USB Dual Control Switches

Impala Linear Corporation

4

(408) 574-3939

www.impalalinear.com

Dec 2000

ILC7526/7536 1.5

Preliminary

Note 1. Stresses above those listed under ABSOLUTE MAXIMUM RAT-

INGS may cause permanent device failure.

Functionality at or above

these limits is not implied.

Exposure to absolute maximum ratings for

extended periods may affect device reliability. Operating ranges define

those limits between which the functionality of the device is guaranteed.

Note 2.

Specified min/max limits are production tested or guaranteed

through correlation based on statistical control methods. Measurements

are taken at constant junction temperature as close to ambient as possible

using low duty pulse testing.

Note 3. Off is < 0.8V and On is > 2.4V for the ILC7526. Off is > 2.4V for

the ILC7536. The enable input has approximately 200mV of hysteresis.

ILC7526

5V

10k

0.1µF

ENA

FLGA

FLGB

ENB

OUTA

IN

GND

OutB

I

OUT

C

L

+

R

L

(1 output shown)

The ILC7526 and ILC7536 are dual high-side switches with

active-high and active-low enable inputs, respectively.

Fault conditions turn-off or inhibit turn-on of one or more of

the output transistors, depending upon the type of fault,

and also activate the open-drain error flag transistors

which sink current to ground.

Input and Output

IN (input) is the power supply connection to the logic circuit-

ry and the drains of both of the output MOSFET’s. OUTx

(output) is the source of each MOSFET. In a typical circuit,

current flows through the switch from IN to OUT toward the

current will flow from OUT to IN since the MOSFET is bidi-

rectional when on.

The output MOSFET and driver circuitry are also designed to

allow the MOSFET source to be externally forced to a higher

this situation, the ILC7526 avoids undesirable current flow

Thermal Shutdown

Thermal shutdown shuts off the affected output MOSFET’s

and signals all fault flags if the die temperature exceeds

135°C. 10°C of hysteresis prevents the switch from turn-

ing on until the die temperature drops to 125°C.

Overtemperature detection functions only when at least

one switch is enabled.

Internal circuitry increases the output MOSFET on-resist-

ance until the series combination of the MOSFET on-resist-

ance and the load impedance limit current to typically

850mA. The increase in power dissipation, in most cases,

will cause the ILC7526 to go into thermal shutdown, dis-

abling affected channels. When this is undesirable, thermal

shutdown can be avoided by externally responding to the

fault and disabling the current limited channel before the

shutdown temperature is reached. The delay between the

flag indication of a current limit fault and thermal shutdown

will vary with ambient temperature, board layout, and load

impedance, but is typically several hundred milliseconds.

The USB controller must therefore recognize a fault and

disable the appropriate channel within this time. If the fault

is not removed or the switch is not disabled within this time,

the device will enter into a thermal oscillation of about 2Hz.

This does not cause any damage to the device.

Functional Description

Current Limit Induced Thermal Shutdown