NCP630

http://onsemi.com

7

APPLICATION INFORMATION

Input Capacitor

The minimum capacitance required for stability is a 68

mF

aluminum electrolytic or tantalum capacitor. The maximum

ESR allowed for stability is 5.0

W. The capacitor should be

place as close as possible to the input of the device.

The placement of a ceramic capacitor in parallel is not

recommend due to possible instabilities.

Output Capacitor

A minimum output capacitor value of 33

mF is required for

stability. The type of capacitor can be aluminum electrolytic

or tantalum capacitor. ESR can vary up to a maximum of

2.0 ohms for stability. The capacitor should be placed as

close as possible to the output of the device.

The placement of a ceramic capacitor in parallel is not

recommend due to possible instabilities.

Sense Pin

The sense pin of the NCP630G will need to be connected

near the output voltage. This provides great advantages

when the linear regulator can’t be near the load. The sense

pin will monitor the load and allow the linear regulator to

adjust for losses in the line between itself and the load. Thus

it will provide good accuracy for a remote load.

ADJ Pin

The typical application circuits for the fixed and

adjustable output regulators are shown in Figures 1 and 2.

The adjustable devices develop and maintain the nominal

1.216 V reference voltage between the adjust and ground

normally lower than the current flowing through R1 and R2,

thus it generates a small output voltage error that can usually

be ignored. For the fixed output devices R1 and R2 are

included within the device.

Reverse Current

Some situations might occur were the output pin is raised

to a voltage while the input pin is at zero volts. This situation

will not damage the device.

If the output voltage is raised to a higher voltage than the

input voltage a diode is recommended from output to input

with the anode connect to the output pin.

Thermal Considerations

This series contains an internal thermal limiting circuit

that is designed to protect the regulator in the event that the

maximum junction temperature is exceeded. When

activated, typically at 165

°C, the regulator output switches

off and then back on as the die cools. As a result, if the device

is continuously operated in an overheated condition, the

output will appear to be oscillating. This feature provides

protection from a catastrophic device failure due to

accidental overheating. It is not intended to be used as a

substitute for proper heatsinking. The maximum device

power dissipation can be calculated by:

PD +

TJ(max) * TA

R

qJA

package. The package has an exposed metal tab that is

specifically designed to reduce the junction to air thermal

values that can be obtained from a square pattern using

economical single sided 2.0 ounce copper board material.

The final product thermal limits should be tested and

quantified in order to insure acceptable performance and

graphs shown. This will be due to any changes made in the

copper aspect ratio of the final layout, adjacent heat sources,

and air flow.

30

40

50

60

70

80

1.0

1.5

2.0

2.5

3.0

3.5

010

20

30

25

15

5.0

L, LENGTH OF COPPER (mm)

Minimum

Size Pad

2.0 oz. Copper

L

L

Free Air

Mounted

Vertically

Thermal Resistance and Maximum Power

Dissipation versus P.C.B. Copper Length