MIC2545A/2549A
Programmable Current-Limit
High-Side Switch
General Description
The MIC2545A and MIC2549A are integrated high-side
power switches optimized for low-loss DC power switching
and other power-management applications, including
advanced configuration and power interface (ACPI). The
MIC2545A/49A is a cost-effective, highly-integrated
solution that requires few external components to satisfy
USB and ACPI requirements.
Load current management features include a precision,
resistor-programmable output current-limit and a soft-start
circuit, which minimizes inrush current when the switch is
enabled. Thermal shutdown, along with adjustable current-
limit, protects the switch and the attached device.
The MIC2545A/49A’s open-drain flag output is used to
indicate current-limiting or thermal shutdown to a local
controller. The MIC2549A has an additional internal latch
which turns the output off upon thermal shutdown,
providing robust fault control. The enable signal is
compatible with both 3V and 5V logic, and is also used as
the thermal shutdown latch reset for the MIC2549A.
The MIC2545A and MIC2549A are available in active-high
and active-low enable versions in 8-pin DIP, SOIC, and
TSSOP packages.
Data sheets and support documentation can be found on
Micrel’s web site at:
www.micrel.com.
Features
•
•
•
•
•
•
•
•
•
•
•
2.7V to 5.5V input
Adjustable current-limit up to 3A
Reverse current flow blocking
90µA typical on-state supply current
1µA typical off-state supply current
50mΩ maximum on-resistance
Open-drain fault flag
Thermal shutdown
Thermal-shutdown output latch (MIC2549A)
2ms (slow) soft-start turn-on, fast turnoff
Available with active-high or active-low enable
Applications
•
•
•
•
•
•
USB power distribution
PCI Bus Power Switching
Notebook PC
ACPI power distribution
PC card hot swap applications
Inrush current-limiting
_________________________________________________________________________________________________________________________
Typical Application
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 •
http://www.micrel.com
June 2011
M9999-062711-A
Micrel, Inc.
MIC2545A/2549A
Ordering Information
Part Number
MIC2545A-1BM
MIC2545A-1BN
MIC2545A-1BTS
MIC2545A-2BM
MIC2545A-2BN
MIC2545A-2BTS
MIC2545A-1YM
MIC2545A-1YN
MIC2545A-1YTS
MIC2545A-2YM
MIC2545A-2YN
MIC2545A-2YTS
MIC2549A-1BM
MIC2549A-1BN
MIC2549A-1BTS
MIC2549A-2BM
MIC2549A-2BN
MIC2549A-2BTS
MIC2549A-1YM
MIC2549A-1YN
MIC2549A-1YTS
MIC2549A-2YM
MIC2549A-2YN
MIC2549A-2YTS
Enable
Active HIGH
Active HIGH
Active HIGH
Active LOW
Active LOW
Active LOW
Active HIGH
Active HIGH
Active HIGH
Active LOW
Active LOW
Active LOW
Active HIGH
Active HIGH
Active HIGH
Active LOW
Active LOW
Active LOW
Active HIGH
Active HIGH
Active HIGH
Active LOW
Active LOW
Active LOW
Temperature Range
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
–40°C to +85°C
Latch
No
No
No
No
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Pb-Free
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Package
8-Pin SOP
8-Pin DIP
14-Pin TSSOP
8-Pin SOP
8-Pin DIP
14-Pin TSSOP
8-Pin SOP
8-Pin DIP
14-Pin TSSOP
8-Pin SOP
8-Pin DIP
14-Pin TSSOP
8-Pin SOP
8-Pin DIP
14-Pin TSSOP
8-Pin SOP
8-Pin DIP
14-Pin TSSOP
8-Pin SOP
8-Pin DIP
14-Pin TSSOP
8-Pin SOP
8-Pin DIP
14-Pin TSSOP
June 2011
2
M9999-062711-A
Micrel, Inc.
MIC2545A/2549A
Pin Configuration
8-Pin SOP (M)
8-Pin DIP (N)
14-Pin TSSOP (TS)
Pin Description
Pin Number
SOP, DIP
1
2
3
4
5, 7
6, 8
Pin Number
TSSOP
1
3
5
7
8, 12
10, 14
2, 4, 6, 9,
11, 13
Pin Name
EN
FLG
GND
ILIM
IN
OUT
NC
Pin Function
Enable (Input): Logic-compatible enable input (−1 version is active high,
−2
version is active low). High input
>1.8V
typical; low input
<1.4V
typical. Do not
float. MIC2549A only: Also resets thermal-shutdown latch.
Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent or
thermal shutdown. MIC2549A only: Latched low on thermal shutdown.
Ground: supply return.
Current Limit: Sets current-limit threshold using an external resistor (R
SET
)
connected to ground. 76.8Ω
<
R
SET
<
459Ω.
Supply Input: Output MOSFET drain. Also powers internal circuitry. Both IN
pins must be externally connected together.
Switch Output: Output MOSFET source. Both OUT pins must be externally
connected together.
Not internally connected.
June 2011
3
M9999-062711-A
Micrel, Inc.
MIC2545A/2549A
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
) ....................................................+7.0V
Output Voltage (V
OUT
). ................................................+7.0V
Output Current (I
OUT
) .................................Internally Limited
Enable Input (V
EN
) ...........................................
−0.3V
to
+7V
Fault Flag Voltage (V
FLG
).............................................+7.0V
Fault Flag Current (I
FLG
) ..............................................50mA
Storage Temperature (Ts).........................–65°C to +150°C
Junction Temperature (T
J
) ........................Internally Limited
Lead Temperature (soldering, 5sec.)......................... 260°C
ESD Rating
(3)
..............................................................1500V
Operating Ratings
(2)
Supply Voltage (V
IN
)..................................... +2.7V to +5.5V
Ambient Temperature (T
A
) .......................... –40°C to +85°C
Package Thermal Resistance
PDIP (θ
JA
) ........................................................130°C/W
SOIC (θ
JA
) ........................................................160°C/W
TSSOP (θ
JA
)
(4)
..................................................100°C/W
Current-Limit Set Range
(5)
.................................. 0.5A to 3A
Electrical Characteristics
(4)
V
IN
=
+5V;
T
A
= 25°C,
bold
values indicate –40°C to +85°C, unless noted.
Symbol
Parameter
Supply Current
V
EN
Condition
Switch Off, OUT = Open
(6)
Switch On, OUT = Open
(6)
Min.
Typ.
0.75
90
Max.
5
125
150
Units
µA
µA
V
µA
pF
Enable Input Voltage
Enable Input Current
Enable Input Capacitance
Enable High Transition
(6)
Enable Low Transition
(6)
V
EN
= V
OH(MIN)
= 2.4V
V
EN
= V
OL(MAX)
= 0.8V
Note 7
I
OUT
= 500mA
I
LIMIT
= 0.5A to 3A, V
OUT
= 1V to 4V
(5)
I
LIMIT
= 1A to 2.5A, V
OUT
= 1V to 4V
(5)
Switch Off, V
OUT
= 0V
R
L
= 10Ω, C
L
= 1µF,
Figures 1a, 1b
R
L
= 10Ω, C
L
= 1µF,
Figures 1a, 1b
R
L
= 10Ω, C
L
= 1µF,
Figures 1a, 1b
2.4
1.6
1.5
0.01
0.01
1
35
50
276
264
10
5
4.9
0.8
1
1
R
DS(ON)
Switch Resistance
Current-Limit Factor
Output Leakage Current
mΩ
V
µA
ms
ms
µs
184
195
1
0.75
230
230
1
2
1.8
25
t
ON
t
R
t
OFF
Output Turn-On Delay
Output Turn-On Rise Time
Output Turn-Off Delay
Notes:
1. Exceeding the absolute maximum rating may damage the device.
2.
3.
4.
5.
The device is not guaranteed to function outside its operating rating.
Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
Assumes 4-layer PCB is used.
Current limit is determined by I
LIMIT
=
230
R
SET
, where R
SET
is in
Ωs,
and 230 is typical current-limit factor in volts.
6.
7.
Off is
≤
0.8V and on is
≥
2.4V for the MIC2545A-1 and MIC2549A-1. Off is
≥
2.4V and on is
≤
9.8V for the MIC2545A-2 and MIC2549A-2. The
enable input has about 100mV of hysteresis.
Guaranteed by design but not production tested.
June 2011
4
M9999-062711-A
Micrel, Inc.
MIC2545A/2549A
Electrical Characteristics
(4)
(Continued)
V
IN
=
+5V;
T
A
= 25°C,
bold
values indicate –40°C to +85°C, unless noted.
Symbol
t
F
Parameter
Output Turn-Off Fall Time
Overtemperature Threshold
Shutdown
Error Flag Off Current
EN Pulse Reset Width
t
SU
V
OL
V
IN
to EN Set-Up
Current-Limit Response Time
Error Flag Output Resistance
Condition
R
L
= 10Ω, C
L
= 1µF,
Figures 1a, 1b
T
J
Increasing
T
J
Decreasing
V
FLG
= 5V
MIC2549A Thermal-Shutdown Latch
(7)
MIC2549
(7)
,
Figure 1c
V
OUT
= 0V to I
OUT
= 2A, I
SET
= 1A
(7)
I
FLG
= 10mA
1
0
40
4
15
Min.
Typ.
23
135
120
0.01
1
Max.
Units
µs
°C
µA
µs
µs
µs
Ω
Test Circuit
Functional Characteristics Test Circuit
June 2011
5
M9999-062711-A
嵌入式系统
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