SPX29300 Sipex Corporation, SPX29300 Datasheet - Page 5

• Manufacturer Part Number: SPX29300
• Description: (SPX29300 - SPX29303) 3A High Current / Low Dropout Voltage Regulator Adjustable & Fixed Output / Fast Response Time
• Manufacturer: Sipex Corporation

The SPX29300/01/02/03 incorporates protec-
tion against over-current faults, reversed load
insertion, over temperature operation, and
positive and negative transient voltage.
Thermal Considerations
Although the SPX29300/01/02/03 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.
TO-220 Design Example:
Assume that V
1.5A, T
and θ
The power calculated under these conditions
is:
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
recommended if a faster load transient
Date: 5/25/04
And the junction temperature is calculated as
JC
= 3C°/W, where:
P
A
D
T
θ
θ
θ
T
T
= 50°C, θ
HA
CH
JC
= (V
A
J
J
= 50 + 7.5 * (1+2+3) = 95°C
= T
= ambient temperature,
= case to heatsink thermal
= heatsink to ambient thermal
= junction to case thermal
resistance
resistance
resistance
IN
IN
A
= 10V, V
+ P
– V
HA
D
OUT
= 1°C/W, θ
* (θ
) * I
HA
OUT
OUT
+ θ
= 5V, I
SPX29300/01/02/03 3A Low Dropout Voltage Regulator
= 7.5W.
CH
CH
= 2°C/W,
+ θ
OUT
JC
=
) or
5
response is needed. If the power source has a
high AC impedance, a 0.1µF ceramic capaci-
tor between input & ground is recommended.
Minimum Load Current
To ensure a proper behavior of the regulator
under light load, a minimum load of 5mA for
SPX29300/01/02/03 is required.
Adjustable Regulator Design
The SPX29302/03 are adjustable regulators
that can be programmed to any value between
1.25V and 16V using 2 resistors, R1 and R2.
The relationship between the resistors is:
Error Flag
The SPX29301/03 features an error flag that
indicates either an over current or under
voltage condition. The flag output goes low,
sinking 10mA when either condition occurs.
Enable Input
The SPX29301/02 have an Enable function
that switches the regulator on and off. Their
thresholds are TTL compatible. When the
regulator is active, approximately 20 uA flows
through the Enable pin.
Typical Application Circuits
Figure 1 represents at typical fixed output
regulator. Figure 2 represents an adjustable
output regulator. The values of R1 and R2 set
the output voltage value as follows:
For best results, the total series resistance
should be small enough to pass a minimum
regulator load current of 5 mA. A minimum
value of 10kohms is recommended for R2
with a range between 10kohms and 47 kohms.
R1 = R2(Vout/1.240-1).
V
OUT
APPLICATION INFORMATION
=V
REF
* [1 + (R1/R2)].
© Copyright 2004 Sipex Corporation