March 2001
1
MIC2546/2547
MIC2546/2547
Micrel
MIC2546/2547
Dual Programmable Current Limit Switch
Final Information
General Description
The MIC2546 and MIC2547 are integrated high-side dual
power switches optimized for low loss dc power switching and
other power management applications, including Advanced
Configuration and Power Interface (ACPI). The MIC2546/47
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 resis-
tor-programmable output current-limit and a soft-start circuit
which minimizes inrush current when the switch is enabled.
Thermal shutdown, along with current-limit, protects the
switch and the attached device.
The MIC2546/47's open-drain flag outputs are used to indi-
cate current-limiting or thermal shutdown to a local controller.
The MIC2547 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 MIC2547.
The MIC2546 and MIC2547 are available in active-high and
active-low enable versions in 16-pin TSSOP and SOP
packages.
Typical Application
MIC2546-xBM
ENA
FLGA
GNDA
ILIMA
OUTA
INA
OUTA
ENB
FLGB
GNDB
ILIMB
OUTB
INB
OUTB
NC
On/Off
Peripheral
+5V
On/Off
R
FLGA
Peripheral
NC
33
F
0.1
F
R
SETA
R
SETB
R
FLGB
+3.3V
0.1
F
33
F
Typical Advanced Configuration and Power Interface (ACPI) Application
Features
2.7V to 5.5V input
Adjustable current-limit up to 1.5A
Reverse current flow blocking (no "body diode")
100
A typical on-state supply current per channel
2
A typical off-state supply current
120m
maximum on-resistance
Open-drain fault flag
Thermal shutdown
Thermal shutdown output latch (MIC2547)
2ms (slow) turn-on and 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
Ideal for dual supply applications
Micrel, Inc. 1849 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 http://www.micrel.com
UL Recognized Component
MIC2546/2547
Micrel
MIC2546/2547
2
March 2001
Pin Configuration
1
INA
OUTA
ENA
NC
FLGA
GNDB
ILIMB
OUTB
16 OUTA
ILIMA
GNDA
FLGB
ENB
OUTB
NC
INB
15
14
13
12
11
10
9
2
3
4
5
6
7
8
MIC2546/2547
16-Pin SOP (M)
16-Pin TSSOP (TS)
Ordering Information
Part Number
Enable
Latch*
Temperature Range
Package
MIC2546-1BM
Active High
40
C to +85
C
16-pin SOP
MIC2546-1BTS
Active High
40
C to +85
C
16-pin TSSOP
MIC2546-2BM
Active Low
40
C to +85
C
16-pin SOP
MIC2546-2BTS
Active Low
40
C to +85
C
16-pin TSSOP
MIC2547-1BM
Active High
40
C to +85
C
16-pin SOP
MIC2547-1BTS
Active High
40
C to +85
C
16-pin TSSOP
MIC2547-2BM
Active Low
40
C to +85
C
16-pin SOP
MIC2547-2BTS
Active Low
40
C to +85
C
16-pin TSSOP
* Thermal Shutdown Latch
LOGIC,
CHARGE
PUMP
(OUTA)
(INA)
(ENA)
(FLGA)
MIC2546/2547
(ILIMA)
LOGIC,
CHARGE
PUMP
(OUTB)
(INB)
(ENB)
(FLGB)
(ILIMB) (GND)
Functional Pinout
Pin Description
Pin Number
Pin Name
Pin Function
1
INA
Input A: Output A MOSFET drain. Also supplies internal circuitry.
2, 16
OUTA
Switch A (Output): Output A MOSFET source. Pins 2 and 16 must be
externally connected.
3
ENA
Enable A (Input): Logic-compatible enable input. Active-high (1) or active-
low (2). High input >1.7V typical; low input <1.5V typical. Do not float.
MIC2547 only: Also resets thermal shutdown latch.
4, 10
NC
Not internally connected.
5
FLGA
Fault Flag A (Output): Active-low, open-drain output. Indicates overcurrent
or thermal shutdown conditions. MIC2547 only: latched low on thermal
shutdown.
6, 14
GNDB, GNDA
Ground. Both pins must be connected to GND.
7
ILIMB
Current Limit Channel B: Sets current-limit threshold using an external
resistor, R
SET
, connected to ground. 154
< R
SET
< 2.29k
.
8, 11
OUTB
Switch B (Output): Pins 8 and 11 must be externally connected.
9
INB
Input B
12
ENB
Enable B (Input)
13
FLGB
Fault Flag B (Output)
15
ILIMA
Current Limit Channel A.
March 2001
3
MIC2546/2547
MIC2546/2547
Micrel
Electrical Characteristics
V
IN
= +5V; T
A
= 25
C, bold indicates 40
C to +85
C; unless noted
Symbol
Parameter
Condition
Min
Typ
Max
Units
Supply Current
Switch off, OUT = open, Note 4
1.5
10
A
Switch on, OUT = open, Note 4
200
320
A
V
EN
Enable Input Voltage
Enable High, Note 4
2.4
1.7
V
Enable Low, Note 4
1.5
0.8
V
Enable Input Current
V
EN
= V
OH(min)
= 2.4V
.01
1
A
V
EN
= V
OL(max)
= 0.8V
.01
1
A
Enable Input Capacitance
Note 5
1
pF
R
DS(on)
Switch Resistance
I
OUT
= 500mA
80
120
m
Current Limit Factor, Note 6
I
OUT
= 100mA to 1.5A, V
OUT
= 1.0V to 4.0V,
184
230
276
V
Note 6
Output Leakage Current
Switch off
1
10
A
t
ON
Output Turn-On Delay
R
L
= 10
, C
L
= 1
F, Figure 1a and 1b
1
2
5
ms
t
R
Output Turn-On Rise Time
R
L
= 10
, C
L
= 1
F, Figure 1a and 1b
1
2
5
ms
t
OFF
Output Turnoff Delay
R
L
= 10
, C
L
= 1
F, Figure 1a and 1b
22
s
t
F
Output Turnoff Fall Time
R
L
= 10
, C
L
= 1
F, Figure 1a and 1b
21
s
Overtemperature Threshold
T
J
increasing
140
C
Shutdown
T
J
decreasing
130
C
Error Flag Output Resistance
V
IN
= 5V, I
L
= 10
A
4
15
V
IN
= 3.3V, I
L
= 10
A
5
20
Error Flag Off Current
V
FLG
= 5V
0.01
1
A
EN Pulse Reset Width
MIC2547 Thermal Shutdown Latch
5
s
V
IN
to EN Set-Up
MIC2547, Note 5
0
s
Current-Limit Response Time
V
OUT
= 0V
25
s
Overcurrent FLG Response Time
V
OUT
= V
IN
/2
to FLG low
5
s
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.
Off is
0.8V and on is
2.4V for the MIC2546-1 and MIC2547-1. Off is
2.4V and on is
0.8V for the MIC2546-2 and MIC2547-2. The
enable input has about 200mV of hysteresis.
Note 5.
Guaranteed by design, but not production tested.
Note 6.
Current limit threshold is determined by:
I
230V
R
LIMIT
SET
=
, where R
SET
is in ohms.
Absolute Maximum Ratings
(Note 1)
Supply Voltage (V
IN
) .................................................. +6.0V
Output Voltage (V
OUT
) ............................................... +6.0V
Output Current (I
OUT
) ............................... Internally Limited
Enable Input (V
EN
) ................................ 0.3V to V
IN
+0.3V
Fault Flag Voltage (V
FLG
) ........................................... +6.0V
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, Note 3 ...................................................... 2kV
Operating Ratings
(Note 2)
Supply Voltage (V
IN
) ................................... +2.7V to +5.5V
Current Limit Set Range ..................................... 0.1 to 1.5A
Ambient Temperature Range (T
A
) ............. 40
C to +85
C
Package Thermal Resistance
SOP
(
JA
) .......................................................... 120
C/W
TSSOP
(
JA
) ..................................................... 100
C/W
MIC2546/2547
Micrel
MIC2546/2547
4
March 2001
50
60
70
80
90
100
2.5
3.0
3.5
4.0
4.5
5.0
5.5
ON-RESISTANCE (m
)
SUPPLY VOLTAGE (V)
Output On-Resistance
vs. Supply Voltage
T
A
= 27
C
40
60
80
100
120
-40 -20
0
20
40
60
80 100
ON-RESISTANCE (m
)
TEMPERATURE (
C)
Output On-Resistance
vs. Temperature
2.7V
3.3V
5.0V
0
40
80
120
160
200
240
280
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY CURRENT (mA)
SUPPLY VOLTAGE (V)
On-State Supply Current
vs. Supply Voltage
T
A
= 27
C
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.20
2.5
3.0
3.5
4.0
4.5
5.0
5.5
SUPPLY CURRENT (
A)
SUPPLY VOLTAGE (V)
Off-State Supply Current
vs. Supply Voltage
T
A
= 27
C
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
ENABLE THRESHOLD (V)
SUPPLY VOLTAGE (V)
Enable Threshold Voltage
vs. Supply Voltage
T
A
= 27
C
V
EN
RISING
V
EN
FALLING
0
40
80
120
160
200
240
280
-40 -20
0
20
40
60
80 100
SUPPLY CURRENT (
A)
TEMPERATURE (
C)
On-State Supply Current
vs. Temperature
2.7V
3.3V
5.0V
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
-40 -20
0
20
40
60
80 100
SUPPLY CURRENT (
A)
TEMPERATURE (
C)
Off-State Supply Current
vs. Temperature
2.7V
3.3V
5.0V
R
L
= 44
1.0
1.2
1.4
1.6
1.8
2.0
-40 -20
0
20
40
60
80 100
ENABLE THRESHOLD (V)
TEMPERATURE (
C)
Enable Threshold Voltage
vs. Temperature
V
EN
RISING
V
EN
FALLING
0
1
2
3
4
5
6
7
-40 -20
0
20
40
60
80 100
OUTPUT RISE TIME (ms)
TEMPERATURE (
C)
Rise Time
vs. Temperature
2.7V
3.3V
5.0V
R
L
= 44
0
0.5
1.0
1.5
2.0
2.5
-40 -20
0
20
40
60
80 100
OUTPUT FALL TIME (
s)
TEMPERATURE (
C)
Output Fall Time
vs. Temperature
2.7V
3.3V
R
L
= 44
5.0V
0
500
1000
1500
2000
100
1000
5000
CURRENT LIMIT (mA)
R
SET
(
)
Current Limit
vs. R
SET
I
TH
V
IN
= 5V
I
SET
I
SHORT
0
500
1000
1500
2000
0
1
2
3
4
5
6
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE (V)
Output Current
vs. Output Voltage
R
SET
= 150
V
IN
= 5V
R
SET
= 470
R
SET
= 2.3k
Typical Characteristics
March 2001
5
MIC2546/2547
MIC2546/2547
Micrel
600
700
800
900
1000
1100
-40 -20
0
20
40
60
80 100
OUTPUT CURRENT (mA)
TEMPERATURE (
C)
Current Limit
vs. Temperature
I
TH
I
SET
I
SHORT
V
IN
= 5V
R
SET
= 230
600
700
800
900
1000
1100
2.5
3.0
3.5
4.0
4.5
5.0
5.5
CURRENT LIMIT (mA)
SUPPLY VOLTAGE (V)
Current Limit
vs. Supply Voltage
I
TH
I
SET
I
SHORT
T
A
= 27
C
R
L
= 230
MIC2546/2547
Micrel
MIC2546/2547
6
March 2001
Functional Characteristics
Turn-On Response
TIME (500
s/div.)
MIC2546-1
I
OUT
(200mA/div
.
)
V
OUT
(2V/div
.
)
V
EN
(5V/div
.
)
V
FLG
(10V/div
.
)
V
IN
= 5V
C
IN
= 4.7
F
C
L
= 1
F
R
L
= 10
Turnoff Response
TIME (1ms/div.)
MIC2546-1
V
IN
= 5V
C
IN
= 4.7
F
C
L
= 1
F
R
L
= 10
I
OUT
(200mA/div
.)
V
OUT
(2V/div
.)
V
EN
(10V/div
.)
V
FLG
(5V/div
.)
Current-Limit Response
TIME (100ms/div.)
MIC2546-1
I
OUT
(500mA/div
.
)
V
OUT
(5V/div
.
)
V
EN
(10V/div
.
)
V
FLG
(10V/div
.
)
I
SET
= 1A
Thermal Shutdown
V
IN
= 5V
C
IN
= 4.7
F
R
L
= 1
Enable Into Heavy Load
TIME (100ms/div.)
MIC2546-1
I
OUT
(500mA/div
.
)
V
OUT
(5V/div
.
)
V
EN
(10V/div
.
)
V
FLG
(10V/div
.
)
V
IN
= 5V
C
IN
= 4.7
F
I
SET
= 1A
R
L
= 1
Inrush Current Response
TIME (500
s/div.)
MIC2546-1
V
IN
= 5V
C
IN
= 4.7
F
R
L
= 10
I
OUT
(500mA/div
.
)
V
EN
(10V/div
.
)
V
FLG
(5V/div
.
)
C
L
= 10
F
C
L
= 60
F
C
L
= 110
F
Enable Into Heavy Load
TIME (500
s/div.)
MIC2547-1
V
IN
= 5V
C
IN
= 4.7
F
R
L
= 1
I
SET
= 1A
I
OUT
(1A/div
.
)
V
EN
(10V/div
.
)
V
FLG
(5V/div
.
)
V
OUT
(5V/div
.
)
Reset
Thermal Shutdown
Output Latched
March 2001
7
MIC2546/2547
MIC2546/2547
Micrel
Test Circuit
Device
Under
Test
C
L
OUT
R
L
V
OUT
I
OUT
90%
V
OUT
10%
90%
10%
t
r
t
f
Functional Characteristics Test Circuit
Timing Diagrams
V
EN
50%
90%
V
OUT
10%
t
OFF
t
ON
Figure 1a. MIC2546/47-1
V
EN
50%
90%
V
OUT
10%
t
OFF
t
ON
Figure 1b. MIC2546/47-2
MIC2546/2547
Micrel
MIC2546/2547
8
March 2001
EN
V
OUT
I
OUT
Short-Circuit Fault
Thermal Shutdown
Reached
Fault Removed
FLG
I
LIMIT
I
DC
Output Reset
Figure 2a. MIC2547-2 Timing: Output is reset by toggling EN
EN
V
OUT
I
OUT
Short-Circuit
Fault
Thermal Shutdown
Reached
Fault
Removed
FLG
I
LIMIT
I
DC
Figure 2b. MIC2546-2 Timing
March 2001
9
MIC2546/2547
MIC2546/2547
Micrel
Block Diagram
1.2V
REFERENCE
THERMAL
SHUTDOWN
OSC.
CHARGE
PUMP
OUTA
GATE
CONTROL
INA
FLGA
ENA
CURRENT
LIMIT
ILIMA
R
SETA
THERMAL
SHUTDOWN
LATCH
(MIC2547)
RESET
1.2V
REFERENCE
THERMAL
SHUTDOWN
OSC.
CHARGE
PUMP
OUTB
GATE
CONTROL
INB
FLGB
ENB
CURRENT
LIMIT
ILIMB
R
SETB
THERMAL
SHUTDOWN
LATCH
(MIC2547)
RESET
GNDB
GNDA
MIC2546/2547
Micrel
MIC2546/2547
10
March 2001
Functional Description
The MIC2546 and MIC2547 are dual high-side N-channel
switches available with active-high or active-low enable in-
puts. Fault conditions turn off or inhibit turn-on of the output
transistor and activate the open-drain error flag transistor
making it sink current to ground.
Input and Output
INX is the power supply connection to the logic circuitry and
the drain of the output MOSFET. OUTX is the source of the
output MOSFET. In a typical circuit, current flows from INX to
OUTX toward the load. If V
OUT
is greater than V
IN
, current will
flow from OUTX to INX since the switch is bidirectional when
enabled. The output MOSFET and driver circuitry are also
designed to allow the MOSFET source to be externally forced
to a higher voltage than the drain (V
OUT
> V
IN
) when the
switch is disabled. In this situation, the MIC2546/47 avoids
undesirable current flow from OUTX to INX. Both OUT pins
for a given channel must be connected together.
Thermal Shutdown
Thermal shutdown shuts off the output MOSFET and signals
the fault flag if the die temperature exceeds 140
C. 10
C of
hysteresis prevents the switch from turning on until the die
temperature drops to 130
C. Overtemperature detection
functions only when the switch is enabled.
The MIC2547 features an internal latch which causes the part
to remain off after thermal shutdown until a reset pulse is
provided via the enable pin. While in current-limit, the thermal
shutdown latch prevents on/off cycling of the output. Refer to
Figure 2 for timing diagram. The flag remains low until reset.
Enable Input
ENX must be driven logic high or logic low, or be pulled high
or low for a clearly defined input. Floating the input may cause
unpredictable operation. ENX should not be allowed to go
negative with respect to GND, and V
ENX
should be less than
or equal to V
INX
.
Adjustable Current-Limit
The short-circuit current-limit is user-adjustable with an exter-
nal set resistor. Current-limit in the range of 100mA to 1.5A is
available with a set point accuracy of better than
20%. The
current-limit circuit prevents damage to the output MOSFET
and external load.
The nominal current-limit value is set with an external resistor
between ILIMX and GND. For a desired current-limit, the
value of the external set resistor is given by:
R
230V
I
SETX
LIMITX
=
where:
154
< R
SET
< 2.29k
For example, to set a 1A nominal current-limit, R
SET
is
calculated as:
230V
1A
230
=
Current through R
SETX
increases with OUT current. The
voltage across R
SETX
could be monitored with a high imped-
ance comparator to provide an indication of output current.
R
SETX
should be between 154
and 2.29k
(0.5% resistor
value).
Short-Circuit Protection
In the event of a short-circuit, the output current will fold back
to approximately 80% of the short-circuit current-limit.
Fault Flag
FLGX is an N-channel, open-drain MOSFET output. The
fault-flag is active (low) for current-limit or thermal shutdown
conditions. The flag output MOSFET is capable of sinking a
10mA load to typically 100mV above ground.
March 2001
11
MIC2546/2547
MIC2546/2547
Micrel
Applications Information
Supply Filtering
A 0.1
F to 1
F bypass capacitor from INX to GND, located
near the MIC2546 and MIC2547, is strongly recommended to
control supply transients. Without a bypass capacitor, an
output short may cause sufficient ringing on the input (from
supply lead inductance) to damage internal control circuitry.
Input transients must not exceed the absolute maximum
supply voltage (V
IN max
= 6V) even for a short duration.
MIC2546-1BM
INA
OUTA
OUTA
ENA
GNDA
NC
FLGB
ILIMA
1
16
2
15
3
14
4
13
4.0V to 5.5V
.
FLGA
GNDB
ILIMB
OUTB
ENB
OUTB
NC
INB
5
6
7
8
12
11
10
9
R
SETA
0.1 to 1
F
R
SETB
0.1 to 1
F
Supply Bypassing
Power Dissipation
The device's junction temperature depends on several fac-
tors such as the load, PCB layout, ambient temperature and
package type. Equations that can be used to calculate power
dissipation and junction temperature are found below.
Calculation of power dissipation can be accomplished by the
following equation:
P
D
= R
DS(on)
(I
OUT
)2
To relate this to junction temperature, the following equation
can be used:
T
j
= P
D
JA
+ T
A
where:
T
j
= junction temperature
T
A
= ambient temperature
JA
= is the thermal resistance of the package
Transient Overcurrent Filter
The inrush current from the connection of a heavy capacitive
load may cause the fault flag to fall for 10
s to 200
s while the
switch is in a constant-current mode, charging the capaci-
tance.
Adding an optional series resistor-capacitor (R
SET2
) in paral-
lel with R
SET
, as shown in Figure 3, allows the transient
current-limit to be set to a different value than steady state. A
typical USB hot-plug inrush is 2A to 3A for 10
s to 20
s. If
R
SET
is 435
(510mA), an R
SET2
of 88
(2.5A) and C
SET
of
1
F (RC = 100
s) allows transient surge of 3A to pass for
100
s without tripping the overcurrent flag (FLG).
USB Power Distribution
The MIC2546 is ideal for meeting USB power distribution
requirements. Figure 3 depicts a USB Host application. R
SET
should be set to a value providing a current-limit >500mA.
The accurate current-limit of the MIC2546 will reduce power
supply current requirements. Also, fast reaction to short
circuit faults prevent voltage droop in mobile PC applications.
Printed Circuit Board Hot-Plug
The MIC2546/47 are ideal inrush current-limiters suitable for
hot-plug applications. Due to the integrated charge pump,
the MIC2546/47 presents a high impedance when off and
slowly becomes a low impedance as it turns on. This "soft-
start" feature effectively isolates power supplies from highly
capacitive loads by reducing inrush current during hot-plug
events.
R
SET
ON/OFF
OVERCURRENT
MIC2546-2BM
3.3V USB Controller
V
BUS
D+
D
GND
10k
MIC5203-3.3
LDO Regulator
IN
OUT
GND
Ferrite Bead
D+
D
GND
D+
D
V+
INA
OUTA
OUTA
ILIMA
ENA
GNDA
NC
FLGB
Bold lines indicate
0.1" wide, 1-oz. copper
high-current traces.
Downstream
USB
Port 1
4.75V min.
500mA max.
120
F
0.01
F
GND
5V
(+)
()
4.7
F
(optional)
1.5k 2%
FLGA
GNDB
ILIMB
OUTB
ENB
OUTB
NC
INB
R
SET
10k
V
BUS
V
BUS
D+
D
GND
Downstream
USB
Port 2
4.75V min.
500mA max.
120
F
0.01
F
Ferrite Bead
100k
R
SET(2)
C
SET
100k
Figure 3. USB Host Application
MIC2546/2547
Micrel
MIC2546/2547
12
March 2001
Package Information
45
0
8
0.244 (6.20)
0.228 (5.79)
0.394 (10.00)
0.386 (9.80)
SEATING
PLANE
0.020 (0.51)
REF
0.020 (0.51)
0.013 (0.33)
0.157 (3.99)
0.150 (3.81)
0.050 (1.27)
0.016 (0.40)
0.0648 (1.646)
0.0434 (1.102)
0.050 (1.27)
BSC
PIN 1
DIMENSIONS:
INCHES (MM)
0.0098 (0.249)
0.0040 (0.102)
16-Pin SOP (M)
Rev. 01
16-Pin TSSOP (TS)
MICREL INC.
1849 FORTUNE DRIVE
SAN JOSE, CA 95131
USA
TEL
+ 1 (408) 944-0800
FAX
+ 1 (408) 944-0970
WEB
http://www.micrel.com
This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or
other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.
2001 Micrel Incorporated
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