Datasheet MIC2545A-2BM, MIC2548-2BMM, MIC2548-2BM, MIC2548-1BM, MIC2544-2BMM Datasheet (MICREL)

MIC2544/2548

EN

FLG

GND

ILIM

OUT

IN

OUT

NC

MIC2544-xBM

On/Off

Peripheral

0.1µF

R

SET

+5V

R

FLG

33µF

SOP pinout shown

Micrel

MIC2544/2548

Programmable Current Limit High-Side Switch

Preliminary Information

General Description

The MIC2544 and MIC2548 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 MIC2544/48 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 current-limit, protects the
switch and the attached device.

The MIC2544/48’s open-drain flag output is used to indicate
current-limiting or thermal shutdown to a local controller. The
MIC2548 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 MIC2548.

The MIC2544 and MIC2548 are available in active-high and
active-low enable versions in the 8-pin SOP (small-outline
package) and 8-pin MSOP (micro-small-outline package).

Features

• 2.7V to 5.5V input

• Adjustable current-limit up to 1.5A

• Reverse current flow blocking (no “body diode”)

• 75µA typical on-state supply current

• 1µA typical off-state supply current

• 120mΩ maximum on-resistance

• Open-drain fault flag

• Thermal shutdown

• Thermal shutdown output latch (MIC2548)

• 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

Typical Application

Typical Advanced Configuration and Power Interface (ACPI) Application

June 2000 1 MIC2544/2548

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com

MIC2544/2548

Ordering Information

Part Number Enable Latch* Temperature Range Package

MIC2544-1BM Active High –40°C to +85°C 8-pin SOP
MIC2544-1BMM Active High –40°C to +85°C 8-pin MSOP
MIC2544-2BM Active Low –40°C to +85°C 8-pin SOP
MIC2544-2BMM Active Low –40°C to +85°C 8-pin MSOP
MIC2548-1BM Active High •–40°C to +85°C 8-pin SOP
MIC2548-1BMM Active High •–40°C to +85°C 8-pin MSOP
MIC2548-2BM Active Low •–40°C to +85°C 8-pin SOP
MIC2548-2BMM Active Low •–40°C to +85°C 8-pin MSOP

* Thermal Shutdown Latch

Pin Configuration

Micrel

EN

FLG

GND

ILIM

MIC2544/2548

1

2

3

4

8-Pin SOP (M)

OUT

8

IN

7

OUT

6

NC

5

MIC2544/2548

(EN)

(FLG)

LOGIC,

CHARGE

PUMP

(OUT)

(IN)

(GND)(ILIM)

FLG

GND

NOTE: PINS 4 AND 5
FOR SOIC AND MSOP
ARE DIFFERENT.

MIC2544/2548

EN

1

2

3

NC

4

8-Pin MSOP (MM)

OUT

8

IN

7

OUT

6

ILIM

5

Pin Description

Pin Number Pin Number Pin Name Pin Function

MSOP-8 SOP-8

1 1 EN Enable (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.
MIC2548 only: Also resets thermal shutdown latch.

2 2 FLG Fault Flag (Output): Active-low, open-drain output. Indicates overcurrent or

thermal shutdown conditions.
MIC2548 only: latched low on thermal shutdown.

3 3 GND Ground

5 4 ILIM Current Limit: Sets current-limit threshold using an external resistor, R

connected to ground. 154Ω < R

7 7 IN Input: Output MOSFET drain. Also powers internal circuitry.

6,8 6,8 OUT Switch (Output): Output MOSFET source. Pins 6 and 8 must be externally

connected.

4 5 NC Not internally connected

< 2.29kΩ.

SET

SET

,

MIC2544/2548 2 June 2000

MIC2544/2548

Micrel

Absolute Maximum Ratings (Note 1)

Supply Voltage (V
Output Voltage (V
Output Current (I

Enable Input (VEN) ................................. –0.3V to VIN+0.3V

Fault Flag Voltage (V
Fault Flag Current (I

) .................................................. +6.0V

IN

) ............................................... +6.0V

OUT

) ............................... Internally Limited

OUT

)...........................................+6.0V

FLG

) ............................................ 50mA

FLG

Operating Ratings (Note 2)

Supply Voltage (V

Current Limit Set Range.................................. 0.1A to 1.5A

Ambient Temperature Range (TA) ............. –40°C to +85°C

Package Thermal Resistance

SOP (θJA) ..........................................................160°C/W

MSOP (θJA) .......................................................206°C/W

) ................................... +2.7V to +5.5V

IN

Storage Temperature (TS) ....................... –65°C to +150°C

Junction Temperature (T

) ....................... Internally Limited

J

Lead Temperature (soldering 5 sec.) ........................ 260°C

ESD Rating, Note 3 ...................................................... 2kV

Electrical Characteristics

VIN = +5V; TA = 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 0.75 5 µA

switch on, OUT = open, Note 4 75 160 µA

V

EN

R

DS(on)

t

ON

t

R

t

OFF

t

F

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 MIC2544-1 and MIC2548-1. Off is ≥ 2.4V and on is ≤ 0.8V for the MIC2544-2 and MIC2548-2. The

Note 5. Current limit threshold is determined by

Note 6. Guaranteed by design but not production tested.

Enable Input Voltage enable high, Note 4 2.4 1.7 V

enable low, Note 1 1.5 0.8 V

Enable Input Current VEN = V

VEN = V

= 2.4V 0.01 1 µA

OH(min)

= 0.8V 0.01 1 µA

OL(max)

Enable Input Capacitance Note 6 1pF

Switch Resistance I

Current Limit Factor

= 500mA 80 120 mΩ

OUT

I

= 100mA to 1A, V

OUT

I

= 500mA to 1.5A, V

OUT

= 1V to 4V, Note 5

OUT

= 1V to 4V, Note 5

OUT

184 230 276 V

161 230 299 V

Output Leakage Current switch off 1 10 µA

Output Turn-On Delay RL = 10Ω, CL = 1µF, Figures 1a, 1b 125ms

Output Turn-On Rise Time RL = 10Ω, CL = 1µF, Figures 1a, 1b 125ms

Output Turnoff Delay RL = 10Ω, CL = 1µF, Figures 1a, 1b 22 µs

Output Turnoff Fall Time RL = 10Ω, CL = 1µF, Figures 1a, 1b 21 µs

Overtemperature Threshold TJ increasing 140 °C

Shutdown TJ decreasing 130 °C

Error Flag Output Resistance VIN = 5V, IL = 10µA415 Ω

VIN = 3.3V, IL = 10µA520 Ω

Error Flag Off Current V

= 5V 0.01 1 µA

FLG

EN Pulse Reset Width MIC2548 thermal shutdown latch 5 µs

VIN to EN Set-Up MIC2548, Note 6 0 µs

Current-Limit Response Time V

Overcurrent Flag Response Time V

enable input has about 200mV of hysteresis.

I

LIMIT

==

230V
R

= 0V, Note 6 25 µs

OUT

= VIN/2 to FLG low 5 µs

OUT

SET

, where R

is in ohms.

SET

June 2000 3 MIC2544/2548

MIC2544/2548

Test Circuit

Device
Under
Test

OUT

I

OUT

Micrel

V

OUT

C

R

L

L

Timing Diagrams

t

r

V

OUT

90%

10%

90%

10%

t

f

Functional Characteristics Test Circuit

V

EN

V

OUT

50%

t

OFF

t

ON

90%

10%

Figure 1a. MIC2544/48-1

50%

t

OFF

t

ON

90%

10%

V

V

OUT

EN

Figure 1b. MIC2544/48-2

MIC2544/2548 4 June 2000

MIC2544/2548

O

Micrel

utput Reset

V

I

V

I

LIMIT

I

EN

OUT

LIMIT

I

DC

I

OUT

FLG

EN

OUT

I

DC

OUT

FLG

Short-Circuit Fault

Fault Removed

Thermal Shutdown

Reached

Figure 2a. MIC2548-2 Timing: Output is reset by toggling EN

Short-Circuit

Fault

Fault

Removed

Thermal Shutdown

Reached

Figure 2b. MIC2544-2 Timing

June 2000 5 MIC2544/2548

MIC2544/2548

Typical Characteristics

Micrel

Output On-Resistance

vs. Supply Voltage

100

90

80

70

60

ON-RESISTANCE (mΩ)

50

2.5 3.0 3.5 4.0 4.5 5.0 5.5

SUPPLY VOLTAGE (V)

TA = 27°C

On-State Supply Current

140

120

100

SUPPLY CURRENT (µA)

vs. Temperature

80

60

40

20

5.0V

3.3V

2.7V

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Output On-Resistance

120

100

ON-RESISTANCE (mΩ)

vs. Temperature

2.7V

3.3V

80

5.0V

60

40

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Off-State Supply Current

0.4

0.3

0.2

0.1

SUPPLY CURRENT (µA)

vs. Temperature

RL = 44Ω

5.0V

3.3V

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

2.7V

On-State Supply Current

vs. Supply Voltage

140

120

100

80

60

40

20

SUPPLY CURRENT (mA)

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

SUPPLY VOLTAGE (V)

TA = 27°C

Off-State Supply Current

vs. Supply Voltage

0.10

0.09

0.08

0.07

0.06

0.05

0.04

0.03

0.02

SUPPLY CURRENT (µA)

0.01

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

SUPPLY VOLTAGE (V)

TA = 27°C

Enable Threshold Voltage

vs. Supply Voltage

2.0

1.9

1.8
VEN RISING

1.7

1.6

1.5

1.4

1.3

1.2

ENABLE THRESHOLD (V)

1.1

1.0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

VEN FALLING

SUPPLY VOLTAGE (V)

TA = 27°C

Output Fall Time

2.5

2.0

1.5

1.0

0.5

OUTPUT FALL TIME (µs)

vs. Temperature

RL = 44Ω

2.7V

3.3V

5.0V

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Enable Threshold Voltage

2.0

1.8

1.6

1.4

1.2

ENABLE THRESHOLD (V)

1.0

vs. Temperature

VEN RISING

VEN FALLING

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Current Limit

vs. R

2000

1500

1000

500

CURRENT LIMIT (mA)

I

SHORT

0
100 1000 5000

SET

VIN = 5V

I

SET

R

(Ω)

SET

Rise Time

vs. Temperature

7

6

5

4

3

2

1

OUTPUT RISE TIME (ms)

0

-40 -20 0 20 40 60 80 100

2.7V

3.3V

5.0V

RL = 44Ω

TEMPERATURE (°C)

Output Current

2000

1500

1000

I

TH

OUTPUT CURRENT (mA)

vs. Output Voltage

R

= 150

SET

VIN = 5V

R

= 470

500

0

0123456

OUTPUT VOLTAGE (V)

SET

R

= 2.3k

SET

MIC2544/2548 6 June 2000

MIC2544/2548

Micrel

Current Limit

1100

1000

900

800

700

OUTPUT CURRENT (mA)

600

vs. Temperature

VIN = 5V
R

= 230Ω

SET

I

SHORT

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Current Limit

I

TH

I

SET

1100

1000

CURRENT LIMIT (mA)

vs. Supply Voltage

I

TA = 27°C

900

R

= 230Ω

L

800

I

700

600

2.5 3.0 3.5 4.0 4.5 5.0 5.5

SHORT

SUPPLY VOLTAGE (V)

SET

I

TH

June 2000 7 MIC2544/2548

MIC2544/2548

Functional Characteristics

Micrel

EN

V

FLG

V

OUT

V

OUT

I

EN

V

FLG

V

OUT

V

OUT

I

(5V/div.)

(10V/div.)

(2V/div.)

(200mA/div.)

(10V/div.)

(10V/div.)

(5V/div.)

(500mA/div.)

MIC2544-1

V

= 5V

IN

= 4.7µF

C

IN

= 1Ω

R

L

MIC2544-1

Turn-On Response

VIN = 5V

= 4.7µF

C

IN

= 1µF

C

L

= 10Ω

R

L

TIME (500µs/div.)

Current-Limit Response

Thermal Shutdown

I

= 1A

SET

V

V

V

I

EN

FLG

OUT

OUT

(10V/div.)

(5V/div.)

(2V/div.)

(200mA/div.)

EN

V

FLG

V

OUT

V

OUT

I

MIC2544-1

(10V/div.)

(10V/div.)

(5V/div.)

(500mA/div.)

MIC2544-1

Turnoff Response

V

= 5V

IN

= 4.7µF

C

IN

TIME (1ms/div.)

Enable Into Heavy Load

VIN = 5V

= 4.7µF

C

IN

C

L

R

L

= 1µF
= 10Ω

I

SET

= 1Ω

R

L

= 1A

EN

V

FLG

V

OUT

V

OUT

I

(10V/div.)

(5V/div.)

(5V/div.)

(1A/div.)

MIC2548-1

TIME (100ms/div.)

Enable Into Heavy Load

= 5V

V

IN

= 4.7µF

C

IN

= 1Ω

R

L

= 1A

I

SET

Thermal Shutdown

TIME (500µs/div.)

Reset

Output Latched

V

V

I

EN

FLG

OUT

(10V/div.)

(5V/div.)

(500mA/div.)

MIC2544-1

TIME (100ms/div.)

Inrush Current Response

= 5V

V

IN

= 4.7µF

C

IN

= 10Ω

R

L

CL = 110µF

CL = 60µF

CL = 10µF

TIME (500µs/div.)

MIC2544/2548 8 June 2000

MIC2544/2548

Block Diagram

EN

Micrel

OSC.

CHARGE

PUMP

RESET

THERMAL

SHUTDOWN

THERMAL

SHUTDOWN

LATCH

(MIC2548)

Functional Description

The MIC2544 and MIC2548 are high-side N-channel switches
available with active-high or active-low enable inputs. 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

IN is the power supply connection to the logic circuitry and the
drain of the output MOSFET. OUT is the source of the output
MOSFET. In a typical circuit, current flows from IN to OUT
toward the load. If V
from OUT to IN 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
switch is disabled. In this situation, the MIC2544/48 avoids
undesirable current flow from OUT to IN. Both OUT pins 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 MIC2548 features an internal latch which causes the part
to remain off after thermal shutdown until a reset pulse is
provided via the enable pin (pin 1). 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

EN 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. EN should not be allowed to go
negative with respect to GND, and VEN should be less than
or equal to VIN.

is greater than VIN, current will flow

OUT

> VIN) when the

OUT

CONTROL

GND

GATE

1.2V

REFERENCE

CURRENT

LIMIT

IN

ILIM

OUT

FLG

R

SET

Adjustable Current-Limit

The short-circuit current-limit is user-adjustable with an exter­nal 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 ILIM and GND. For a desired current-limit, the value
of the external set resistor is given by:





R =

SET

230V



I



LIMIT




where:

154Ω < R

< 2.29kΩ

SET

For example, to set a 1A nominal current-limit, R
calculated as:

230V

1A



==ΩΩ230




increases with OUT current. The

SET

could be monitored with a high imped-

SET





Current through R
voltage across R
ance comparator to provide an indication of output current.
R

should be between 154Ω ±0.5% and 2.29kΩ ±0.5%.

SET

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

FLG is an N-channel, open-drain MOSFET output. The fault­flag 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.

SET

is

June 2000 9 MIC2544/2548

MIC2544/2548

Applications Information

Supply Filtering

A 0.1µF to 1µF bypass capacitor from IN to GND, located near
the MIC2544 and MIC2548, 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

On/OffOn/Off

NOTE: MSOP PACKAGE OPTION USES PIN 5 FOR I
PIN 4 IS NOT CONNECTED (NC).

Figure 3. Supply Bypassing

Power Dissipation

The device's junction temperature depends on several fac­tors 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:

PD = R

DS(on)

To relate this to junction temperature, the following equation
can be used:

= 6V) even for a short duration.

IN max

4.0V to 5.5V

MIC2548-1BM

18

EN OUT

27

FLG

36

GND OUT

45

ILIM

R

SET

× (I

OUT

)2

NC

IN

0.1µF to 1µF

.

LIM

Power
Output

Micrel

= PD × θJA + T

T

j

A

where:

T

= junction temperature

j

TA = ambient temperature

θJA = 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 10µs to 200µs while the
switch is in a constant-current mode, charging the capaci­tance.

Adding an optional series resistor-capacitor (R
lel with R

, as shown in Figure 4, allows the transient

SET

SET2

) in paral-

current-limit to be set to a different value than steady state. A
typical USB hot-plug inrush is 2A to 3A for 10µs to 20µs. If
R

is 435Ω (510mA), an R

SET

of 88Ω (2.5A) and C

SET2

SET

of

1µF (RC = 100µs) allows transient surge of 3A to pass for
100µs without tripping the overcurrent flag (FLG).

USB Power Distribution

The MIC2544 is ideal for meeting USB power distribution
requirements. Figure 4 depicts a USB Host application. R

SET

should be set to a value providing a current-limit >500mA.
The accurate current-limit of the MIC2544 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 MIC2544/48 are ideal inrush current-limiters suitable for
hot-plug applications. Due to the integrated charge pump,
the MIC2544/48 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. Figure 5 shows how the MIC2544 may be used in a
hot-plug application.

5V

(+)

4.7µF

(–)

V

BUS

D+

D–

GND

Bold lines indicate

0.1" wide, 1-oz. copper
high-current traces.

NOTE: MSOP PACKAGE OPTION USES PIN 5 FOR I
PIN 4 IS NOT CONNECTED (NC).

1.5k 2%

MIC5203-3.3

LDO Regulator

IN OUT

GND

1.0
µF

.

LIM

10k

3.3V USB Controller

V+

D+

D–

ON/OFF

OVERCURRENT

GND

100k

MIC2544-2BM

EN OUT

FLG IN

GND OUT

ILIM NC

R

R

SET

(optional)

SET(2)

C

120µF

0.1µF

SET

Ferrite

Bead

0.01µF

V

BUS

D+

D–

GND

Downstream

USB

Port 1

4.75V min.

500mA max.

Figure 4. USB Host Application

MIC2544/2548 10 June 2000

MIC2544/2548

V

CC

to "Hot"
Receptacle

GND

MIC2544-2BM

18

EN OUT

27

FLG

0.1
µF

36

GND OUT

4

I

LIM

NC

IN

5

0.1µF

Adaptor Card

Micrel

Backend
Function

C

BULK

NOTE: MSOP PACKAGE OPTION USES PIN 5 FOR I
AND PIN 4 IS NO CONNECT (NC).

LIM

Figure 5. Hot Plug Application

June 2000 11 MIC2544/2548

MIC2544/2548

Package Information

0.026 (0.65)
MAX)

Micrel

PIN 1

0.157 (3.99)

0.150 (3.81)

0.064 (1.63)

0.045 (1.14)

0.122 (3.10)

0.112 (2.84)

0.036 (0.90)

0.032 (0.81)

0.050 (1.27)
TYP

0.197 (5.0)

0.189 (4.8)

8-Pin SOP (M)

0.199 (5.05)

0.187 (4.74)

0.120 (3.05)

0.116 (2.95)

0.020 (0.51)

0.013 (0.33)

0.0098 (0.249)

0.0040 (0.102)

0°–8°

SEATING

PLANE

0.043 (1.09)

0.038 (0.97)

0.012 (0.30) R

DIMENSIONS:

INCHES (MM)

0.050 (1.27)

0.016 (0.40)

0.244 (6.20)

0.228 (5.79)

45°

0.010 (0.25)

0.007 (0.18)

DIMENSIONS:

INCH (MM)

0.007 (0.18)

0.005 (0.13)

0.012 (0.03)

0.0256 (0.65) TYP

0.008 (0.20)

0.004 (0.10)

5° MAX

0° MIN

0.012 (0.03) R

0.039 (0.99)

0.035 (0.89)

0.021 (0.53)

8-Pin MSOP (MM)

MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA

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MIC2544/2548 12 June 2000