MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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MIC2027/2077
Quad USB Power Distribution Switch
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 are available in 16-pin narrow (150 mil)
and wide (300 mil) SOIC packages.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
150mmaximum 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
®
UL Recognized Component
4-Port Self-Powered Hub
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
September 2006
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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Ordering Information(1)
Part Number
Standard
Pb-Free
MIC2027-1BWM MIC2027-1YWM
MIC2027-1BM
MIC2027-1YM
MIC2027-2BWM MIC2027-2YWM
MIC2027-2BM
MIC2027-2YM
MIC2077-1BWM MIC2077-1YWM
MIC2077-1BM
MIC2077-1YM
MIC2077-2BWM MIC2077-2YWM
MIC2077-2BM
MIC2077-2YM
Enable
Active High
Active High
Active Low
Active Low
Active High
Active High
Active Low
Active Low
Temperature Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Package
16-Pin Wide SOIC
16-Pin SOIC
16-Pin Wide SOIC
16-Pin SOIC
16-Pin Wide SOIC
16-Pin SOIC
16-Pin Wide SOIC
16-Pin SOIC
MIC2027/2077
Pin Configuration
16-Pin SOIC (M)
16-Pin Wide SOIC (WM)
Functional Pinout
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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MIC2027/2077
Pin Description
Pin Number
1
2
3
4, 12
5
6
7
8
9
10
11
13
14
15
16
Pin Name
FLG
ENA
OUTA
GND
IN(C/D)
OUTC
ENC
FLGC
FLGD
END
OUTD
IN(A/B)
OUTB
ENB
FLGB
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)
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Quad USB Power Distribution Switch

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Absolute Maximum Ratings(1)
Supply Voltage (VIN) ............................................ –0.3V +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 VIN +3V
Lead Temperature (soldering, 5sec.)......................... 260°C
Storage Temperature (TS).........................–65°C to +150°C
EDS Rating(3).................................................................. 1kV
MIC2027/2077
Operating Ratings(2)
Supply voltage (VIN) ..................................... +2.7V to +5.5V
Ambient Temperature (TA) .......................... –40°C to +85°C
Junction Thermal Range(TJ) ..................... Internally Limited
Thermal Resistance
[300 mil] Wide SOIC (θJA)................................120°C/W
[150 mil] SOIC (θJA).........................................112°C/W
DIP (θJA) ..........................................................130°C/W
Electrical Characteristics
VIN = +5V; TA = 25°C, bold values indicate –40°C< TA < +85°C, 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 Enable Input Current
VEN = 0V to 5.5V
Enable Input Capacitance
RDS(on)
Switch Resistance
VIN = 5V, IOUT = 500mA
Output Leakage Current
VIN = 3.3V, IOUT = 500mA
MIC20x7-1, VENx 0.8V;
MIC20x7-2, VENx 2.4V, (output off)
Output Current in
Latched Thermal Shutdown
MIC2077 (per Latch Output)
(during thermal shutdown state)
tON Output Turn-On Delay
RL = 10, CL = 1µF, see “Timing Diagrams”
tR
Output Turn-On Rise Time
RL = 10, CL = 1µF, see “Timing Diagrams”
tOFF Output Turnoff Delay
RL = 10, CL = 1µF, see “Timing Diagrams”
tF Output Turnoff Fall Time RL = 10, CL = 1µF, see “Timing Diagrams”
ILIMIT
Short-Circuit Output Current
VOUT = 0V, enabled into short-circuit
Current-Limit Threshold
ramped load applied to output
Short-Circuit Response Time
VOUT = 0V to IOUT = ILIMIT
(short applied to output)
tD
Overcurrent Flag Response
VIN = 5V, apply VOUT = 0V until FLG low
Delay
VIN = 3.3V, apply VOUT = 0V until FLG low
Min Typ Max Units
1.5 10
µA
1.5 10
µA
200 320
µA
200 320
µA
1.7 2.4
0.8 1.45
250
–1 0.01
1
1
100 150
110 180
10
V
V
mV
µA
pF
m
m
µA
50 µA
1.3 5
1.15 4.9
35 100
32 100
0.5 0.9 1.25
1.0 1.25
20
ms
ms
µs
µs
A
A
µs
1.5 3 7 ms
3 ms
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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MIC2027/2077
Symbol
Parameter
Undervoltage Lockout
Threshold
Error Flag Output Resistance
Error Flag Off Current
Overtemperature Threshold
Note 4
Condition
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
Min Typ Max Units
2.2 2.4
2.7
V
2.0 2.15
10
15
2.5
25
40
V
10 µA
140 °C
120 °C
160 °C
150 °C
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. Human body model, 1.5k in series with 100pF.
4. If there is an output current limit fault on one channel, that channel will shut down when the die reaches approximately 140°C. If the diereaches
approximately 160°C, the other channel driven by the same input will shut down, even if neither channel is in current limit.
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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Test Circuit
MIC2027/2077
Timing Diagrams
Output Rise and Fall Times
Active-Low Switch Delay Times (MIC20x7-2)
September 2006
Active-High Switch Delay Times (MIC20x7-1)
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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Typical Characteristics
MIC2027/2077
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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Typical Characteristics (cont.)
MIC2027/2077
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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Micrel, Inc.
Functional Characteristics
MIC2027/2077
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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Functional Characteristics (cont.)
MIC2027/2077
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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Functional Characteristics (cont.)
MIC2027/2077
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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Block Diagram
MIC2027/2077
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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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 140°C and the
overheated channel is in current limit. The other
channels are not affected. If however, the die
temperature exceeds 160°C, 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 120°C. 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) × 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 × θJA + TA
MIC2027/2077
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 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, 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 current-limit 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
fold-back 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 thresh-old.
The FLG response delay time tD is typically 3ms.
Undervoltage Lockout
Undervoltage lockout (UVLO) prevents the output
MOSFET from turning on until VIN exceeds approx-
imately 2.5V. Undervoltage detection functions only
when the switch is enabled.
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Quad USB Power Distribution Switch

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MIC2027/2077
Figure 1. MIC2077-2 Fault Timing: Output Reset by Removing Load
VEN
VOUT
ILIMIT
ILOAD
IOUT
VFLG
Short-Circuit Fault
Load/Fault
Removed
3ms typ.
delay
Thermal
Shutdown
Reached
Figure 2. MIC2207-2 Fault Timing
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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Application Information
Supply Filtering
A 0.1µF to 1µF 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 present 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 (>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 flag delay
specification, FLG will be asserted during this time. To
prevent the logic controller from responding to FLG
MIC2027/2077
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 bus-powered (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 120µF 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.
Figure 3. Transient Filter
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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Package Information
MIC2027/2077
16-Pin SOIC (M)
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MIC2027 (Micrel Semiconductor)
Quad USB Power Distribution Switch

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Micrel, Inc.
MIC2027/2077
16-Pin Wide SOIC (WM)
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.
© 2001 Micrel, Incorporated.
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