NCP500, NCV500

www.onsemi.com

13

The maximum dissipation the package can handle is

given by:

PD

+

TJ(max) *TA

R

qJA

°C, then the

NCP500 can dissipate up to 400 mW @ 25

°C.

The power dissipated by the NCP500 can be calculated

from the following equation:

Ptot + Vin *Ignd (Iout) ) [Vin * Vout] *Iout

or

VinMAX +

Ptot ) Vout * Iout

Ignd ) Iout

If a 150 mA output current is needed the ground current

is extracted from the data sheet curves: 200

mA @ 150 mA.

For a NCP500SN18T1 (1.8 V), the maximum input voltage

will then be 4.4 V, good for a 1 Cell Li−ion battery.

Hints

When the impedance of these lines is high, there is a chance

to pick up noise or cause the regulator to malfunction.

Set external components, especially the output capacitor,

as close as possible to the circuit, and make leads as short

as possible.

Package Placement

DFN packages can be placed using standard pick and

place equipment with an accuracy of

"0.05 mm.

Component pick and place systems are composed of a vision

system that recognizes and positions the component and a

mechanical system which physically performs the pick and

place operation. Two commonly used types of vision

systems are: (1) a vision system that locates a package

silhouette and (2) a vision system that locates individual

bumps on the interconnect pattern. The latter type renders

more accurate place but tends to be more expensive and time

consuming. Both methods are acceptable since the parts

align due to a self−centering feature of the DFN solder joint

during solder re−flow.

Solder Paste

Type 3 or Type 4 solder paste is acceptable.

Re−flow and Cleaning

The DFN may be assembled using standard IR/IR

convection SMT re−flow processes without any special

considerations. As with other packages, the thermal profile

for specific board locations must be determined. Nitrogen

purge is recommended during solder for no−clean fluxes.

The DFN is qualified for up to three re−flow cycles at 235

°C

peak (J−STD−020). The actual temperature of the DFN is a

function of:

Figure 27. Typical Application Circuit

Battery or

Unregulated

Voltage

C1

C2

OFF

ON

1

2

3

5

4

+

+

Figure 28. Typical Application Circuit

Battery or

Unregulated

Voltage

+

C1

OFF

ON

1

3

2

4

5

6

+

C2