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MIC2026/2076
Dual-Channel Power Distribution Switch
General Description
The MIC2026 and MIC2076 are high-side MOSFET switches optimized for general-purpose power distribution requiring circuit protection. The MIC2026/76 are internally current limited and have thermal shutdown that protects the device and load. The MIC2076 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 faults are internally filtered. The MIC2026/76 are available in 8-pin DIP or 8-pin SOIC. All support documentation can be found on Micrel's web site at www.micrel.com.
Features
* * * * * * * * * * * * * * 140m maximum on-resistance per channel 2.7V to 5.5V operating range 500mA minimum continuous current per channel Shortcircuit 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 (MIC2076) Logic-compatible inputs Soft-start circuit Low quiescent current Pin compatible with MIC2526 UL File # E179633
Applications
* USB peripherals * General purpose power switching * ACPI power distribution * Notebook PCs * PDAs * PC card hot swap ___________________________________________________________________________________________________________
Typical Application
VCONT. 10k 10k Logic Controlle r VIN ON/OFF OVERCURRENT OVERCURRENT ON/OFF MIC2026-2 ENA FLGAI FLGB ENB OUTA N GND OUTB Load 0.1F Load VCC 2.7V to 5.5V
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
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MIC2026/2076
Ordering Information
Part Number Standard MIC2026-1BM MIC2026-2BM MIC2026-1BN MIC2026-2BN MIC2076-1BM MIC2076-2BM MIC2076-1BN MIC2076-2BN
Note: 1. RoHS compliant and Halogen free.
Pb-Free MIC2026-1YM(1) MIC2026-2YM -- -- MIC2076-1YM(1) MIC2076-2YM(1) -- --
(1)
Enable Active High Active Low Active High Active Low Active High Active Low Active High Active Low
Temperature Range
Package 8-Pin SOIC 8- Pin SOIC 8- Pin DIP
-40C to +85C
8- Pin DIP 8- Pin SOIC 8- Pin SOIC 8-Pin DIP 8-Pin DIP
Pin Configuration
ENA 1 FLGA 2 FLGB 3 ENB 4 8 OUTA 7 IN 6 GND 5 OUTB
8-Pin SOIC (M) 8-Pin DIP (N)
Pin Description
Pin Number 1 2 Pin Name ENA FLGA Pin Function Switch A Enable (Input): Logic-compatible, enable input. Active high (-1) or active low (-2). Fault Flag A (Output): Active-low, open-drain output. Indicates overcurrent or thermal shutdown conditions. Overcurrent conditions must last longer than tBD in order to assert FLGA.
B
3
FLGB
Fault Flag B (Output): Active-low, open-drain output. Low indicates overcurrent or thermal shutdown conditions. Overcurrent conditions must last longer than tBD in order to assert FLGB.
B
4 5 6 7 8
ENB OUTB GND IN OUTA
Switch B Enable (Input): Logic-compatible enable input. Active-high (-1) or active-low (-2). Switch B (Output) Ground Input: Switch and logic supply input. Switch A (Output)
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Absolute Maximum RatingsP(1)
Supply Voltage (VBIN) ........................................ -0.3V to +6V Fault Flag Voltage (VBFLG) ................................................+6V Fault Flag Current (IBFLG) ..............................................25mA Output Voltage (VBOUT) ....................................................+6V Output Current (IBOUT) .................................Internally Limited Enable Input (IBEN) ..................................... -0.3V to VIN + 3V Storage Temperature (TBS) ........................-65C to +150 C ESD Rating(3) HBM ......................................................................... 1kV MM .........................................................................200V
B B B B B B B
Operating RatingsP(2)
Supply Voltage (VBIN) ..................................... +2.7V to +5.5V Ambient Temperature (TBA) .......................... -40C to +85C Junction Temperature Range (TBJ) ............. Internally Limited Thermal Resistance SOIC (BJA) ........................................................160C/W PDIP (BJA) ........................................................105C/W
B B B B B
Electrical Characteristics(4)
P
VBIN = +5V; TBA = 25C, bold values indicate -40C TBA +85C; unless noted
B B B
Symbol IBDD
B
Parameter Supply Current
Condition MIC20x6-1, VBENA = VBENB 0.8V (switch off), OUT = open
B B
Min
Typ 0.75 9.5 100 100 1.7
Max 5 20 160 160 2.4
Units A A A A V V mV
MIC20x6-2, VBENA = VBENB 2.4V (switch off), OUT = open
B B
MIC20x6-1, VBENA = VBENB 2.4V (switch on), OUT = open
B B
MIC20x6-2, VBENA = VBENB 0.8V (switch on), OUT = open
B B
VBEN
B
Enable Input Threshold
low-to-high transition high-to-low transition 0.8
1.45 250
Enable Input Hysteresis IBEN
B
Enable Input Current Enable Input Capacitance
VBEN = 0V to 5.5V
B
-1
0.01 1
1
A pF
RBDS(ON)
B
Switch Resistance
VBIN = 5V, IBOUT = 500mA
B B
90 100
140 170 10
m m A A
VBIN = 3.3V, IBOUT = 500mA
B B
Output Leakage Current OFF Current in Latched Thermal Shutdown tBON
B
MIC20x6-1, VENx 0.8V; MIC20x6-1, VENx 2.4V, (output off) MIC2076 (during thermal shutdown state) RBL = 10, CBL = 1F, see "Timing Diagrams"
B B
50 1.3 0.5 1.15 1.75 35 32 0.5 0.65 0.9 1.0 20 100 100 1.25 1.25 5 4.9
Output Turn-On Delay Output Turn-On Rise Time
ms ms ms s s A A s
tBR
B
RBL = 10, CBL = 1F, see "Timing Diagrams"
B B
RBL = 10, CBL = 1F, see "Timing Diagrams"
B B
tBOFF
B
Output Turn-Off Delay Output Turn-Off Fall Time
B
RBL = 10, CBL = 1F, see "Timing Diagrams"
B B
tBF
B
RBL = 10, CBL = 1F, see "Timing Diagrams"
B B
IBLIMIT
Short-Circuit Output Current Current-Limit Threshold Short-Circuit Response Time
VBOUT = 0V, enabled into short-circuit
B
ramped load applied to output VBOUT = 0V to IBOUT = IBLIMIT (short applied to output)
B B B
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Symbol tD Parameter Overcurrent Flag Response Delay Undervoltage Lockout Threshold Error Flag Output Resistance Condition VBIN = 5V, apply VBOUT = 0V until FLG low
B B
MIC2026/2076
Min 1.5 Typ 3 3 2.2 2.0
B
Max 7
Units ms ms
VBIN = 3.3V, apply VBOUT = 0V until FLG low
B B
VBIN rising
B
2.4 2.15 10 15
2.7 2.5 25 40 10
V V A C C C C
VBIN falling
B
IBL = 10mA, VBIN = 5V
B
IBL = 10mA, VBIN = 3.3V
B B
Error Flag Off Current Overtemperature ThresholdP
(5)
P
VBFLAG = 5V
B
TBJ increasing, each switch TBJ decreasing, each switch
B B
140 120 160 150
TBJ increasing, both switches TBJ decreasing, both switches
B B
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. 4. Specification for packaged product only. 5. If there is a fault on one channel, that channel will shut down when the die reaches approximately 140C. If the die reaches approximately 160C, both channels will shut down, even if neither channel is in current limit.
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Test Circuit
VOUT Device Under OUT Test RL CL
Timing Diagrams
tR VOUT 10%
Output Rise and Fall Times
tF 90% 90% 10%
VEN
50% tOFF tON
VOUT
90% 10%
Active-Low Switch Delay Times (MIC20x6-2)
VEN
50% tOFF tON 90% 10%
Active-High Switch Delay Time (MIC20x6-1)
VOUT
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Typical Characteristics
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Typical Characteristics (continue)
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Functional Characteristics
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Functional Characteristics (continue)
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Functional Characteristics (continue)
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Block Diagram
FLGA
FLAG RESPONSE DELAY ENA CHARGE PUMP GATE CONTROL
OUTA
CURRENT LIMIT
OSC.
THERMAL SHUTDOWN
UVLO
1.2V REFERENCE
IN
CHARGE PUMP ENB
GATE CONTROL
CURRENT LIMIT
FLAG RESPONSE DELAY
OUTB FLGB
MIC2026/2076 GND
MIC2026/2076 Block Diagram
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 MIC2026/76 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 channel is not affected. If however, the die temperature exceeds 160C, both channels will be shut off. Upon determining a thermal shutdown condition, the MIC2076 will latch the output off. In this case, a pull-up current source is June 2010 11
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 timing details. The MIC2026 will automatically reset its output when the die temperature cools down to 120C. The MIC2026 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 both channels. To relate this to junction temperature, the following equation can be used:
M9999-060410-B
Micrel, Inc. 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 Current-Limit Response--Ramped Load
MIC2026/2076
The MIC2026/76 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 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 for up to 1ms. 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.
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.
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 current-limit circuitry responds. Once this occurs, the device limits current to less than the short-circuit current limit specification.
VEN VOUT ILIMIT ILOAD IOUT VFLG 3ms typ. delay
Short-Circuit Fault
Load and Fault Removed (Output Reset)
Thermal Shutdown Reached
Figure 1. MIC2076-2 Fault Timing: Output Reset by Removing Load
VEN VOUT ILIMIT ILOAD IOUT VFLG 3ms typ. delay
Short-Circuit Faul t Load/Fault Removed Thermal Shutdown Reached
Figure 2. MIC2026-2 Fault Timing
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MIC2026/2076 Universal Serial Bus (USB) Power Distribution The MIC2026/76 are 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 bus-powered (that is, powered from the bus). Figure 5 shows a typical USB Host application that may be suited for mobile PC applications employing USB. The requirement 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. Please 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.
Application 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 MIC2026/76 are ideal inrush current-limiters for hot plug applications. Due to their integrated charge pumps, the MIC2026/76 present a high impedance when off and slowly become a low impedance as their integrated charge pumps turn on. This "soft-start" feature effectively isolates power supplies from highly capacitive loads by reducing inrush current. Figure 3 shows how the MIC2076 may be used in a card 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 should be selected to match the length of the transient, less tD(min) of the MIC2026/76.
USB Controller SPN010012 VBUS 4.7 F
1 2 3 4
ENA FLGA FLGB ENB
OUTA IN GND OUTB
8 7 6 5
USB Function CBULK USB Function CBULK
to "Hot" Receptacle
GND Cable USB Peripheral
Figure 3. Hot-Plug Application
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Figure 4. Transient Filter
Figure 5. USB Two-Port Host Application
Figure 6. USB Two-Port Bus-Powered Hub
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Package Information
8-Pin SOIC (M)
8-Pin DIP (N)
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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) 2006 Micrel, Incorporated.
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