UCC2918/81510

LOW ONRESISTANCE HOT SWAP POWER MANAGER

SLUS457C − JULY 2000 - REVISED APRIL 2001

2

POST OFFICE BOX 655303

description (continued)

Fast overload protection is accomplished by an additional overload comparator. Its threshold is internally set

above the maximum sourcing current limit setting. In the event of a short circuit or extreme current condition,

this comparator is tripped, shutting down the output. This function is needed since the maximum sourcing

current limit loop has a finite bandwidth.

When the output current is below the fault level, the output MOSFET is switched on with a nominal resistance

of 0.075

Ω. When the output current exceeds the fault level or the maximum sourcing level, the output remains

threshold, the switch is turned off, and remains off for 30 times the programmed fault time. When the output

current reaches the maximum sourcing level, the MOSFET transitions from a switch to a constant current

source.

The UCC2918 is designed for unidirectional current flow, emulating an ideal diode in series with the power

switch. This feature is particularly attractive in applications where many devices are powering a common bus,

such as with SCSI termintation power (Termpwr). The UCC2918 can also be put into the sleep mode, drawing

only 1

µA of supply current.

Other features include an open-drain fault output indicator, thermal shutdown, undervoltage lockout, 3 V to 6 V

operation, and a low thermal resistance small-outline power package.

Input voltage

8 V

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SOIC power dissipation

2.5 W

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fault output sink current

50 mA

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fault output voltage

VIN

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Output current (dc)

Internally Limited

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Input voltage

SHTDWN, IFAULT, IMAX

−0.3 V to VIN

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

−65

_C to 150_C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

−55

_C to 150_C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Lead temperature (soldering, 10 seconds)

300

_C

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

† Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and

functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not

implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

‡ Unless otherwise indicated, voltages are reference to ground and currents are positive into, negative out of the specified terminal. Pulsed is

defined as a less than 10% duty cycle with a maximum duration of 500

µs. Consult Packaging Section of Databook for thermal limitations and

considerations of package.