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MIC2027/2077
Micrel
MIC2027/2077
Quad USB Power Distribution Switch Preliminary Information
General Description
The MIC2027 and MIC2077 are quad high-side MOSFET switches optimized for general-purpose power distribution requiring circuit protection. The MIC2027/77 are internally current limited and have thermal shutdown that protects the device and load. The MIC2077 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 asserted during overcurrent and thermal shutdown conditions. Transient current limit faults are internally filtered. The MIC2027/77 is available in narrow (150 mil) and wide (300 mil) SOP (small outline packages).
Features
* * * * * * * * * * * * 140m maximum on-resistance per channel 2.7V to 5.5V operating range 500mA minimum continuous current per channel Short-circuit protection with thermal shutdown Thermally isolated channels Fault status flag with 3ms filter eliminates false assertions Undervoltage lockout Reverse current flow blocking (no "body diode") Circuit breaker mode (MIC2077) reduces power consumption Logic-compatible inputs Soft-start circuit Low quiescent current Pin-compatible with MIC2524 and MIC2527
Applications
* * * * * * USB peripherals General purpose power switching ACPI power distribution Notebook PCs PDAs PC card hot swap
Typical Application
5V 3% 10k MIC5203-3.3 LDO Regulator IN 4.7 F OUT 1F GND 3.3V USB Controller V+ ON/OFF OVERCURRENT MIC2027 ENA FLGA ENB FLGB D+ D- GND ENC FLGC END FLGD Bold lines indicate 0.1" wide, 1-oz. copper high-current traces. * 33F, 16V tantalum or 100F, 10V electrolytic per port IN IN OUTA OUTB OUTC OUTD GND GND 33F* 0.01F 0.1 F 33F* 0.01F 33F* 0.01F Ferrite Bead VBUS D+ D- GND Downstream USB Port 1 500mA max.
VBUS D+ D- GND Downstream USB Port 2 500mA max.
VBUS D+ D- GND Downstream USB Port 3 500mA max.
VBUS 33F* 0.01F D+ D- GND Downstream USB Port 4 500mA max.
4-Port Self-Powered Hub
Micrel, Inc. * 1849 Fortune Drive * San Jose, CA 95131 * USA * tel + 1 (408) 944-0800 * fax + 1 (408) 944-0970 * http://www.micrel.com
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Ordering Information
Part Number MIC2027-1BWM MIC2027-1BM MIC2027-2BWM MIC2027-2BM MIC2077-1BWM MIC2077-1BM MIC2077-2BWM MIC2077-2BM Enable Active High Active High Active Low Active Low Active High Active High Active Low 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 16-lead wide SOP 16-lead SOP 16-lead wide SOP 16-lead SOP 16-lead wide SOP 16-lead SOP 16-lead wide SOP 16-lead SOP
Pin Configuration
FLGA ENA OUTA GND IN(C/D) OUTC ENC FLGC 1 2 3 4 5 6 7 8 16 FLGB 15 ENB 14 OUTB 13 IN(A/B) 12 GND 11 OUTD 10 END 9 FLGD 4 GND 12 ENC 7 FLGC 8 END 10 FLGD 9
LOGIC, CHARGE PUMP
3 OUTA ENA 2 FLGA 1 ENB 15 FLGB 16
LOGIC, CHARGE PUMP
13 IN(A/B)
LOGIC, CHARGE PUMP
14 OUTB 6 OUTC 5 IN(C/D)
LOGIC, CHARGE PUMP
11 OUTD
16-Lead SOP (M) 16-Lead Wide SOP (WM)
Functional Pinout
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Pin Description
Pin Number 1 Pin Name FLGA Pin Function Fault Flag A: (Output): Active-low, open-drain output. Low indicates overcurrent or thermal shutdown conditions. Overcurrent conditions must last longer than tD to assert flag. Switch A Enable (Input): Logic-compatible enable input. Active high (-1) or active low (-2). Switch A Output Ground Input: Channel C and D switch and logic supply input. Switch C Output Switch C Enable (Input) Fault Flag C (Output) Fault Flag D (Output) Switch D Enable (Input) Switch D Output Supply Input: Channel A and B switch and logic supply input. Switch B Output Switch B Enable (Input) Fault Flag B (Output)
2 3 4, 12 5 6 7 8 9 10 11 13 14 15 16
ENA OUTA GND IN(C/D) OUTC ENC FLGC FLGD END OUTD IN(A/B) OUTB ENB FLGB
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 +150 C Lead Temperature (soldering 5 sec.) ........................ 260C ESD Rating, Note 3 ...................................................... 1kV
Operating Ratings (Note 2)
Supply Voltage (VIN) ................................... +2.7V to +5.5V Ambient Temperature (TA) ......................... -40C to +85C Junction Temperature Range (TJ) ........... Internally Limited Thermal Resistance [300 mil] Wide SOP (JA) .................................. 120C/W [150 mil] SOP (JA) ........................................... 112C/W DIP(JA) ............................................................. 130C/W
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Electrical Characteristics
VIN = +5V; TA = 25C, bold values indicate -40C TA +85C; unless noted Symbol IDD Parameter Supply Current Condition MIC20x7-1, VENA-D 0.8V (switch off), OUT = open MIC20x7-2, VENA-D 2.4V (switch off), OUT = open MIC20x7-1, VENA-D 2.4V (switch on), OUT = open MIC20x7-2, VENA-D 0.8V (switch on), OUT = open VEN Enable Input Threshold low-to-high transition high-to-low transition Enable Input Hysteresis IEN RDS(on) Enable Input Current Enable Input Capacitance Switch Resistance VIN = 5V, IOUT = 500mA VIN = 3.3V, IOUT = 500mA Output Leakage Current Output 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 Error Flag Output Resistance Error Flag Off Current Overtemperature Threshold Note 4 MIC20x7-1, VENx 0.8V; MIC20x7-2, VENx 2.4V, (output off) MIC2077 (per Latch Output) (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 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 IL = 10mA, VIN = 5V IL = 10mA, VIN = 3.3V VFLAG = 5V TJ increasing, each switch TJ decreasing, each switch TJ increasing, both switches TJ decreasing, both switches
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. Human body model, 1.5k in series with 100pF. If there is an output current limit fault on one channel, that channel will shut down when the die reaches approximately 140C. If the die reaches approximately 160C, the other channel driven by the same input will shut down, even if neither channel is in current limit.
Min
Typ 1.5 1.5 200 200 1.7
Max 10 10 320 320 2.4
Units A A A A V V mV A pF
0.8
1.45 250
VEN = 0V to 5.5V
-1
0.01 1 100 110
1
150 170 10
m m A A
50 1.3 1.15 35 32 0.5 0.9 1.0 20 1.5 3 3 2.2 2.0 2.4 2.15 10 15 2.7 2.5 25 40 10 140 120 160 150 7 5 4.9 100 100 1.25 1.25
ms ms s s A A s ms ms V V A C C C C
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Test Circuit
VOUT Device Under OUT Test 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 (MIC20x7-2)
VEN
50% tOFF tON
VOUT
90% 10%
Active-High Switch Delay Times (MIC20x7-1)
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Supply On-Current vs. Temperature
350 ON-RESISTANCE (m) 300 5V CURRENT (A) 250 200 150 100 50 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 3.3V 160 140
On-Resistance vs. Temperature
5 3.3V RISE TIME (ms) 4 3 2 1
Turn-On Rise Time vs. Temperature
120 100 80 60 40 20
5V
RL=10 CL=1F VIN = 3.3V
IOUT = 500mA
VIN = 5V 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
400 200
On-Resistance vs. Input Voltage
2.5 2.0 +85C +25C 100 -40C 50 IOUT = 500mA RISE TIME (ms)
Turn-Off Rise Time vs. Input Voltage
CURRENT (A)
300
RESISTANCE (m)
-40C
150
+85C 1.5 1.0 0.5 0 2.5 -40C RL=10 CL=1F 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 +25C
200 +25C 100 +85C
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
1000 CURRENT LIMIT (mA) 800 600 VIN = 5V 400 200 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) VIN = 3.3V
CURRENT LIMIT THRESHOLD (mA)
Short-Circuit Current-Limit vs. Temperature
Current-Limit Threshold vs. Temperature
1200 VIN = 5V 1000 800 600 400 200 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) VIN = 3.3V FALL TIME (s) 300 400
Fall Time vs. Temperature
VIN = 3.3V 200
RL=10 CL=1F
100
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
CURRENT LIMIT THRESHOLD (mA)
Short-Circuit Current-Limit vs. Input Voltage
800 700 CURRENT LIMIT (mA) 600 500 +85C 400 300 200 100 0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 +25C -40C
1200 1000 800 600 400 200 0 2.5
Current-Limit Threshold vs. Input Voltage
300 250 RISE TIME (s) +85C +25C -40C 200 150 100 50 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 0 2.5
Fall Time vs. Input Voltage
TA = 25C CL = 1F RL = 10 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5
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Enable Threshold vs. Temperature
2.5 ENABLE THRESHOLD (V) 2.0 1.5 VEN FALLING 1.0 0.5 VIN = 5V 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) VEN RISING 5 4
Flag Delay vs. Temperature
0.35 SUPPLY CURRENT (A) VIN = 3.3V DELAY TIME (ms) VIN = 5V 3 2 1 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 0.30 0.25 0.20 0.15 0.10 0.05
Supply Off Current vs. Temperature
5V
3.3V
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
2.5 ENABLE THRESHOLD (V) 2.0 1.5 1.0 0.5
Enable Threshold vs. Input Voltage
5 4 3 2 1 0 2.5
Flag Delay vs. Input Voltage
SUPPLY CURRENT (A) +85C
0.35 0.30 0.25 0.20 0.15 0.10 0.05 0 2.5
Supply Off Current vs. Input Voltage
DELAY TIME (ms)
VEN RISING
+85C
+25C -40C
VEN FALLING
+25C -40C
TA = 25C 0 2.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) 5.5
3.0
3.5 4.0 4.5 VOLTAGE (V)
5.0
5.5
UVLO Threshold vs. Temperature
3.0 UVLO THRESHOLD (V) 2.5 2.0 VIN FALLING 1.5 1.0 0.5 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) VIN RISING
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Functional Characteristics
UVLO--VIN Rising (MIC2027-1)
VIN VFLG (2V/div.) (2V/div.) VFLG VIN (2V/div.) (2V/div.)
UVLO--VIN Falling (MIC2027-1)
2.4V
2.2V
VEN = VIN CL = 57F RL = 35
VOUT IOUT (100mA/div.) (5V/div.)
VOUT (2V/div.)
IOUT (100mA/div.)
VEN = VIN CL = 57F RL = 35
TIME (10ms/div.)
TIME (100ms/div.)
VEN VOUT VFLG (5V/div.) (5V/div.) (10V/div.)
712mA (Inrush Current) VIN = 5V CL = 147F RL = 35 140mA
VOUT VFLG VEN (5V/div.) (5V/div.) (10V/div.)
Turn-On/Turnoff (MIC2027-1)
Turn-On (MIC2027-1)
IOUT (200mA/div.)
IOUT (200mA/div.)
VIN = 5V CL = 147F RL = 35 140mA
TIME (10ms/div.)
TIME (500s/div.)
VEN VOUT VFLG (5V/div.) (5V/div.) (10V/div.)
Turnoff (MIC2027-1)
VEN VOUT VFLG (5V/div.) (5V/div.) (10V/div.)
Enabled Into Short (MIC2027-1)
3.1ms (tD)
700mA
IOUT (200mA/div.)
140mA
VIN = 5V CL = 147F RL = 35
IOUT (500mA/div.)
VIN = 5V
TIME (5ms/div.)
TIME (500s/div.)
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Inrush Current Response (MIC2027-1)
VEN VFLG (5V/div.) (10V/div.) VFLG VIN (10V/div.) (10V/div.)
Current-Limit Response (Ramped Load-MIC2027-1)
VIN = 5V CL = 47F
CL = 110F
IOUT (200mA/div.)
CL = 210F CL = 310F
VIN = 5V RL = 31
VOUT (5V/div.)
IOUT (500mA/div.)
Current-Limit Threshold (1A)
Short-Circuit Current (800mA) Thermal Shutdown
Short Removed
Thermal Shutdown Hysteresis
CL = 10F TIME (1ms/div.)
TIME (100ms/div.)
Current-Limit Response (Stepped Short--MIC2027-1)
VEN VFLG (5V/div.) (10V/div.)
Current-Limit Response (MIC2027-1)
VIN = 5V CL = 47F RL = stepped short
VOUT (5V/div.)
VIN = 5V CL = 0 RL = stepped short
VOUT (5V/div.)
IOUT (2A/div.)
IOUT (5A/div.)
Short-Circuit (800mA)
800mA
TIME (1ms/div.)
TIME (50s/div.)
VENB VFLGA (5V/div.) (10V/div.)
VOUTA = No Load (No Thermal Shutdown)
VENA VFLGB VFLGA (5V/div.) (5V/div.) (10V/div.)
Independent Thermal Shutdown (MIC2027-1)
Independent Thermal Shutdown (MIC2027-1)
VFLGB (5V/div.)
VOUTB = No Load (No Thermal Shutdown)
IOUTA (500mA/div.)
IOUTB (500mA/div.)
Thermal Shutdown VENA = 5V VENB = 5V VENC = 0V VEND = 0V TIME (100ms/div.)
Thermal Shutdown VENA = 5V VENB = 5V VENC = 0V VEND = 0V TIME (100ms/div.)
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Load Removed
VOUT VFLG (5V/div.) (10V/div.)
No Load
RL = 0
VEN (10V/div.)
Thermal Shutdown (MIC2077-2--Output Latched Off)
Thermal Shutdown (Output Reset by Toggling Enable--MIC2077-2)
VFLG (5V/div.)
Enable Reset
Output Reset Thermal Shutdown
IOUTB (500mV/div.)
IOUT (500mA/div.)
VIN = 5V CL = 47F VENB = 0V
VOUT (5V/div.)
Ramp Load to Short
Output Reset
CL = 57F RL = 35
Thermal Shutdown VIN = 5V
TIME (2.5s/div.)
TIME (100ms/div.)
VEN VFLG (5V/div.) (10V/div.)
Thermal Shutdown (Output Reset by Removing Load--MIC2077-2)
RL = 0
Independent Thermal Shutdown (MIC2077-2)
Load Removed No Load
VFLGB VFLGA (5V/div.) (5V/div.)
Output Latched Off Ramp Load to Short
No Thermal Shutdown on Channel B
Load Removed (Output Reset)
VOUT (5V/div.)
Output Reset Thermal Shutdown VIN = 5V CL = 47F VENB = 0V VENA = 0V VENC = 5V VEND = 5V
IOUT (500mA/div.)
Thermal Shutdown
VIN = 5V CL = 47F
TIME (100ms/div.)
IOUTA (500mA/div.)
TIME (2.5s/div.)
Independent Thermal Shutdown (MIC2077-2)
RL = 0
VFLGA VFLGB (5V/div.) (10V/div.)
Load Removed
No Load
Output Reset
No Thermal Shutdown on Channel A VIN = 5V CL = 47F VENB = 0V VENA = 0V VENC = 5V VEND = 5V
IOUTB (500mA/div.)
Thermal Shutdown
TIME (2.5s/div.)
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Block Diagram
RESET (MIC2077 ONLY)
THERMAL SHUTDOWN LATCH FLAG DELAY
FLGA
OUTA
CHARGE PUMP
GATE CONTROL CURRENT LIMIT
OSC.
THERMAL SHUTDOWN
UVLO
1.2V REFERENCE
IN (A/B)
CHARGE PUMP GATE CONTROL ENB
CURRENT LIMIT
FLAG DELAY RESET (MIC2077 ONLY) RESET (MIC2077 ONLY) THERMAL SHUTDOWN LATCH
OUTB FLGB
THERMAL SHUTDOWN LATCH FLAG DELAY
FLGC
OUTC
ENC CHARGE PUMP GATE CONTROL CURRENT LIMIT
OSC.
THERMAL SHUTDOWN
UVLO
1.2V REFERENCE
IN (C/D)
CHARGE PUMP GATE CONTROL END
CURRENT LIMIT
FLAG DELAY RESET (MIC2077 ONLY) MIC2027 THERMAL SHUTDOWN LATCH GND
OUTD FLGD
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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:
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 MIC2027/77 prevents 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 and the overheated channel is in current limit. The other channels are not effected. If however, the die temperature exceeds 160C, all channels will be shut off. Upon determining a thermal shutdown condition, the MIC2077 will latch the output off and activate a pull-up current source. When the load is removed, this current source will pull the output up and reset the latch. Toggling EN will also reset the latch. The MIC2027 will automatically reset its output when the die temperature cools down to 120C. The MIC2027 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. 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. This time will be shortest in the case of a dead short on the output. 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 all channels. To relate this to junction temperature, the following equation can be used: TJ = PD x JA + TA
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, limiting the output voltage. The FLG signal is asserted indicating an overcurrent condition. Short-Circuit Applied to Enabled Output When a heavy load or short-circuit is applied to an enabled switch, a large transient current may flow until the currentlimit circuitry responds. Once this occurs the device limits current to less than the short-circuit current limit specification. Current-Limit Response--Ramped Load The MIC2027/77 current-limit profile exhibits a small foldback effect of about 100mA. 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 up to the current-limit threshold. 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 of an overcurrent condition, 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.
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Load and Fault Removed (Output Reset) VEN VOUT ILIMIT ILOAD IOUT VFLG 3ms typ. delay Short-Circuit Fault
Thermal Shutdown Reached
Figure 1. MIC2077-2 Fault Timing: Output Reset by Removing Load
VEN VOUT ILIMIT ILOAD IOUT VFLG 3ms typ. delay
Short-Circuit Fault Load/Fault Removed
Thermal Shutdown Reached
Figure 2. MIC2027-2 Fault Timing
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controller from responding to FLG being asserted, an external RC filter, as shown in Figure 3, can be used to filter out transient FLG assertion. The value of the RC time constant should be selected to match the length of the transient, less tD(min) of the MIC2027/77. Universal Serial Bus (USB) Power Distribution The MIC2027/77 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). The requirement for USB self-powered hubs 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. Please refer to Application Note 17 for more details on designing compliant USB hub and host systems.
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 MIC2027/77 are ideal inrush current-limiters for hot-plug applications. Due to the integrated charge pump, the MIC2027/77 presents a high impedance when off and slowly becomes a low impedance as it turns on. This "soft-start" feature effectively isolates power supplies from highly capacitive loads by reducing inrush current. 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 flag delay specification, FLG will be asserted during this time. To prevent the logic
V+ Logic Controller OVERCURRENT 10k R C MIC2027
1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9
FLGA ENA
FLGB ENB
OUTA OUTB GND IN(A/B) IN(C/D) GND OUTC OUTD ENC FLGC END FLGD
Figure 3. Transient Filter
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Package Information
PIN 1
0.157 (3.99) 0.150 (3.81)
DIMENSIONS: INCHES (MM)
0.020 (0.51) REF 0.050 (1.27) BSC
0.020 (0.51) 0.013 (0.33) 0.0098 (0.249) 0.0040 (0.102)
45 0-8 0.050 (1.27) 0.016 (0.40) 0.244 (6.20) 0.228 (5.79)
0.0648 (1.646) 0.0434 (1.102)
0.394 (10.00) 0.386 (9.80)
SEATING PLANE
16-Lead SOP (M)
PIN 1
0.301 (7.645) 0.297 (7.544)
DIMENSIONS: INCHES (MM)
0.027 (0.686) 0.031 (0.787)
0.103 (2.616) 0.050 (1.270) 0.016 (0.046) 0.099 (2.515) TYP TYP
0.094 (2.388) 0.090 (2.286)
0.409 (10.389) 0.405 (10.287)
7 TYP 0.015 R (0.381) 0.015 (0.381) SEATING MIN PLANE
0.297 (7.544) 0.293 (7.442)
0.022 (0.559) 0.018 (0.457) 5 TYP 10 TYP
0.330 (8.382) 0.326 (8.280) 0.032 (0.813) TYP 0.408 (10.363) 0.404 (10.262)
16-Lead Wide SOP (WM)
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MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131
TEL
USA
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
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MIC2027/2077
16
June 2000

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Price & Availability of MIC2027

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