SPX29150T View Datasheet(PDF) - Signal Processing Technologies

Part Name

Description

Manufacturer

SPX29150T

1.5A Low Dropout Voltage Regulator

Signal Processing Technologies 

The SPX29150/51/52/53 incorporates pro-

tection against over-current faults, reversed

load insertion, over temperature operation,

and positive and negative transient volt-

ages.

Thermal Considerations

Although the SPX29150/51/52/53 offers

limiting circuitry for overload conditions, it is

still necessary to insure that the maximum

junction temperature is not exceeded in the

application. Heat will flow through the lowest

resistance path, the junction-to-case path.

In order to insure the best thermal flow of

the component, proper mounting is required.

Consult the heatsink manufacturer for ther-

mal resistance and heat sink design.

TO-220 Design Example:

Assume that Vin = 10V, Vout = 5V, Iout =

1.5A, Ta = 50°C, θh= 1°C/W, θch= 2°C/W,

and θjc= 3C°/W, where:

Ta = ambient temperature,

θha = heatsink to ambient thermal resis-

tance

θch = case to heatsink thermal resistance

θjc = junction to case thermal resistance

The power calculated under these condi-

tions is:

Pd = (Vin – Vout) * Iout = 7.5W.

And the junction temperature is calculated

as

Tj = Ta + Pd * (θha + θch + θjc) or

APPLICATION INFORMATION

Tj = 50 + 7.5 * (1+2+3) = 95°C

Reliable operation is insured.

Capacitor Requirements

The output capacitor is needed to insure

stability and minimize the output noise. The

value of the capacitor varies with the load.

However, a minimum value of 10µF alumi-

num capacitor will guarantee stability over all

load conditions. A tantalum capacitor is rec-

ommended if a faster load transient response

is needed. If the power source has a high

AC impedance, a 0.1µF ceramic capacitor

between input & ground is recommended.

The output capacitors maximum ESR value

for stable operation is 0.33ohms.

Minimum Load Current

To ensure proper behavior of the regulator

under light loads, a minimum load of 5mA

for SPX29150/51/52/53 is required.

Typical Application Circuits

Figure 19 represents a typical fixed output

regulator. Figure 20 represents an adjustable

output regulator. The values of R1 and R2

set the output voltage value as follows: Vout

=Vref * [1 + (R1/R2)]. A minimum value of

10kΩ is recommended for R2 with a range

between 10kΩ and 47kΩ.

VIN

+

6.8µF

SPX29150

VOUT

+ 10µF

VIN

+

6.8µ F

1 SPX29152 4

2

3

GND

5

ADJ

VOUT

+

R1

10µ F

R2

Figure 19. Fixed Output Linear Regulator

Figure 20. Adjustable Output Linear Regulator

Rev A 8/15/06

SP29150/51/52/53 1.5A Low Dropout Voltage Regulator



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