SPX1582T5-L/TR Exar Corporation, SPX1582T5-L/TR Datasheet - Page 4

• Manufacturer Part Number: SPX1582T5-L/TR
• Description: 3A Ultra Low Dropout Voltage Regulator
• Manufacturer: Exar Corporation

Specifications of SPX1582T5-L/TR

• Regulator Topology: Positive Adjustable
• Voltage - Output: 1.25 V ~ 6 V
• Voltage - Input: Up to 6V
• Voltage - Dropout (typical): 0.4V @ 3A
• Number Of Regulators: 1
• Current - Output: 3A
• Current - Limit (min): 3.1A
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: TO-263-6, D²Pak (5 leads + Tab), TO-263BA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The SPX1582 is designed as a high performance
and low cost solution for applications requiring
a lower dropout than traditional NPN regulators.
The SPX1582 uses a separate input voltage V
( V
voltage. This allows the 2.5V power for the load
to come from a 3.3V system supply. As an added
benefit this will reduce the heat dissipation*, and
lower heatsink and cooling fan costs.
The SPX1582 can power the 2.5V core voltage
for microprocessors such as a PentiumPC
P55C
PowerPC
A typical application would use 3.3V for V
5.0V for V
ply to provide a nominal 2.5V output. Using the
sense pin provides a Kelvin measurement of
output for reducing resistance-associated errors.
Power Up Sequencing
The SPX1582 requires a power up sequence in
that V
a latchup condition. If this is not possible, then a
10Ω series resistor should be added to the V
input to prevent the device from entering into
latchup if V
Jun 17-06 Rev F
CTRL
TM
IN
≥ V
, AMD5k86
must be applied before V
TM
CTRL
OUT
CTRL
603EV and 604EV processors.
+ 1.3V) to minimize the dropout
from a motherboard power sup-
is applied before V
TM
and K6
TM
CTRL
SPX1582 3A Ultra Low Dropout Voltage Regulator
and the IBM
IN
to prevent
.
IN
CTRL
CTRL
and
TM
,
4
Adjustable Regulator Design
1.25V reference voltage is being developed be-
tween the SENSE pin and the ADJ pin of the
SPX1582. Adding two external resistors (see fig
1.) will allow setting the output voltage from
1.25V to 6V. R
specified at a minimum load current of 10mA.
R
V
The current flowing from the ADJ pin is typicaly
50μA. This ADJ pin contributes to the final
V
sense pin to the top of the resistor divider will
improve load regulation.
Lowering Noise
For the fixed voltage device, adding a capacitor
at the GND pin will improve transient response.
This capacitor is chosen in the range of 1μF to
0.1μF and will depend on the amount of output
capacitance in the system.
2
OUT
OUT
is given by the formula:
= V
but is usually neglected. Connecting the
REF
APPLICATION INFORMATION
(1+ R
1
is chosen so that this current is
2
/R
1
) + I
ADJ
© 2006 Sipex Corporation
(R
2
).