MIC2095/MIC2097/MIC2098/MIC2099
Current-Limiting Power Distribution Switches
MLF and MicroLeadFrame are registered trademarks of Amkor Technology, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
General Description
The MIC2095/97/98/99 family of switches are self-
contained, current-limiting, high-side power switches, ideal
for power-control applications. These switches are useful
for general purpose power distribution applications such as
digital televisions (DTV), printers, set-top boxes (STB),
PCs, PDAs, and other peripheral devices.
The current limiting switches feature either a fixed
0.5A/0.9A or resistor programmable output current limit.
The family also has fault blanking to eliminate false noise-
induced, over current conditions. After an over-current
condition, these devices automatically restart if the enable
pin remains active. The MIC2097 switch offers a unique
new patented Kickstart feature, which allows momentary
high-current surges up to the secondary current limit
(ILIMIT_2nd). This is useful for charging loads with high inrush
currents, such as capacitors.
The MIC2095/97/98/99 family of switches provides under-
voltage, over-temperature shutdown, and output fault
status reporting. The family also provides either an active
low or active high, logic level enable pin.
The MIC2095/97/98/99 family is offered in a space saving
1.6mm x 1.6mm Thin MLF® (TMLF) package.
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
• MIC2095: 0.5A fixed current limit
• MIC2098: 0.9A fixed current limit
• MIC2097/99: Resistor programmable current limit
– 0.1A to 1.1A
• MIC2097: Kickstart for high peak current loads
• Under voltage lock-out (UVLO)
• Soft start prevents large current inrush
• Automatic-on output after fault
• Thermal protection
• Enable active high or active low
• 170m typical on-resistance @ 5V
• 2.5V – 5.5V operating range
Applications
• Digital televisions (DTV)
• Set top boxes
• PDAs
• Printers
• USB / IEEE 1394 power distribution
• Desktop and laptop PCs
• Game consoles
• USB keyboard
• Docking stations
_________________________________________________________________________________________________________________________
Typical Application
MIC2095 USB Power Switch
August 2011 M9999-080211-C
Micrel, Inc. MIC2095/97/98/99
August 2011 2 M9999-080211-C
Ordering Information
Part Number Marking ENABLE
Logic Kickstart(™) ILIMIT FAULT/
Output
Junction
Temperature
Range(1)
Package
MIC2095-1YMT J1K Active High No 0.5A Yes –40°C to +125°C 6-Pin 1.6mm x
1.6mm TMLF
MIC2095-2YMT J2K Active Low No 0.5A Yes –40°C to +125°C 6-Pin 1.6mm x
1.6mm TMLF
MIC2097-1YMT K1K Active High Yes 0.1 A – 1.1A Yes –40°C to +125°C 6-Pin 1.6mm x
1.6mm TMLF
MIC2097-2YMT K2K Active Low Yes 0.1 A – 1.1A Yes –40°C to +125°C 6-Pin 1.6mm x
1.6mm TMLF
MIC2098-1YMT H1K Active High No 0.9A Yes –40°C to +125°C 6-Pin 1.6mm x
1.6mm TMLF
MIC2098-2YMT H2K Active Low No 0.9A Yes –40°C to +125°C 6-Pin 1.6mm x
1.6mm TMLF
MIC2099-1YMT G1K Active High No 0.1 A – 1.1A Yes –40°C to +125°C 6-Pin 1.6mm x
1.6mm TMLF
MIC2099-2YMT G2K Active Low No 0.1 A – 1.1A Yes –40°C to +125°C 6-Pin 1.6mm x
1.6mm TMLF
Pin Configuration
6-Pin 1.6mm x 1.6mm TMLF (MT) (Top View)
MIC2095-1YMT/MIC2098-1YMT
6-Pin 1.6mm x 1.6mm TMLF (MT) (Top View)
MIC2095-2YMT/MIC2098-2YMT
6-Pin 1.6mm x 1.6mm TMLF (MT) (Top View)
MIC2097-1YMT / MIC2099-1YMT
6-Pin 1.6mm x 1.6mm TMLF (MT) (Top View)
MIC2097-2YMT / MIC2099-2YMT
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Pin Description
Pin Number Pin Name Pin Function
1 VOUT Switch output (Output): The load being driven by the switch is connected to this pin.
2
(MIC2095/MIC2098) NC No Connect; Pin not used.
2
(MIC2097/MIC2099) ILIMIT Current Limit (Input): A resistor from this pin to ground sets the current limit value. See
the “setting ILMIIT” section for details on setting the resistor value.
3 FAULT/
Fault status (Output): A logic low on this pin indicates the switch is in current limiting, or
has been shut down by the thermal protection circuit. This is an open-drain output
allowing logical OR’ing of FAULT/ outputs from multiple devices.
4
(MIC2095-1/MIC2097-1/
MIC2098-1/MIC2099-1)
ENABLE Switch Enable (Input): Logic high on this pin enables the switch.
4
(MIC2095-2/MIC2097-2/
MIC2098-2/MIC2099-2)
ENABLE/ Switch Enable (Input): Logic low on this pin enables the switch.
5 GND Ground.
6 VIN
Power input (Input): This pin provides power to both the output power switch and the
internal control circuitry.
EP EP
Used to remove heat from die. Connect to ground. Use multiple vias to the ground
plane to minimize thermal impedance. See Applications Section for additional
information.
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Absolute Maximum Ratings(1)
Supply Voltage (VIN)....................................... −0.3V to 6.0V
Output Voltage (VOUT) ....................................... −0.3V to VIN
FAULT Pin Voltage (VFAULT) .............................. −0.3V to VIN
ENABLE Pin Voltage (VENABLE).......................... −0.3V to VIN
ILIMIT Pin Voltage (VILIMIT) ................................ −0.3V to VIN
Power Dissipation (PD)..............................Internally Limited
Maximum Junction Temperature (TJ)......................... 150°C
Storage Temperature (Ts).........................−65°C to +150°C
Lead Temperature (soldering, 10sec.)....................... 260°C
ESD HBM Rating (VOUT, GND)(3) ................................. 4kV
ESD HBM Rating (FAULT, ENABLE, VIN)(3) ................. 2kV
Operating Ratings(2)
Supply Voltage (VIN)......................................... 2.5V to 5.5V
ENABLE Pin Voltage (VENABLE) ..............................0V to VIN
FAULT Pin Voltage (VFAULT) ................................... 0V to VIN
Ambient Temperature Range (TA) .............. –40°C to +85°C
Package Thermal Resistance(6)
1.6mm × 1.6mm TMLF (JA) .............................. 93ºC/W
Electrical Characteristics(4)
VIN = 5V; CIN = 1µF TA = 25°C unless noted, bold values indicate –40°C TA +85°C.
Symbol Parameter Condition Min. Typ. Max. Units
Power Input Supply
VIN Input Voltage Range
2.5
5.5 V
Quiescent Supply Current(5)
Switch = ON
Active Low Enable, VEN = 0V
Active High Enable, VEN = 1.5V
80 300 µA
Switch = OFF
Active Low Enable, VEN = 1.5V 8 15 µA
IIN
Shutdown Current
Switch = OFF
Active High Enable, VEN = 0.5V 0.1 5 µA
VIN Rising 2 2.25 2.5 V
VIN UVLO Threshold
VIN Falling 1.9 2.15 2.4 V
UVLOTHRESHOLD
VIN UVLO Hysteresis 100 mV
Enable Control
ENABLE Logic Level Low(5) V
IL(MAX)
0.5 V
VEN
ENABLE Logic Level High(5) V
IH(MIN) 1.5 V
IEN ENABLE Bias Current 0V VEN 5V 0.1 5 µA
tON_DLY Output Turn-on Delay RL = 43, CL = 120µF
VEN = 50% to VOUT = 10% 1000 1500 µs
tOFF_DLY Output Turn-off Delay RL = 43, CL = 120µF
VEN = 50% to VOUT = 90% 700 µs
tRISE Output Turn-on rise time RL = 100, CLOAD = 1µF
VOUT = 10% to 90% 500 1000 1500 µs
Thermal Protection
TJ Rising 145 °C
OTThreshold Over-temperature Shutdown
TJ Falling 135 °C
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Electrical Characteristics (Continued)
VIN = 5V; CIN = 1µF TA = 25°C unless noted, bold values indicate –40°C TA +85°C.
Symbol Parameter Condition Min. Typ. Max. Units
Internal Switch
170 220 m
RDS(ON) On Resistance VIN = 5V, IOUT = 100mA
275 m
ILEAK Output Leakage Current
Switch = OFF, VOUT = 0V
Active Low Enable, VEN = 1.5V
Active High Enable, VEN = 0V
0.1
10 µA
Output Current Limit (MIC2095)
ILIMIT Fixed Current Limit VOUT = 0.8 × VIN 0.5 0.7 0.9 A
Output Current Limit (MIC2098)
ILIMIT Fixed Current Limit VOUT = 0.8 × VIN 0.9 1.1 1.5 A
Output Current Limit (MIC2097, MIC2099)
IOUT = 1.1A, VOUT = 0.8 × VIN; VIN =2.5V 175 215 263 V
IOUT = 0.5A, VOUT = 0.8 × VIN; VIN =2.5V 152 206 263 V
IOUT = 0.2A, VOUT = 0.8 × VIN; VIN =2.5V 138 200 263 V
CLF Variable Current Limit
Factors
IOUT = 0.1A, VOUT = 0.8 × VIN; VIN =2.5V 121 192 263 V
KickstartTM Current Limit (MIC2097)
ILIMIT_2nd Secondary Current Limit VIN = 2.5V; VOUT = 0V 1.5 A
tD_LIMIT Duration of KickstartTM
Current Limit VIN = 2.5V 77 105 192 ms
Fault Flag
Fault Flag Output Voltage IOL = 10mA 0.25 0.4 V
VFAULT/
Fault Flag Off Current VFAULT/ =5V 0.01
1 µA
Fault Delay (MIC2095, MIC2098, MIC2099)
tD_FAULT Delay before asserting or
releasing FAULT/
Time from current limiting (VOUT = 0.4 x
VIN) to FAULT/ state change 20 32 49 ms
Fault Delay (MIC2097)
tD_FAULT Delay before asserting or
releasing FAULT/
Time from current limiting (VOUT = 0.8 x
VIN) to FAULT/ state change; VIN = 2.5V 77 105 192 ms
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. Specifications for packaged product only.
5. Check the Ordering Information section to determine which parts are Active High or Active Low.
6. Requires proper thermal mounting to achieve this performance.
Micrel, Inc. MIC2095/97/98/99
August 2011 6 M9999-080211-C
Timing Diagrams
90%
10%
90%
10%
tFALL
tRISE
Rise and Fall Times
ENABLE
VOUT
50%
90%
10%
tON_DLY tOFF_DLY
50%
Switching Delay Times
Micrel, Inc. MIC2095/97/98/99
August 2011 7 M9999-080211-C
Typical Characteristics
VIN Shutdown Current
vs. Input Voltage
0
2
4
6
8
10
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
SUPPLY CURRENT (µA)
-2 Version
VIN Shutdown Current
vs. Input Voltage
-2
0
2
4
6
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
SUPPLY CURRENT (µA)
-1 Version
VIN Supply Current
vs. Input Voltage
0
20
40
60
80
100
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
SUPPLY CURRENT (µA)
Current Limit vs. Input Voltage
MIC2097/MIC2099
0.0
0.2
0.4
0.6
0.8
1.0
1.2
2.53.03.54.04.55.05.5
INPUT VOLTAGE (V)
CURRENT LIMIT (A)
R
SET
= 200, I
SET
= 1.08A
R
SET
= 298, I
SET
= 0.7A
R
SET
= 508, I
SET
= 0.4A
R
SET
= 1920, I
SET
=0.1A
V
OUT
=0.8*V
IN
Current Limit vs. Input Voltage
MIC2095
0.0
0.2
0.4
0.6
0.8
1.0
2.53.03.54.04.55.05.5
INPUT VOLTAGE (V)
CURRENT LIMIT (A)
I
LIMIT
I
SC
V
OUT
= 0.8*V
IN
Current Limit vs. Input Voltage
MIC2098
0.0
0.2
0.4
0.6
0.8
1.0
1.2
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
CURRENT LIMIT (A)
I
LIMIT
I
SC
V
OUT
= 0.8*V
IN
Current Limit vs. Input Voltage
MIC2097/MIC2099
0.0
0.2
0.4
0.6
0.8
1.0
1.2
2.53.03.54.04.55.05.5
INPUT VOLTAGE (V)
CURRENT LIMIT (A)
I
LIMIT
I
SC
R
SET
=195
I
SET
= 1.1A
V
OUT
= 0.8*V
IN
Switch On Resistance
vs. Input Voltage
100
120
140
160
180
200
220
240
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
RESISTANCE (mΩ)
I
OUT
= 100mA
Fault Delay vs. Input Voltage
MIC2095/MIC2098/MIC2099
0
5
10
15
20
25
30
35
40
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
DELAY (ms)
C
LOAD
= 1F
R
LOAD
= 100
Fault Delay vs. Input Voltage
MIC2097
0
20
40
60
80
100
120
140
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
DELAY (ms)
C
LOAD
= 1F
R
LOAD
= 100
Kickstart Current vs. Input Voltage
MIC2097
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.53.03.54.04.55.05.5
INPUT VOLTAGE (V)
PEAK CURRENT (A)
R
SET
= 195
I
SET
= 1.1A
V
OUT
= 0.8*V
IN
Kickstart Period vs. Input Voltage
MIC2097
0
20
40
60
80
100
120
140
2.53.03.54.04.55.05.5
INPUT VOLTAGE (V)
TIME (ms)
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August 2011 8 M9999-080211-C
Typical Characteristics (Continued)
V
IN
ShutdownCurrent
vs. Temperature
0.0
0.2
0.4
0.6
0.8
1.0
-40 -15 10 35 60 85
TEMPERATURE (°C)
SHUTDOWN CURRENT (µA)
V
IN
= 5V
V
IN
= 3V
-1 Version
V
IN
ShutdownCurrent
vs. Temperature
0.0
2.0
4.0
6.0
8.0
10.0
-40 -15 10 35 60 85
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
V
IN
= 5V
V
IN
= 3V
-2 Version
V
IN
Supply Current
vs.Temperature
0
20
40
60
80
100
-40 -15 10 35 60 85
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
V
IN
= 5V
V
IN
= 3V
Current Limit vs. Temperature
MIC2095
0.0
0.2
0.4
0.6
0.8
1.0
-40 -15 10 35 60 85
TEMPERATURE (°C)
CURRENT LIMIT (A)
V
IN
= 5.0V
V
OUT
= 4V
I
LIMIT
I
SC
Current Limit vs. Temperature
MIC2098
0.0
0.2
0.4
0.6
0.8
1.0
1.2
-40 -15 10 35 60 85
TEMPERATURE (°C)
CURRENT LIMIT (A)
V
IN
= 5.0V
V
OUT
= 4V
I
THRESH OLD
I
SC
Current Limit vs.Temperature
MIC2097/MIC2099
0.0
0.2
0.4
0.6
0.8
1.0
1.2
-40 -15 10 35 60 85
TEMPERATURE (°C)
CURRENT LIMIT (A)
I
LIMIT
V
IN
= 5.0V
V
OUT
= 4V
R
SET
=195
I
SET
= 1.1A
I
SC
R
DS(ON)
vs. Temperature
100
120
140
160
180
200
220
240
-40 -15 10 35 60 85
TEMPERATURE (°C)
RESISTANCE (mΩ)
V
IN
= 5.0V
V
IN
= 3.3V
Output Fall Time
vs. Temperature
100
140
180
220
260
300
340
-40 -15 10 35 60 85
TEMPERATURE (°C)
FALL TIME (μs)
V
IN
= 3V
V
IN
= 5.0V
C
LOAD
= 1F
R
LOAD
=100
Output Rise Time
vs. Temperature
0
200
400
600
800
1000
1200
-40 -15 10 35 60 85
TEMPERATURE (°C)
RISE TIME (μs)
V
IN
= 3V
V
IN
= 5.0V
C
LOAD
= 1F
R
LOAD
=100
V
IN
UVLO Thresholds
vs. Temperature
2.0
2.1
2.2
2.3
2.4
2.5
-40 -15 10 35 60 85
TEMPERATURE (°C)
V
IN
ULVO THRESHOLDS (V)
V
IN
Rising
V
IN
Falling
Fault Delay vs. Temperature
MIC2095/MIC2099
0
5
10
15
20
25
30
35
40
-40 -15 10 35 60 85
TEMPERATURE (°C)
Delay (ms)
C
LOAD
= 1F
R
LOAD
=100
V
IN
= 3V
V
IN
= 5.0V
Kickstart Current vs. Temperature
MIC2097
1.20
1.25
1.30
1.35
1.40
1.45
1.50
1.55
1.60
-40 -15 10 35 60 85
TEMPERATURE (°C)
PEAK CURRENT (A)
V
IN
= 3V
V
IN
= 5.0V
V
OUT
= 4V
R
SET
=195
I
SET
= 1.1A
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August 2011 9 M9999-080211-C
Typical Characteristics (Continued)
Kickstart Period vs. Temperature
MIC2097
0
20
40
60
80
100
120
140
160
-40 -15 10 35 60 85
TEMPERATURE (°C)
TIME (ms)
V
IN
= 3V
V
IN
= 5.0V
I
LIMIT
& I
SET
vs. R
SET
MIC2097/MIC2099
V
IN
= 5V
Vo=4V
T
A
= 25°C
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
0 300 600 900 1200 1500 1800 2100
R
SET
(Ω)
I
SET
(A)
I
LIMIT
I
SET
V
IN
- V
OUT
(V
IN
= 5.0V)
vs. Output Current
0
50
100
150
200
250
0.0 0.2 0.4 0.6 0.8 1.0 1.2
OUTPUT CURRENT (A)
V
IN
- V
OUT
(mV)
V
IN
= 5V
85ºC
25ºC
-40ºC
V
IN
- V
OUT
(V
IN
= 3.0V)
vs. Output Current
0
50
100
150
200
250
0.0 0.2 0.4 0.6 0.8 1.0 1.2
OUTPUT CURRENT (A)
V
IN
- V
OUT
(mV)
85ºC
25ºC
-40ºC
V
IN
= 3V
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August 2011 10 M9999-080211-C
Functional Characteristics
Micrel, Inc. MIC2095/97/98/99
August 2011 11 M9999-080211-C
Functional Characteristics (Continued)
Micrel, Inc. MIC2095/97/98/99
August 2011 12 M9999-080211-C
Functional Characteristics (Continued)
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August 2011 13 M9999-080211-C
Functional Characteristics (Continued)
Micrel, Inc. MIC2095/97/98/99
August 2011 14 M9999-080211-C
Functional Characteristics (Continued)
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August 2011 15 M9999-080211-C
Functional Diagram
MIC2095/97/98/99 Functional Diagram
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Functional Description and Application
Information
VIN and VOUT
VIN is both the power supply connection for the internal
circuitry driving the switch and the input (Source
connection) of the power MOSFET switch. VOUT is the
Drain connection of the power MOSFET and supplies
power to the load. In a typical circuit, current flows from
VIN to VOUT toward the load. Since the switch is bi-
directional when enabled, if VOUT is greater than VIN,
current will flow from VOUT to VIN.
When the switch is disabled, current will not flow to the
load, except for a small unavoidable leakage current of a
few micro amps. However, should VOUT exceed VIN by
more than a diode drop (~0.6V), while the switch is
disabled, current will flow from output to input via the
power MOSFET’s body diode. When the switch is
enabled, current can flow both ways, from VIN to VOUT, or
VOUT to VIN.
CIN
A minimum 1F bypass capacitor positioned as close as
possible to the VIN and GND pins of the switch is both
good design practice and required for proper operation
of the switch. This will control supply transients and
ringing. Without a sufficient bypass capacitor, large
current surges or a short may cause sufficient ringing on
VIN (from supply lead inductance) to cause erratic
operation of the switch’s control circuitry. For best
performance a good quality, low-ESR ceramic capacitor
is recommended.
An additional 22F (or greater) capacitor, positioned
close to the VIN and GND pins of the switch is necessary
if the distance between a larger bulk capacitor and the
switch is greater than 3 inches. This additional capacitor
limits input voltage transients at the switch caused by
fast changing input currents that occur during a fault
condition, such as current limit and thermal shutdown.
When bypassing with capacitors of 10F and up, it is
good practice to place a smaller value capacitor in
parallel with the larger to handle the high frequency
components of any line transients. Values in the range of
0.1F to 1F are recommended. Again, good quality,
low-ESR capacitors, preferably ceramic, should be
chosen.
COUT
An output capacitor is recommended to reduce ringing
and voltage sag on the output during a transient
condition. A value between 1µf and 10µf is
recommended, however, larger values can be used.
Limitations on COUT
The part may enter current limit when turning on with a
large output capacitance. This is an acceptable
condition, however, if the part remains in current limit for
a time greater than tD_FAULT, the FAULT pin will assert
low. The maximum value of COUT may be approximated
by the following equation:
MAX_IN
MIN_FAULT_DMIN_LIMIT
MAX_OUT V
tI
C×
= Eq. 1
Where: ILIMIT_MIN and tD_FAULT_MIN are the minimum
specified values listed in the Electrical Characteristic
table and VIN_MAX is the maximum input voltage to the
switch.
Current Sensing and Limiting
The current limiting switches protect the system power
supply and load from damage by continuously
monitoring current through the on-chip power MOSFET.
Load current is monitored by means of a current mirror
in parallel with the power MOSFET switch. Current
limiting is invoked when the load exceeds the over-
current threshold. When current limiting is activated the
output current is constrained to the limit value, and
remains at this level until either the load/fault is removed,
the load’s current requirement drops below the limiting
value, or the switch goes into thermal shutdown.
Kickstart™
The MIC2097 has a Kickstart feature that allows higher
momentary current surges before the onset of current
limiting. This permits dynamic loads, such as small disk
drives or portable printers to draw the inrush current
needed to overcome inertial loads without sacrificing
system safety. The Kickstart parts differ from the non-
Kickstart parts which more rapidly limit load current,
potentially starving a motor and causing the appliance to
stall or stutter.
During the Kickstart delay period, (typically 105ms), a
secondary current limit (nominally set at 1.5A), is in
effect. If the load demands a current in excess the
secondary limit, Kickstart parts act immediately to restrict
output current to the secondary limit for the duration of
the Kickstart period. After this time the Kickstart parts
revert to their normal current limit. An example of
Kickstart operation is in Figure 1.
Kickstart may be over-ridden by the thermal protection
circuit and if sufficient internal heating occurs, Kickstart
will be terminated and the output switch will be turned
off. After the parts cools, if the load is still present IOUT Æ
ILIMIT, not ILIMIT_2nd.
Micrel, Inc. MIC2095/97/98/99
August 2011 17 M9999-080211-C
Figure 1. MIC2097 Kickstart Operation
Figure 1 Label Key:
A. The MIC2097 is enabled into an excessive load
(slew-rate limiting not visible at this time scale) The
initial current surge is limited by either the overall
circuit resistance and power-supply compliance, or
the secondary current limit, whichever is less.
B. RON of the power FET increases due to internal
heating.
C. Kickstart period.
D. Current limiting initiated. FAULT/ goes low.
E. VOUT is non-zero (load is heavy, but not a dead short
where VOUT = 0V. Limiting response will be the same
for dead shorts).
F. Thermal shutdown followed by thermal cycling.
G. Excessive load released, normal load remains.
MIC2097 drops out of current limiting.
H. FAULT/ delay period followed by FAULT/ going
HIGH.
Enable Input
The ENABLE pin is a logic level compatible input which
turns on or off the main MOSFET switch. There are two
versions of each device. The −1 version has an active
high (ENABLE) and the −2 version has an active low
(ENABLE/).
Fault Output
The FAULT/ is an N-channel open-drain output, which is
asserted (LOW true) when the device either begins
current limiting or enters thermal shutdown. The FAULT/
signal asserts after a brief delay period in order to filter
out very brief over current conditions. After an over-
current or over-temperature fault clears, the FAULT/ pin
remains asserted (low) for the delay period.
The FAULT/output is open-drain and must be pulled
HIGH with an external resistor. The FAULT/ signal may
be wire-OR’d with other similar outputs, sharing a single
pull-up resistor. FAULT/ may be tied to a pull-up voltage
source which is less than or equal to VIN.
Soft-Start Control
Large capacitive loads can create significant inrush
current surges when charged through the current limiting
switch. When the switch is enabled, the built-in soft-start
limits the initial inrush current by slowly turning on the
output.
Power Dissipation and Thermal Shutdown
Thermal shutdown is used to protect the current limiting
switch from damage should the die temperature exceed
a safe operating temperature. Thermal shutdown shuts
off the output MOSFET and asserts the FAULT/ output if
the die temperature reaches 145°C (typical).
The switch will automatically resume operation when the
die temperature cools down to 135°C. If resumed
operation results in reheating of the die, another
shutdown cycle will occur and the switch will continue
cycling between ON and OFF states until the reason for
the overcurrent condition has been resolved.
Depending on PCB layout, package type, ambient
temperature, etc., hundreds of milliseconds may elapse
from the time a fault occurs to the time the output
MOSFET will be shut off. This delay is caused because
of the time it takes for the die to heat after the fault
condition occurs.
Power dissipation depends on several factors such as
the load, PCB layout, ambient temperature, and supply
voltage. Calculation of power dissipation can be
accomplished by the following equation:
(
)
2
OUTDS(ON)D IRP ×= Eq. 2
To relate this to junction temperature, the following
equation can be used:
AA)-(JDJ TRPT
+
×
=
θ
Eq. 3
Where TJ = junction temperature, TA = ambient
temperature, and Rθ(J-A) is the thermal resistance of the
package.
In normal operation, excessive switch heating is most
often caused by an output short circuit. If the output is
shorted, when the switch is enabled, the switch limits the
output current to the maximum value. The heat
generated by the power dissipation of the switch
continuously limiting the current may exceed the
package and PCB’s ability to cool the device and the
switch will shut down and signal a fault condition. Please
see the Fault Output description in the previous page for
more details on the FAULT/ output. After the switch
Micrel, Inc. MIC2095/97/98/99
August 2011 18 M9999-080211-C
shuts down, and cools, it will re-start itself if the Enable
signal retains true (high on the ENABLE parts, low on
the ENABLE/ parts).
In Figure 2, die temperature is plotted against IOUT
assuming a constant ambient temperature of 85°C. The
plot also assumes the maximum specified switch
resistance at high temperature.
Die Temperature vs Output Current
(Ambient Temperature = 85°C)
70
80
90
100
110
120
130
0.0 0.2 0.4 0.6 0.8 1.0 1.2
I
OUT
(A)
DIE TEMPERATURE (°C)
Tamb=85°C
Figure 2. Die Temperature vs. IOUT
Setting ILIMIT
The current limit of the MIC2097 and MIC2099 parts are
user programmable and controlled by a resistor
connected between the ILIMIT pin and Ground. The value
of the current limit resistor is determined by the following
equations:
LIMIT
LIMIT R
LF)itFactor(CCurrentLim
I= Eq. 4
or
LIMIT
LIMIT I
LF)itFactor(CCurrentLim
R= Eq. 5
The Current-Limit Factor (CLF) is a number that is
characteristic to the MIC2097/9 switches. The CLF is a
product of the current-setting resistor value, and the
desired current-limit value. Please note that the CLF
varies with the current output current, so caution is
necessary to use the correct CLF value for the current
that you intend to use the part at. For example: If one
wishes to set a ILIMIT = 1.1A, looking in the electrical
specifications we will find CLF at ILIMIT = 1.1 A, as noted
in Table 1.
Min. Typ. Max. Units
175 215 263 V
Table 1. CLF at ILIMIT = 1.1A
For the sake of this example, the typical value of CLF at
an IOUT of 1.1A is 215V. Applying Equation 5:
Ω==Ω 195
1.1A
215V
)(RLIMIT Eq. 6
Choose RLIMIT = 196 (the closest standard 1% value)
Designers should be aware that variations in the
measured ILIMIT for a given RLIMIT resistor, will occur
because of small differences between individual ICs
(inherent in silicon processing) resulting in a spread of
ILIMIT values. In the example above we used the typical
value of CLF to calculate RLIMIT. We can determine
ILIMIT’s spread by using the minimum and maximum
values of CLF and the calculated value of RLIMIT:
A89.0
196
175V
ILIMIT_MIN =
Ω
= Eq. 7
A34.1
196
V263
IMAX_LIMIT =
Ω
= Eq. 8
Giving us a maximum ILIMIT variation of:
ILIMIT_MIN I
LIMIT_TYP I
LIMIT_MAX
0.89A (-19%) 1.1A 1.34A (+22%)
For convenience, Table 2 lists the resistance values for
the RSET pin, for various current limit values.
Nominal
ILIMIT RLIMIT I
LIMIT_MIN I
LIMIT_MAX
0.1A 1920 0.063 0.137
0.2A 1000 0.138 0.263
0.3A 672 0.211 0.391
0.4A 508 0.288 0.517
0.5A 412 0.369 0.638
0.6A 344 0.448 0.764
0.7A 298 0.533 0.884
0.8A 263 0.620 1.002
0.9A 235 0.709 1.118
1.0A 213 0.801 1.233
1.1A 195 0.895 1.346
Table 2. MIC2097 and MIC2099 RLIMIT Table
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When measuring IOUT it is important to remember voltage
dependence, otherwise the measurement data may
appear to indicate a problem when none really exists.
This voltage dependence is illustrated in Figures 5 and
6.
ILIMIT vs. IOUT Measured
When in current limit, the switches are designed to act
as a constant-current source to the load. As the load
tries to pull more than the maximum current, VOUT drops
and the input-to-output voltage differential increases. As
the (VIN − V
OUT) voltage differential increases, the IC
internal temperature also increases. To limit the IC’s
power dissipation, the current limit is reduced as a
function of output voltage.
In Figure 5, output current is measured as VOUT is pulled
below VIN, with the test terminating when VOUT is 1V
below VIN. Observe that once ILIMIT is reached IOUT
remains constant throughout the remainder of the test. In
Figure 6 this test is repeated but with (VIN − VOUT) is 4V.
This folding back of ILIMIT can be generalized by plotting
ILIMIT as a function of VOUT, as shown in Figures 3 and 4.
The slope of VOUT between IOUT = 0V and IOUT = ILIMIT
(where ILIMIT is a normalized 1A) is determined by RON of
the switch and ILIMIT.
0
0.2
0.4
0.6
0.8
1.0
1.2
0123456
NORMALIZED OUTPUT CURRENT (A)
OUTPUT VOLTAGE (V)
Normalized Output Current
vs. Output Voltage (5V)
Figure 5. IOUT in Current Limiting for VOUT = 4V
Figure 3. Normalized Output Current vs. Output Voltage
0
0.2
0.4
0.6
0.8
1.0
1.2
0 0.5 1.0 1.5 2.0 2.5 3.0
NORMALIZED OUTPUT CURRENT (A)
OUTPUT VOLTAGE (V)
Normalized Output Current
vs. Output Voltage (2.5V)
Figure 6. IOUT in Current Limiting for VOUT = 1V
Under Voltage Lock Out (UVLO)
The switches have an Under Voltage Lock Out (UVLO)
feature that will shut down the switch in a reproducible
manner when the input power supply voltage goes too
low. The UVLO circuit disables the output until the
supply voltage exceeds the UVLO threshold. Hysteresis
in the UVLO circuit prevents noise and finite circuit
impedance from causing chatter during turn-on and turn-
off. While disable by the UVLO circuit, the output switch
(power MOSFET) is OFF and no circuit functions, such
as FAULT/ or ENABLE, are considered to be valid or
operative.
Figure 4. Normalized Output Current vs. Output Voltage
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Typical Application Schematics
Figure 7. MIC2095-1 or MIC2098-1 Typical Schematic
Note: MIC2095-1 and MIC2098-1; R5=NF; EN pin uses R4 (pull-up resistor to VIN) to enable the output without an external enable signal. MIC2095-2
and MIC2098-2; R4=NF; EN/ pin uses R5 (pull-down resistor to GND) to enable the output without an external enable signal.
Figure 8. MIC2097-1 Typical Schematic
Note: MIC2097-1; R5=NF; EN pin uses R4 (pull-up resistor to VIN) to enable the output without an external enable signal. MIC2097-2; R4=NF; EN/
pin uses R5 (pull-down resistor to GND) to enable the output without an external enable signal.
Figure 9. MIC2099-1 Schematic
Note: MIC2099-1; R5=NF; EN pin uses R4 (pull-up resistor to VIN) to enable the output without an external enable signal. MIC2099-2; R4=NF; EN/
pin uses R5 (pull-down resistor to GND) to enable the output without an external enable signal.
Micrel, Inc. MIC2095/97/98/99
August 2011 21 M9999-080211-C
Evaluation Board Schematic
Figure 10. Schematic of MIC209X Evaluation Board
Notes:
1. Evaluation board is used for all parts.
2. Part numbering scheme is 209X-Y where X is the place holder for the last number (i.e. MIC2095, MIC2097, MIC2098 or MIC2099) and Y is the
polarity of the enable signal (-1 indicates active high logic and -2 indicates active low logic).
3. MIC209X-1 EN pin only requires R4 (pull-up resistor to VIN) to enable the output without an external enable signal.
4. MIC209X-2 EN/ pin only requires R3 (pull-down resistor-to-GND) to enable the output without an external enable signal.
5. R1 is NF (no fill) with the MIC2095 (fixed current limit).
Micrel, Inc. MIC2095/97/98/99
August 2011 22 M9999-080211-C
MIC209x Bill of Materials
Item Part Number Manufacturer Description Qty.
C1 08056D106MAT2A AVX(1) Ceramic Capacitor, 10µF, 6.3V, X5R 1
C2 06033D105MAT2A AVX(1) Ceramic Capacitor, 1µF, 25V, X5R 1
C3 0805D226MAT2A AVX(1) Ceramic Capacitor, 22µF, 6.3V, X5R 1
C4 120µF (optional) 0
R1(4) CRCW06032000FRT1 Vishay Dale(2) Resistor, 200 (0603 size), 1% 1
R2, R3, R4 CRCW06031002FRT1 Vishay Dale(2) Resistor, 10k (0603 size), 1% 3
U1 MIC2095-1YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch – 0.5A
Fixed Current Limit – Active High Enable 1
U1 MIC2095-2YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch – 0.5A
Fixed Current Limit – Active Low Enable 0
U1 MIC2097-1YMT Micrel, Inc.(3)
Current-Limiting Power Distribution Switch –
Adjustable Current Limit with Kickstart – Active High
Enable
0
U1 MIC2097-2YMT Micrel, Inc.(3)
Current-Limiting Power Distribution Switch –
Adjustable Current Limit with Kickstart – Active Low
Enable
0
U1 MIC2098-1YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch – 0.9A
Fixed Current Limit – Active High Enable 0
U1 MIC2098-2YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch – 0.9A
Fixed Current Limit – Active Low Enable 0
U1 MIC2099-1YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch –
Adjustable Current Limit – Active High Enable 0
U1 MIC2099-2YMT Micrel, Inc.(3) Current-Limiting Power Distribution Switch –
Adjustable Current Limit – Active Low Enable 0
Notes:
1. AVX: www.avx.com.
2. Vishay: www.vishay.com.
3. Micrel, Inc.: www.micrel.com.
4. May be omitted when used with the MIC2095 or MIC2098 (fixed current limit).
Micrel, Inc. MIC2095/97/98/99
August 2011 23 M9999-080211-C
PCB Layout Recommendations
Figure 11. MIC209X Evaluation Board Top Layer
Figure 12. MIC209X Evaluation Board Bottom Layer
Micrel, Inc. MIC2095/97/98/99
August 2011 24 M9999-080211-C
Package Information
6-Pin 1.6mm x 1.6mm TMLF (MT)
Micrel, Inc. MIC2095/97/98/99
August 2011 25 M9999-080211-C
Recommended Landing Pattern
6-Pin 1.6mm x 1.6mm TMLF (MT)
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