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MIC2025/2075 Micrel MIC2025/2075 Single-Channel Power Distribution Switch Preliminary Information General Description The MIC2025 and MIC2075 are high-side MOSFET switches optimized for general-purpose power distribution requiring circuit protection. The MIC2025/75 are internally current limited and have thermal shutdown that protects the device and load. The MIC2075 offers "smart" thermal shutdown that reduces current consumption in fault modes. When a thermal shutdown fault occurs, the output is latched off until the faulty load is removed. Removing the load or toggling the enable input will reset the device output. Both devices employ soft-start circuitry that minimizes inrush current in applications where highly capacitive loads are employed. A fault status output flag is provided that is asserted during overcurrent and thermal shutdown conditions. The MIC2025/75 is available in the MM8TM 8-lead MSOP and 8-lead SOP. Features * * * * * * * * * * * * 140m maximum on-resistance 2.7V to 5.5V operating range 500mA minimum continuous output current Short-circuit protection with thermal shutdown Fault status flag with 3ms filter eliminates false assertions Undervoltage lockout Reverse current flow blocking (no "body diode") Circuit breaker mode (MIC2075) reduces power consumption Logic-compatible input Soft-start circuit Low quiescent current Pin-compatible with MIC2525 Applications * * * * * * USB peripherals General purpose power switching ACPI power distribution Notebook PCs PDAs PC card hot swap Typical Application VCC 2.7V to 5.5V 10k Logic Controller VIN 1F ON/OFF OVERCURRENT GND MIC2025/75 EN FLG GND NC OUT IN OUT NC 0.1F Load MM8 is a trademark of Micrel, Inc. Micrel, Inc. * 1849 Fortune Drive * San Jose, CA 95131 * USA * tel + 1 (408) 944-0800 * fax + 1 (408) 944-0970 * http://www.micrel.com March 2000 1 MIC2025/2075 MIC2025/2075 Micrel Ordering Information Part Number MIC2025-1BM MIC2025-2BM MIC2025-1BMM MIC2025-2BMM MIC2075-1BM MIC2075-2BM MIC2075-1BMM MIC2075-2BMM Enable Active High Active Low Active High Active Low Active High Active Low Active High Active Low Temperature Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C Package 8-lead SOP 8-lead SOP 8-lead MSOP 8-lead MSOP 8-lead SOP 8-lead SOP 8-lead MSOP 8-lead MSOP Pin Configuration MIC2025/75 EN FLG GND NC 1 2 3 4 8 7 6 5 OUT IN OUT NC 8-Lead SOP (BM) 8-Lead MSOP (BMM) Pin Description Pin Number 1 2 Pin Name EN FLG Pin Function Switch Enable (Input): Active-high (-1) or active-low (-2). Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent or thermal shutdown conditions. Overcurrent condition must exceed tD in order to assert FLG. Ground not internally connected not internally connected Supply (Output): Pins must be connected together. Supply Voltage (Input). 3 4 5 6, 8 7 GND NC NC OUT IN MIC2025/2075 2 March 2000 MIC2025/2075 Micrel Absolute Maximum Ratings (Note 1) Supply Voltage (VIN) ........................................ -0.3V to 6V Fault Flag Voltage (VFLG) .............................................. +6V Fault Flag Current (IFLG) ............................................ 25mA Output Voltage (VOUT) .................................................. +6V Output Current (IOUT) ............................... Internally Limited Enable Input (IEN) ..................................... -0.3V to VIN +3V Storage Temperature (TS) ....................... -65C to +150C ESD Rating, Note 3 Operating Ratings (Note 2) Supply Voltage (VIN) ................................... +2.7V to +5.5V Ambient Temperature (TA) ......................... -40C to +85C Junction Temperature (TJ) ....................... Internally Limited Thermal Resistance SOP (JA) .......................................................... 160C/W MSOP(JA) ........................................................ 206C/W Electrical Characteristics VIN = +5V; TA = 25C, bold values indicate -40C TA +85C; unless noted Symbol IDD Parameter Supply Current Condition MIC20x5-1, VEN 0.8V, (switch off), OUT = open MIC20x5-2, VEN 2.4V, (switch off), OUT = open MIC20x5-1, VEN 2.4V, (switch on), OUT = open MIC20x5-2, VEN 0.8V, (switch on), OUT = open VEN Enable Input Voltage low-to-high transition high-to-low transition Enable Input Hysteresis IEN RDS(on) Enable Input Current Control Input Capacitance Switch Resistance VIN = 5V, IOUT = 500mA VIN = 3.3V, IOUT = 500mA Output Leakage Current OFF Current in Latched Thermal Shutdown tON tR tOFF tF ILIMIT Output Turn-On Delay Output Turn-On Rise Time Output Turnoff Delay Output Turnoff Fall Time Short-Circuit Output Current Current-Limit Threshold Short-Circuit Response Time tD Overcurrent Flag Response Delay Undervoltage Lockout Threshold MIC2025/2075 (output off) MIC2075 (during thermal shutdown state) RL = 10, CL = 1F, see "Timing Diagrams" RL = 10, CL = 1F, see "Timing Diagrams" RL = 10, CL = 1F, see "Timing Diagrams" RL = 10, CL = 1F, see "Timing Diagrams" VOUT = 0V, enabled into short-circuit. ramped load applied to output, Note 4 VOUT = 0V to IOUT = ILIMIT (Short applied to output) VIN = 5V, apply VOUT = 0V until FLG low VIN = 3.3V, apply VOUT = 0V until FLG low VIN rising VIN falling 1.5 1.5 2.2 2.0 0.5 1 0.5 50 2.5 2.3 50 50 0.7 0.85 24 3 3 2.5 2.3 7 8 2.7 2.5 6 5.9 100 100 1.25 1.25 VEN = 0V to 5.5V -1 0.8 2.1 1.9 200 0.01 1 90 100 140 160 10 1 Min Typ 0.75 0.75 Max 5 5 160 160 2.4 Units A A A A V V mV A pF m m A A ms ms s s A A s ms ms V V March 2000 3 MIC2025/2075 MIC2025/2075 Symbol Parameter Error Flag Output Resistance Error Flag Off Current Overtemperature Threshold Condition IL = 10mA, VIN = 5V IL = 10mA, VIN = 3.3V VFLAG = 5V TJ increasing TJ decreasing Note 1. Note 2. Note 3. Note 4. Exceeding the absolute maximum rating may damage the device. The device is not guaranteed to function outside its operating rating. Devices are ESD sensitive. Handling precautions recommended. See "Functional Characteristics: Current-Limit Response" graph. Micrel Min Typ 8 11 Max 25 40 10 140 120 Units A C C Test Circuit VOUT Device Under OUT Test IOUT RL CL Timing Diagrams tR VOUT 10% 90% 90% 10% tF Output Rise and Fall Times VEN 50% tOFF tON VOUT 90% 10% Active-Low Switch Delay Times (MIC20x5-2) VEN 50% tOFF tON VOUT 90% 10% Active-High Switch Delay Times (MIC20x5-1) MIC2025/2075 4 March 2000 MIC2025/2075 Micrel Supply On-Current vs. Temperature 180 ON-RESISTANCE (m) 160 140 CURRENT (A) 120 100 80 60 40 20 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 3.3V 5V 160 140 On-Resistance vs. Temperature 5 4 RISE TIME (ms) 3 2 1 Turn-On Rise Time vs. Temperature VIN = 3.3V 120 100 80 60 40 20 3.3V 5V VIN = 5V RL=10 CL=1F IOUT = 500mA 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) Supply On-Current vs. Input Voltage 200 200 On-Resistance vs. Input Voltage 5.0 4.0 +85C 100 +25C RISE TIME (ms) 3.0 Turn-On Rise Time vs. Input Voltage CURRENT (A) 150 -40C 100 +25C +85C RESISTANCE (m) 150 +85C +25C -40C 2.0 1.0 RL=10 CL=1F 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 50 50 -40C IOUT = 500mA 0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 0 2.5 CURRENT LIMIT THRESHOLD (mA) Short-Circuit Current-Limit vs. Temperature 1000 CURRENT LIMIT (mA) 800 600 400 200 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) VIN = 5V VIN = 3.3V 1200 1000 800 600 400 200 Current-Limit Threshold vs. Temperature 2.5 VIN = 3.3V VIN = 5V ENABLE THRESHOLD (V) 2.0 Enable Threshold vs. Temperature VEN RISING 1.5 VEN FALLING 1.0 0.5 VIN = 5V 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 800 700 CURRENT LIMIT (mA) 600 500 400 300 200 100 CURRENT LIMIT THRESHOLD (mA) Short-Circuit Current-Limit vs. Input Voltage +25C +85C -40C 0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 1200 1100 1000 900 800 700 600 +85C +25C -40C 500 400 300 200 100 0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) Current-Limit Threshold vs. Input Voltage ENABLE THRESHOLD (V) 2.5 2.0 Enable Threshold vs. Input Voltage VEN RISING 1.5 VEN FALLING 1.0 0.5 TA = 25C 0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 5.5 March 2000 5 MIC2025/2075 MIC2025/2075 Micrel Flag Delay vs. Temperature 5 4 3 2 1 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) VIN = 3.3V VIN = 5V DELAY TIME (ms) 5 4 3 2 Flag Delay vs. Input Voltage 3.0 UVLO THRESHOLD (V) +85C 2.5 2.0 UVLO Threshold vs. Temperature VIN RISING DELAY TIME (ms) +25C VIN FALLING 1.5 1.0 0.5 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) -40C 1 0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 MIC2025/2075 6 March 2000 MIC2025/2075 Micrel Functional Characteristics UVLO--VIN Rising (MIC2025-1) VIN VFLG (1V/div.) (1V/div.) UVLO--VIN Falling (MIC2025-1) 2.5V VFLG VIN (2V/div.) (2V/div.) 2.3V VOUT IOUT (100mA/div.) (2V/div.) VEN = VIN VIN = 5V CL = 57F RL = 35 VEN = VIN VIN = 5V CL = 57F RL = 35 IOUT (100mA/div.) VOUT (2V/div.) TIME (10ms/div.) TIME (25ms/div.) VEN VOUT VFLG (5V/div.) (5V/div.) (10V/div.) 640mA VIN = 5V CL = 147F RL = 35 144mA VEN VOUT VFLG (5V/div.) (5V/div.) (10V/div.) Turn-On Response (MIC2025-1) Turnoff Response (MIC2025-1) IOUT (200mA/div.) IOUT (200mA/div.) 144mA VIN = 5V CL = 147F RL = 35 TIME (1ms/div.) TIME (2.5ms/div.) VEN VFLG (5V/div.) (10V/div.) VFLG VEN (5V/div.) (10V/div.) Inrush Current Response (MIC2025-1) Enable Into Short (MIC2025-1) CL = 310F CL = 210F IOUT (200mA/div.) VIN = 5V RL = 35 3.1ms (tD) VIN = 5V VOUT IOUT (500mA/div.) (2V/div.) CL = 110F CL = 10F 640mA Short-Circuit Current TIME (1ms/div.) TIME (1ms/div.) March 2000 7 MIC2025/2075 MIC2025/2075 Micrel Current-Limit Response (Ramped Load Into Short--MIC2025-1) VIN VFLG (5V/div.) (10V/div.) Current-Limit Transient Response (Enable Into Short--MIC2025-1) No Load VFLG (5V/div.) Load VIN = 5V CL = 47F Short Removed VOUT (5V/div.) IOUT (500mA/div.) IOUT (5A/div.) Current-Limit Threshold (780mA) Short-Circuit Current (650mA) VOUT (5V/div.) VIN = 5V CL = 47F 640mA Short-Circuit Current Thermal Shutdown TIME (100ms/div.) TIME (500s/div.) No Load Load VIN = 5V CL = 47F VOUT (5V/div.) VOUT (5V/div.) VFLG VEN (5V/div.) (10V/div.) Current-Limit Transient Response (MIC2025-1) Thermal Shutdown Response (Output Reset by Removing Load--MIC2075-1) Output Latched Off Ramped Load to a Short Output is Reset (Load Removed) VIN = 5V IOUT (500mA/div.) IOUT (5A/div.) Thermal Shutdown 24s 640mA Short-Circuit Current TIME (10s/div.) TIME (100ms/div.) Thermal Shutdown (Output Reset by Toggling Enable--MIC2075-1) VEN VFLG (5V/div.) (10V/div.) VIN = 5V Enable Reset VOUT (5V/div.) Output Reset Ramped Load to a Short RL = 35 Thermal Shutdown RL = 35 IOUT (500mA/div.) TIME (100ms/div.) MIC2025/2075 8 March 2000 MIC2025/2075 Micrel Block Diagram EN THERMAL SHUTDOWN 1.2V REFERENCE OSC. UVLO IN CHARGE PUMP GATE CONTROL CURRENT LIMIT FLAG RESPONSE DELAY OUT FLG GND Functional Description 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 MIC2025/75 avoids undesirable current flow from OUT to IN. Thermal Shutdown Thermal shutdown is employed to protect the device from damage should the die temperature exceed safe margins due mainly to short circuit faults. Each channel employs its own thermal sensor. Thermal shutdown shuts off the output MOSFET and asserts the FLG output if the die temperature reaches 140C. The MIC2025 will automatically reset its output should the die temperature cool down to 120C. The MIC2025 output and FLG signal will continue to cycle on and off until the device is disabled or the fault is removed. Figure 2 depicts typical timing. If the MIC2075 goes into thermal shutdown, its output will latch off and a pull-up current source is activated. This allows the output latch to automatically reset when the load (such as a USB device) is removed. The output can also be reset by toggling EN. Refer to Figure 1 for details. Depending on PCB layout, package, ambient temperature, etc., it may take several hundred milliseconds from the incidence of the fault to the output MOSFET being shut off. The worst-case scenario of thermal shutdown is that of a short-circuit fault and is shown in the in the "Function Characteristics: Thermal Shutdown Response" graph. 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 of each channel and junction temperature are found below. PD = RDS(on) x IOUT2 Total power dissipation of the device will be the summation of PD for both channels. To relate this to junction temperature, the following equation can be used: TJ = PD x JA + TA where: TJ = junction temperature TA = ambient temperature JA = is the thermal resistance of the package Current Sensing and Limiting The current-limit threshold is preset internally. The preset level prevents damage to the device and external load but still allows a minimum current of 500mA to be delivered to the load. The current-limit circuit senses a portion of the output MOSFET switch current. The current-sense resistor shown in the block diagram is virtual and has no voltage drop. The reaction to an overcurrent condition varies with three scenarios: Switch Enabled into Short-Circuit If a switch is enabled into a heavy load or short-circuit, the switch immediately enters into a constant-current mode, reducing the output voltage. The FLG signal is asserted indicating an overcurrent condition. See the Short-Circuit Response graph under Functional Characteristics. March 2000 9 MIC2025/2075 MIC2025/2075 Short-Circuit Applied to Enabled Output When a heavy load or short-circuit is applied, a large transient current may flow until the current-limit circuitry responds. Once this occurs the device limits current to less than the short-circuit current limit specification. See the Short-Circuit Transient Response graph under Functional Characteristics. Current-Limit Response--Ramped Load The MIC2025/75 current-limit profile exhibits a small foldback effect of about 200mA. Once this current-limit threshold is exceeded the device switches into a constant current mode. It is important to note that the device will supply current until the current-limit threshold is exceeded. See the Current-Limit Response graph under Functional Characteristics. Micrel Fault Flag The FLG signal is an N-channel open-drain MOSFET output. FLG is asserted (active-low) when either an overcurrent or thermal shutdown condition occurs. In the case where an overcurrent condition occurs, FLG will be asserted only after the flag response delay time, tD, has elapsed. This ensures that FLG is asserted only upon valid overcurrent conditions and that erroneous error reporting is eliminated. For example, false overcurrent conditions can occur during hot-plug events when a highly capacitive load is connected and causes a high transient inrush current that exceeds the current-limit threshold. The FLG response delay time tD is typically 3ms. Undervoltage Lockout Undervoltage lockout (UVLO) prevents the output MOSFET from turning on until VIN exceeds approximately 2.5V. Undervoltage detection functions only when the switch is enabled. Load Removed (Output Reset) VEN VOUT ILIMIT IDC IOUT VFLG tD Thermal Shutdown Reached Short-Circuit Fault Figure 1. MIC2075-2 Timing: Output Reset by Removing Load VEN VOUT ILIMIT IDC IOUT VFLG Short-Circuit Fault Load/Fault Removed Thermal Shutdown Reached tD Figure 2. MIC2025-2 Timing MIC2025/2075 10 March 2000 MIC2025/2075 Micrel Universal Serial Bus (USB) Power Distribution The MIC2025/75 is ideally suited for USB (Universal Serial Bus) power distribution applications. The USB specification defines power distribution for USB host systems such as PCs and USB hubs. Hubs can either be self-powered or buspowered (that is, powered from the bus). Figure 5 below shows a typical USB Host application that may be suited for mobile PC applications employing USB. The requirements for USB host systems is that the port must supply a minimum of 500mA at an output voltage of 5V 5%. In addition, the output power delivered must be limited to below 25VA. Upon an overcurrent condition, the host must also be notified. To support hot-plug events, the hub must have a minimum of 120F of bulk capacitance, preferably low-ESR electrolytic or tantulum. Refer to Application Note 17 for more details on designing compliant USB hub and host systems. For bus-powered hubs, USB requires that each downstream port be switched on or off under control by the host. Up to four downstream ports each capable of supplying 100mA at 4.4V minimum are allowed. In addition, to reduce voltage droop on the upstream VBUS, soft-start is necessary. Although the hub can consume up to 500mA from the upstream bus the hub must consume only 100mA max at start-up, until it enumerates with the host prior to requesting more power. The same requirements apply for bus-powered peripherals that have no downstream ports. Figure 6 shows a bus-powered hub. Applications Information Supply Filtering A 0.1F to 1F bypass capacitor positioned close to VIN and GND of the device 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. Printed Circuit Board Hot-Plug The MIC2025/75 are ideal inrush current-limiters suitable for hot-plug applications. Due to the integrated charge pump, the MIC2025/75 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 3 shows how the MIC2075 may be used in a hot-plug application. In cases of extremely large capacitive loads (>400F), the length of the transient due to inrush current may exceed the delay provided by the integrated filter. Since this inrush current exceeds the current-limit delay specification, FLG will be asserted during this time. To prevent the logic controller from responding to FLG being asserted, an external RC filter, as shown in Figure 4, can be used to filter out transient FLG assertion. The value of the RC time constant will be selected to match the length of the transient. MIC2025-2 VCC 0.1 F 1 2 EN FLG GND NC OUT IN OUT NC 8 7 6 5 to "Hot" Receptacle 3 4 Backend Function CBULK GND Adaptor Card Figure 3. Hot Plug Application V+ Logic Controller OVERCURRENT 10k 1 MIC2025 EN FLG GND NC OUT IN OUT NC 8 7 6 5 R C 2 3 4 Figure 4. Transient Filter March 2000 11 MIC2025/2075 MIC2025/2075 Micrel VCC 5.0V 4.50V to 5.25V Upstream VBUS 100mA max. VBUS D+ D- GND 1F 3.3V 10k 3.3V USB Controller VIN ON/OFF OVERCURRENT GND MIC2025/75 EN FLG GND NC OUT IN OUT NC 0.1F 120F MIC5203-3.3 IN OUT GND 1F Ferrite Beads VBUS D+ 0.01F D- GND USB Port Data Data Figure 5 USB Host Application 3.3V 1.5k USB Logic Controller VIN ON/OFF OVERCURRENT GND MIC2025/75 EN FLG GND NC OUT IN OUT NC 0.1F 120F USB Upstream Connector VBUS D+ D- GND MIC5203-3.3 (LDO) IN OUT GND 0.1F 1.5K Ferrite Beads VBUS D+ 0.01F D- GND USB Downstream Connector (Up to four ganaged ports) 0.1F Data Data Figure 6. USB Bus-Powered Hub MIC2025/2075 12 March 2000 MIC2025/2075 Micrel Package Information 0.026 (0.65) MAX) PIN 1 0.157 (3.99) 0.150 (3.81) DIMENSIONS: INCHES (MM) 0.050 (1.27) TYP 0.020 (0.51) 0.013 (0.33) 0.0098 (0.249) 0.0040 (0.102) 0-8 SEATING PLANE 45 0.010 (0.25) 0.007 (0.18) 0.064 (1.63) 0.045 (1.14) 0.197 (5.0) 0.189 (4.8) 0.050 (1.27) 0.016 (0.40) 0.244 (6.20) 0.228 (5.79) 8-Lead SOP (M) 0.122 (3.10) 0.112 (2.84) 0.199 (5.05) 0.187 (4.74) 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 0.007 (0.18) 0.005 (0.13) 0.012 (0.03) 0.0256 (0.65) TYP 0.008 (0.20) 0.004 (0.10) 5 MAX 0 MIN 0.012 (0.03) R 0.039 (0.99) 0.035 (0.89) 0.021 (0.53) MM8TM 8-Pin MSOP (MM) March 2000 13 MIC2025/2075 MIC2025/2075 Micrel MIC2025/2075 14 March 2000 MIC2025/2075 Micrel March 2000 15 MIC2025/2075 MIC2025/2075 Micrel MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 TEL USA + 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. (c) 2000 Micrel Incorporated MIC2025/2075 16 March 2000 |
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