MIC2026A/2076A
Dual-Channel Power Distribution Switch
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
July 2009
M9999-072309-B
(408) 955-1690
General Description
The MIC2026A and MIC2076A are high-side MOSFET
switches optimized for general-purpose power distribution
requiring circuit protection. The MIC2026A is particularly
well suited for USB applications.
The MIC2026A/2076A are internally current limited and
have thermal shutdown that protects the device and load.
The MIC2076A offers “smart” shutdown that reduces
current consumption in fault modes. When the MIC2076A
goes into thermal shutdown due to current limiting, the
output is latched off until the switch is reset. The
MIC2076A can be reset by removing the load, toggling the
enable input, or cycling VIN.
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 or
thermal shutdown conditions. Transient faults are internally
filtered.
The MIC2026A/2076A are available in an 8-pin SOIC
package.
All support documentation can be found on Micrel’s web
site at www.micrel.com.
Features
• 100mΩ typical RDS(ON) at 5.0V
• 140mΩ maximum RDS(ON) at 5.0V
• 2.7 V to 5.5 V operating range
• 500mA minimum continuous current per channel
• Short circuit protection with thermal shutdown
• Thermally isolated channels
• Soft-start circuit
• Fault status flag with 3ms filter eliminates false
assertions
• UVLO (Undervoltage lockout)
• Reverse current flow blocking (no “body diode”)
• Circuit breaker mode (MIC2076A)
• Pin compatible with the MIC2026/2076
• Logic-compatible inputs
• Low quiescent current
Applications
• USB peripherals
• General purpose power switching
• ACPI power distribution
• Notebook PCs
• PDAs
• PC card hot swap
_______________________________________________________________________________________________
Typical Application
Micrel, Inc. MIC2026A/2076A
July 2009 2 M9999-072309-B
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Ordering Information
Part Number Enable Temperature Range Package Lead Finish
MIC2026A-1YM Active High –40° to +85°C 8- Pin SOIC Pb-Free
MIC2026A-2YM Active Low –40° to +85°C 8- Pin SOIC Pb-Free
MIC2076A-1YM Active High –40° to +85°C 8- Pin SOIC Pb-Free
MIC2076A-2YM Active Low –40° to +85°C 8- Pin SOIC Pb-Free
Pin Configuration
1ENA
FLGA
FLGB
ENB
8OUTA
IN
GND
OUTB
7
6
5
2
3
4
8-Pin SOIC (M)
Pin Description
Pin Number Pin Name Pin Function
1 ENA Switch A Enable (Input): Logic-compatible, enable input. Active high (-1) or active low (-2).
2 FLGA
Fault Flag A (Output): Active-low, open-drain output. A logic LOW state Indicates
overcurrent or thermal shutdown conditions. Overcurrent conditions must last longer than tBDB
in order to assert FLGA. The FLGA pin can be left floating; however, fault reporting
information will be lost.
3 FLGB
Fault Flag B (Output): Active-low, open-drain output. A logic LOW state indicates
overcurrent or thermal shutdown conditions. Overcurrent conditions must last longer than tBDB
in order to assert FLGB. The FLGB pin can be left floating; however, fault reporting
information will be lost.
4 ENB Switch B Enable (Input): Logic-compatible enable input. Active-high (-1) or active-low (-2).
5 OUTB Switch B (Output).
6 GND Ground.
7 IN Input: Switch and logic supply input.
8 OUTA Switch A (Output).
Micrel, Inc. MIC2026A/2076A
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Absolute Maximum RatingsP
(1)
Supply Voltage (VIN)....................................... –0.3V to +6V
Output Voltage (OUTA and OUTB) ................ –0.3V to +6V
All other pins voltages ..................................... –0.3V to +6V
Fault Flag Current (IBFLGB)..............................................25mA
Output Current (IBOUTB).................................Internally Limited
Storage Temperature (TBSB) .......................–65°C to +150 °C
ESD Rating(3)
HBM......................................................................... 3kV
MM.........................................................................200V
Lead Temperature (Soldering 10 sec) ....................... 260°C
Operating RatingsP
(2)
Supply Voltage (VBINB) .................................... +2.7V to +5.5V
Ambient Temperature (TBAB).......................... –40°C to +85°C
Junction Temperature Range (TBJB) ............Internally Limited
Thermal Resistance
SOIC (θBJAB) .......................................................160°C/W
Electrical Characteristics(4)
VIN = 5V; TA = 25°C, unless noted, bold values indicate –40°C ≤ TA ≤ +85°C.
Symbol Parameter Condition Min Typ Max Units
MIC20X6A-1, VBENA B= VBENB B= 0V
(switch off), OUT = open 0.75 5 µA
MIC20X6A-2, VBENA B= VBENB B = 5V
(switch off), OUT = open 0.75
20 µA
MIC20X6A-1, VBENA B= VBENB = 5V
(switch on), OUT = open 100 160 µA
IBDDB Supply Current
MIC20X6A-2, VBENA B= VBENB B= 0V
(switch on), OUT = open 100 160 µA
low-to-high transition 1.6 2.4 V
VBENB Enable Input Threshold
high-to-low transition 0.8 1.45 V
VBEN_HYSTB Enable Input Hysteresis 150 mV
IBENB Enable Input Current VBENB = 0V to 5V -1 0.01 1 µA
CBENB Enable Input Capacitance 1 pF
VBINB = 5.0V, IBOUTB = 500mA 100
140 mΩ
RBDS(ON)B Switch On Resistance
VBINB = 3.3V, IBOUTB = 500mA 90
170 mΩ
MIC20X6A-1, VENX = 0V;
MIC20X6A-2, VENX = VIN, (output off) 0.01
10 µA
IBLEAKAGE Output Leakage Current
MIC2076A, Thermal shutdown state 50 µA
IBLIMITB Short-Circuit Output Current VBOUTB = 0V, enabled into short-circuit 0.5 0.7 1.25 A
IBLMT_TRSH Current-Limit Threshold Ramped load applied to output 1.0 1.25 A
VBINB rising 2.2 2.45 2.7 V
VUVLO Undervoltage Lockout
Threshold (UVLO) VBINB falling 2.0 2.25 2.5 V
VUVHYST UVLO Hysteresis VBINB rising or VINB falling 200 mV
RBFLGB Error Flag Output Resistance IBLB = 10mA 10
25 Ω
IBFLG_OFFB Error Flag Off Current VBFLAGB = VBINB 10 µA
tSC_RESP Short-Circuit Response Time VBOUTB = 0V,
short circuit applied to enabled switch 20 µs
tBONB Output Turn-On Delay See Timing Diagrams, RL = 10Ω, CL = 1µF 1.3
5 ms
tBRB Output Turn-On Rise Time See Timing Diagrams, RL = 10Ω, CL = 1µF 0.5 1.5 4.9 ms
tBOFFB Output Turn-Off Delay See Timing Diagrams, RL = 10Ω, CL = 1µF 32 100 µs
Micrel, Inc. MIC2026A/2076A
July 2009 4 M9999-072309-B
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Symbol Parameter Condition Min Typ Max Units
tBFB Output Turn-Off Fall Time See Timing Diagrams, RL = 10Ω, CL = 1µF 32 100 µs
tD Overcurrent Flag Response
Delay From short circuit to FLG pin assertion 1.5 3.5 7 ms
TBJB increasing, each switch
TBJB decreasing, each switch 140
120 °C
°C
TOVERTEMP Overtemperature ThresholdP
(5)
P
TBJB increasing, both switches
TBJB decreasing, both switches 160
150 °C
°C
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2. The device is not guaranteed to function properly 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 140°C. If the die reaches approximately 160°C,
both channels will shut down, even if neither channel is in current limit.
Test Circuit
Micrel, Inc. MIC2026A/2076A
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Timing Diagrams
Output Rise and Fall Times
Active-Low Switch Delay Times (MIC20x6A-2)
Active-High Switch Delay Time (MIC20x6A-1)
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July 2009 6 M9999-072309-B
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Typical Characteristics
I
DD_ON
vs. Temperature
0
20
40
60
80
100
120
140
160
180
-40-200 20406080100
TEMPERATURE (°C)
I
DD_ON
(µA)
R
DS_ON
vs. Temperature
0
20
40
60
80
100
120
140
160
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
R
DS_ON
(mΩ)
Output Rise Time
vs. Temperature
0
1
2
3
4
5
-40-200 20406080100
TEMPERATURE (°C)
RISE TIME (ms)
I
DD_ON
vs. V
IN
0
20
40
60
80
100
120
140
160
180
2.53.03.54.04.55.05.5
V
IN
(V)
I
DD_ON
(µA)
R
DS_ON
vs. V
IN
0
20
40
60
80
100
120
140
160
180
200
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
IN
(V)
R
DS_ON
(mΩ)
Output Rise Time
vs. V
IN
0
1
2
3
4
5
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
IN
(V)
RISE TIME (ms)
Short-Circuit Current-Limit
vs. Temperature
0
200
400
600
800
1000
-40-20 0 20406080100
TEMPERATURE (°C)
CURRENT LIMIT (mA)
Current-Limit Threshold
vs. Temperature
0
200
400
600
800
1000
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
CURRENT-LIMIT (mA)
Output Fall Time
vs. Temperature
0
20
40
60
80
100
-40-200 20406080100
TEMPERATURE (°C)
FALL TIME (µs)
Short-Circuit Current-Limit
vs. VIN
0
200
400
600
800
1000
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
IN
(V)
CURRENT LIMIT (mA)
Current-Limit Threshold
vs. V
IN
0
200
400
600
800
1000
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
IN
(V)
CURRENT-LIMIT (mA)
Output Fall Time
vs. V
IN
0
20
40
60
80
100
2.53.03.54.04.55.05.5
V
IN
(V)
FALL TIME (µs)
5V
3V
5V
3V
5V
3V
-40°C
25°C
85°C
-40°C
25°C 85°C
-40°C
25°C
85°C
5V 3V
5V
3V
5V
3V
85°C
-40°C
-40°C
25°C
85°C
-40°C 25°C
85°C
25°C
Micrel, Inc. MIC2026A/2076A
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Typical Characteristics (continued)
Enable Threshold
vs. Temperature
0.0
0.5
1.0
1.5
2.0
2.5
3.0
-40 -20 0 20 40 60 80 100
TEMPERATURE (°C)
ENABLE THRESHOLD (V)
Overcurrent Flag Delay
vs. Temperature
0
1
2
3
4
5
-40-200 20406080100
TEMPERATURE (°C)
FLAG DELAY (ms)
I
DD_OFF
vs. Temperature
0
2
4
6
8
10
-40-200 20406080100
TEMPERATURE (°C)
I
DD_OFF
(µA)
Enable Threshold
vs. V
IN
0
1
2
3
4
5
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
IN
(V)
ENABLE THRESHOLD (V)
Overcurrent Flag Delay
vs. VIN
0
1
2
3
4
5
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
IN
(V)
FLAG DELAY (ms)
I
DD_OFF
vs. V
IN
0.0
2.0
4.0
6.0
8.0
10.0
2.5 3.0 3.5 4.0 4.5 5.0 5.5
V
IN
(V)
I
DD_OFF
(µA)
UVLO Threshold vs.
Temperature
0.0
0.5
1.0
1.5
2.0
2.5
3.0
-40-20 0 20406080100
TEMPERATURE (°C)
UVLO THRESHOLD (V)
5V
3V
5V
3V
5V
3V
-40°C 25°C
85°C
85°C
-40°C
25°C
-40°C 25°C
85°C
Micrel, Inc. MIC2026A/2076A
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Functional Characteristics
Micrel, Inc. MIC2026A/2076A
July 2009 9 M9999-072309-B
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Functional Characteristics (continued)
Micrel, Inc. MIC2026A/2076A
July 2009 10 M9999-072309-B
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Functional Characteristics (continued)
Micrel, Inc. MIC2026A/2076A
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Block Diagram
MIC2026A/2076A 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 when the switch is
enabled.
An important consideration in choosing a switch is
whether it has “reverse voltage protection.” This is
accomplished by eliminating the body diode during the
fabrication process. Reverse voltage protection is
important when the switch is disabled and a voltage is
presented to the OUT pin that is greater than the VIN pin
voltage. The reverse voltage protection prevents current
flow in the reverse path from OUT to IN.
On other hand when the switch is enabled the switch is
bidirectional. In this case when a voltage is presented to
the OUT pin that is greater than the VIN voltage, current
will 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 140°C and the
overheated channel is in current limit. The other channel
is not affected. If however, the die temperature exceeds
160°C, both channels will be shut off.
The MIC2026A will automatically reset its output when
the die temperature cools down to 120°C. The
MIC2026A’s 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.
On the other hand, the MIC2076A’s output will be turned
off, and remain off until the MIC2076A is reset. This is
often called latched output, that is, the output is “latched”
off and stays off. This is different from the MIC2026A’s
output that will cycle on and off. The MIC2076A will
latch off the output when the MIC2076A is in current
limiting and the switch goes in to thermal shutdown.
Upon entering thermal shutdown, the output will be
immediately latched off. The MIC2076A (latched output)
can be reset by any of the following three methods:
1. Remove the fault load
2. Toggle the EN (Enable) pin
3. Cycle VIN (input power supply)
Resetting the MIC2076A will return it to normal
operation.
Depending on PCB layout, package, ambient
temperature, etc., it may take several hundred
Micrel, Inc. MIC2026A/2076A
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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 IOUT
2
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 × θJA + TA
where:
TJ = junction temperature
TA = ambient temperature
θJA = 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 a 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.
• 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 the short-circuit
current limit specification.
• Current-Limit Response
The MIC2026A/2076A current-limit response is often
called the foldback current-limit. The foldback
current-limit is the current limit reached when the
output current is increased slowly rather than
abruptly. An approximation of slowly is tens of
milliamps per second. The foldback current-limit is
typical 200 mA higher than the short-circuit current-
limit. When the foldback current-limit is reached, the
output current will abruptly decrease to the short-
circuit current-limit.
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 2.45V. Undervoltage detection functions
only when the switch is enabled.
Figure 1. MIC2076A Fault Timing: Output Reset by Removing Load
Micrel, Inc. MIC2026A/2076A
July 2009 13 M9999-072309-B
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Figure 2. MIC2026A Fault Timing
Application Information
Supply Filtering
A 0.1µF to 1µF bypass capacitor positioned close to VIN
and GND pins 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 MIC2026A/2076A are ideal inrush current-limiters
for hot plug applications. Due to their integrated charge
pumps, the MIC2026A/2076A 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 MIC2026A may be used in a card hot-plug
application.
In cases of extremely large capacitive loads (>400µF),
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
MIC2026A/2076A.
Universal Serial Bus (USB) Power Distribution
The MIC2026A/2076A 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 120µF of bulk capacitance, preferably low
ESR electrolytic or tantalum. 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.
Micrel, Inc. MIC2026A/2076A
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Figure 3. Hot-Plug Application
Figure 4. Transient Filter
Micrel, Inc. MIC2026A/2076A
July 2009 15 M9999-072309-B
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Figure 5. USB Two-Port Host Application
Figure 6. USB Two-Port Bus-Powered Hub
Micrel, Inc. MIC2026A/2076A
July 2009 16 M9999-072309-B
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Package Information
8-Pin SOIC (M)
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
reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical impla
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.
can nt
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