11

FN6156.5

February 20, 2008

reduce the risk of oscillation. The combination of a 4.7µF

tantalum capacitor in parallel with a 0.01µF capacitor has

been shown to work well when placed at each supply pin.

For good AC performance, parasitic capacitance should be

kept to a minimum, especially at the inverting input. When

ground plane construction is used, it should be removed

from the area near the inverting input to minimize any stray

capacitance at that node. Carbon or Metal-Film resistors are

acceptable with the Metal-Film resistors giving slightly less

peaking and bandwidth because of additional series

inductance. Use of sockets, particularly for the SOIC

package, should be avoided if possible. Sockets add

parasitic inductance and capacitance, which will result in

additional peaking and overshoot.

Current Limiting

The ISL28191 and ISL28291 have no internal current-limiting

circuitry. If the output is shorted, it is possible to exceed the

Absolute Maximum Rating for output current or power

dissipation, potentially resulting in the destruction of the

device. This is why the output short circuit current is specified

Power Dissipation

It is possible to exceed the +125°C maximum junction

temperatures under certain load and power-supply

conditions. It is therefore important to calculate the

to determine if power supply voltages, load conditions, or

package type need to be modified to remain in the safe

operating area. These parameters are related in Equation 1:

where:

where:

•

θ

application

T

JMAX

T

MAX

θ

()

+

=

(EQ. 1)

PD

MAX

2*V

S

I

SMAX

V

S

(

- V

V

OUTMAX

R

L

----------------------------

×

+

×

=

(EQ. 2)

ISL28191, ISL28291