G525A 查看數據表（PDF） - Global Mixed-mode Technology Inc

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G525A

USB High-Side Power Switch Advance Information

Global Mixed-mode Technology Inc 

Global Mixed-mode Technology Inc.

G525A

from turning on until the die temperature drops to

125°C. Thermal shutdown circuit functions only when

the switch is enabled.

Undervoltage Lockout

UVLO (undervoltage lockout) prevents the output

MOSFET from turning on until IN (input voltage) ex-

ceeds 2.5V typically. After the switch turns on, if the

voltage drops below 2.3V typically, UVLO shuts off the

output MOSFET and signals the fault flag. UVLO de-

tection functions only when the switch is enabled.

Current Sensing and Limiting

The current limit threshold is preset internally. The

preset level prevents damage to the output MOSFET

and external load but allows a minimum current of

0.5A through the output MOSFET.

A current sense circuit senses the output current of

MOSFET switch. If output current exceeds the current

limit threshold, the output MOSFET switch is shut off

and a fault flag is pulled low. The reaction to an over-

current is measured with the following scenarios:

Switch Enabled into Heavy Load

If the switch is powered on or enabled into a heavy

load or short-circuit, the switch immediately goes into

a constant-current mode, reducing the output voltage.

The fault flag goes low until the load is reduced or

thermal shutdown occurs. See the "Enable into Short

Circuit" graph.

Fault Flag

FLG is a 2-channel, open-drain MOSFET output. The

fault-flag is active (low) for one or more of the follow-

ing conditions: current limiting, undervoltage, or ther-

mal shutdown. The flag output MOSFET is capable of

sinking a 10mA load to typically 100mV above ground.

Applications Information

Supply filtering

A 0.1µF to 1µF bypass capacitor from IN to GND, lo-

cated near the G525A, 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 maxi-

mum supply voltage (VIN max = 6V) even for a short du-

ration.

Figure 1. Supply Bypassing

3.0V to 5.5V

G525A

1 EN

OUT 8

Heavy Load Applied to Enabled Switch

When a heavy load is applied, a large current may

flow from the switch. The current limit circuit may shut

the switch off briefly, then fold back into con-

stant-current mode. In that case, the fault flag falls

until the load is reduced. See the “Short Applied to

Output” graph and the "Ramped Load to Enable De-

vice" graph.

2 FLG

3 GND

4 NC

IN 7

OUT 6

NC 5

0.1 µF to 1 µF

VBUS

USB Host

GND

Cable

Ver: 1.2

Nov 11, 2002

USB

Controller

G525A

1

8

2

EN

FLG

3 GND

4.7

µF

4 NC

OUT

IN

7

OUT 6

NC 5

CBULK

0.1 µF

Bus Powered Hub

Cable

Figure 2. Soft Start

Capacitive

Load

Downstream USB Device

TEL: 886-3-5788833

http://www.gmt.com.tw

6

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