MIC2027/2077
Quad USB 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
September 2006 1 M9999-091506
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
• 150m 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 channel s
• 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
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September 2006 2 M9999-091506
Ordering Information(1)
Part Number
Standard Pb-Free
Enable Temperature Range Package
MIC2027-1BWM MIC2027-1YWM Active High –40°C to +85°C 16-Pin Wide SOIC
MIC2027-1BM MIC2027-1YM Active High –40°C to +85°C 16-Pin SOIC
MIC2027-2BWM MIC2027-2YWM Active Low –40°C to +85°C 16-Pin Wide SOIC
MIC2027-2BM MIC2027-2YM Active Low –40°C to +85°C 16-Pin SOIC
MIC2077-1BWM MIC2077-1YWM Active High –40°C to +85°C 16-Pin Wide SOIC
MIC2077-1BM MIC2077-1YM Active High –40°C to +85°C 16-Pin SOIC
MIC2077-2BWM MIC2077-2YWM Active Low –40°C to +85°C 16-Pin Wide SOIC
MIC2077-2BM MIC2077-2YM Active Low –40°C to +85°C 16-Pin SOIC
Pin Configur ation
16-Pin SOIC (M)
16-Pin Wide SOIC (WM)
Functional Pinout
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Pin Description
Pin Number Pin Name Pin Function
1 FLG
Fault Flag A (Output): Active-low, open-drain output. Low indicates overcur r ent or thermal
shutdown conditions. Overcurrent conditions must last longer than t
D
to assert flag.
2 ENA Switch A Enable (Input): Logic-compatible enable input. Active high (-1) or active low (-2).
3 OUTA Switch A Output
4, 12 GND Ground
5 IN(C/D) Input: Channel C and D switch and logic supply input.
6 OUTC Switch C Output
7 ENC S witch C Enable (Input)
8 FLGC Fault Flag C (O utput)
9 FLGD Fault Flag D (O utput)
10 END Switch D Enable (Input)
11 OUTD Switch D Output
13 IN(A/B) Supply Input: Channel A and B switch and logic supply input.
14 OUTB Switch B Output
15 ENB Switch B Enable (Input)
16 FLGB Fault Flag B (Output)
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Absolute Maximum Ratings(1)
Supply Voltage (V
IN
)............................................–0.3V +6V
Fault Flag Voltage (V
FLG
)................................................+6V
Fault Flag Current (I
FLG
) ..............................................25mA
Output Voltage (V
OUT
) ....................................................+6V
Output Current (I
OUT
).................................Internally Limited
Enable Input (I
EN
) .......................................... –0.3V V
IN
+3V
Lead Temperature (soldering, 5sec.).........................260°C
Storage Temperature (T
S
).........................–65°C to +150°C
EDS Rating
(3)
..................................................................1kV
Operating Ratings(2)
Supply voltage (V
IN
) .....................................+2.7V to +5.5V
Ambient Temperature (T
A
)..........................–40°C to +85°C
Junction Thermal Range(T
J
).....................Internally Limited
Thermal Resistance
[300 mil] Wide SOIC (θ
JA
)................................120°C/W
[150 mil] SOIC (θ
JA
).........................................112°C/W
DIP (θ
JA
) ..........................................................130°C/W
Electrical Characteristics
V
IN
= +5V; T
A
= 25°C, bold values indicate –40°C< T
A
< +85°C, unless noted.
Symbol Parameter Condition Min Typ Max Units
MIC20x7-1, V
ENA–D
0.8V
(switch off), OUT = open 1.5 10 µA
MIC20x7-2, V
ENA–D
2.4V
(switch off), OUT = open 1.5 10 µA
MIC20x7-1, V
ENA–D
2.4V
(switch on), OUT = open 200 320 µA
I
DD
Supply Current
MIC20x7-2, V
ENA–D
0.8V
(switch on), OUT = open 200 320 µA
low-to-high transition 1.7 2.4 V Enable Input Threshold high-to-low transition 0.8 1.45 V
V
EN
Enable Input Hysteresis 250 mV
Enable Input Current V
EN
= 0V to 5.5V –1 0.01 1 µA I
EN
Enable Input Capacitance 1 pF
V
IN
= 5V, I
OUT
= 500mA 100 150 m R
DS(on)
Switch Resistance V
IN
= 3.3V, I
OUT
= 500mA 110 180 m
Output Leakage Current MIC20x7-1, V
ENx
0.8V;
MIC20x7-2, V
ENx
2.4V, (output off)
10 µA
Output Current in
Latched Thermal Shutdown MIC2077 (per Latch Output)
(during thermal shutdown state) 50 µA
t
ON
Output Turn-On Delay RL = 10, CL = 1µF, see “Timing Di agrams” 1.3 5 ms
t
R
Output Turn-On Rise Time RL = 10, CL = 1µF, see “Timing Diagrams” 1.15 4.9 ms
t
OFF
Output Turnoff Delay RL = 10, CL = 1µF, see “Timing Diagrams” 35 100 µs
t
F
Output Turnoff Fall T ime RL = 10, CL = 1µF, see “Timing Diagrams” 32 100 µs
I
LIMIT
Short-Circuit Output Current V
OUT
= 0V, enabled into short-circuit 0.5 0.9 1.25 A
Current-Limit Threshold ramped load applied to out put 1.0 1.25 A
Short-Circuit Response Time V
OUT
= 0V to I
OUT
= I
LIMIT
(short applied to output) 20 µs
V
IN
= 5V, apply V
OUT
= 0V until FLG low 1.5 3 7 ms t
D
Overcurrent Flag Response
Delay V
IN
= 3.3V, apply V
OUT
= 0V until FLG low 3 ms
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Symbol Parameter Condition Min Typ Max Units
V
IN
rising 2.2 2.4 2.7 V Undervoltage Lockout
Threshold V
IN
falling 2.0 2.15 2.5 V
I
L
= 10mA, V
IN
= 5V 10 25 Error Flag Output Resistance I
L
= 10mA, V
IN
= 3.3V 15 40
Error Flag Off Current V
FLAG
= 5V 10 µA
Overtemperature Threshold
Note 4 T
J
increasing, each switch
T
J
decreasing, each switch 140
120 °C
°C
T
J
increasing, both switches
T
J
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 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.
Micrel, Inc. MIC2027/2077
September 2006 6 M9999-091506
Test Circuit
Timing Diagrams
Output Rise and Fall Times
Active-Low Switch Delay Times (MIC20x7-2)
Active-High Switch Delay Times (MIC20x7-1)
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Typical Characteristics
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Typical Characteristics (cont.)
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Functional Characteristics
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Functional Characteristics (cont.)
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Functional Characteristics (cont.)
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Block Diagram
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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 V
OUT
is greater than
V
IN
, 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 (V
OUT
> V
IN
) 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.
P
D
= R
DS(on)
× I
OUT2
Total power dissipation of the device will be the
summation of P
D
for all channels. To relate this to
junction temperature, the following equation can be
used:
T
J
= P
D
×
JA
+ T
A
where:
T
J
= junction temperature
T
A
= 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, 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, t
D
, 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 t
D
is typically 3ms.
Undervoltage Lockout
Undervoltage lockout (UVLO) prevents the output
MOSFET from turning on until V
IN
exceeds approx-
imately 2.5V. Undervoltage detection functions only
when the switch is enabled.
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Figure 1. MIC2077-2 Fault Timing: Outpu t Reset by Removing Load
V
EN
V
OUT
I
OUT
Short-Circuit Fault
Thermal
Shutdown
Reached
Load/Fault
Removed
V
FLG
I
LOAD
I
LIMIT
3ms typ.
delay
Figure 2. MIC2207-2 Fault Timing
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September 2006 15 M9999-091506
Application Information
Supply Filtering
A 0.1µF to 1µF bypass capacitor positioned close to V
IN
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
being asserted, an external RC filter, as shown in Fi gure
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 t
D(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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September 2006 16 M9999-091506
Package Information
16-Pin SOIC (M)
Micrel, Inc. MIC2027/2077
September 2006 17 M9999-091506
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.
