Datasheet MIC2547-1BTS, MIC2547-1BM, MIC2546-1BM, MIC2546-1BTS, MIC2546-2BM Datasheet (MICREL)

MIC2546/2547 Micrel

MIC2546/2547

Dual Programmable Current Limit Switch

Preliminary 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 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 MIC2546/47’s open-drain flag outputs are used to indi­cate 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.

Features

• 2.7V to 5.5V input

• Adjustable current-limit up to 1.5A

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

• 100µA typical on-state supply current per channel

• 2µA typical off-state supply current

• 120mΩ 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

Typical Application

Typical Advanced Configuration and Power Interface (ACPI) Application

+5V

+3.3V

R

R

R

FLGA

SETA

FLGB

On/Off

On/Off

MIC2546-xBM

ENA
FLGA
GNDA
ILIMA
ENB
FLGB
GNDB
ILIMB

R

SETB

OUTA

INA

OUTA

NC

OUTB

INB

OUTB

NC

0.1µF

Peripheral

33µF

Peripheral

33µF

0.1µF

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

June 2000 1 MIC2546/2547

MIC2546/2547 Micrel

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

Pin Configuration

MIC2546/2547

LOGIC,

CHARGE

PUMP

LOGIC,

CHARGE

PUMP

(ILIMB) (GND)

(OUTA)

(INA)
(OUTB)

(INB)

OUTA

ENA

NC

FLGA

GNDB

MIC2546/2547

1INA
2
3
4
5
6

16 OUTA

ILIMA

15

GNDA

14

FLGB

13

ENB

12

OUTB

11

(ENA)

(FLGA)
(ILIMA)

(ENB)

(FLGB)

ILIMB

OUTB

7
8

10

NC
INB

9

16-Pin SOP (M)

16-Pin TSSOP (TS)

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

3 ENA Enable A (Input): Logic-compatible enable input. Active-high (–1) or active-

4, 10 NC Not internally connected.

5 FLGA Fault Flag A (Output): Active-low, open-drain output. Indicates overcurrent

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

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.

Functional Pinout

externally connected.

low (–2). High input >1.7V typical; low input <1.5V typical. Do not float.
MIC2547 only: Also resets thermal shutdown latch.

or thermal shutdown conditions. MIC2547 only: latched low on thermal
shutdown.

resistor, R

, connected to ground. 154Ω < R

SET

< 2.29kΩ.

SET

MIC2546/2547 2 June 2000

MIC2546/2547 Micrel

Absolute Maximum Ratings (Note 1)

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

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

Fault Flag Voltage (V
Fault Flag Current (I

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

IN

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

OUT

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

OUT

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

FLG

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

FLG

IN

+0.3V

Operating Ratings (Note 2)

Supply Voltage (V

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

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

Package Thermal Resistance

SOP (θJA) ..........................................................120°C/W

TSSOP (θJA) .....................................................100°C/W

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

IN

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

Junction Temperature (TJ) .......................Internally Limited

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 1.5 10 µA

Switch on, OUT = open, Note 4 200 320 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 MIC2546-1 and MIC2547-1. Off is ≥ 2.4V and on is ≤ 0.8V for the MIC2546-2 and MIC2547-2. The

Note 5. Guaranteed by design, but not production tested.

Note 6. Current limit threshold is determined by:

Enable Input Voltage Enable High, Note 4 2.4 1.7 V

Enable Low, Note 4 1.5 0.8 V

Enable Input Current VEN = V

VEN = V

= 2.4V .01 1 µA

OH(min)

= 0.8V .01 1 µA

OL(max)

Enable Input Capacitance Note 5 1pF
Switch Resistance I
Current Limit Factor, Note 6 I

= 500mA 80 120 mΩ

OUT

= 100mA to 1.5A, V

OUT

= 1.0V to 4.0V, 184 230 276 V

OUT

Note 6

Output Leakage Current Switch off 1 10 µA
Output Turn-On Delay RL = 10Ω, CL = 1µF, Figure 1a and 1b 125ms
Output Turn-On Rise Time RL = 10Ω, CL = 1µF, Figure 1a and 1b 125ms
Output Turnoff Delay RL = 10Ω, CL = 1µF, Figure 1a and 1b 22 µs
Output Turnoff Fall Time RL = 10Ω, CL = 1µF, Figure 1a and 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 MIC2547 Thermal Shutdown Latch 5 µs
VIN to EN Set-Up MIC2547, Note 5 0 µs
Current-Limit Response Time V
Overcurrent FLG Response Time V

enable input has about 200mV of hysteresis.

I

LIMIT

=

= 0V 25 µs

OUT

= VIN/2 to FLG low 5 µs

OUT

230V
R

SET

, where R

is in ohms.

SET

June 2000 3 MIC2546/2547

MIC2546/2547 Micrel

Typical Characteristics

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

280
240
200
160
120

SUPPLY CURRENT (µA)

vs. Temperature

3.3V

80
40

5.0V

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

80

60

40

-40 -20 0 20 40 60 80 100

3.3V

5.0V

TEMPERATURE (°C)

Off-State Supply Current

0.8

0.7

0.6

0.5

0.4

0.3

0.2

SUPPLY CURRENT (µA)

0.1

vs. Temperature

RL = 44Ω

3.3V

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

5.0V

2.7V

On-State Supply Current

vs. Supply Voltage

280
240
200
160
120

80
40

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

0.20

0.18

0.16

0.14

0.12

0.1

0.08

0.06

0.04

SUPPLY CURRENT (µA)

0.02
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

MIC2546/2547 4 June 2000

MIC2546/2547 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)

I

I

SET

Current Limit

1100

TH

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 5 MIC2546/2547

MIC2546/2547 Micrel

Functional Characteristics

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.)

MIC2546-1

V

= 5V

IN

= 4.7µF

C

IN

= 1Ω

R

L

MIC2546-1

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

MIC2546-1

(10V/div.)

(10V/div.)

(5V/div.)

(500mA/div.)

MIC2546-1

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.)

MIC2547-1

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.)

MIC2546-1

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.)

MIC2546/2547 6 June 2000

MIC2546/2547 Micrel

Test Circuit

V

OUT

Device
Under
Test

OUT

I

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. MIC2546/47-1

V

EN

V

OUT

50%

t

OFF

t

ON

90%

10%

Figure 1b. MIC2546/47-2

June 2000 7 MIC2546/2547

MIC2546/2547 Micrel

O

utput Reset

V
I

LIMIT

I

FLG

V

OUT

I

LIMIT

I

OUT

FLG

EN

OUT

I

DC

OUT

EN

I

DC

Short-Circuit Fault

Fault Removed

Thermal Shutdown

Reached

Figure 2a. MIC2547-2 Timing: Output is reset by toggling EN

Short-Circuit

Fault

Fault

Removed

Thermal Shutdown

Reached

Figure 2b. MIC2546-2 Timing

MIC2546/2547 8 June 2000

MIC2546/2547 Micrel

Block Diagram

ENA

ENB

OSC.

CHARGE

PUMP

RESET

OSC.

CHARGE

PUMP

RESET

THERMAL

SHUTDOWN

THERMAL

SHUTDOWN

LATCH

(MIC2547)

THERMAL

SHUTDOWN

THERMAL

SHUTDOWN

LATCH

(MIC2547)

REFERENCE

GATE

CONTROL

REFERENCE

GATE

CONTROL

1.2V

1.2V

CURRENT

LIMIT

CURRENT

LIMIT

INA

ILIMA

OUTA

FLGA

INB

ILIMB

OUTB

FLGB

R

SETA

R

SETB

GNDB GNDA

June 2000 9 MIC2546/2547

MIC2546/2547 Micrel

Functional Description

The MIC2546 and MIC2547 are dual 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

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
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
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
or equal to V

INX

.

is greater than VIN, current will

OUT

> VIN) when the

OUT

should be less than

ENX

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 ILIMX and GND. For a desired current-limit, the
value of the external set resistor is given by:

R

SETX



=



I



230V

LIMITX






where:

154Ω < R

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

< 2.29kΩ

SET

SET

is

calculated as:

230V

1A



=

Ω

230





increases with OUT current. The

SETX

could be monitored with a high imped-

SETX






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

should be between 154Ω and 2.29kΩ (0.5% resistor

SETX

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.

MIC2546/2547 10 June 2000

MIC2546/2547 Micrel

Applications Information

Supply Filtering

A 0.1µF to 1µF 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

0.1 to 1µF

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:

= 6V) even for a short duration.

IN max

4.0V to 5.5V

MIC2546-1BM

116

INA OUTA

215

OUTA

ILIMA

FLGB

ENB

OUTB

NC

INB

14

13

12

11

10

.

9

3

ENA GNDA

4

NC

5

FLGA

6

GNDB

7

ILIMB

8

OUTB

R

SETB

Supply Bypassing

R

SETA

0.1 to 1µF

= R

P

D

DS(on)

× (I

OUT

)2

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

Tj = PD × θJA + T

A

where:

Tj = junction temperature
TA = ambient temperature

θ

= is the thermal resistance of the package

JA

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 3, 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 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.

5V

(+)

4.7µF

(–)

V

BUS

D+
D–
GND

Bold lines indicate

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

1.5k 2%

MIC5203-3.3

LDO Regulator

IN OUT

GND

10k
10k

3.3V USB Controller

V+

ON/OFF

OVERCURRENT

D+
D–

GND

100k

R

SET(2)

C

SET

(optional)

100k

120µF

120µF

Ferrite Bead

0.01µF

0.01µF

Ferrite Bead

V

BUS

GND

V

BUS

GND

D+
D–

D+
D–

Downstream

USB

Port 1

4.75V min.

500mA max.

Downstream

USB

Port 2

4.75V min.

500mA max.

MIC2546-2BM

INA OUTA
OUTA ILIMA
ENA GNDA
NC FLGB
FLGA

ENB

GNDB

R

SET

ILIMB
OUTB

OUTB

NC

INB

R

SET

Figure 3. USB Host Application

June 2000 11 MIC2546/2547

MIC2546/2547 Micrel

Package Information

PIN 1

0.157 (3.99)

0.150 (3.81)

0.020 (0.51)
REF

0.0648 (1.646)

0.0434 (1.102)

0.30 (0.012)

0.19 (0.007)

7.90 (0.311)

7.70 (0.303)

0.050 (1.27)
BSC

0.394 (10.00)

0.386 (9.80)

4.50 (0.177)

4.30 (0.169)

0.020 (0.51)

0.013 (0.33)

16-Pin SOP (M)

6.4 BSC (0.252)

1.10 MAX (0.043)

0.0098 (0.249)

0.0040 (0.102)

SEATING

PLANE

DIMENSIONS:

INCHES (MM)

0.050 (1.27)

0.016 (0.40)

0.244 (6.20)

0.228 (5.79)

DIMENSIONS:

MM (INCH)

45°

0°–8°

0.20 (0.008)

0.09 (0.003)

0.65 BSC
(0.026)

0.15 (0.006)

0.05 (0.002)

8°
0°

1.00 (0.039) REF

0.70 (0.028)

0.50 (0.020)

16-Pin TSSOP (TS)

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MIC2546/2547 12 June 2000