SPX1202M3-1.5 Просмотр технического описания (PDF) - Signal Processing Technologies

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SPX1202M3-1.5

600mA Low Dropout NPN Voltage Regulator

Signal Processing Technologies 

APPLICATION NOTES EXTERNAL

CAPACITOR

To ensure the stability of the SPX1202 an output capacitor of

at least 10µF (tantalum)or 50µF (aluminum) is required. The

value may change based on the application requirements on

the output load or temperature range. The capacitor

equivalent series resistance (ESR) will effect the SPX1202

stability. The value of ESR can vary from the type of

capacitor used in the applications. The recommended value

for ESR is 0.5Ω. The output capacitance could increase in

size to above the minimum value. The larger value of output

capacitance as high as 100µF can improve the load transient

response.

SOLDERING METHODS

The SPX1202 SOT-223 package is designed to be

compatible with infrared reflow or vapor-phase reflow

soldering techniques. During soldering the non-active or

mildly active fluxes may be used. The SPX1202 die is

attached to the heatsink lead which exits opposite the input,

output, and ground pins.

Hand soldering and wave soldering should be avoided since

these methods can cause damage to the device with excessive

thermal gradients on the package. The SOT-223

recommended soldering method are as follows: vapor phase

reflow and infrared reflow with the component preheated to

within 65°C of the soldering temperature range.

THERMAL CHARACTERISTICS

The thermal resistance of SPX1202 is 15°C/W from junction

to tab and 31 °C/W from tab to ambient for a total of 46

°C/W from junction to ambient. The SPX1202 features the

internal thermal limiting to protect the device during

overload conditions. Special care needs to be taken during

continuos load conditions the maximum junction temperature

does not exceed 125 °C.

Taking the FR-4 printed circuit board and 1/16 thick with 1

ounce copper foil as an experiment (fig.1 & fig.2), the PCB

material is effective at transmitting heat with the tab attached

to the pad area and a ground plane layer on the backside of

the substrate. Refer to table 1 for the results of the

experiment.

The thermal interaction from other components in the

application can effect the thermal resistance of the SPX1202.

The actual thermal resistance can be determined with

experimentation. SPX1202 power dissipation is calculated as

follows:

PD = (VIN - VOUT)(IOUT)

SPX1202

Maximum Junction Temperature range:

TJ = Tambient (max) + PD* thermal resistance(Junction-to-

ambient)

Maximum Junction temperature must not exceed the 125°C.

10V

SPX1202

+

10uF

+

10uF

2.85V

27KΩ ..

PO = (10V - 2.85)(105mA) = (7.15)(105mA) = 703mW

Fig. 1. Circuit Layout, Thermal Experiments.

50 X 50 mm

35 X 17 mm

16 X 10 mm

Fig. 2. Substrate Layout for SOT-223

Rev. 10/19/00

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