Micrel MIC2544/2548 MIC2544/2548 Programmable Current Limit High-Side Switch Preliminary Information General Description Features The MIC2544 and MIC2548 are integrated high-side power switches optimized for low loss dc power switching and other power management applications, including Advanced Configuration and Power Interface (ACPI). The MIC2544/48 is a cost-effective, highly integrated solution that requires few external components to satisfy USB and ACPI requirements. • • • • • • • • • • • Load current management features include a precision resistor-programmable output current-limit and a soft-start circuit which minimizes inrush current when the switch is enabled. Thermal shutdown, along with current-limit, protects the switch and the attached device. The MIC2544/48’s open-drain flag output is used to indicate current-limiting or thermal shutdown to a local controller. The MIC2548 has an additional internal latch which turns the output off upon thermal shutdown providing robust fault control. The enable signal is compatible with both 3V and 5V logic, and is also used as the thermal shutdown latch reset for the MIC2548. The MIC2544 and MIC2548 are available in active-high and active-low enable versions in the 8-pin SOP (small-outline package) and 8-pin MSOP (micro-small-outline package). 2.7V to 5.5V input Adjustable current-limit up to 1.5A Reverse current flow blocking (no “body diode”) 75µA typical on-state supply current 1µA typical off-state supply current 120mΩ maximum on-resistance Open-drain fault flag Thermal shutdown Thermal shutdown output latch (MIC2548) 2ms (slow) turn-on and fast turnoff Available with active-high or active-low enable Applications • • • • • • USB power distribution PCI Bus Power Switching Notebook PC ACPI power distribution PC card hot swap applications Inrush current-limiting Typical Application +5V RFLG On/Off MIC2544-xBM EN OUT FLG IN GND OUT NC ILIM RSET 0.1µF Peripheral 33µF SOP pinout shown Typical Advanced Configuration and Power Interface (ACPI) Application Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com June 2000 1 MIC2544/2548 Micrel MIC2544/2548 Ordering Information Part Number Enable Temperature Range Package MIC2544-1BM Active High Latch* –40°C to +85°C 8-pin SOP MIC2544-1BMM Active High –40°C to +85°C 8-pin MSOP MIC2544-2BM Active Low –40°C to +85°C 8-pin SOP MIC2544-2BMM Active Low –40°C to +85°C 8-pin MSOP MIC2548-1BM Active High • –40°C to +85°C 8-pin SOP MIC2548-1BMM Active High • –40°C to +85°C 8-pin MSOP MIC2548-2BM Active Low • –40°C to +85°C 8-pin SOP MIC2548-2BMM Active Low • –40°C to +85°C 8-pin MSOP * Thermal Shutdown Latch Pin Configuration MIC2544/2548 MIC2544/2548 EN 1 8 OUT FLG 2 7 GND 3 ILIM 4 EN 1 8 OUT IN FLG 2 7 IN 6 OUT GND 3 6 OUT 5 NC NC 4 5 ILIM 8-Pin SOP (M) 8-Pin MSOP (MM) MIC2544/2548 (OUT) (EN) (FLG) LOGIC, CHARGE PUMP NOTE: PINS 4 AND 5 FOR SOIC AND MSOP ARE DIFFERENT. (IN) (ILIM) (GND) Pin Description Pin Number MSOP-8 Pin Number SOP-8 Pin Name 1 1 EN Enable (Input): Logic-compatible enable input. Active-high (-1) or active-low (-2). High input >1.7V typical; low input <1.5V typical. Do not float. MIC2548 only: Also resets thermal shutdown latch. 2 2 FLG Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent or thermal shutdown conditions. MIC2548 only: latched low on thermal shutdown. 3 3 GND Ground 5 4 ILIM Current Limit: Sets current-limit threshold using an external resistor, RSET, connected to ground. 154Ω < RSET < 2.29kΩ. 7 7 IN 6,8 6,8 OUT 4 5 NC MIC2544/2548 Pin Function Input: Output MOSFET drain. Also powers internal circuitry. Switch (Output): Output MOSFET source. Pins 6 and 8 must be externally connected. Not internally connected 2 June 2000 Micrel MIC2544/2548 Absolute Maximum Ratings (Note 1) Operating Ratings (Note 2) 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) ....................... –65°C to +150°C Junction Temperature (TJ) ....................... Internally Limited Lead Temperature (soldering 5 sec.) ........................ 260°C ESD Rating, Note 3 ...................................................... 2kV Supply Voltage (VIN) ................................... +2.7V to +5.5V Current Limit Set Range .................................. 0.1A to 1.5A Ambient Temperature Range (TA) ............. –40°C to +85°C Package Thermal Resistance SOP (θJA) .......................................................... 160°C/W MSOP (θJA) ....................................................... 206°C/W Electrical Characteristics VIN = +5V; TA = 25°C, bold indicates –40°C to +85°C; unless noted Symbol VEN Parameter Condition Supply Current Enable Input Voltage Enable Input Current RDS(on) Min Typ Max Units switch off, OUT = open, Note 4 0.75 5 µA switch on, OUT = open, Note 4 75 160 µA enable high, Note 4 2.4 1.7 V enable low, Note 1 1.5 0.8 V VEN = VOH(min) = 2.4V 0.01 1 µA VEN = VOL(max) = 0.8V 0.01 1 µA Enable Input Capacitance Note 6 1 pF Switch Resistance IOUT = 500mA 80 120 mΩ Current Limit Factor IOUT = 100mA to 1A, VOUT = 1V to 4V, Note 5 184 230 276 V IOUT = 500mA to 1.5A, VOUT = 1V to 4V, Note 5 161 230 299 V 1 10 µA Output Leakage Current switch off tON Output Turn-On Delay RL = 10Ω, CL = 1µF, Figures 1a, 1b 1 2 5 ms tR Output Turn-On Rise Time RL = 10Ω, CL = 1µF, Figures 1a, 1b 1 2 5 ms tOFF Output Turnoff Delay RL = 10Ω, CL = 1µF, Figures 1a, 1b 22 µs tF Output Turnoff Fall Time RL = 10Ω, CL = 1µF, Figures 1a, 1b 21 µs Overtemperature Threshold TJ increasing 140 °C Shutdown TJ decreasing 130 °C Error Flag Output Resistance VIN = 5V, IL = 10µA 4 15 Ω VIN = 3.3V, IL = 10µA 5 20 Ω 0.01 1 µA Error Flag Off Current VFLG = 5V EN Pulse Reset Width MIC2548 thermal shutdown latch 5 µs VIN to EN Set-Up MIC2548, Note 6 0 µs Current-Limit Response Time VOUT = 0V, Note 6 25 µs Overcurrent Flag Response Time VOUT = VIN/2 to FLG low 5 µs 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 MIC2544-1 and MIC2548-1. Off is ≥ 2.4V and on is ≤ 0.8V for the MIC2544-2 and MIC2548-2. The enable input has about 200mV of hysteresis. Note 5. 230V Current limit threshold is determined by ILIMIT = R , where RSET is in ohms. SET Note 6. Guaranteed by design but not production tested. June 2000 3 MIC2544/2548 Micrel MIC2544/2548 Test Circuit VOUT Device Under OUT Test IOUT RL CL tr tf 90% 90% VOUT 10% 10% Functional Characteristics Test Circuit Timing Diagrams VEN 50% tOFF tON 90% VOUT 10% Figure 1a. MIC2544/48-1 VEN 50% tOFF tON VOUT 90% 10% Figure 1b. MIC2544/48-2 MIC2544/2548 4 June 2000 Micrel MIC2544/2548 Output Reset EN Short-Circuit Fault VOUT ILIMIT IDC IOUT Fault Removed Thermal Shutdown Reached FLG Figure 2a. MIC2548-2 Timing: Output is reset by toggling EN EN Short-Circuit Fault Fault Removed VOUT ILIMIT IDC IOUT Thermal Shutdown Reached FLG Figure 2b. MIC2544-2 Timing June 2000 5 MIC2544/2548 Micrel MIC2544/2548 Typical Characteristics Output On-Resistance vs. Supply Voltage Output On-Resistance vs. Temperature 80 TA = 27°C 70 60 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) 100 3.3V 5.0V 60 80 60 40 20 5.0V 3.3V 60 2.7V 20 0.3 5.0V 0.2 3.3V 0.1 2.7V 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) Enable Threshold Voltage vs. Supply Voltage Enable Threshold Voltage vs. Temperature 2.0 0.09 0.08 0.06 0.05 0.04 0.03 0.02 0.01 0 2.5 1.6 1.5 1.4 1.3 VEN FALLING 1.2 1.1 1.0 2.5 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) 1.8 VEN RISING 1.6 1.4 VEN FALLING 1.2 1.0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) 5.5 Output Fall Time vs. Temperature 2.5 2000 1.0 3.3V 5.0V 0.5 CURRENT LIMIT (mA) 1.5 2.7V 1000 ITH ISHORT 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) MIC2544/2548 0 100 1000 RSET (Ω) 6 3.3V 4 3 5.0V 2 1 RL = 44Ω Output Current vs. Output Voltage 1500 ISET 2.7V 5 2000 VIN = 5V 500 6 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) Current Limit vs. RSET RL = 44Ω 2.0 5.5 7 OUTPUT RISE TIME (ms) VEN RISING 1.7 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) Rise Time vs. Temperature OUTPUT CURRENT (mA) 1.8 ENABLE THRESHOLD (V) TA = 27°C TA = 27°C 0.07 2.0 1.9 5.5 0.10 RL = 44Ω SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) 100 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) Off-State Supply Current vs. Supply Voltage Off-State Supply Current vs. Temperature 120 40 TA = 27°C 100 0 2.5 0.4 80 120 40 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) 5.5 140 SUPPLY CURRENT (µA) 2.7V 80 On-State Supply Current vs. Temperature OUTPUT FALL TIME (µs) SUPPLY CURRENT (mA) 90 50 2.5 ENABLE THRESHOLD (V) 140 120 ON-RESISTANCE (mΩ) ON-RESISTANCE (mΩ) 100 On-State Supply Current vs. Supply Voltage 5000 RSET = 150 1500 VIN = 5V 1000 RSET = 470 500 RSET = 2.3k 0 0 1 2 3 4 5 OUTPUT VOLTAGE (V) 6 June 2000 Micrel MIC2544/2548 Current Limit vs. Temperature Current Limit vs. Supply Voltage 1100 ITH ITH CURRENT LIMIT (mA) OUTPUT CURRENT (mA) 1100 1000 900 VIN = 5V RSET = 230Ω ISET 800 700 ISHORT 600 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) June 2000 1000 900 800 700 600 2.5 7 ISET TA = 27°C RL = 230Ω ISHORT 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) 5.5 MIC2544/2548 Micrel MIC2544/2548 Functional Characteristics VOUT VFLG VEN (2V/div.) (5V/div.) (10V/div.) Turnoff Response VIN = 5V CIN = 4.7µF VIN = 5V CIN = 4.7µF CL = 1µF RL = 10Ω MIC2544-1 MIC2544-1 TIME (1ms/div.) TIME (500µs/div.) VOUT VFLG VEN (5V/div.) (10V/div.) (10V/div.) Enable Into Heavy Load Thermal Shutdown VIN = 5V CIN = 4.7µF RL = 1Ω ISET = 1A ISET = 1A RL = 1Ω MIC2544-1 MIC2544-1 TIME (100ms/div.) TIME (100ms/div.) Enable Into Heavy Load Inrush Current Response VOUT (5V/div.) VIN = 5V CIN = 4.7µF RL = 1Ω ISET = 1A VFLG VEN (5V/div.) (10V/div.) VFLG VEN (5V/div.) (10V/div.) VIN = 5V CIN = 4.7µF IOUT (500mA/div.) IOUT (500mA/div.) VOUT VFLG VEN (5V/div.) (10V/div.) (10V/div.) Current-Limit Response Reset VIN = 5V CIN = 4.7µF RL = 10Ω Output Latched IOUT (500mA/div.) CL = 110µF IOUT (1A/div.) Thermal Shutdown MIC2548-1 CL = 60µF CL = 10µF MIC2544-1 TIME (500µs/div.) MIC2544/2548 CL = 1µF RL = 10Ω IOUT (200mA/div.) IOUT (200mA/div.) VOUT (2V/div.) VFLG VEN (10V/div.) (5V/div.) Turn-On Response TIME (500µs/div.) 8 June 2000 Micrel MIC2544/2548 Block Diagram EN OSC. THERMAL SHUTDOWN 1.2V REFERENCE CHARGE PUMP GATE CONTROL RESET CURRENT LIMIT THERMAL SHUTDOWN LATCH (MIC2548) IN ILIM RSET OUT FLG GND Functional Description Adjustable Current-Limit The MIC2544 and MIC2548 are high-side N-channel 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. 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 ILIM and GND. For a desired current-limit, the value of the external set resistor is given by: Input and Output IN is the power supply connection to the logic circuitry and the drain of the output MOSFET. OUT is the source of the output MOSFET. In a typical circuit, current flows from IN to OUT toward the load. If VOUT is greater than VIN, current will flow from OUT to IN 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 MIC2544/48 avoids undesirable current flow from OUT to IN. Both OUT pins must be connected together. Thermal Shutdown 230V RSET = ILIMIT where: 154Ω < RSET < 2.29kΩ For example, to set a 1A nominal current-limit, RSET is calculated as: 230V = 230Ω 1A Thermal shutdown shuts off the output MOSFET and signals the fault flag if the die temperature exceeds 140°C. 10°C of hysteresis prevents the switch from turning on until the die temperature drops to 130°C. Overtemperature detection functions only when the switch is enabled. The MIC2548 features an internal latch which causes the part to remain off after thermal shutdown until a reset pulse is provided via the enable pin (pin 1). While in current-limit, the thermal shutdown latch prevents on/off cycling of the output. Refer to Figure 2 for timing diagram. The flag remains low until reset. Current through RSET increases with OUT current. The voltage across RSET could be monitored with a high impedance comparator to provide an indication of output current. RSET should be between 154Ω ±0.5% and 2.29kΩ ±0.5%. Short-Circuit Protection In the event of a short-circuit, the output current will fold back to approximately 80% of the short-circuit current-limit. Fault Flag FLG is an N-channel, open-drain MOSFET output. The faultflag 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. Enable Input EN 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. EN should not be allowed to go negative with respect to GND, and VEN should be less than or equal to VIN. June 2000 9 MIC2544/2548 Micrel MIC2544/2548 Tj = PD × θJA + TA where: Applications Information Supply Filtering Tj = junction temperature A 0.1µF to 1µF bypass capacitor from IN to GND, located near the MIC2544 and MIC2548, 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. TA = ambient temperature θJA = 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 10µs to 200µs while the switch is in a constant-current mode, charging the capacitance. 4.0V to 5.5V Adding an optional series resistor-capacitor (RSET2) in parallel with RSET, as shown in Figure 4, 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 10µs to 20µs. If RSET is 435Ω (510mA), an RSET2 of 88Ω (2.5A) and CSET of 1µF (RC = 100µs) allows transient surge of 3A to pass for 100µs without tripping the overcurrent flag (FLG). USB Power Distribution The MIC2544 is ideal for meeting USB power distribution requirements. Figure 4 depicts a USB Host application. RSET should be set to a value providing a current-limit >500mA. The accurate current-limit of the MIC2544 will reduce power supply current requirements. Also, fast reaction to short circuit faults prevent voltage droop in mobile PC applications. MIC2548-1BM 1 On/Off 2 3 4 EN OUT FLG IN GND OUT ILIM NC Power Output 8 7 6 5 RSET 0.1µF to 1µF NOTE: MSOP PACKAGE OPTION USES PIN 5 FOR ILIM. PIN 4 IS NOT CONNECTED (NC). Figure 3. 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. Printed Circuit Board Hot-Plug The MIC2544/48 are ideal inrush current-limiters suitable for hot-plug applications. Due to the integrated charge pump, the MIC2544/48 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. Figure 5 shows how the MIC2544 may be used in a hot-plug application. Calculation of power dissipation can be accomplished by the following equation: PD = RDS(on) × (IOUT)2 To relate this to junction temperature, the following equation can be used: Ferrite Bead 5V (+) 1.5k 2% 4.7µF (–) VBUS D+ 10k IN D– 3.3V USB Controller V+ OUT GND VBUS 100k D+ MIC5203-3.3 LDO Regulator 1.0 µF MIC2544-2BM ON/OFF OVERCURRENT GND EN OUT FLG IN GND OUT ILIM NC 120µF D– GND Downstream USB Port 1 4.75V min. 500mA max. 0.1µF D+ D– 0.01µF GND RSET RSET(2) CSET Bold lines indicate 0.1" wide, 1-oz. copper high-current traces. (optional) NOTE: MSOP PACKAGE OPTION USES PIN 5 FOR ILIM. PIN 4 IS NOT CONNECTED (NC). Figure 4. USB Host Application MIC2544/2548 10 June 2000 Micrel MIC2544/2548 MIC2544-2BM 1 VCC 2 to "Hot" Receptacle 0.1 µF 3 4 EN OUT FLG IN GND OUT ILIM NC 8 7 Backend Function 6 5 CBULK 0.1µF GND Adaptor Card NOTE: MSOP PACKAGE OPTION USES PIN 5 FOR ILIM AND PIN 4 IS NO CONNECT (NC). Figure 5. Hot Plug Application June 2000 11 MIC2544/2548 Micrel MIC2544/2548 Package Information 0.026 (0.65) MAX) PIN 1 0.157 (3.99) 0.150 (3.81) DIMENSIONS: INCHES (MM) 0.020 (0.51) 0.013 (0.33) 0.050 (1.27) TYP 0.064 (1.63) 0.045 (1.14) 45° 0.0098 (0.249) 0.0040 (0.102) 0°–8° 0.197 (5.0) 0.189 (4.8) 0.010 (0.25) 0.007 (0.18) 0.050 (1.27) 0.016 (0.40) SEATING PLANE 0.244 (6.20) 0.228 (5.79) 8-Pin SOP (M) 0.199 (5.05) 0.187 (4.74) 0.122 (3.10) 0.112 (2.84) DIMENSIONS: INCH (MM) 0.120 (3.05) 0.116 (2.95) 0.036 (0.90) 0.032 (0.81) 0.043 (1.09) 0.038 (0.97) 0.012 (0.30) R 0.012 (0.03) 0.0256 (0.65) TYP 0.008 (0.20) 0.004 (0.10) 5° MAX 0° MIN 0.007 (0.18) 0.005 (0.13) 0.012 (0.03) R 0.039 (0.99) 0.035 (0.89) 0.021 (0.53) 8-Pin MSOP (MM) MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB http://www.micrel.com This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. © 2000 Micrel Incorporated MIC2544/2548 12 June 2000