MIC2012ZM [MICROCHIP]
2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8;
| 型号： | MIC2012ZM |
| 厂家： | 
MICROCHIP |
| 描述： | 2-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8 光电二极管 |
| 文件： | 总16页 (文件大小：694K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MIC2012/MIC2072
USB Power Controller
General Description
Features
TheMIC2012isadualchannelUSBpowerswitchdesignedto
supportthepowerdistributionrequirementsforUSBWakeup
from the ACPI S3 state. The MIC2012 will directly switch its
two outputs between a 5V main supply and a 5V auxiliary
supply normally provided in ATX style power supplies.
• Compliant to USB power distribution specifications
• UL Recognized Component
• Two completely independent switches
• Integrated switching matrix supports ACPI S0/S3 state
transitions without external FET circuits
• Make-before-break switching ensures glitch-free
transitions
The MIC2012 will adjust its current-limit threshold according
to theACPI state it is in. In the normal active S0 state the cur-
rent-limit is set at 500mAminimum per channel satisfying the
USB continuous output current specification. In the S3 state
the current-limit can be reduced to only 100mA per channel
to minimize the current that is supplied by the auxiliary supply
thereby ensuring that voltage regulation is maintained even
during fault conditions.
TheMIC2012providesmake-before-breakswitchingtoensure
glitch-free transitions between the S3 and S0 states. Each
channel is also thermally isolated from the other so that a
fault in one channel does not effect the other. FAULT status
output signals are also provided indicating overcurrent and
thermal shutdown conditions.
• No back-feed of auxiliary supply onto main supply dur-
ing standby mode
• Bi-level current-limit preserves auxiliary supply voltage
regulation in standby mode
• Thermally isolated channels
• Thermal shutdown protection
• Fault status outputs with filter prevents false assertions
during hot-plug events
• Latched thermal shutdown options with auto-reset
(MIC2072)
• Undervoltage lockout
Applications
The MIC2072 option latches the output off upon detecting
an overcurrent condition for more than 5ms minimum. The
output can be reset by either toggling the EN inputs of the
MIC2072-1, -2 or by removing the load. Latching the output
offprovidesacircuitbreakermodeofoperationwhichreduces
power consumption during fault conditions.
• Desktop PCs
• Notebook PCs
• Notebook Docking stations
• LAN Servers
• PC Motherboards
Typical Application
ATX Power Supply
5V MAIN
VBUS
5V STANDBY
Downstream
D+
D–
MIC2012P
USB
Port 1
OUT1
OUT2
MAIN
AUX
GND
100F
S3 Control
S3#
VBUS
D+
D–
FAULT1#
FAULT2#
GND
Downstream
USB
Port 2
100F
GND
82801AA or Equivalent
SLP S3#
SLP S5#
Overcurrent Port 1
Overcurrent Port 1
OC0
OC1
Figure 1. USB Wakeup with Control Input
UL Recognized Component
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
January 2005
1
MIC2012/2072
MIC2012
Micrel
Ordering Information
Part Number
Circuit Breaker
Range
Temperature
Range
Enable
Fault Output
Package
Standard
Pb-Free
MIC2012BM(1)
MIC2012CM
MIC2012PCM
MIC2012-1PCQS MIC2012-1PZQS
MIC2012-2PCQS MIC2012-2PZQS
MIC2072-1PCQS MIC2072-2PZQS
MIC2072-2PCQS MIC2072-2PZQS
MIC2012YM(1)
MIC2012ZM
MIC2012PZM
n/a
n/a
n/a
Open-Drain
Open-Drain
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C 16-lead QSOP
0°C to +70°C 16-lead QSOP
0°C to +70°C 16-lead QSOP
0°C to +70°C 16-lead QSOP
8-lead SOIC
8-lead SOIC
8-lead SOIC
Internal Pull-Up
Internal Pull-Up
Internal Pull-Up
Internal Pull-Up
Internal Pull-Up
Active High
Active Low
Active High
Active Low
Δ
Δ
Note:
1. Contact factory for availablity
Pin Configuration
FAULT1
1
2
3
4
5
6
7
8
16 FAULT2
15 EN2
EN1
S3#
NC
FAULT1
S3#
1
2
3
4
8
7
6
5
FAULT2
OUT1
MAIN
14 OUT1
13 OUT1
12 MAIN
11 MAIN
10 OUT2
AUX
AUX
NC
GND
OUT2
8-Pin SOIC (M)
NC
GND
9
OUT2
16-Pin QSOP (QS)
MIC2012/2072
2
January 2005
MIC2012
Micrel
Pin Description
Pin Number
(MIC2012)
Pin Number
Pin Name
Pin Function
(MIC2012-1,-2)
1
1
FAULT1
Fault Status (Output): Internal pull-up or open-drain. Asserted LOW when
Channel is in a thermal shutdown state or overcurrent condition for more
than 5ms. MIC2072 latches this output in its asserted state upon an over-
current condition. Toggling EN1 or removing the load will reset the circuit
breaker latch and deassert FAULT1.
n/a
2
2
3
EN1
S3#
Enable (Input): Channel 1, active-high (–1) or active-low (–2). Toggling this
input also resets the latched output of the MIC2072.
Control (Input): When this input is HIGH, the MAIN inputs are connected to
OUT1 and OUT2 via 100mΩ MOSFET switches. When this input is LOW
the AUX inputs are connected to OUT1 and OUT2 via 500mΩ MOSFET
switches.
3
n/a
4
5
4, 6, 7
8
AUX
NC
GND
OUT2
Auxiliary 5V Supply (Input): Also used as power supply for internal circuitry.
No Connection: This pin may be connected to other pins without restriction.
Ground
Channel 2 (Output): For MIC2012-1, -2 both pins must be externally con-
nected together.
5
9, 10
6
7
11, 12
13, 14
15
MAIN
OUT1
EN2
5V Main Supply (Input): All MAIN inputs must be connected together exter-
nally.
Channel 1 (Output): For MIC2012-1, -2 both pins must be externally con-
nected together.
Enable (Input): Channel 2, active-high (–1) or active-low (–2). Toggling this
input also resets the latched output of the MIC2072.
Fault Status (Output): Internal pull-up or open-drain. Asserted LOW when
Channel 2 is in a thermal shutdown state or overcurrent condition for more
than 5ms. MIC2072 latches this output in its asserted state upon an over-
current condition. Toggling EN2 or removing the load will reset the circuit
breaker latch and deassert FAULT2.
n/a
8
16
FAULT2
January 2005
3
MIC2012/2072
MIC2012
Micrel
Absolute Maximum Ratings (Note 1, Note 4)
Operating Ratings (Note 2)
Supply Voltage (V
V
V
).....................–0.3V to 6V
Supply Voltage (V
V
)...................... +4.5V to +5.5V
IN, MAIN, AUX
MAIN, AUX
EN1, EN2, S3# Input Pins.................................–0.3V to 6V
FAULT#, OUT1, OUT2 Output Pins...................–0.3V to 6V
FAULT Output Current................................................ 25mA
ESD Rating, Note 3 ...................................................... 2kV
Ambient Temperature (T )............................ –0°C to +70°C
A
Junction Temperature (T )........................ Internally Limited
J
Package Thermal Resistance
.......................................................................
QSOP(θ )
163°C/W
160°C/W
JA
.........................................................................
SOIC(θ )
JA
Electrical Characteristics
VMAIN = 5V; AUX = 5V; TA = 25°C; unless noted
Symbol
VMAIN
IMAIN (ON)
Parameter
MAIN Supply Voltage
MAIN Supply Current Switches On
Note 5
MAIN Supply Current Switches Off
Note 5, (MIC20x2-1, MIC20x2-2 only)
MAIN Reverse Leakage Current,
AUX Supply Voltage
Condition
Min
4.5
Typ
5.0
16
Max
5.5
22
Units
V
µA
S3# = 1, no load
S3# = 1, no load
IMAIN (OFF)
ILEAK
5
µA
µA
S3# = 0, both switches ON, VMAIN = 0V
–10
4.5
+10
VAUX
IAUX ON
5.0
0.6
5.5
1
V
mA
AUX Supply Current,
both switches on, Note 5
No load
S3# = 0
IAUX OFF
VUV/AUX
VHYS
AUX Supply Current, switches
No load
S3# = 0
5
µA
off. (MIC20x2-1, MIC20x2-2 only)
AUX Undervoltage Lockout
Threshold
AUX Undervoltage Lockout
Hysteresis
VAUX increasing
3.1
2.9
200
4.0
3.8
V
V
mV
VAUX decreasing
RDSMAIN
RDSAUX
ILIMIT(MAIN)
MAIN On-Resistance, Each Output
AUX On-Resistance, Each Output
MAIN Current-Limit Threshold
MAIN Short-Circuit Current-Limit
AUXCurrent-Limit Threshold
S3# = 1, IOUT = 500mA
S3# = 0, IOUT = 100mA
S3# = 1, VOUT = 4.0V, ramped load
100
500
140
700
2.0
1.8
195
mΩ
mΩ
A
0.8
0.65
105
V
OUT = 0V
S3# = 0, VOUT = 4.0V, ramped load
VOUT = 0V, COUT = 100µF
A
ILIMIT(AUX)
VTH
150
80
1.5
1.7
mA
mA
V
AUX Short-Circuit Current-Limit
S3#, EN1, EN2. Input
High-to-Low transition
Low-to-High transition
0.8
Threshold Voltage
2.0
V
(EN1, EN2, for MIC20x2-x only)
VHYS
IIN
EN1, EN2 and S3# Input Hysteresis
(EN1, EN2, for MIC20x2-x only)
S3#, EN1, EN2 Input Current
(EN1, EN2, for MIC20x2-x only)
200
mV
µA
VS3/EN = 5V, 0V
–1
1
IOFF
OUT1, OUT2 Leakage Current
(MIC2012-x, MIC2072-x only)
Pull-Up Current During Latched
Output State (MIC2072-1,-2)
Outputs are off, VOUT = 0
Outputs latched off
–10
10
µA
1
mA
MIC2012/2072
4
January 2005
MIC2012
Micrel
Symbol
Parameter
Condition
Min
Typ
Max
Units
VTH LATCH
Latch Reset Threshold
(MIC2072, MIC2072-x only)
VOUT Rising
1.95
V
Minimum Output Slew Rate
to Reset Latch
(MIC2072, MIC2072-x only), Note 6
0.4
V/s
Overtemperature Threshold
TJ increasing, single channel
TJ decreasing, single channel
TJ increasing, both channels
TJ decreasing, both channels
140
120
160
150
°C
°C
°C
°C
VOL
VOH
FAULT Output Low Voltage
FAULT Output High Voltage
(MIC2012-1P,-2P),(MIC2072-1P,-2P)
FAULT Output Off Current
(Not Applicable to 'P' Options)
MAIN to S3# Hold Time, Note 6
MAIN to S3# Set-up Time, Note 6
IFAULT = 5mA
IFAULT = –20µA
0.2
10
V
V
4
VFAULT = 5V
0.2
10
µA
TH
TS
tDLY
Figure 5
Figure 5
5
0
5
ms
ms
ms
FAULT Delay Filter Response Time
(Overcurrent only), Note 7
Output shorted to ground, Figure 4
20
tOC
Overcurrent Response Time
Output shorted to ground, Figure 4
MAIN output
AUX output
2
2
µs
µs
tON(MAIN)
tOFF(MAIN)
MAIN Output Turn-On Time
MAIN Output Turn-Off Time
(MIC20x2-x only)
RL = 10Ω, CL = 1µF, Figure 3
RL = 10Ω, CL = 1µF, Figure 3
2
35
ms
µs
tr(MAIN)
tf(MAIN)
MAIN Output Rise Time
MAIN Output Fall Time
(MIC20x2-x only)
RL = 10Ω, CL = 1µF, Figure 3
RL = 10Ω, CL = 1µF, Figure 3
2
32
ms
µs
tON(AUX)
tOFF(AUX)
AUX Output Turn-On Time
AUX Output Turn-Off Time
(MIC20x2-x only)
RL = 50Ω, CL = 1µF, Figure 3
RL = 50Ω, CL = 1µF, Figure 3
0.6
120
ms
µs
tr(AUX)
tf(AUX)
AUX Output Rise Time
AUX Output Fall Time
(MIC20x2-x only)
RL = 50Ω, CL = 1µF, Figure 3
RL = 50Ω, CL = 1µF, Figure 3
0.5
115
ms
µs
tXMA
tXAM
MAIN to AUX
S3# transition to 0
S3# transition to 1
5
5
7.5
7.5
ms
ms
Cross Conduction Time, Note 8
AUX to MAIN
Cross Conduction Time, Note 8
Note 1. Exceeding the absolute maximum rating may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
Note 4. All voltages are referenced to ground.
Note 5. For MIC20x2-1(P) OFF occurs when V < 0.8V and ON occurs when V > 2.4V. For MIC20x2-2(P) OFF occurs when V > 2.4V and ON
EN
EN
EN
occurs when V < 0.8V.
EN
Note 6. Guaranteed by design. Not production tested.
Note 7. Assumes only one channel in current-limit. Delay circuitry is shared among channels so it is possible for t
to be 40ms max if one channel
DLY
enters current-limit as the other is about to time-out.
Note 8. Cross conduction time is the duration in which both MAIN and AUX internal switches are on subsequent to S3# transitioning.
January 2005
5
MIC2012/2072
MIC2012
Micrel
Timing Diagrams
50%
VEN
tOFF
tON
90%
VOUT
10%
Figure 2. MIC2012/72-1
50%
V
EN
t
OFF
t
ON
90%
V
OUT
10%
Figure 3. MIC2012/72-2
Output shorted to ground
VOUT
IOUT
ILIMIT
tOC
FAULT#
tDLY
Figure 4. Overcurrent Response Timing
tH
tS
MAIN
S3#
1.5V
1.5V
Figure 5. MAIN to S3# Timing
MIC2012/2072
6
January 2005
MIC2012
Micrel
Test Circuit
VOUT
IOUT
Device
Under
Test
OUT
RL
CL
tr
tf
90%
10%
90%
VOUT
10%
January 2005
7
MIC2012/2072
MIC2012
Micrel
Typical Characteristics
Main Supply Current
Main Supply Current
Main Short-Circuit Current-Limit
vs. Temperature
vs. Temperature
vs. Temperature
(Main 1 and Main 2 = ON)
(Main 1 and Main 2 = OFF)
30
0.25
0.225
0.2
1.30
VMAIN = 5.0V
VMAIN = 4.5, 5.0, 5.5V
VMAIN = 4.5, 5.0, 5.5V
VAUX = S3# = 4.5, 5.0, 5.5V
EN1 = EN2 = [ON],V
= S3# = 5.0V
EN1 = EN2 = [OFF],V
= S3# = 5.0V
AUX
AUX
25
20
15
10
5
1.25
1.20
1.15
1.10
1.05
1.00
5.5V
0.175
0.15
0.125
0.1
MAIN
5.5V MAIN
5.0 VMAIN
5.0 VMAIN
5.5V AUX
4.5 VMAIN
5.0V AUX
0.075
0.05
0.025
0
4.5 VMAIN
4.5V AUX
IOUT = 0µA
IOUT = 0µA
20 40 60 80 100
0
-40 -20
0
20 40 60 80 100
-40 -20
0
-40 -20
0
20 40 60 80 100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
Main Short-Circuit
Current-Limit Threshold
vs. Temperature
Main Rise-Time
AUX Supply Current
vs. Temperature
vs. Temperature
(EN Toggled)
(AUX 1 and AUX 2 = ON)
2000
1800
1600
1400
1200
1000
800
1000
900
800
700
600
500
400
300
200
100
1.40
1.35
1.30
1.25
1.20
1.15
1.10
VMAIN = 5.0V
VAUX = S3# = 4.5, 5.0, 5.5V
VAUX = 4.5, 5.0, 5.5V
VMAIN = S3# = 0V
VMAIN = 5.0V
VAUX = S3# = 4.5, 5.0, 5.5V
5.5V
AUX
4.5V AUX
5.5V AUX
5.0 VAUX
5.0 VAUX
4.5 VAUX
5.0V
AUX
4.5V
AUX
600
5.5 VAUX
R L = 10Ω
C L = 1µF
IOUT = 0µA
EN1 = EN2 = [ON]
400
200
-40 -20
0
20 40 60 80 100
-40 -20
0
20 40 60 80 100
-40 -20
0
20 40 60 80 100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
Enable Threshold
(decreasing)
vs. Temperature
Enable Threshold
(increasing)
vs. Temperature
AUX Supply Current
vs. Temperature
(AUX 1 and AUX 2 = OFF)
(MIC2012-1/-2)
(MIC2012-1/-2)
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
2.2
2.0
1.8
1.6
1.4
1.2
2.0
1.8
1.6
1.4
1.2
1.0
V
V
I
= 4.5, 5.0, 5.5V
AUX
VAUX = 4.5, 5.0, 5.5V
VMAIN = S3# = 5.0V
= S3# = 0V
MAIN
= 0µA
5.5V AUX
OUT
EN1 = EN2 = [OFF]
5.5V
AUX
5.0 VAUX
4.5 VAUX
4.5 VAUX
5.0 VAUX
4.5 VAUX
5.5V AUX
VAUX = 4.5, 5.0, 5.5V
VMAIN = S3# = 5.0V
5.0 VAUX
-40 -20
0
20 40 60 80 100
-40 -20
0
20 40 60 80 100
-40 -20
0
20 40 60 80 100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
Enable Threshold
(decreasing)
vs. Temperature
(MIC2012-1/-2)
Pull-Up Current
vs. Temperature
Enable Threshold
(increasing)
vs. Temperature
(Output Latched Off–MIC2072)
(MIC2012-1/-2)
2.2
2.0
1.8
1.6
1.4
1.2
1800
1600
1400
1200
1000
800
2.0
1.8
1.6
1.4
1.2
1.0
VMAIN = 5.0 V
VAUX = S3# = 4.5, 5.0, 5.5V
4.5V
MAIN
5.5V
MAIN
5.5V AUX
4.5V
5.0V MAIN
MAIN
5.0V MAIN
5.5V
MAIN
5.0V
AUX
600
4.5V
VMAIN = 4.5V to 5.5V
VAUX = S3# = 5.0V
AUX
VMAIN = 4.5V to 5.5V
VAUX = S3# = 5.0V
400
200
-40 -20
0
20 40 60 80 100
-40 -20
0
20 40 60 80 100
-40 -20
0
20 40 60 80 100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
MIC2012/2072
8
January 2005
MIC2012
Micrel
Output Reset Threshold
vs. Temperature
3.00
(Output Latched Off –MIC2072)
VOUT Rising
2.75
2.50
2.25
2.00
1.75
1.50
V
= 5.0 V
MAIN
AUX
V
= S3# = 4.5, 5.0, 5.5V
5.5V
AUX
5.0V
AUX
4.5V
0
AUX
-40 -20
20 40 60 80 100
TEMPERATURE (°C)
January 2005
9
MIC2012/2072
MIC2012
Micrel
Functional Characteristics
AUX Start-up by UVLO
AUX Shutdown by UVLO
2.96V
VAUX ramps from 0V to 5V
VAUX ramps from 5V to 0V
V
MAIN = S3# = 0V
VMAIN = S3# = 0V
EN = [ON]
EN = [ON]
R
LOAD = 50
R
C
LOAD = 50
LOAD = 1F
CLOAD = 1F
TIME (500s/div)
TIME (10ms/div)
Main Start-up by UVLO
Main Shut-down by UVLO
VMAIN = VAUX;VMAIN & VAUX ramp from 0V to 5V
S3# = 5V
2.96V
EN = [ON]
R
C
LOAD = 10
LOAD = 1F
3.20V
S3# = 5V
EN = [ON]
R
C
LOAD = 10½
LOAD = 1µF
VMAIN = VAUX;VMAIN & VAUX ramp from 5V to 0V
TIME (500s/div)
TIME (10ms/div)
Main Turn-On Response
Main Turn-Off Response
VMAIN = VAUX =5V
S3# = 5V
VMAIN = VAUX =5V
S3# = 5V
EN toggles from [ON] to [OFF]
R
LOAD = 10
EN toggles from [OFF] to [ON]
CLOAD = 1F
R
LOAD = 10
CLOAD = 1F
TIME (250s/div)
TIME (100s/div)
MIC2012/2072
10
January 2005
MIC2012
Micrel
AUX Turn-On Response
AUX Turn-Off Response
VAUX =5V
MAIN = S3# = 0V
EN toggles from [ON] to [OFF]
LOAD = 50
CLOAD = 1F
V
R
VAUX =5V
MAIN = S3# = 0V
EN toggles from [OFF] to [ON]
LOAD = 50
CLOAD = 1F
V
R
TIME (100s/div)
TIME (100s/div)
Turn-On from S3# to AUX
Turn-Off from AUX to S3#
VAUX =5V, VMAIN = 0V
EN = [ON]
VAUX =5V, VMAIN = 0V
S3# toggles from [LO] to [HI]
EN = [ON]
S3# toggles from [HI] to [LOW]
R
LOAD = 50
R
LOAD = 50
C
LOAD = 1F
CLOAD = 1F
TIME (100s/div)
TIME (1ms/div)
Main Inrush Current into CLOAD
Main-Ramped to Short by MOSFET
VMAIN = VAUX = 5V
S3# = 5V
EN toggles from [OFF] to [ON]
R
LOAD = OPEN
CLOAD = 10F, 100F, 560F
CL = 560F
1.4A
V
MAIN = VAUX =5V
S3# = 5V, EN = [ON]
LOAD = 1F
CL = 100F
C
RLOAD toggles from > 1k to <0.5
CL = 10F
TIME (500s/div)
TIME (50ms/div)
January 2005
11
MIC2012/2072
MIC2012
Micrel
AUX Ramped to Short by MOSFET
Main Turn-On into Short
VAUX = 5V
VMAIN = S3# = 0V, EN = [ON]
RLOAD toggles from >1k to <0.5
CLOAD = 1F
1.2A
VMAIN = VAUX =5V
S3# = 5V
EN toggles from [OFF] to [ON]
R
LOAD = Short
CLOAD = 1F
TIME (25ms/div)
TIME (2.5ms/div)
AUX Turn-On into Short
AUX Inrush Current into Large CLOAD
VAUX =5V
MAIN = S3# = 0V
EN toggles from [OFF] to [ON]
LOAD = 100F
V
C
VAUX =5V
VMAIN = S3#= 0V
EN toggles from [OFF] to [ON]
I
LOAD < 10mA
230mA
C
LOAD = 220F
TIME (2.5ms/div)
TIME (2.5ms/div)
Main-to-AUX Cross Conduction
AUX Inrush Current into Small CLOAD
VMAIN = VAUX = 5V
S3# toggles from [HI] to [LO]
EN = [ON]
VAUX =5V
VMAIN = S3# = 0V
R
C
LOAD = 50
LOAD = 1F
EN toggles from [OFF] to [ON]
950s
I
LOAD < 10mA
LOAD = 10F
C
TIME (250s/div)
TIME (100s/div)
MIC2012/2072
12
January 2005
MIC2012
Micrel
AUX-to-Main Cross Conduction
VMAIN = VAUX =5V
S3# toggles from [LO] to [HI]
EN = [ON]
R
LOAD = 50
C
LOAD = 1F
3.96ms
TIME (1ms/div)
January 2005
13
MIC2012/2072
MIC2012
Micrel
Functional Diagram
MAIN
Current
Limit
MAIN
FET
Charge Pump
+
EN
OUT
AUX
Gate Control
AUX
FET
S3#
Current
Limit
Thermal
Sense
AUX
*
* 'P' options only
10ms
Timer
Latch
/FAULT
*MIC2070-1/2 Only
To Other Channel
TJ = P × θ + T
A
where:
Functional Description
D
JA
The MIC2012/2072 are designed to support the power distri-
bution requirements for USB wakeup from theACPI S3 state.
It integrates two independent channels under control of input
S3#.WhenS3#isassertedLOW(S3state)theMIC2012/2072
will switch a 500mΩ, 100mA MOSFET switch from the AUX
input to each of its two outputs. Conversely when the S3#
inputisHIGH(S0state)theMIC2012/72willswitcha100mΩ,
500mA MOSFET switch from the MAIN input to each of its
two outputs. The lower current limit during theACPI S3 state
helps to ensure that the standby supply maintains regulation
even during fault conditions.
T = junction temperature
J
T = ambient temperature
A
θ
= is the thermal resistance of the package
JA
Current Sensing and Limiting
The current-limit thresholds are preset internally for each
state. The preset level prevents damage to the device and
external load but still allows a minimum current of 100mA or
500mA to be delivered to the load depending on the state of
the device according to the S3# input. When S3# is LOW the
current-limit is set at 100mA minimum. When S3# is HIGH
the current-limit is set at 500mA minimum.
Thermal Shutdown
Thermal shutdown is employed to protect the device from
damage should the die temperature exceed safe margins
due mainly to short circuit faults. Thermal shutdown shuts off
the output MOSFET and asserts the FAULT output if the die
temperature reaches 140°C and the overheated channel is
in current limit. The other channel is not affected. If, however,
the die temperature exceeds 160°C, both channels will be
shut off even if neither channel is in current limit.
Should an over-current condition last longer than t , the
DLY
MIC2072 will latch the faulty output off.The output will remain
offuntileithertheloadisremovedortheENsignal(MIC2072-
1, -2) is toggled. When the MIC2072 enters a latched output
condition a 1mA pull-up current source is activated. This
provides a way to automatically reset the output once the
load is removed without the need to toggle the enable input
such as in the MIC2072. Please refer to Figure 7 for timing
details.
Power Dissipation
The device’s junction temperature depends on several fac-
tors such as the load, PCB layout, ambient temperature and
package type. The power dissipated in each channel is
2
The MIC2012 will automatically reset its output when the
die temperature cools down to 120°C. The MIC2012 output
and FAULT signal will continue to cycle on and off until the
device is disabled or the fault is removed. Figure 6 depicts
typical timing. Depending on PCB layout, package, ambient
temperature, etc., it may take several hundred milliseconds
from the incidence of the fault to the output MOSFET being
shut off. This time duration will be shortest in the case of a
P = R
× I
where R
is the on-resistance of
DS(on)
D
DS(on)
OUT
the internal MOSFETs and I
current.
is the continuous output
OUT
Total power dissipation of the device will be the summation of
P for both channels. To relate this to junction temperature,
D
the following equation can be used:
MIC2012/2072
14
January 2005
MIC2012
Micrel
dead short on the output.
exceeds the current-limit threshold. The FAULT response
delay time t
is typically 10ms.
DLY
Undervoltage Lockout
Fault Status Output
Undervoltage lockout (UVLO) prevents the output MOSFET
from turning on until the AUX input exceeds approximately
3.5V. UVLO ensures that the output MOSFETs remain off
to prevent high transient inrush current due to stray or bulk
load capacitance. This helps to ensure that the power supply
The FAULT signal is an active-low output with an open-drain
or weak pull-up configuration. FAULTis asserted (active-low)
when either an overcurrent or thermal shutdown condition
occurs. In the case of an overcurrent condition, FAULT will
be asserted only after the flag response delay time, t , has
DLY
elapsed.This ensures that FAULTis asserted only upon valid
overcurrent conditions and that erroneous error reporting is
eliminated. For example, false overcurrent conditions can
occur during hot-plug events when a highly capacitive load
is connected and causes a high transient inrush current that
Overcurrent Fault
EN
(MIC2010-2)
V
OUT
FAULT
Thermal Shutdown
Reached
Figure 6. MIC2012 System Timing
Overcurrent Fault
EN
(MIC2070-2)
V
OUT
FAULT
Load Removed–
Output Reset
Figure 7. MIC2072 System Timing—
Output Resets When Load is Removed
January 2005
15
MIC2012/2072
MIC2012
Micrel
Package Information
16-Pin QSOP (QS)
8-Pin SOIC (M)
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
This information furnished by Micrel in this data sheet is believed to be accurate and reliable. However no responsibility is assumed by Micrel for its use.
Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can
reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into
the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's
use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify
Micrel for any damages resulting from such use or sale.
© 2004 Micrel Incorporated
MIC2012/2072
16
January 2005
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