IMP2524-1BN 查看數據表（PDF） - A1 PROs co., Ltd.

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IMP2524-1BN

Quad USB High-Side Power Switch with Fault Detection

A1 PROs co., Ltd. 

IMP2525

Detailed Descriptions

The IMP2525 is a high-side N-channel MOSFET switch that inter-

faces with a USB controller by means of a Switch-Enable input

and a Fault-Flag output. The Enable input turns ON the power

MOSFET with either a logic “1” for the IMP2525-1 or logic “0” for

the IMP2525-2. Any one of three fault conditions will activate the

open-drain Fault-Flag Output to alert the controller that the

power MOSFET has been turned OFF.

Input and Output

The IN (input) pin is the power supply connection to the logic cir-

cuitry and the “High-Side” of the switch (the Drain of the power

MOSFET). The OUT (output) pin is the “Low-Side” of the switch

(the Source of the power MOSFET). In a typical circuit, current

flows through the switch from IN to OUT toward the load.

The switch is referred to as a “High-Side” switch since it drives

the positive (or high) side of the load. The output MOSFET source

can be forced to a higher voltage than the drain (VOUT > VIN) when

the output is OFF with little leakage current. If, however, VIN

drops below 2.3V, reverse current may flow out the IN pin regard-

less of the enable state.

When the power switch is ON, current can flow in either

direction.

Fault Flag - FLG Pin

The Fault Flag pin, FLG, connects to an N-channel, open-drain

MOSFET and goes LOW (“0”) for an occurrence of one or more of

three conditions: undervoltage, current limit, or thermal shut-

down. The FLG output MOSFET is capable of sinking a 10mA

load to typically 100mV above ground. Table 1 gives the states of

the FLG and OUT pins when a fault condition is detected.

Thermal Shutdown

Thermal shutdown is active when the output switch is enabled

(turned ON). Thermal shutdown shuts off the output MOSFET

and sets the Fault Flag if the on-chip temperature sensor exceeds

135°C. The switch is held OFF until the die temperature drops to

125°C or below. This 10°C of hysteresis will result in ON-OFF

short-circuit cycling if the short-circuit condition is not removed

or the bus-controller does turn off the switch with the Enable

input. Over temperature detection is active only if the chip is

enabled.

Undervoltage Lockout

The Undervoltage lockout (UVLO) prevents the output

MOSFET from being put into the ON state until the positive sup-

ply voltage, VIN, exceeds 2.5V. When the output switch is in the

ON state and the positive supply voltage drops below 2.3V, the

UVLO circuitry will assert the Fault Flag, FLG, and shut OFF the

output MOSFET. The FLG output will only assert an active LOW

state when the MOSFET switch is in the ON state. Undervoltage

detection is active only if the chip is enabled.

Current Limiting

Current limiting is achieved by sensing the voltage drop from

Drain-to-Source of the power MOSFET. When the internal thresh-

old is exceeded the power MOSFET is turned OFF.

Table 1. Fault Flag Conditions - Switch Enabled

Condition

Thermal Shutdown

Undervoltage Lockout (UVLO)

Current Limiting

Cause

TJ > 135°C

VIN < 2.3V

IO > 0.5A (step load)

IO > 0.63A (ramped load)

FLG pin “0” Until

TJ ≤ 125°C

VIN > 2.5V

Enable off or

Thermal Shutdown

Switch State (FLG = “0”)

Turns OFF

Turns OFF

Stays ON

4

408-432-9100/www.impweb.com

© 2000 IMP, Inc. 6

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