MIC2546-2YTSTR - Micrel

MIC2546/2547

Dual Programable Current Limit Switch

UL Recognized Component

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

January 2008 M9999-012508-A

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 theswitch 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.

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 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

___________________________________________________________________________________________________________

Typical Application

Typical Advanced Configuration and Power Interface (ACPI) Application

Micrel, Inc. MIC2546/2547

January 2008 2 M9999-012508-A

Ordering Information

Part Number

Standard Pb-Free

Enable Latch(1) Junction Temp. Range(1) Package

MIC2546-1BM MIC2546-1YM Active High –40° to +85°C 16-pin SOP

MIC2546-1BTS MIC2546-1YTS Active High –40° to +85°C 16-pin TSSOP

MIC2546-2BM MIC2546-2YM Active Low –40° to +85°C 16-pin SOP

MIC2546-2BTS MIC2546-2YTS Active Low –40° to +85°C 16-pin TSSOP

MIC2547-1BM MIC2547-1YM Active High

• –40° to +85°C 16-pin SOP

MIC2547-1BTS MIC2547-1YTS Active High • –40° to +85°C 16-pin TSSOP

MIC2547-2BM MIC2547-2YM Active Low

• –40° to +85°C 16-pin SOP

MIC2547-2BTS MIC2547-2YTS Active Low • –40° to +85°C 16-pin TSSOP

Note:

1. Thermal Shutdown Latch.

Pin Configur ation

LOGIC,

CHARGE

PUMP

(OUTA)

(INA)

(ENA)

(FLGA)

MIC2546/2547

(ILIMA)

LOGIC,

CHARGE

PUMP

(OUTB)

(INB)

(ENB)

(FLGB)

(ILIMB) (GND)

Function Pinout

16-Pin SOP (M)

16-Pin TSSOP (TS)

Micrel, Inc. MIC2546/2547

January 2008 3 M9999-012508-A

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- activelow (–2). High

input >1.7V typical; low input <1.5V typical. 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 resistor, RSET,

connected to ground. 154 < RSET < 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 Fault Flag B (Output)

Micrel, Inc. MIC2546/2547

January 2008 4 M9999-012508-A

Absolute Maximum Ratings(1)

Supply Voltage (VIN) ...................................................+6.0V

Output Voltage (VOUT) ................................................+6.0V

Output Current (IOUT) ................................Internally Limited

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

Fault Flag Voltage (VFLG)............................................+6.0V

Fault Flag Current (IFLG) .............................................50mA

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

Operating Ratings(2)

Supply Voltage (VIN) .................................... +2.7V to +5.5V

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

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

Package Thermal Resistance

SOP (JA) .........................................................120°C/W

TSSOP (JA) ....................................................100°C/W

Electrical Characteristics(4)

VIN = +5V; TA = 25°C, bold values indicate –40°C to +85°C, unless noted.

Symbol Parameter Condition Min Typ Max Units

Switch off, OUT = open, Note 4 1.5

10 µA

Supply Current

Switch on, OUT = open, Note 4 200

320 µA

Enable High, Note 4 2.4 1.7 V

VEN Enable Input Voltage

Enable Low, Note 4 1.5

0.8 V

VEN = VOH(MIN) = 2.4V 0.01 1 µA Enable Input Current

VEN = VOH(MAX) = 0.8V 0.01 1 µA

Enable Input Capacitance Note 5 1 pF

RDS(ON) Switch Resistance IOUT = 500mA 80 120 m

Current Limit Factor, Note 6 IOUT = 500mA to 1.5A, VOUT = 1.0V to 4.0V

Note 6

184 230 276 V

Output Leakage Current Swich off 1 10 µA

tON Output Turn-On Delay RL = 10, CL = 1µF, Figure 1a and 1b 1 2 5 ms

tR Output Turn-On Rise Time RL = 10, CL = 1µF, Figure 1a and 1b 1 2 5 ms

tOFF Output Turn-Off Delay RL = 10, CL = 1µF, Figure 1a and 1b 22 µs

tF Output Turn-Off Fall Time RL = 10, CL = 1µF, Figure 1a and 1b 21 µs

TJ increasing 140 °C Overtemperature Threshold

Shutdown TJ decreasing 130 °C

VIN = 5V, IL = 10µA 4 15  Error Flag Output Resisitance

VIN = 3.3V, IL = 10µA 5 20 

Error Flag Off Current VFLG = 5V 0.01 1 µA

EN Pulse Reset Width MIC2547 Thermal Shutdown Latch 5 µs

IN to EN Set-Up MIC2547, Note 5 0 µs

Current-Limit Response Time VOUT = oV 25 µs

Overcurrent FLG Response

Time

VOUT = VIN/2 to FLG low 5 µs

Notes:

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.

Micrel, Inc. MIC2546/2547

January 2008 5 M9999-012508-A

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

Note 6. Current limit threshold is determined by: SET

LIMIT R

230V

, where RSET is in ohms.

Micrel, Inc. MIC2546/2547

January 2008 6 M9999-012508-A

Typical Characteristics

Micrel, Inc. MIC2546/2547

January 2008 7 M9999-012508-A

Micrel, Inc. MIC2546/2547

January 2008 8 M9999-012508-A

Functional Characteristics

Micrel, Inc. MIC2546/2547

January 2008 9 M9999-012508-A

Test Circuit

Functional Characteristics Test Circuit

Timing Diagrams

Figure 1a. MIC2546/47-1

Figure 1b. MIC2546/47-2

Micrel, Inc. MIC2546/2547

January 2008 10 M9999-012508-A

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

Figure 2b. MIC2546-2 Timing

Micrel, Inc. MIC2546/2547

January 2008 11 M9999-012508-A

Block Diagram

Micrel, Inc. MIC2546/2547

January 2008 12 M9999-012508-A

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 VOUT is

greater than VIN, 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 (VOUT > VIN) 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 VENX

should be less than or equal to VINX.

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:

⎟

⎠

⎞

⎜

⎝

⎛

LIMITX

SETX I

230V

where:

154 < RSET < 2.29k

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

calculated as:

230

230V =

⎟

⎠

⎞

⎜

⎝

⎛

Current through RSETX increases with OUT current. The

voltage across RSETX could be monitored with a high

impedance comparator to provide an indication of output

current. RSETX 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.

Micrel, Inc. MIC2546/2547

January 2008 13 M9999-012508-A

Application 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 (VIN max = 6V) even for a short duration.

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 = RDS(ON) × (IOUT)2

To relate this to junction temperature, the following

equation can be used:

TJ = PD × JA + TA

where:

TJ = junction temperature

TA = ambient temperature

JA = is the thermal resistance of the package

Transient Overcurrent Fil ter

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 capacitance.

Adding an optional series resistor-capacitor (RSET2) in

parallel with RSET, 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 RSET is 435 (510mA), an RSET2 of

88 (2.5A) and CSET of 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.

RSET 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 “softstart” feature effectively isolates power supplies

from highly capacitive loads by reducing inrush current

during hot-plug events.

Micrel, Inc. MIC2546/2547

January 2008 14 M9999-012508-A

Figure 3. USB Host Application

Micrel, Inc. MIC2546/2547

January 2008 15 M9999-012508-A

Package Information

16-Pin SOP (M)

16-Pin TSSOP (TS)

MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com

The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its

use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product

can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant

into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A

Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully

indemnify Micrel for any damages resulting from such use or sale.