MIC2044/2045
Micrel
MIC2044/2045
Single Channel, High Current, Low Voltage,
Protected Power Distribution Switch
General Description
The MIC2044 and MIC2045 are high-side MOSFET switches
optimized for general purpose power distribution applications
that require circuit protection. These devices switch up to
5.5V and as low as 0.8V while offering both programmable
current limiting and thermal shutdown to protect the device
and the load. A fault status output is provided to indicate
overcurrent and thermal shutdown fault conditions. Both
devices employ soft-start circuitry to minimize the inrush
current in applications that employ highly capacitive loads.
Additionally, for tighter control over inrush current during start
up, the output slew-rate may be adjusted by an external
capacitor.
The MIC2045 features a auto-reset circuit breaker that latches
the output OFF upon detecting an overcurrent condition
lasting more than 32ms. The output is reset by removing or
reducing the load.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
30mΩ maximum on-resistance
0.8V to 5.5V operating range
Adjustable current limit
Up to 6A continuous output current
Short circuit protection
Very fast reaction to short circuits
Thermal shutdown
Adjustable slew-rate control
Circuit breaker mode (MIC2045)
Fault status flag
Power-Good detection
Undervoltage lockout
No reverse current flow through the switching MOSFET
when OFF or disabled
• Low quiescent current
•
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•
•
•
•
•
•
•
•
•
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Applications
•
•
•
•
•
•
•
•
•
Docking stations
LAN servers
WAN switches
Hot swap board insertions
Notebook PCs
PDAs
Base stations
RAID controllers
USB hosts
Typical Application
+3.3V
Power
Supply
OUT1
OUT2
C1
0.1
m
F
ON/OFF
C2
0.1
m
F
MIC2044-1BTS
8
7, 11,
13, 16
2
3
4
6
VBIAS
VIN
EN
/FAULT
VOUT
PGREF
9,12,14
15
V
OUT
3.3V@ 3.5A
R2
294k
W
1%
R3
24.3k
W
1%
C
LOAD
33
m
F
IN
Logic
Controller
C3
4.7
m
F
R1
20k
W
OVERCURRENT
R4
20k
W
1
5
IN
EN
MIC39100-2.5BS
OUT
SLEW PWRGD
ILIM
UVLOIN
GND
10
2.5V
C4*
0.022
m
F
(OPEN)
GND
R
SET
100
W
Note:
All V
IN
pins (7, 11, 13, 16) must be externally tied together.
All V
OUT
pins (9, 12, 14) must be externally tied together.
I
LIMIT
= 4A.
Output Power-Good = 3.0V.
*C4 is optional. See
"Applications Information."
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
January 2005
1
MIC2044/2045
MIC2044/2045
Micrel
Ordering Information
Part Number
Standard
MIC2044-1BTS
MIC2044-2BTS
MIC2045-1BTS
MIC2045-2BTS
Pb-Free
MIC2044-1YTS
MIC2044-2YTS
MIC2045-1YTS
MIC2045-2YTS
Enable
Active-High
Active-Low
Active-High
Active-Low
X
X
Circuit Breaker
Package
16-Pin TSSOP
16-Pin TSSOP
16-Pin TSSOP
16-Pin TSSOP
Pin Configuration
PWRGD 1
EN 2
/FAULT 3
SLEW 4
UVLOIN 5
ILIM 6
VIN 7
VBIAS 8
16 VIN
15 PGREF
14 VOUT
13 VIN
12 VOUT
11 VIN
10 GND
9 VOUT
MIC2044/MIC2045
16-Pin TSSOP (TS)
MIC2044/2045
2
January 2005
MIC2044/2045
Micrel
Pin Description
Pin Number
1
2
3
Pin Name
PWRGD
EN
/FAULT
Pin Function
Power-Good (Output): Open drain N-Channel device, active high. This pin
asserts high when the voltage at PGREF exceeds its threshold.
Switch Enable (Input): Gate control pin of the output MOSFET available as
an active high (–1) or active low (–2) input signal.
Fault Status (Output): Open drain N-Channel device, active low. This pin
indicates an overcurrent or thermal shutdown condition. For an overcurrent
event, /FAULT is asserted if the duration of the overcurrent condition lasts
longer than 32ms.
Ground connection: Tie to analog ground.
Slew-Rate Control (Input): A capacitor connected between this pin and
ground will reduce (slow) the output slew-rate. The output turn-on time must
be less than the nominal flag delay of 32ms in order to avoid nuisance
tripping of the /FAULT output since V
OUT
must be “fully on” (i.e., within
200mV of the voltage at the input) before the /FAULT signal delay elapses.
The slew-rate limiting capacitor requires a 16V rating or greater, 25V is
recommended. See
“Applications Information: Output Slew-Rate Adjust-
ment”
for further details.
Current Limit (Input): A resistor (R
SET
) connected from this pin to ground
sets the current limit threshold as I
LIMIT
= CLF/R
SET
. CLF is the current limit
factor specified in the
“Electrical Characteristics”
table. For the MIC2044/45,
the continuous output current range is 1A to 6A.
Undervoltage Lockout Adjust (Input): With this pin left open, the UVLO
threshold is internally set to 1.45V. When the switching voltage (V
IN
) is at or
below 1.5V, connecting an external resistive divider to this input will lower the
UVLO threshold. The total resistance of the divider must be less than 200kΩ.
To disable the UVLO, tie this pin to VIN. See
“Applications Information”
for
further detail.
Switch Supply (Input): Connected to the drain of the output MOSFET. The
range of input for the switch is 0.8V to 5.5V. These pins must be externally
connected together to achieve rated performance.
Switch (Output): Connected to the source of the output MOSFET. These
pins must be externally connected together to achieve rated performance.
Bias Supply (Input): This input pin supplies power to operate the switch and
internal circuitry. The input range for VBIAS is 1.6V to 5.5V. When switched
voltage (V
IN
) is between 1.6V to 5.5V and the use of a single supply is
desired, connect VBIAS to VIN externally.
Power-Good Threshold (Input): Analog reference used to specify the
PWRGD threshold. When the voltage at this pin exceeds its threshold, V
TH
,
PWRGD is asserted high. An external resistive divider network is used to
determine the output voltage level at which V
TH
is exceeded. See the
“Functional Description”
for further detail. When the PWRGD signal is not
utilized, this input should be tied to VOUT.
10
4
GND
SLEW
6
ILIM
5
UVLOIN
7,11,13,16
VIN
9,12,14
8
VOUT
VBIAS
15
PGREF
January 2005
3
MIC2044/2045
MIC2044/2045
Micrel
Absolute Maximum Ratings
(Note 1)
V
IN
and V
BIAS ..................................................................................
6V
/FAULT, PWRGD Output Voltage ................................... 6V
/FAULT, PWRGD Output Current .............................. 25mA
ESD Rating,
Note 3
Human Body Model ................................................... 2kV
Machine Model ........................................................ 200V
Operating Ratings
(Note 2)
Supply Voltage
V
IN
............................................................... 0.8V to 5.5V
V
BIAS
........................................................... 1.6V to 5.5V
Continuous Output Current ................................... 1A to 6A
Ambient Temperature (T
A
) ........................... –40°C to 85°C
Package Thermal Resistance
(R
θ(J-A)
)
TSSOP ................................................................ 85°C/W
Electrical Characteristics
(Note 4)
V
IN
= V
BIAS
= 5V, T
A
= 25°C unless specified otherwise.
Bold
indicates –40°C to +85°C.
Symbol
V
IN
V
BIAS
I
BIAS
Parameter
Switch Input Voltage
Bias Supply Voltage
V
BIAS
Supply Current - Switch OFF
V
BIAS
Supply Current - Switch ON
Note 5
Enable Input Voltage
V
IL(max)
V
IH(min)
V
ENHYST
I
EN
R
DS(ON)
I
LEAK
CLF
V
TH
V
LATCH
I
LATCH
V
OL
I
OFF
V
UV
V
UVHYST
V
UVINTH
V
UVINHYST
Enable Input Threshold Hysteresis
Enable Input Current
Switch Resistance
Output Leakage Current
Current Limit Factor
Note 6
PGREF Threshold
Output Reset Threshold
Latched Output Off Current
Output Low Voltage
(/FAULT, PWRGD)
/FAULT, PWRGD Off Current
Undervoltage Lockout Threshold
Undervoltage Lockout
Threshold Hysteresis
UVLO Adjust Pin Threshold Voltage
UVLO Adjust Pin Threshold Hysteresis
Overtemperature Threshold
T
J
increasing
T
J
decreasing
V
IN
rising
V
IN
falling
200
185
V
EN
= 0V to 5.5V
V
IN
= V
BIAS
= 3V, 5V
I
OUT
= 500mA
Output off
V
IN
= 3V, 5V, 0.5V
≤
V
OUT
< 0.5V
IN
1A
≤
I
OUT
≤
6A
V
IN
= V
BIAS
= 1.6V to 5.5V
V
IN
= 0.8V to 5.5V
V
OUT
rising (MIC2045)
Output latched off (MIC2045)
I
OL
(/FAULT) = 15mA
I
OL
(PWRGD) = 5mA
V
FAULT
= V
PWRGD
= 5V
V
IN
rising
V
IN
falling
1.30
1.20
1.45
1.35
100
230
215
15
140
120
260
245
1
300
215
380
230
V
IN
–.0.2
3
5
0.4
1
1.58
1.50
–1
3.5
No load
No load
Condition
V
IN
≤
V
BIAS
Min
0.8
1.6
0.1
300
2.4
2.5
100
.01
20
1
30
10
460
245
Typ
Max
5.5
5.5
5
400
1.5
Units
V
V
µA
µA
V
V
mV
µA
mΩ
µA
A•Ω
mV
V
mA
V
µA
V
V
mV
mV
mV
mV
°C
°C
V
EN
MIC2044/2045
4
January 2005
MIC2044/2045
Symbol
t
FLAG
t
ON
t
R
t
OFF
t
F
Note 1.
Note 2.
Note 3.
Note 4.
Note 5.
Note 6.
Micrel
Condition
V
IN
= V
BIAS
= 3V, 5V
R
LOAD
= 10Ω, C
LOAD
= 1µF
R
LOAD
= 10Ω, C
LOAD
= 1µF
R
LOAD
= 10Ω, C
LOAD
= 1µF
R
LOAD
= 10Ω, C
LOAD
= 1µF
Min
25
0.75
1.5
Typ
32
1
2.5
1
24
Max
40
1.25
3.5
5
Units
ms
ms
ms
µs
µs
Parameter
Flag Response Delay
Output Turn-on Delay
Output Turn-on Rise Time
Output Turn-off Delay
Output Turn-off Fall Time
Exceeding the absolute maximum rating may damage the device.
The device is not guaranteed to function outside its operating rating.
Devices are ESD sensitive. Handling precautions recommended. Human body model: 1.5kΩ in series with 100pF.
Specification for packaged product only.
OFF is V
EN
< 1.0V for MIC2044/MIC2045–1 and V
EN
> 4.0V for MIC2044/MIC2045 –2. ON is V
EN
> 4.0V for MIC2044/MIC2045–1 and
V
EN
< 1.0V for MIC2044/MIC2045 –2.
The current limit is determined as follows: I
LIM
= CLF/R
SET
.
Timing Diagrams
50%
V
EN
0
t
ON
t
OFF
90%
10%
(a) MIC2044/45-1
V
OUT
0
50%
V
EN
0
t
ON
t
OFF
90%
V
OUT
0
10%
(b) MIC2044/45-2
Figure 1. Turn-On/Turn-Off Delay
V
EN
0
V
IN
0.2V
Increase the load
V
OUT
0
I
LIMIT
I
OUT
0
t
FLAG
/FAULT
0
Figure 2. Overcurrent Fault Response — MIC2044-2
January 2005
5
MIC2044/2045
传感器
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