Ceramic Capacitor, 22µF, 6.3V, X5R 1 C4 (4) R1 R2, R3, R4 CRCW06032000FRT1 CRCW06031002FRT1 Vishay Dale 120µF (optional) 0 (2) Resistor, 200 (0603 size), 1% 1 (2) Resistor, 10k (0603 size), 1% 3 Current-Limiting Power Distribution Switch – 0.5A Fixed Current Limit – Active High Enable 1 Vishay Dale (3) U1 MIC2095-1YMT Micrel, Inc. U1 MIC2095-2YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch – 0.5A Fixed Current Limit – Active Low Enable 0 U1 MIC2097-1YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch – Adjustable Current Limit with Kickstart – Active High Enable 0 U1 MIC2097-2YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch – Adjustable Current Limit with Kickstart – Active Low Enable 0 U1 MIC2098-1YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch – 0.9A Fixed Current Limit – Active High Enable 0 U1 MIC2098-2YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch – 0.9A Fixed Current Limit – Active Low Enable 0 U1 MIC2099-1YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch – Adjustable Current Limit – Active High Enable 0 U1 MIC2099-2YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch – Adjustable Current Limit – Active Low Enable 0 Notes: 1. AVX: www.avx.com. 2. Vishay: www.vishay.com. 3. Micrel, Inc.: www.micrel.com. 4. May be omitted when used with the MIC2095 or MIC2098 (fixed current limit). August 2011 22 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 PCB Layout Recommendations Figure 11. MIC209X Evaluation Board Top Layer Figure 12. MIC209X Evaluation Board Bottom Layer August 2011 23 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Package Information 6-Pin 1.6mm x 1.6mm TMLF (MT) August 2011 24 M9999-080211-C Micrel, Inc. MIC2095/97/98/99 Recommended Landing Pattern 6-Pin 1.6mm x 1.6mm TMLF (MT) 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 Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. 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. © 2010 Micrel, Incorporated. August 2011 25 M9999-080211-C