MIC2091-2YM5-TR [MICROCHIP]
1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO5;
| 型号： | MIC2091-2YM5-TR |
| 厂家： | 
MICROCHIP |
| 描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO5 光电二极管 |
| 文件： | 总23页 (文件大小：1115K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC2090/MIC2091
Current Limiting Power
Distribution Switches
General Description
Features
The MIC2090 and MIC2091 are high-side MOSFET power
switches optimized for general-purpose 50mA or 100mA
low power distribution in circuits requiring over-current
limiting and circuit protection. Typical applications for these
parts are for switching power in USB ports, portable
consumer items, camera and camcorder motor protection,
thermal printer head protection, and many other low
current-load switching applications.
• 1.8V to 5.5V supply voltage
• 790 mΩ typical RDSON at 3.3V
• MIC2090 is rated for 50mA minimum continuous current
• MIC2091 is rated for 100mA minimum continuous
current
• Reverse current blocking (OGI)
• 20ns super fast reaction time to hard short at output
• 10ms fault flag delay (tD_FAULT/) eliminates false
assertions
The MIC2090 and MIC2091 come in two versions: auto-
retry current limit and output latch off on an over current
fault. The MIC2090 and MIC2091 are offered in a space
saving 5-pin SOT-23 package with an operating junction
temperature range of -40°C to +125°C.
• Auto-retry overcurrent and short-circuit protection (-1
version)
• Latch-off on current limit (-2 version)
• Thermal shutdown
• Fault status flag indicates: over-current, over-
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
temperature, or UVLO
• Under-voltage lockout (UVLO)
• Low quiescent current
Applications
• USB peripherals
• Camcorder
• DSC
• MP3/iPod
• SD protection
• USB low-power hub
_________________________________________________________________________________________________________________________
Typical Application
MIC2091 USB Power Switch
Startup into Short Circuit
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
M9999-070611-B
July 2011
Micrel, Inc.
MIC2090/MIC2091
Ordering Information
Current
Limit
Current-Limit
Recovery
Junction Temperature
Range
Part Number
Marking
Package
MIC2090-1YM5
MIC2091-1YM5
MIC2090-2YM5
MIC2091-2YM5
L1K
M1K
L2K
M2K
50mA
100mA
50mA
Auto-Retry
Auto-Retry
Latch-Off
Latch-Off
SOT-23-5
SOT-23-5
SOT-23-5
SOT-23-5
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
–40°C to +125°C
100mA
Pin Configuration
5-Pin SOT-23 (M5)
Pin Description
Pin Number
Pin Name
Pin Function
Supply (Input): +1.8V to +5.5V. Provides power to the output switch and the MIC2090/MIC2091
internal control circuitry.
1
2
3
VIN
GND
EN
Ground.
Enable (Input): Active-high TTL compatible control input. A high signal turns on the internal
switch and supplies power to the load. This pin cannot be left floating.
Fault Status (Output): Open drain output. Can be connected to other open drain outputs. Must
be pulled high with an external resistor.
When EN=0, FAULT/ pin is high
When EN=1, a low on the FAULT/ pin indicates one or more of the following conditions:
1. The part is in current limit and is turned off.
2. The part is in thermal limit and is turned off.
3. The part is in UVLO
4
5
FAULT/
VOUT
Switched Output (Output): The voltage on this pin is controlled by the internal switch. Connect
the load driven by the MIC2090/MIC2091 to this pin.
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July 2011
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Micrel, Inc.
MIC2090/MIC2091
Absolute Maximum Ratings(1)
Operating Ratings(2)
Supply Voltage (VIN)..................................... +1.8V to +5.5V
Output Voltage (VOUT) .................................. +1.8V to +5.5V
EN Pin Voltage (VEN).............................................. 0V to VIN
FAULT/ Pin Voltage (VFAULT/) .............................. 0V to 5.5V
FAULT/ Pin Current (I FAULT/) .........................................1mA
Ambient Temperature (TA) ..........................–40°C to +85°C
Junction Temperature (TJ) ........................–40°C to +125°C
Package Thermal Resistance
Supply Voltage (VIN)..................................... −0.3V to +6.0V
Output Voltage (VOUT). ................................. −0.3V to +6.0V
FAULT/ Pin Voltage (VFAULT/) ....................... −0.3V to +6.0V
FAULT/ Pin Current (I FAULT/) .......................................25mA
EN Pin Voltage (VEN)........................... −0.3V to (VIN + 0.3V)
Power Dissipation (PD)..............................Internally Limited
Maximum Junction Temperature (TJ)......................... 150°C
Storage Temperature (TS).........................−65°C to +150°C
Lead Temperature (soldering, 10s)............................ 260°C
ESD HBM Rating(3).........................................................3kV
ESD MM Rating(3).........................................................200V
SOT23-5 (θJA)...............................................252.7°C/W
Electrical Characteristics(4)
VIN = 5V; TA = 25°C, bold values indicate –40°C ≤ TA ≤ +85°C, unless noted.
Symbol
Power Input Supply
VIN Input Voltage Range
Parameter
Condition
Min.
1.8
Typ.
Max.
Units
5.5
10
V
Shutdown Current
Supply Current
5
VEN ≤ 0.5V (switch off), VOUT = open
VEN ≥ 1.5V (switch on), VOUT = open
IVIN
µA
70
110
Under-Voltage Lockout
Threshold
VUVLO
VIN rising
1.75
V
Under-Voltage Lockout
Threshold Hysteresis
VUVLO_HYS
100
mV
Enable Input
Enable Logic Level High(5) VIH (MIN)
1.5
VEN
V
Enable Logic Level Low(5)
VIL (MAX)
0.5
IEN
Enable Bias Current
VEN = 5V
0.1
215
5
µA
µs
µs
µs
µs
tON
Output Turn-On Delay
RL = 500Ω, CL = 0.1µF See “Timing Diagrams”
tR
Output Turn-On Rise Time RL = 500Ω, CL = 0.1µF See “Timing Diagrams”
tOFF
Output Turn-Off Delay
RL = 500Ω, CL = 0.1µF See “Timing Diagrams”
RL = 500Ω, CL = 0.1µF See “Timing Diagrams”
125
115
tF
Output Turn-Off Fall Time
Internal Switch
MIC2090 VIN = 5.0V, IOUT = 50mA
MIC2090 VIN = 3.3V, IOUT = 50mA
MIC2090 VIN = 1.8V, IOUT = 50mA
MIC2091 VIN = 5.0V, IOUT = 100mA
MIC2091 VIN = 3.3V, IOUT = 100mA
MIC2091 VIN = 1.8V, IOUT = 100mA
700
790
1200
1200
1300
700
RDSON
On Resistance RDS(ON)
mꢀ
μA
1200
1200
790
1300
Input-to-Output Leakage
Current (Forward leakage
Current)
MIC2090 and MIC2091, VEN ≤ 0.5V, (output
off), VIN = 5.5V, VOUT = 0V
10
M9999-070611-B
July 2011
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Micrel, Inc.
MIC2090/MIC2091
Electrical Characteristics(4) (Continued)
VIN = 5V; TA = 25°C, bold values indicate –40°C ≤ TA ≤ +85°C, unless noted.
Symbol
Parameter
Condition
Min.
Typ.
Max.
10
Units
Output to Input Leakage
Current (Reverse Leakage
Current)
MIC2090 and MIC2091, VEN ≤ 0.5V, (output
off), VOUT = 5.5V, VIN = 0V
µA
Current Limit
MIC2090 @ VOUT = 4.5V
MIC2090 @ VOUT = 0V
MIC2091 @ VOUT = 4.5V
MIC2091 @ VOUT = 0V
50
50
75
100
150
200
250
100
150
175
ILIMIT
Current-Limit Threshold
mA
100
100
Short-Circuit Response
Time
Short circuit applied to output after switch is
turned on, see “Timing Diagrams”. VIN = 3.3V.
tSC_RESP
20
ns
Time After Switch Shuts
Down From An Over-
Current Condition Before
It Tries To Turn On Again.
TAUTORESTART
30
60
90
0.4
20
ms
FAULT/ Flag
Error Flag Output Voltage
Output voltage high (1mA Sinking)
V
When an over-current condition happens, the
part will go into constant output current for this
time. After this time it will turn off the output
and pull low the PIN FAULT/. The MIC2090-1
and MIC2091-1 will automatically restart
themselves after the auto restart time
Time After Switch Comes
Into Current Limit Before
The PIN FAULT/ Is Pulled
Low.
tD_FAULT/
5
10
ms
TAUTORESTART
.
FAULT/ is connected to VIN = 5V through 10kꢀ
and 100pF in parallel. See “Timing Diagrams”
tR_FAULT/
tF_FAULT/
FAULT/ Rising Time
FAULT/ Falling Time
5
1
µs
µs
Reverse Voltage Protection (OGI)
If the output voltage is greater than the input
voltage by this amount, the part will shut down.
The enable pin must be recycled to reset.
Output Voltage Greater
OGI
85
10
mV
ms
Than Input Voltage (OGI)
Time that the output voltage can be greater
than the input voltage before the chip is shut
down.
OGITIME
Thermal Protection
TJ Rising
TJ Falling
150
140
Over-Temperature
TOVERTEMP
°C
Shutdown
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. Specification for packaged product only.
5.
V
IL(MAX) = Maximum positive voltage applied to the input which will be accepted by the device as a logic low.
VIH(MIN) = Minimum positive voltage applied to the input which will be accepted by the device as a logic high.
M9999-070611-B
July 2011
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Micrel, Inc.
MIC2090/MIC2091
Timing Diagrams
Output Rise and Fall Times (tR, tF)
Switch Delay Time (tON, tOFF
)
M9999-070611-B
July 2011
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Micrel, Inc.
MIC2090/MIC2091
Typical Characteristics
VIN Shutdown Current
vs. Input Voltage
VIN Supply Current
vs. Input Voltage
Enable Thresholds
vs. Input Voltage
1.3
1.2
1.1
1.0
0.9
0.8
0.7
10
8
80
70
60
50
40
VEN Rising
6
VEN Falling
4
2
0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.5
2.0
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
MIC2090
Auto-Reset Time vs. Input
Voltage (MIC2090)
FAULT/ Delay vs. Input Voltage
(MIC2090)
110.0
100.0
90.0
8.0
7.8
7.6
7.4
7.2
7.0
ILIMIT @ VOUT = 0V
61.0
60.5
60.0
59.5
59.0
58.5
58.0
ILIMIT @ VOUT = 0.9V * VOUT
80.0
CLOAD = 10μF
70.0
1.5 2.0
2.5 3.0 3.5 4.0
4.5 5.0 5.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.5
2.0
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
MIC2091
Switch On Resistance
vs. Input Voltage
Output Turn-On Delay
vs. Input Voltage
1.5
1.3
1.1
0.9
0.7
0.5
205
200
195
190
185
220.0
210.0
200.0
190.0
180.0
170.0
160.0
150.0
ILIMIT @ VOUT = 0V
ILIMIT @ VOUT = 0.9V * VOUT
CLOAD = 0.1μF
RLOAD = 500ꢀ
IOUT = 10mA
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
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July 2011
6
Micrel, Inc.
MIC2090/MIC2091
Typical Characteristics (Continued)
Output Rise Time
vs. Input Voltage
Output Turn-Off Delay
vs. Input Voltage
Output Fall Time
vs. Input Voltage
8
7
6
5
4
3
2
1
0
110
100
90
35
34
33
32
31
30
29
80
CLOAD = 0.1μF
RLOAD = 500ꢀ
CLOAD = 0.1μF
RLOAD = 500ꢀ
CLOAD = 0.1μF
RLOAD = 500ꢀ
70
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
OGI Threshold
vs. Input Voltage
OGI Delay
vs. Input Voltage
VIN ShutdownCurrent
vs. Temperature
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
10
9
100
90
80
70
60
50
VIN = 5V
8
7
VIN = 1.8V
6
5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
-40
-15
10
35
60
85
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
TEMPERATURE (°C)
Current Limit vs. Temperature
(MIC2090)
VIN Supply Current
vs.Temperature
Enable Threshold
vs. Temperature
96
94
92
90
88
86
84
82
80
78
76
74
72
70
80
75
70
65
60
55
50
45
40
1.40
1.35
1.30
1.25
1.20
1.15
1.10
1.05
1.00
ILIMIT @ VOUT = 0V
VEN Rising
VIN = 5V
ILIMIT @ VOUT = 4.5V
VIN = 1.8V
VEN Falling
VIN = 5.0V
VIN = 5.0V
35
RLOAD
35
= 0
-40
-15
10
35
60
85
-40
-15
10
60
85
-40
-15
10
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
M9999-070611-B
July 2011
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Micrel, Inc.
MIC2090/MIC2091
Typical Characteristics (Continued)
Auto-Reset Time vs.
Temperature (MIC2090)
Current Limit vs.
Temperature (MIC2090)
FAULT/ Delay vs. Temperature
(MIC2090)
8.5
8.0
7.5
7.0
6.5
110
105
100
95
66
65
64
63
62
61
60
59
58
VIN = 1.8V
ILIMIT @ VOUT = 0V
VIN = 5V
90
VIN = 1.8V
ILIMIT @ VOUT = 1.6V
85
80
VIN = 5.0V
VIN = 1.8V
35
75
70
-40
-15
10
35
60
85
-40
-15
10
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
Current Limit vs. Temperature
(MIC2091)
Current Limit vs. Temperature
(MIC2091)
RDS(ON)
240
230
220
210
200
190
180
170
160
150
140
vs. Temperature
190
180
170
160
150
140
1.6
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
ILIMIT @ VOUT = 0V
VIN = 1.8V
ILIMIT @ VOUT = 0V
ILIMIT @ VOUT = 1.6V
VIN = 5.0V
ILIMIT @ VOUT = 4.5V
VIN = 1.8V
IOUT = 10mA
VIN = 5.0V
-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 Rise Time
vs. Temperature
Output Turn-Off Delay
vs. Temperature
Output Turn-On Delay
vs. Temperature
7
6
5
4
3
2
1
0
215
210
205
200
195
190
185
35
33
31
29
27
25
VIN = 5.0V
VIN = 5.0V
VIN = 1.8V
VIN = 1.8V
CLOAD = 0.1μF
RLOAD =500ꢀ
CLOAD = 0.1μF
VIN = 1.8V
RLOAD =500ꢀ
CLOAD = 0.1μF
RLOAD =500ꢀ
VIN = 5.0V
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
M9999-070611-B
July 2011
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Micrel, Inc.
MIC2090/MIC2091
Typical Characteristics (Continued)
Output Fall Time
vs. Temperature
OGI Threshold
vs. Temperature
OGI Delay
vs. Temperature
120
110
100
90
120
100
80
60
40
20
0
9.0
8.8
8.6
8.4
8.2
8.0
7.8
7.6
VIN = 5.0V
VIN = 5.0V
VIN = 5.0V
VIN = 1.8V
VIN = 1.8V
80
VIN = 1.8V
CLOAD = 0.1μF
70
RLOAD =500ꢀ
60
-40
-15
10
35
60
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
VIN UVLO Thresholds
vs. Temperature
1.4
1.3
1.2
1.1
1.0
VIN Rising
VIN Falling
-40
-15
10
35
60
85
TEMPERATURE (°C)
M9999-070611-B
July 2011
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Micrel, Inc.
MIC2090/MIC2091
Functional Characteristics
M9999-070611-B
July 2011
10
Micrel, Inc.
MIC2090/MIC2091
Functional Characteristics (Continued)
M9999-070611-B
July 2011
11
Micrel, Inc.
MIC2090/MIC2091
Functional Characteristics (Continued)
M9999-070611-B
July 2011
12
Micrel, Inc.
MIC2090/MIC2091
Functional Characteristics (Continued)
M9999-070611-B
July 2011
13
Micrel, Inc.
MIC2090/MIC2091
Functional Diagram
MIC2090/MIC2091 Functional Diagram
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Micrel, Inc.
MIC2090/MIC2091
Functional Description
Limitations on COUT
The part may enter current limit when turning on with a
large output capacitance, which 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 Equation 1:
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.
I
×T
LIMIT_MIN
D_FAULT_MIN
When the switch is disabled, current will not flow to the
load, except for a small unavoidable leakage current of a
few microamps (forward leakage current).
C
=
Eq. 1
OUT_MAX
V
IN_MAX
CIN
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.
A minimum 1μF bypass capacitor positioned close 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, place a
ceramic capacitor next to the IC.
Current Sensing and Limiting
The MIC2090/MIC2091 protects 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 in
the -1 version, 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. If the overcurrent fault is large
enough to drop VOUT below (typically) 1.8V, the internal
MOSFET turns off very quickly (typically 20ns). This
prevents excessive current from flowing through the
device and damaging the internal MOSFET.
An additional 10µF (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 three 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 or more, 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.
The latch-off feature of the -2 version latches the output
off when the output current exceeds the overcurrent
threshold. VIN or the enable pin must be toggled to reset
the latch.
COUT
Enable Input
An output capacitor is required to reduce ringing and
voltage sag on the output during a transient condition. A
value between 1μF and 10μF is recommended.
The EN pin is a TTL logic level compatible input which
turns the internal MOSFET switch on and off. The
FAULT/ pin remains high when the EN pin is pulled low
and the output is turned off. Toggling the enable pin
resets the output after an OGI (output greater than input)
condition occurs. In the -2 version, toggling the enable
pin resets the output after an overcurrent event.
A 10μF or larger capacitor should be used if the distance
between the MIC2090/MIC2091 and the load is greater
than three inches. The internal switch in the
MIC2090/MIC2091 turns off in (typically) 20ns. This
extremely fast turn-off can cause an inductive spike in
the output voltage when the internal switch turns off
during an overcurrent condition. The larger value
capacitor prevents the output from glitching too low.
Fault Output
The FAULT/ is an N-channel open-drain output, which is
asserted LOW when the MIC2090/MIC2091 switch
either begins current limiting or enters thermal shutdown.
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July 2011
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Micrel, Inc.
MIC2090/MIC2091
During an overcurrent or short circuit, The FAULT/ signal
asserts after a brief delay period, tD_FAULT/, in order to
filter out false or transient over-current conditions.
may exceed the package and PCB’s ability to cool the
device and the MIC2090/MIC2091 will shut down and
signal a fault condition. Please see the “Fault Output”
description for more details on the FAULT/ output.
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.
After the MIC2090/MIC2091 shuts down, and cools, it
will re-start itself if the enable signal remains true.
n Figure 2, die temperature is plotted against IOUT
assuming a constant ambient temperature of 85°C and a
worst case internal switch on-resistance (RON). This plot
is valid for both the MIC2090 and MIC2091.
Power Dissipation and Thermal Shutdown
Thermal
shutdown
is
used
to
protect
the
MIC2090/MIC2091 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
Die Temperature vs. Output Current
(Ambient Temperature = 85°C)
reaches the over-temperature threshold, TOVERTEMP
.
90
89
88
87
86
85
84
83
The switch will automatically resume operation when the
die temperature cools down to 140°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 upon the 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.
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
IOUT (A)
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 Equation 2:
Figure 2. Die Temperature vs. IOUT
ILIMIT vs. IOUT Measured (-1 version only)
When the MIC2090/MIC2091 is current limiting, it is
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. When VOUT drops below 1.8V, then the output
switch momentarily turns off to insure the internal
MOSFET switch is not damaged by a very fast short
circuit event.
2
PD = RDS(ON) × (IOUT
)
Eq.2
To relate this to junction temperature, Equation 3 can be
used:
TJ = PD × Rθ(J-A) + TA
Eq. 3
When measuring IOUT in an overcurrent condition, 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 3 and 4.
Where:
TJ = Junction Temperature
TA = Ambient Temperature
In Figure 3, output current is measured as VOUT is pulled
below VIN, with the test terminating when VOUT is 2.5V
below VIN. Observe that once ILIMIT is reached IOUT
remains constant throughout the remainder of the test.
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
Figure 4 repeats this test but simulates operation deeper
into an overcurrent condition. When VOUT drops below
1.8V, the switch turns off for a few microseconds before
turning back on.
shorted,
when
the
switch
is
enabled,
the
MIC2090/MIC2091 switch limits the output current to the
maximum value. The heat generated by the power
dissipation of the switch continuously limiting the current
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July 2011
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Micrel, Inc.
MIC2090/MIC2091
Under-Voltage Lock Out (UVLO)
The MIC2090/MIC2091 switches have an Under-Voltage
Lock Out (UVLO) feature that will shut down the switch
in a reproducible way 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 EN, are considered to be
valid or operative.
OGI (Output Greater than Input)
The internal MOSFET switch turns off when it senses an
output voltage that is greater than the input voltage.
This feature prevents continuous current from flowing
from the output to the input.
Figure 3. IOUT in Current Limiting for VOUT > 1.8V
If the output voltage rises above VIN by the OGI
threshold voltage (typically 85mV), the internal MOSFET
switch turns off after a period of time, specified in the
electrical characteristics table as OGITIME. The FAULT/
pin remains high during and after an OGI event.
Figure 5 shows the output voltage, input current and
FAULT/ pin voltage when the output voltage is raised
above the input. Reverse current flows through the
internal MOSFET switch for the OGITIME period, until the
internal MOSFET switch is turned off and the input
current goes to 0A.
Figure 4. IOUT in Current Limiting for VOUT < 1.8V
Figure 5. OGI Event
M9999-070611-B
July 2011
17
Micrel, Inc.
MIC2090/MIC2091
MIC2090/MIC2091 Evaluation Board Schematic
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18
Micrel, Inc.
MIC2090/MIC2091
Bill of Materials
Item
C1, C2
C3, C4
R1, R3
R2
Part Number
Manufacturer Description
Qty.
2
08056D106MAT2A
AVX(1)
10µF, 6.3V Ceramic Capacitor, X5R
NF (No Fill)
2
CRCW06031002FRT1
Vishay Dale(2)
10k, 1%, 0603 Resistor
2
NF (No Fill)
1
U1
MIC2090-1YM5
MIC2091-1YM5
MIC2090-2YM5
MIC2091-2YM5
Micrel, Inc.(3)
Micrel, Inc.(3)
Micrel, Inc.(3)
Micrel, Inc.(3)
Current Limiting Power Distribution Switch
Current Limiting Power Distribution Switch
Current Limiting Power Distribution Switch
Current Limiting Power Distribution Switch
1
U1
0
U1
0
U1
0
Notes:
1. AVX: www.avx.com.
2. Vishay Tel: www.vishay.com.
3. Micrel, Inc.: www.micrel.com.
M9999-070611-B
July 2011
19
Micrel, Inc.
MIC2090/MIC2091
PCB Layout Recommendations
Top Silk Screen
Top Copper
M9999-070611-B
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20
Micrel, Inc.
MIC2090/MIC2091
PCB Layout Recommendations (Continued)
Bottom Copper
Bottom Silk Screen
M9999-070611-B
July 2011
21
Micrel, Inc.
MIC2090/MIC2091
Package Information
5-Pin SOT23 (SOT23-5)
M9999-070611-B
July 2011
22
Micrel, Inc.
MIC2090/MIC2091
Recommended Landing Pattern
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
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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.
© 2011 Micrel, Incorporated.
M9999-070611-B
July 2011
23
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