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| MIC2546/2547 Dual Programable Current Limit Switch General Description Features The MIC2546 and MIC2547 are integrated high-side dual * 2.7V to 5.5V input power switches optimized for low loss dc power switching * Adjustable current-limit up to 1.5A and other power management applications, including * Reverse current flow blocking (no "body diode") Advanced Configuration and Power Interface (ACPI). The * 100A typical on-state supply current per channel MIC2546/47 is a cost-effective, highly integrated solution * 2A typical off-state supply current that requires few external components to satisfy USB and ACPI requirements. * 120m maximum on-resistance Load current management features include a precision * Open-drain fault flag resistor-programmable output current-limit and a soft-start * Thermal shutdown circuit which minimizes inrush current when the switch is * Thermal shutdown output latch (MIC2547) enabled. Thermal shutdown, along with current-limit, * 2ms (slow) turn-on and fast turnoff protects theswitch and the attached device. * Available with active-high or active-low enable The MIC2546/47's open-drain flag outputs are used to indicate current-limiting or thermal shutdown to a local controller. The MIC2547 has an additional internal latch Applications which turns the output off upon thermal shutdown providing robust fault control. The enable signal is * USB power distribution compatible with both 3V and 5V logic, and is also used as * PCI Bus Power Switching the thermal shutdown latch reset for the MIC2547. * Notebook PC The MIC2546 and MIC2547 are available in active-high * ACPI power distribution and active-low enable versions in 16-pin TSSOP and SOP * PC card hot swap applications packages. * Inrush current-limiting Data sheets and support documentation can be found on * Ideal for dual supply applications Micrel's web site at www.micrel.com. ___________________________________________________________________________________________________________ Typical Application Typical Advanced Configuration and Power Interface (ACPI) Application UL Recognized Component 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 2008 M9999-012508-A Micrel, Inc. MIC2546/2547 Ordering Information Part Number Standard MIC2546-1BM MIC2546-1BTS MIC2546-2BM MIC2546-2BTS MIC2547-1BM MIC2547-1BTS MIC2547-2BM MIC2547-2BTS Note: 1. Thermal Shutdown Latch. Pb-Free MIC2546-1YM MIC2546-1YTS MIC2546-2YM MIC2546-2YTS MIC2547-1YM MIC2547-1YTS MIC2547-2YM MIC2547-2YTS Enable Active High Active High Active Low Active Low Active High Active High Active Low Active Low Latch (1) Junction Temp. Range(1) -40 to +85C -40 to +85C -40 to +85C -40 to +85C Package 16-pin SOP 16-pin TSSOP 16-pin SOP 16-pin TSSOP 16-pin SOP 16-pin TSSOP 16-pin SOP 16-pin TSSOP * * * * -40 to +85C -40 to +85C -40 to +85C -40 to +85C Pin Configuration MIC2546/2547 (ENA) (FLGA) (ILIMA) (ENB) (FLGB) LOGIC, CHARGE PUMP LOGIC, CHARGE PUMP (OUTA) (INA) (OUTB) (INB) (ILIMB) (GND) Function Pinout 16-Pin SOP (M) 16-Pin TSSOP (TS) January 2008 2 M9999-012508-A Micrel, Inc. MIC2546/2547 Pin Description Pin Number 1 2, 16 3 Pin Name INA OUTA ENA Pin Function Input A: Output A MOSFET drain. Also supplies internal circuitry. Switch A (Output): Output A MOSFET source. Pins 2 and 16 must be externally connected. Enable A (Input): Logic-compatible enable input. Active- activelow (-2). High input >1.7V typical; low input <1.5V typical. MIC2547 only: Also resets thermal shutdown latch. Not internally connected. Fault Flag A (Output): Active-low, open-drain output. Indicates overcurrent or thermal shutdown conditions. MIC2547 only: latched low on thermal shutdown. Ground. Both pins must be connected to GND. Current Limit Channel B: Sets current-limit threshold using an resistor, RSET, connected to ground. 154 < RSET < 2.29k. Switch B (Output): Pins 8 and 11 must be externally connected. Input B Enable B (Input) Fault Flag B (Output) Fault Flag B (Output) 4, 10 5 6, 14 7 8, 11 9 12 13 15 NC FLGA GNDB, GNDA ILIMB OUTB INB ENB FLGB ILIMA January 2008 3 M9999-012508-A Micrel, Inc. MIC2546/2547 Absolute Maximum Ratings(1) Supply Voltage (VIN) ...................................................+6.0V Output Voltage (VOUT) ................................................+6.0V Output Current (IOUT) ................................Internally Limited Enable Input (VEN) ................................. -0.3V to VIN +0.3V Fault Flag Voltage (VFLG)............................................+6.0V Fault Flag Current (IFLG) .............................................50mA Storage Temperature (TS) ........................-65C to +150C Junction Temperature (TJ) ........................Internally Limited Lead Temperature (soldering 5 sec.)......................... 260C ESD Rating, Note 3 ....................................................... 2kV Operating Ratings(2) Supply Voltage (VIN) .................................... +2.7V to +5.5V Current Limit Set Range......................................0.1 to 1.5A Ambient Temperature Range (TA) .............. -40C to +85C Package Thermal Resistance SOP (JA) .........................................................120C/W TSSOP (JA) ....................................................100C/W Electrical Characteristics(4) VIN = +5V; TA = 25C, bold values indicate -40C to +85C, unless noted. Symbol Parameter Supply Current VEN Enable Input Voltage Enable Input Current Enable Input Capacitance RDS(ON) Switch Resistance Current Limit Factor, Note 6 Output Leakage Current tON tR tOFF tF Output Turn-On Delay Output Turn-On Rise Time Output Turn-Off Delay Output Turn-Off Fall Time Overtemperature Threshold Shutdown Error Flag Output Resisitance Error Flag Off Current EN Pulse Reset Width VIN to EN Set-Up Current-Limit Response Time Overcurrent FLG Response Time Notes: Note 1. Exceeding the absolute maximum rating may damage the device. Note 2. The device is not guaranteed to function outside its operating rating. Note 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. Note 4. Off is 0.8V and on is 2.4V for the MIC2546-1 and MIC2547-1. Off is 2.4V and on is 0.8V for the MIC2546-2 and MIC2547-2. The enable input has about 200mV of hysteresis. Condition Switch off, OUT = open, Note 4 Switch on, OUT = open, Note 4 Enable High, Note 4 Enable Low, Note 4 VEN = VOH(MIN) = 2.4V VEN = VOH(MAX) = 0.8V Note 5 IOUT = 500mA IOUT = 500mA to 1.5A, VOUT = 1.0V to 4.0V Note 6 Swich off RL = 10, CL = 1F, Figure 1a and 1b RL = 10, CL = 1F, Figure 1a and 1b RL = 10, CL = 1F, Figure 1a and 1b RL = 10, CL = 1F, Figure 1a and 1b TJ increasing TJ decreasing VIN = 5V, IL = 10A VIN = 3.3V, IL = 10A VFLG = 5V MIC2547 Thermal Shutdown Latch MIC2547, Note 5 VOUT = oV VOUT = VIN/2 to FLG low Min Typ 1.5 200 Max 10 320 0.8 1 1 120 276 10 5 5 Units A A V V A A pF m V A ms ms s s C C 2.4 1.7 1.5 0.01 0.01 1 80 184 230 1 1 1 2 2 22 21 140 130 4 5 0.01 15 20 1 A s s 5 0 25 5 s s January 2008 4 M9999-012508-A Micrel, Inc. Note 5. Guaranteed by design, but not production tested. Note 6. Current limit threshold is determined by: ILIMIT = 230V RSET MIC2546/2547 , where RSET is in ohms. January 2008 5 M9999-012508-A Micrel, Inc. MIC2546/2547 Typical Characteristics January 2008 6 M9999-012508-A Micrel, Inc. MIC2546/2547 January 2008 7 M9999-012508-A Micrel, Inc. MIC2546/2547 Functional Characteristics January 2008 8 M9999-012508-A Micrel, Inc. MIC2546/2547 Test Circuit Functional Characteristics Test Circuit Timing Diagrams Figure 1a. MIC2546/47-1 Figure 1b. MIC2546/47-2 January 2008 9 M9999-012508-A Micrel, Inc. MIC2546/2547 Figure 2a. MIC2547-2 Timing: Output is reset by toggling EN Figure 2b. MIC2546-2 Timing January 2008 10 M9999-012508-A Micrel, Inc. MIC2546/2547 Block Diagram January 2008 11 M9999-012508-A Micrel, Inc. MIC2546/2547 Functional Description The MIC2546 and MIC2547 are dual high-side Nchannel switches available with active-high or active-low enable inputs. Fault conditions turn off or inhibit turn-on of the output transistor and activate the open-drain error flag transistor making it sink current to ground. Input and Output INX is the power supply connection to the logic circuitry and the drain of the output MOSFET. OUTX is the source of the output MOSFET. In a typical circuit, current flows from INX to OUTX toward the load. If VOUT is greater than VIN, current will flow from OUTX to INX since the switch is bidirectional when enabled. The output MOSFET and driver circuitry are also designed to allow the MOSFET source to be externally forced to a higher voltage than the drain (VOUT > VIN) when the switch is disabled. In this situation, the MIC2546/47 avoids undesirable current flow from OUTX to INX. Both OUT pins for a given channel must be connected together. Thermal Shutdown Thermal shutdown shuts off the output MOSFET and signals the fault flag if the die temperature exceeds 140C. 10C of hysteresis prevents the switch from turning on until the die temperature drops to 130C. Overtemperature detection functions only when the switch is enabled. The MIC2547 features an internal latch which causes the part to remain off after thermal shutdown until a reset pulse is provided via the enable pin. While in currentlimit, the thermal shutdown latch prevents on/off cycling of the output. Refer to Figure 2 for timing diagram. The flag remains low until reset. Enable Input ENX must be driven logic high or logic low, or be pulled high or low for a clearly defined input. Floating the input may cause unpredictable operation. ENX should not be allowed to go negative with respect to GND, and VENX should be less than or equal to VINX. Adjustable Current-Limit The short-circuit current-limit is user-adjustable with an external set resistor. Current-limit in the range of 100mA to 1.5A is available with a set point accuracy of better than 20%. The current-limit circuit prevents damage to the output MOSFET and external load. The nominal current-limit value is set with an external resistor between ILIMX and GND. For a desired currentlimit, the value of the external set resistor is given by: 230V RSETX = I LIMITX where: 154 < RSET < 2.29k For example, to set a 1A nominal current-limit, RSET is calculated as: 230V = 230 1A Current through RSETX increases with OUT current. The voltage across RSETX could be monitored with a high impedance comparator to provide an indication of output current. RSETX should be between 154 and 2.29k (0.5% resistor value). Short-Circuit Protection In the event of a short-circuit, the output current will fold back to approximately 80% of the short-circuit currentlimit. Fault Flag FLGX is an N-channel, open-drain MOSFET output. The fault-flag is active (low) for current-limit or thermal shutdown conditions. The flag output MOSFET is capable of sinking a 10mA load to typically 100mV above ground. January 2008 12 M9999-012508-A Micrel, Inc. MIC2546/2547 TJ = PD x JA + TA where: TJ = junction temperature TA = ambient temperature JA = is the thermal resistance of the package Transient Overcurrent Filter The inrush current from the connection of a heavy capacitive load may cause the fault flag to fall for 10s to 200s while the switch is in a constant-current mode, charging the capacitance. Adding an optional series resistor-capacitor (RSET2) in parallel with RSET, as shown in Figure 3, allows the transient current-limit to be set to a different value than steady state. A typical USB hot-plug inrush is 2A to 3A for 10s to 20s. If RSET is 435 (510mA), an RSET2 of 88 (2.5A) and CSET of F (RC = 100s) allows transient surge of 3A to pass for 100s without tripping the overcurrent flag (FLG). USB Power Distribution The MIC2546 is ideal for meeting USB power distribution requirements. Figure 3 depicts a USB Host application. RSET should be set to a value providing a current-limit >500mA. The accurate current-limit of the MIC2546 will reduce power supply current requirements. Also, fast reaction to short circuit faults prevent voltage droop in mobile PC applications. Printed Circuit Board Hot-Plug The MIC2546/47 are ideal inrush current-limiters suitable for hot-plug applications. Due to the integrated charge pump, the MIC2546/47 presents a high impedance when off and slowly becomes a low impedance as it turns on. This "softstart" feature effectively isolates power supplies from highly capacitive loads by reducing inrush current during hot-plug events. Application Information Supply Filtering A 0.1F to 1F bypass capacitor from INX to GND, located near the MIC2546 and MIC2547, is strongly recommended to control supply transients. Without a bypass capacitor, an output short may cause sufficient ringing on the input (from supply lead inductance) to damage internal control circuitry. Input transients must not exceed the absolute maximum supply voltage (VIN max = 6V) even for a short duration. Supply Bypassing Power Dissipation The device's junction temperature depends on several factors such as the load, PCB layout, ambient temperature and package type. Equations that can be used to calculate power dissipation and junction temperature are found below. Calculation of power dissipation can be accomplished by the following equation: PD = RDS(ON) x (IOUT)2 To relate this to junction temperature, the following equation can be used: January 2008 13 M9999-012508-A Micrel, Inc. MIC2546/2547 Figure 3. USB Host Application January 2008 14 M9999-012508-A Micrel, Inc. MIC2546/2547 Package Information 16-Pin SOP (M) 16-Pin TSSOP (TS) 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) 2001 Micrel, Incorporated. January 2008 15 M9999-012508-A |
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