MIC2098-2YMT-TR [MICROCHIP]
1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO6;
| 型号： | MIC2098-2YMT-TR |
| 厂家： | 
MICROCHIP |
| 描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO6 光电二极管 |
| 文件： | 总25页 (文件大小：1234K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC2095/MIC2097/MIC2098/MIC2099
Current-Limiting Power Distribution Switches
General Description
Features
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.
• 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
• 170mΩ typical on-resistance @ 5V
• 2.5V – 5.5V operating range
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.
Applications
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.
• Digital televisions (DTV)
• Set top boxes
• PDAs
• Printers
The MIC2095/97/98/99 family is offered in a space saving
1.6mm x 1.6mm Thin MLF® (TMLF) package.
• USB / IEEE 1394 power distribution
• Desktop and laptop PCs
• Game consoles
Datasheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
• USB keyboard
• Docking stations
_________________________________________________________________________________________________________________________
Typical Application
MIC2095 USB Power Switch
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
M9999-080211-C
August 2011
Micrel, Inc.
MIC2095/97/98/99
Ordering Information
Junction
Temperature
Range(1)
FAULT/
Output
ENABLE
Logic
Part Number
Marking
Kickstart(™)
ILIMIT
Package
6-Pin 1.6mm x
1.6mm TMLF
MIC2095-1YMT
MIC2095-2YMT
MIC2097-1YMT
MIC2097-2YMT
MIC2098-1YMT
MIC2098-2YMT
MIC2099-1YMT
MIC2099-2YMT
J1K
J2K
Active High
Active Low
Active High
Active Low
Active High
Active Low
Active High
Active Low
No
No
0.5A
0.5A
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
6-Pin 1.6mm x
1.6mm TMLF
6-Pin 1.6mm x
1.6mm TMLF
K1K
K2K
H1K
H2K
G1K
G2K
Yes
Yes
No
0.1 A – 1.1A
0.1 A – 1.1A
0.9A
6-Pin 1.6mm x
1.6mm TMLF
6-Pin 1.6mm x
1.6mm TMLF
6-Pin 1.6mm x
1.6mm TMLF
No
0.9A
6-Pin 1.6mm x
1.6mm TMLF
No
0.1 A – 1.1A
0.1 A – 1.1A
6-Pin 1.6mm x
1.6mm TMLF
No
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
M9999-080211-C
August 2011
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Micrel, Inc.
MIC2095/97/98/99
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
NC
No Connect; Pin not used.
(MIC2095/MIC2098)
2
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.
ILIMIT
(MIC2097/MIC2099)
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.
3
FAULT/
4
(MIC2095-1/MIC2097-1/
MIC2098-1/MIC2099-1)
4
(MIC2095-2/MIC2097-2/
MIC2098-2/MIC2099-2)
ENABLE
ENABLE/
Switch Enable (Input): Logic high on this pin enables the switch.
Switch Enable (Input): Logic low on this pin enables the switch.
Ground.
5
GND
VIN
Power input (Input): This pin provides power to both the output power switch and the
internal control circuitry.
6
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.
EP
EP
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August 2011
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Micrel, Inc.
MIC2095/97/98/99
Absolute Maximum Ratings(1)
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)
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
1.6mm × 1.6mm TMLF (θJA)..............................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.
2.5
Typ.
Max.
Units
Power Input Supply
VIN
Input Voltage Range
5.5
V
Switch = ON
Active Low Enable, VEN = 0V
Active High Enable, VEN = 1.5V
Quiescent Supply Current(5)
80
8
300
µA
IIN
Switch = OFF
15
5
µA
Active Low Enable, VEN = 1.5V
Shutdown Current
Switch = OFF
0.1
µA
V
Active High Enable, VEN = 0.5V
VIN Rising
2
2.25
2.5
2.4
VIN UVLO Threshold
VIN UVLO Hysteresis
UVLOTHRESHOLD
VIN Falling
1.9
2.15
100
V
mV
Enable Control
ENABLE Logic Level Low(5)
ENABLE Logic Level High(5)
ENABLE Bias Current
VIL(MAX)
0.5
V
V
VEN
VIH(MIN)
1.5
IEN
0V ≤ VEN ≤ 5V
0.1
5
µA
RL = 43Ω, CL = 120µF
tON_DLY
Output Turn-on Delay
Output Turn-off Delay
Output Turn-on rise time
1000
1500
µs
µs
µs
V
EN = 50% to VOUT = 10%
RL = 43Ω, CL = 120µF
tOFF_DLY
tRISE
Thermal Protection
700
V
EN = 50% to VOUT = 90%
RL = 100Ω, CLOAD = 1µF
500
1000
1500
V
OUT = 10% to 90%
TJ Rising
TJ Falling
145
135
°C
°C
OTThreshold
Over-temperature Shutdown
M9999-080211-C
August 2011
4
Micrel, Inc.
MIC2095/97/98/99
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
mꢀ
mꢀ
RDS(ON)
On Resistance
VIN = 5V, IOUT = 100mA
275
Switch = OFF, VOUT = 0V
ILEAK
Output Leakage Current
Active Low Enable, VEN = 1.5V
Active High Enable, VEN = 0V
0.1
10
µA
Output Current Limit (MIC2095)
ILIMIT Fixed Current Limit
Output Current Limit (MIC2098)
VOUT = 0.8 × VIN
VOUT = 0.8 × VIN
0.5
0.9
0.7
1.1
0.9
1.5
A
A
ILIMIT
Fixed Current Limit
Output Current Limit (MIC2097, MIC2099)
IOUT = 1.1A, VOUT = 0.8 × VIN; VIN =2.5V
IOUT = 0.5A, VOUT = 0.8 × VIN; VIN =2.5V
IOUT = 0.2A, VOUT = 0.8 × VIN; VIN =2.5V
IOUT = 0.1A, VOUT = 0.8 × VIN; VIN =2.5V
175
152
138
121
215
206
200
192
263
263
263
263
V
V
V
V
Variable Current Limit
Factors
CLF
KickstartTM Current Limit (MIC2097)
ILIMIT_2nd
tD_LIMIT
Secondary Current Limit
VIN = 2.5V; VOUT = 0V
VIN = 2.5V
1.5
A
Duration of KickstartTM
Current Limit
77
105
192
ms
Fault Flag
Fault Flag Output Voltage
Fault Flag Off Current
IOL = 10mA
VFAULT/ =5V
0.25
0.01
0.4
1
V
VFAULT/
µA
Fault Delay (MIC2095, MIC2098, MIC2099)
Delay before asserting or
releasing FAULT/
Time from current limiting (VOUT = 0.4 x
VIN) to FAULT/ state change
tD_FAULT
20
77
32
49
ms
ms
Fault Delay (MIC2097)
Delay before asserting or
releasing FAULT/
Time from current limiting (VOUT = 0.8 x
VIN) to FAULT/ state change; VIN = 2.5V
tD_FAULT
105
192
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.
M9999-080211-C
August 2011
5
Micrel, Inc.
MIC2095/97/98/99
Timing Diagrams
tRISE
tFALL
90%
90%
10%
10%
Rise and Fall Times
ENABLE
50%
50%
tON_DLY
tOFF_DLY
90%
VOUT
10%
Switching Delay Times
M9999-080211-C
August 2011
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Micrel, Inc.
MIC2095/97/98/99
Typical Characteristics
VIN Shutdown Current
VIN Shutdown Current
vs. Input Voltage
VIN Supply Current
vs. Input Voltage
vs. Input Voltage
10
6
4
100
80
60
40
20
0
8
6
2
4
-2 Version
0
2
0
-1 Version
-2
2.5
3.0
3.5
4.0
4.5
5.0
5.5
5.5
5.5
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
5.5
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Current Limit vs. Input Voltage
MIC2098
Current Limit vs. Input Voltage
MIC2095
Current Limit vs. Input Voltage
MIC2097/MIC2099
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.2
1.0
0.8
0.6
0.4
0.2
0.0
ILIMIT
1.0
0.8
0.6
0.4
0.2
0.0
ILIMIT
RSET = 200ꢀ, ISET = 1.08A
ISC
ISC
RSET = 298ꢀ, ISET = 0.7A
RSET = 508ꢀ, ISET = 0.4A
VOUT=0.8*VIN
RSET = 1920ꢀ, ISET=0.1A
VOUT = 0.8*VIN
VOUT = 0.8*VIN
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
2.5
3.0
3.5
4.0
4.5
5.0
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Current Limit vs. Input Voltage
MIC2097/MIC2099
Switch On Resistance
vs. Input Voltage
Fault Delay vs. Input Voltage
MIC2095/MIC2098/MIC2099
1.2
1.0
0.8
0.6
0.4
0.2
0.0
240
220
200
180
160
140
120
100
40
35
30
25
20
15
10
5
ILIMIT
ISC
RSET =195ꢀ
I
SET = 1.1A
CLOAD = 1μF
V
OUT = 0.8*VIN
RLOAD = 100ꢀ
IOUT = 100mA
0
2.5
3.0
3.5
4.0
4.5
5.0
2.5
3.0
3.5
4.0
4.5
5.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
Fault Delay vs. Input Voltage
MIC2097
Kickstart Current vs. Input Voltage
MIC2097
Kickstart Period vs. Input Voltage
MIC2097
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
140
120
100
80
140
120
100
80
60
60
RSET = 195ꢀ
40
I
SET = 1.1A
CLOAD = 1μF
40
V
OUT = 0.8*VIN
RLOAD = 100ꢀ
20
20
0
0
2.5
3.0
3.5
4.0
4.5
5.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
M9999-080211-C
August 2011
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Micrel, Inc.
MIC2095/97/98/99
Typical Characteristics (Continued)
VIN ShutdownCurrent
vs. Temperature
VIN Supply Current
vs.Temperature
VIN ShutdownCurrent
vs. Temperature
1.0
0.8
0.6
0.4
0.2
0.0
10.0
8.0
6.0
4.0
2.0
0.0
100
80
60
40
20
0
-2 Version
-1 Version
VIN = 5V
VIN = 5V
VIN = 3V
VIN = 3V
VIN = 3V
VIN = 5V
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
Current Limit vs.Temperature
MIC2097/MIC2099
Current Limit vs. Temperature
MIC2095
Current Limit vs. Temperature
MIC2098
1.0
0.8
0.6
0.4
0.2
0.0
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.2
1.0
0.8
0.6
0.4
0.2
0.0
ILIMIT
ITHRESHOLD
ILIMIT
ISC
ISC
VIN = 5.0V
V
OUT = 4V
SET =195ꢀ
SET = 1.1A
VIN = 5.0V
R
ISC
VIN = 5.0V
OUT = 4V
V
OUT = 4V
I
V
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
Output Fall Time
vs. Temperature
RDS(ON)
Output Rise Time
vs. Temperature
vs. Temperature
240
220
200
180
160
140
120
100
340
300
260
220
180
140
100
1200
VIN = 5.0V
VIN = 5.0V
VIN = 3.3V
1000
800
600
400
200
0
VIN = 3V
VIN = 3V
VIN = 5.0V
CLOAD = 1μF
CLOAD = 1μF
RLOAD =100ꢀ
RLOAD =100ꢀ
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
Kickstart Current vs. Temperature
MIC2097
Fault Delay vs. Temperature
MIC2095/MIC2099
VIN UVLO Thresholds
vs. Temperature
2.5
2.4
2.3
2.2
2.1
2.0
40
35
30
25
20
15
10
5
1.60
1.55
1.50
1.45
1.40
1.35
1.30
1.25
1.20
VIN = 3V
VIN = 5.0V
VIN Rising
VIN = 5.0V
VIN = 3V
VOUT = 4V
SET =195ꢀ
SET = 1.1A
CLOAD = 1μF
RLOAD =100ꢀ
R
VIN Falling
I
0
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
M9999-080211-C
August 2011
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Micrel, Inc.
MIC2095/97/98/99
Typical Characteristics (Continued)
ILIMIT & ISET vs. RSET
MIC2097/MIC2099
VIN - VOUT (VIN = 5.0V)
vs. Output Current
Kickstart Period vs. Temperature
MIC2097
160
140
120
100
80
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
250
200
150
100
50
VIN = 5.0V
85ºC
25ºC
-40ºC
ISET
VIN = 3V
VIN = 5V
60
Vo=4V
TA = 25°C
40
ILIMIT
VIN = 5V
20
0
0
0
300 600 900 1200 1500 1800 2100
-40
-15
10
35
60
85
0.0
0.2
0.4
0.6
0.8
1.0
1.2
R
SET(Ω)
TEMPERATURE (°C)
OUTPUT CURRENT (A)
VIN - VOUT (VIN = 3.0V)
vs. Output Current
250
200
150
100
50
85ºC
25ºC
-40ºC
VIN = 3V
0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
OUTPUT CURRENT (A)
M9999-080211-C
August 2011
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Micrel, Inc.
MIC2095/97/98/99
Functional Characteristics
M9999-080211-C
August 2011
10
Micrel, Inc.
MIC2095/97/98/99
Functional Characteristics (Continued)
M9999-080211-C
August 2011
11
Micrel, Inc.
MIC2095/97/98/99
Functional Characteristics (Continued)
M9999-080211-C
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12
Micrel, Inc.
MIC2095/97/98/99
Functional Characteristics (Continued)
M9999-080211-C
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13
Micrel, Inc.
MIC2095/97/98/99
Functional Characteristics (Continued)
M9999-080211-C
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Micrel, Inc.
MIC2095/97/98/99
Functional Diagram
MIC2095/97/98/99 Functional Diagram
M9999-080211-C
August 2011
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Micrel, Inc.
MIC2095/97/98/99
Functional Description and Application
Information
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:
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.
ILIMIT _MIN × tD_FAULT _MIN
COUT _MAX
=
Eq. 1
VIN_MAX
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.
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.
CIN
A minimum 1μF 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.
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.
An additional 22μF (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 10μF 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
0.1μF to 1μF are recommended. Again, good quality,
low-ESR capacitors, preferably ceramic, should be
chosen.
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.
COUT
An output capacitor is recommended to reduce ringing
and voltage sag on the output during a transient
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
condition.
A
value between 1µf and 10µf is
recommended, however, larger values can be used.
off. After the parts cools, if the load is still present IOUT
ILIMIT, not ILIMIT_2nd
Æ
.
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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).
Figure 1. MIC2097 Kickstart Operation
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.
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.
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.
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).
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:
F. Thermal shutdown followed by thermal cycling.
G. Excessive load released, normal load remains.
MIC2097 drops out of current limiting.
2
PD = RDS(ON)
×
IOUT
)
Eq. 2
H. FAULT/ delay period followed by FAULT/ going
HIGH.
To relate this to junction temperature, the following
equation can be used:
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/).
TJ = PD ×Rθ(J-A) + TA
Eq. 3
Where TJ = junction temperature, TA = ambient
temperature, and Rθ(J-A) is the thermal resistance of the
package.
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.
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
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
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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).
For the sake of this example, the typical value of CLF at
an IOUT of 1.1A is 215V. Applying Equation 5:
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.
215V
RLIMIT (Ω) =
= 195Ω
Eq. 6
1.1A
Choose RLIMIT = 196ꢀ (the closest standard 1% value)
Die Temperature vs Output Current
(Ambient Temperature = 85°C)
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
130
120
110
100
90
values of CLF and the calculated value of RLIMIT
:
Tamb=85°C
80
70
175V
ILIMIT_MIN
=
= 0.89A
= 1.34A
Eq. 7
Eq. 8
0.0
0.2
0.4
0.6
OUT (A)
0.8
1.0
1.2
196Ω
I
Figure 2. Die Temperature vs. IOUT
263V
ILIMIT _MAX
=
196Ω
Setting ILIMIT
The current limit of the MIC2097 and MIC2099 parts are
user programmable and controlled by resistor
Giving us a maximum ILIMIT variation of:
a
connected between the ILIMIT pin and Ground. The value
of the current limit resistor is determined by the following
equations:
ILIMIT_MIN
ILIMIT_TYP
1.1A
ILIMIT_MAX
0.89A (-19%)
1.34A (+22%)
CurrentLimitFactor(CLF)
For convenience, Table 2 lists the resistance values for
the RSET pin, for various current limit values.
ILIMIT
=
Eq. 4
Eq. 5
RLIMIT
or
CurrentLimitFactor(CLF)
ILIMIT
Nominal
RLIMIT
=
RLIMIT
ILIMIT_MIN
ILIMIT_MAX
ILIMIT
0.1A
0.2A
0.3A
0.4A
0.5A
0.6A
0.7A
0.8A
0.9A
1.0A
1.1A
1920
1000
672
508
412
344
298
263
235
213
195
0.063
0.138
0.211
0.288
0.369
0.448
0.533
0.620
0.709
0.801
0.895
0.137
0.263
0.391
0.517
0.638
0.764
0.884
1.002
1.118
1.233
1.346
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
Table 2. MIC2097 and MIC2099 RLIMIT Table
175
215
263
V
Table 1. CLF at ILIMIT = 1.1A
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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 − VOUT) 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
.
Normalized Output Current
vs. Output Voltage (5V)
1.2
1.0
0.8
0.6
0.4
0.2
0
Figure 5. IOUT in Current Limiting for VOUT = 4V
0
1
2
3
4
5
6
OUTPUT VOLTAGE (V)
Figure 3. Normalized Output Current vs. Output Voltage
Normalized Output Current
vs. Output Voltage (2.5V)
1.2
1.0
0.8
0.6
0.4
0.2
0
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.
0
0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT VOLTAGE (V)
Figure 4. Normalized Output Current vs. Output Voltage
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MIC2095/97/98/99
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.
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Micrel, Inc.
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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).
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MIC209x Bill of Materials
Item
C1
Part Number
Manufacturer
AVX(1)
Description
Qty.
1
08056D106MAT2A
06033D105MAT2A
0805D226MAT2A
Ceramic Capacitor, 10µF, 6.3V, X5R
Ceramic Capacitor, 1µF, 25V, X5R
Ceramic Capacitor, 22µF, 6.3V, X5R
120µF (optional)
C2
AVX(1)
AVX(1)
1
C3
1
C4
0
R1(4)
CRCW06032000FRT1
CRCW06031002FRT1
Vishay Dale(2)
Vishay Dale(2)
Resistor, 200 (0603 size), 1%
Resistor, 10k (0603 size), 1%
1
R2, R3, R4
3
Current-Limiting Power Distribution Switch – 0.5A
Fixed Current Limit – Active High Enable
U1
U1
MIC2095-1YMT
MIC2095-2YMT
Micrel, Inc.(3)
Micrel, Inc.(3)
1
0
Current-Limiting Power Distribution Switch – 0.5A
Fixed Current Limit – Active Low Enable
Current-Limiting Power Distribution Switch –
Adjustable Current Limit with Kickstart – Active High
Enable
U1
U1
MIC2097-1YMT
MIC2097-2YMT
Micrel, Inc.(3)
Micrel, Inc.(3)
0
0
Current-Limiting Power Distribution Switch –
Adjustable Current Limit with Kickstart – Active Low
Enable
Current-Limiting Power Distribution Switch – 0.9A
Fixed Current Limit – Active High Enable
U1
U1
U1
MIC2098-1YMT
MIC2098-2YMT
MIC2099-1YMT
MIC2099-2YMT
Micrel, Inc.(3)
Micrel, Inc.(3)
Micrel, Inc.(3)
Micrel, Inc.(3)
0
0
0
0
Current-Limiting Power Distribution Switch – 0.9A
Fixed Current Limit – Active Low Enable
Current-Limiting Power Distribution Switch –
Adjustable Current Limit – Active High Enable
Current-Limiting Power Distribution Switch –
Adjustable Current Limit – Active Low Enable
U1
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).
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PCB Layout Recommendations
Figure 11. MIC209X Evaluation Board Top Layer
Figure 12. MIC209X Evaluation Board Bottom Layer
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Package Information
6-Pin 1.6mm x 1.6mm TMLF (MT)
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Micrel, Inc.
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Recommended Landing Pattern
6-Pin 1.6mm x 1.6mm TMLF (MT)
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
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This
information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability
whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right.
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.
© 2010 Micrel, Incorporated.
M9999-080211-C
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