SPX1202 查看數據表（PDF） - Signal Processing Technologies

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SPX1202

600mA Low Dropout Voltage Regulator

Signal Processing Technologies 

APPLICATION INFORMATION

Output Capacitor

To ensure the stability of the SPX1202, an

output capacitor of at least 10F (tantalum or

ceramic)or 50F (aluminum) is required. The

value may change based on the application

requirements of the output load or temperature

range. The value of ESR can vary based on the

type of capacitor used in the applications. The

recommended value for ESR is 0.5Ω or less. A

larger value of output capacitance (up to 100F)

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 sol-

dering, 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.

50 X 50mm

35 X 17mm

16 X 10mm

Figure 7. Substrate Layout for SOT-223

in the application can effect the thermal resis-

tance of the SPX1202. The actual thermal resis-

tance can be determined with experimentation.

SPX1202 power dissipation is calculated as

follows:

P = (V - V )(I )

D

IN

OUT OUT

Maximum Junction Temperature range:

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 tem-

perature range

THERMAL CHARACTERISTICS

The thermal resistance of SPX1202 depends on

the type of package and PC board layout as

shown in Table 1. The SPX1202 features the

internal thermal limiting to protect the device

during overload conditions. Special care needs

to be taken during continuous load conditions

such that the maximum junction temperature

does not exceed 125C. Thermal protection is

activated at >144C and deactiviated at <137C.

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

thick with 1 ounce copper foil as an experiment,

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 sub-

strate. Refer to table 1 for the results of the

experiment.

The thermal interaction from other components

TJ= T AMBIENT(max) + P D* (Thermal Resistance)

(Junction-to-ambient)

Maximum junction temperature must not ex-

ceed the 125C.

Ripple Rejection

Ripple rejection can be improved by adding a

capacitor between the ADJ pin and ground as

shown in Figure 7. When ADJ pin bypassing is

used, the value of the output capacitor required

increases to its maximum. If the ADJ pin is not

bypassed, the value of the output capacitor can

be lowered to 10F for an electrolytic aluminum

capacitor or 2.2F for a solid tantalum capacitor

(Fig 10).

However the value of the ADJ-bypass capacitor

should be chosen with respect to the following

equation:

C = 1 / ( 6.28 * F * R )

R

1

Where C = value of the capacitor in Farads

(select an equal or larger standard value),

FR= ripple frequency in Hz,

R1= value of resistor R 1in Ohms.

If an ADJ-bypass capacitor is used, the ampli-

Mar13-07

SPX1202 600 mA Low Dropout Linear Regulator



© 2007 Sipex Corporation

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