US202AXL-AF5-R [UTC]

Power Supply Support Circuit,;


型号：	US202AXL-AF5-R
厂家：	Unisonic Technologies
描述：	Power Supply Support Circuit,
文件：	总5页 (文件大小：202K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

UNISONIC TECHNOLOGIES CO., LTD

US202/A

CMOS IC

100mΩ POWER DISTRIBUTION

SWITCHES



DESCRIPTION

The US202/A is a power distribution switch. It is particularly

suitable for self-powered and bus-powered USB (Universal Series

bus) applications. It has 28μA low quiescent supply current that

meets the requirements of battery-powered portable equipments.

A built-in charge pump is used to drive the N-channel N-MOSFET

that is free of parasitic body diode to eliminate any reversed current

flow across the switch when it is powered off.

The US202/A incorporates some protection circuits such as

current limit and short protection circuits, soft start circuit, thermal

shutdown and UVLO (Under-voltage Lockout) protection circuits.

The thermal shutdown circuits protect this device from damage when

over current occurs, and the soft start circuits are used to prevent

inrush current when plug-in event occurs.

The US202/A can be used in such applications such as

battery-powered equipments, motherboard USB power switches,

USB device power switches, hot-plug power supplies,

battery-charger circuits and so on.



FEATURES

* Input Voltage Varies From 2.7V to 5.5V

* Guaranteed Continuous Current: 1.0A/2.0A

* High-Side NMOSFET: 85mΩ (TYP)

* Soft Start

* Current Limit:1.5A/2.5A

* Thermal Protection

* Low Supply Current: 28μA



ORDERING INFORMATION

Ordering Number

Package

Packing

Lead Free

Halogen Free

US202XL-AF5-R

US202AXL-AF5-R

US202XG-AF5-R

US202AXG-AF5-R

SOT-25

Tape Reel

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QW-R502-445.F

US202/A

CMOS IC



MARKING

US202

US202A

Current Code

Blank: 1.5A

A: 2.5A

US2

Logic Level Enable Pin



PIN CONFIGURATION



PIN DESCRIPTION

PIN NO.

PIN NAME

V_OUT

DESCRIPTION

1, 5

Output Voltage

Ground

GND

V_IN

Power Input

Chip Enable (Active High)



BLOCK DIAGRAM

V_IN

Bias

Current

Limiting

Current sense

Oscillator

Charge

Pump

Control

V_OUT

NMOSFET

Thermal

Detection

GND

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US202/A

CMOS IC



ABSOLUTE MAXIMUM RATING

PARAMETER

SYMBOL

V_IN

RATINGS

UNIT

Supply Voltage

Chip Enable

V_CE

-0.3 ~ 6

0.25

Power Dissipation (T_A= 25°C)

Junction Temperature

P_D

T_J

-20 ~ +100

-65 ~ +150

°C

Storage Temperature

T_STG

Note: Absolute maximum ratings are those values beyond which the device could be permanently damaged.

Absolute maximum ratings are stress ratings only and functional device operation is not implied.



ELECTRICAL CHARACTERISTICS

(V_IN= 5V, C_IN= C_OUT= 1μF, T_A= 25°C, unless otherwise specified)

PARAMETER

Input Voltage Range

SYMBOL

V_IN

TEST CONDITIONS

MIN TYP MAX UNIT

2.7

5.5

Output NMOSFET R_DS(ON)

R_DS(ON)I_L=1A

100 mΩ

Supply Current

V_IN=5V

µA

Output Turn-On Rising Time

Current Limit Threshold

T_R

R_L= 10Ω, 90% Settling

400

1.5

2.5

µS

US202

1.1

2.1

2.0

3.2

I_LIMIT

US202A

_OUT= 0V, measured prior to

Short-Circuit Fold Back Current

I_SC(FB)

1.0

thermal shutdown

EN Input High Threshold

EN Input Low Threshold

Shutdown Supply Current

Output Leakage Current

V_INUnder Voltage Lockout

V_INUnder Voltage Hysteresis

Thermal Limit

V_IH

V_IL

2.0

1.2

0.8

1.0

I_OFF

EN = “0”

0.1

0.5

1.8

100

130

µA

I_I(LEAK)

UVLO

EN = “0”, V_OUT= 0V

°C

T_SD

Thermal Limit Hysteresis

∆T_SD

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US202/A

CMOS IC



APPLICATION INFORMATION

The UTC US202/A is a high-side single N-Channel MOSFET switch with active-high enable input.

Input and Output

V_INpin (input) is the power supply connection to the circuitry and the drain of the output MOSFET. V_OUTpin (output)

is the source of the output MOSFET. In a typical circuit, current flows through the switch from V_INto V_OUTtoward the

load. Both V_OUTpins must be short on the board and connected to the load and so do both V_INpins but connected to

the power source.

Thermal Shutdown

Thermal shutdown is used to turn off the output MOSFET when the if the temperature is higher than130°C, 20°C

of hysteresis prevents the switch turn on until the die temperature drops to 110°C.

Soft Start

When hot-plug events occur, the soft start is used to eliminate the upstream voltage droop due to the inrush

current. The soft-start protects power supplies from damage caused by highly capacitive loads.

Under-Voltage Lockout

UVLO (Under voltage Lockout) turn off the MOSFET switch once the input voltage falls below 1.8V (TYP.) and if

the input voltage exceeds 1.8V, the switch will be turned on.

Current Limiting and Short Protection

The current limit threshold is preset internally. The minimum value is 1.1A/2.1A. The current limit circuit protects

this device from damage resulting from undesired excess inrush current, which is encountered during hot plug-in

events. The output current is limited to approximately 1.5A/2.5A (TYP). When the output is short to ground, it will

limit to a constant current 1A until thermal shutdown or short condition removed.

Filtering

During the hot-plug events, in order to limit the input voltage drop, a 1μF ceramic capacitor is recommended to be

placed between V_INto GND. However special care must be taken to the values of the capacitor, because higher

capacitor values will further reduce the voltage drop at the input.

In order to prevent inductive parasitic from pulling V_OUTnegative during turn-off or EMI damage to other

components during the hot detachment, it’s better to connect a sufficient capacitor from V_OUTto GND. This capacitor

is also necessary for meeting the USB specification during hot plug-in operation.

If the UTC US202/A is implanted in device and application, minimum 1μF capacitor from V_OUTto GND is

recommended. If the V_OUTis short to ground frequently during usage, large size input capacitor is necessary,

recommend 22μF.

Choosing these capacitors properly is critical. A lower ESR on the capacitor can get a lower IR drop during the

operation, so the Effective Series Resistance (ESR) of the capacitors must be considered.

For ferrite beads, if they are in series with all power and ground lines, the EMI will be eliminated or reduced. The

DC resistance of the wire kept to a minimum to reduce the voltage drop should be considered in choosing ferrite

beads.

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US202/A

CMOS IC



APPLICATION INFORMATION (Cont.)

Reverse Current Preventing

Since the UTC US202/A’s MOSFET is bi-directional, it allows the voltage on V_OUTpin is higher than that on V_IN

pin. In order to avoid reverse current occur, turn off this switch or connect V_INto a fixed voltage less than 1.2V.

Layout and Thermal Dissipation

The switch should be placed as close to the USB connector as possible and all traces should be as short as

possible to reduce the effect of undesirable parasitic inductance.

Also, place the output capacitor and ferrite beads to the USB connector as close to as possible.

If ferrite beads are used, use wires kept to a minimum resistance and large solder pads to minimize connection

resistance.

If the package is with dual V_OUTor V_INpins, short both the same function pins as Fig.1 or Fig.2 to reduce the

internal turn-on resistance. If the output power is delivered to two individual ports, it is specially necessary to short

both V_OUTpin at the switch output side in order to protect the switch when each port are plug-in separately.

Under normal operating conditions, the package can dissipate the channel heat away. Wide power bus planes

connected to V_INand V_OUTand a ground plane in contact with the device will help dissipate additional heat.



TYPICAL APPLICATION CIRCUIT

V_IN

V_OUT

V_IN

V_OUT

C_IN

1µF

C_OUT(Note)

470µF

GND

Note: 470µF, Low ESR Electrolytic

UTC assumes no responsibility for equipment failures that result from using products at values that

exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other

parameters) listed in products specifications of any and all UTC products described or contained herein.

UTC products are not designed for use in life support appliances, devices or systems where malfunction

of these products can be reasonably expected to result in personal injury. Reproduction in whole or in

part is prohibited without the prior written consent of the copyright owner. UTC reserves the right to

make changes to information published in this document, including without limitation specifications and

product descriptions, at any time and without notice. This document supersedes and replaces all

information supplied prior to the publication hereof.

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US202AXL-AF5-R [UTC]

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