MIC2545A/2549A
Micrel
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 Ad-
vanced 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 indi-
cate 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.
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
USB power distribution
PCI Bus Power Switching
Notebook PC
ACPI power distribution
PC card hot swap applications
Inrush current-limiting
Applications
Typical Application
+5V
10k
On/Off
MIC2545A
EN
FLG
GND
ILIM
R
SET
OUT
IN
OUT
IN
0.1µF
33µF
Peripheral
Typical Advanced Configuration and Power Interface (ACPI) Application
UL Recognized Component
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
April 2004
1
M9999-041204
MIC2545A/2549A
Micrel
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
Latch*
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
Package
8-lead SOP
8-pin DIP
14-lead TSSOP
8-lead SOP
8-pin DIP
14-lead TSSOP
8-lead SOP
8-pin DIP
14-lead TSSOP
8-lead SOP
8-pin DIP
14-lead TSSOP
8-lead SOP
8-pin DIP
14-lead TSSOP
8-lead SOP
8-pin DIP
14-lead TSSOP
8-lead SOP
8-pin DIP
14-lead TSSOP
8-lead SOP
8-pin DIP
14-lead TSSOP
Pb-Free
Pin Configuration
MIC2545A/2549A
EN
FLG
GND
ILIM
1
2
3
4
8
7
6
5
OUT
EN 1
MIC2545A/2549A
14 OUT
13 NC
12 IN
11 NC
10 OUT
9 NC
8 IN
IN
NC 2
OUT
FLG 3
IN
NC 4
GND 5
NC 6
ILIM 7
8-Lead SOP (M)
8-Pin DIP (N)
MIC2545A/2549A
(EN) 1
(FLG) 2
LOGIC,
CHARGE
PUMP
6,8 (OUT)
5,7 (IN)
14-Lead TSSOP (TS)
(ILIM) 4
3 (GND)
M9999-041204
2
April 2004
MIC2545A/2549A
Micrel
Pin Description
Pin Number
SOP, DIP
1
Pin Number
TSSOP
1
Pin Name
EN
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
2
3
FLG
3
4
5, 7
6, 8
5
7
8, 12
10, 14
2,4,6,9,11,13
GND
ILIM
IN
OUT
NC
April 2004
3
M9999-041204
MIC2545A/2549A
Micrel
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 (T
S
) ....................... –65°C to +150°C
Junction Temperature (T
J
) ....................... Internally Limited
Lead Temperature (soldering 5 sec.) ........................ 260°C
ESD Rating
(3) ..........................................................................
2004V
Operating Ratings
(2)
Supply Voltage (V
IN
) ................................... +2.7V to +5.5V
Ambient Temperature Range (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
V
IN
= +5V; T
A
= 25°C,
bold
indicates –40°C to +85°C; unless noted
Symbol
Parameter
Supply Current
Condition
Switch off, OUT = open
(6)
Switch on, OUT = open
(6)
V
EN
Enable Input Voltage
Enable high transition
(6)
Enable low transition
(6)
Enable Input Current
V
EN
= V
OH(min)
= 2.4V
V
EN
= V
OL(max)
= 0.8V
Enable Input Capacitance
R
DS(on)
Switch Resistance
Current Limit Factor
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)
Output Leakage Current
t
ON
t
R
t
OFF
t
F
Output Turn-On Delay
Output Turn-On Rise Time
Output Turnoff Delay
Output Turnoff Fall Time
Overtemperature Threshold
Shutdown
Error Flag Off Current
EN Pulse Reset Width
t
SU
V
OL
Notes:
1.
Exceeding the absolute maximum ratings may damage the device.
2.
The device is not guaranteed to function outside its operating ratings.
3.
Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
4.
Assumes 4 layer PCB is used.
5.
Current limit is determined by:
I
LIMIT
=
230
R
SET
, where R
SET
is in ohms, and 230 is typical current limit factor in volts.
Min
Typ
0.75
90
Max
5
125
150
Units
µA
µA
µA
V
2.4
1.6
1.5
0.01
0.01
1
35
50
300
276
10
5
4.9
0.8
1
1
V
µA
µA
pF
mΩ
V
V
µA
ms
ms
µs
µs
°C
°C
µA
µs
µs
µs
160
184
230
230
1
Switch off, V
OUT
= 0V
R
L
= 10Ω, C
L
= 1µF,
Figures 1a, 1b
R
L
= 10Ω, C
L
= 1µF,
Figure 1a, 1b
R
L
= 10Ω, C
L
= 1µF,
Figure 1a, 1b
R
L
= 10Ω, C
L
= 1µF,
Figure 1a, 1b
T
J
increasing
T
J
decreasing
V
FLG
= 5V
MIC2549A thermal shutdown latch
(7)
MIC2549A
(7)
,
Figure 1c
V
OUT
= 0V to I
OUT
= 2A, I
SET
= 1A
(7)
I
FLG
= 10mA
1
0
1
0.75
2
1.8
25
23
135
120
0.01
1
V
IN
to EN Set-Up
Current-Limit Response Time
Error Flag Output Resistance
40
4
15
Ω
6.
Off is
≤
0.8V and on is
≥
2.4V for the MIC2545A-1 and MIC2549A-1. Off is
≥
2.4V and on is
≤
0.8V for the MIC2545A-2 and MIC2549A-2. The
enable input has about 100mV of hysteresis.
7.
Guaranteed by design but not production tested.
M9999-041204
4
April 2004
MIC2545A/2549A
Micrel
Test Circuit
V
OUT
Device
Under OUT
Test
I
OUT
R
L
C
L
t
r
V
OUT
10%
90%
90%
10%
t
f
Functional Characteristics Test Circuit
Timing Diagrams
50%
t
OFF
t
ON
V
OUT
90%
10%
V
EN
Figure 1a. MIC2545A/49A-2
V
EN
50%
t
OFF
t
ON
V
OUT
90%
10%
Figure 1b. MIC2545A/49A-1
V
IN
t
SU
V
EN
Figure 1c. Input-to-Enable Setup Timing
April 2004
5
M9999-041204
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