AAT4610 datasheet(9/10 Pages) AAT

9 / 10 page

the value of RSET may also be calculated using the

ILIM RSET product found in the chart "RSET

Coefficient vs. ILIM". The maximum current is

derived by multiplying the typical current for the

chosen RSET in the chart by 1.25. A few standard

resistor values are listed in Table 1.

Table 1: Current Limit RSET Values.

Example: A USB port requires 0.5A. 0.5A multiplied

by 1.33 is 0.665A. From the chart "RSET vs. ILIM," RSET

should be less than 11k

Ω. 10.5 kΩ is a standard value

that is a little less than 11k

Ω. The chart gives approx-

imately 0.700A as a typical ILIM value for 10.5kΩ.

Multiplying 0.700A by 0.75 and 1.25 shows that the

AAT4610 will limit the load current to greater than

0.525A but less than 0.875A.

Operation in Current Limit

When a heavy load is applied to the output of the

AAT4610, the load current is limited to the value of

ILIM determined by RSET (see Figure 2). Since the

load is demanding more current than ILIM, the volt-

age at the output drops. This causes the AAT4610 to

dissipate a larger than normal quantity of power, and

results in increased die temperature. When the die

temperature exceeds an over-temperature limit, the

AAT4610 will shut down until is has cooled suffi-

ciently, at which point it will start up again. The

AAT4610 will continue to cycle on and off until the

load is removed, power is removed, or until a logic

high level is applied to ON (Pin 4).

Enable Input

In many systems, power planes are controlled by

integrated circuits which run at lower voltages than

the power plane itself. The enable input ON (Pin 4)

of the AAT4610 has low and high threshold volt-

ages that accommodate this condition. The thresh-

old voltages are compatible with 5V TTL and 2.5V

to 5V CMOS.

Reverse Voltage

The AAT4610 is designed to control current flowing

from IN to OUT. If a voltage is applied to OUT which

is greater than the voltage on IN, large currents may

flow. This could damage the AAT4610.

AAT4610

Current Limited Load Switch

4610.2006.09.1.3

Not recommended for new designs; pin-for-pin upgrade: AAT4610A.

-0.05

0.05

0.1

0.15

0.2

0.25

0.3

0.25

0.5

0.75

Output Current

Output Voltage

Ω load is turned on at time = 0

Device Will Device Always

Current

Not Current Current Limits

RSET

Limit

Limit Below

Below

Ω) Typ (mA)

(mA)

40.2

200

150

250

30.9

250

188

313

24.9

300

225

375

22.1

350

263

438

19.6

400

300

500

17.8

450

338

563

16.2

500

375

625

14.7

550

413

688

13.0

600

450

750

10.5

700

525

875

8.87

800

600

1000

7.50

900

675

1125

6.81

1000

750

1250

6.04

1100

825

1375

5.49

1200

900

1500

4.99

1300

975

1625

4.64

1400

1050

1750

Figure 2: Overload Operation.

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