SPX1587U-L-5-0 Exar Corporation, SPX1587U-L-5-0 Datasheet - Page 6

• Manufacturer Part Number: SPX1587U-L-5-0
• Description: 3A Low Dropout Voltage Regulator
• Manufacturer: Exar Corporation

Specifications of SPX1587U-L-5-0

• Regulator Topology: Positive Fixed
• Voltage - Output: 5V
• Voltage - Input: Up to 10V
• Voltage - Dropout (typical): 1.1V @ 3A
• Number Of Regulators: 1
• Current - Output: 3A
• Current - Limit (min): 3.2A
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Through Hole
• Package / Case: TO-220-3
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

thermal resistance of the SPX1587. The actual
thermal resistance can be determined with
experimentation.
The SPX1587 power dissipation is calculated
as follows:
Maximum Junction Temperature range:
Where θ
resistance of the package.
Maximum
exceed 125°C.
R
Ripple rejection can be improved by adding a
capacitor between the ADJ pin and ground as
shown in Figure 11. 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 22μF for an
electrolytic aluminum capacitor or 10μF for a
solid tantalum capacitor (Fig 10).
However
capacitor should be chosen with respect to the
following equation:
Where
C = value of the capacitor in Farads (select an
equal or larger standard value)
F
R
© 2010 Exar Corporation
R
1
IPPLE
= ripple frequency in Hz
= value of resistor R1 in Ohms.
R
JA
EJECTION
is the junction-to-ambient thermal
the
junction
value
6.28
temperature
1
of
the
ADJ-bypass
must
not
6/11
If an ADJ-bypass capacitor is used, the
amplitude
independent of the output voltage. If an ADJ-
bypass capacitor is not used, the output ripple
will be proportional to the ratio of the output
voltage to the reference voltage:
Where
M = multiplier for the ripple seen when the
ADJ pin is optimally bypassed.
V
Ripple rejection for the adjustable version is
showing in Figure 8.
O
The output of the adjustable regulator can be
set to any voltage between 1.25V and 15V.
The value of V
using the formula
Small correction to this formula is required de-
pending on the values of resistors R1 and R2,
since the adjustable pin current (approx 50μA)
flows through R2. When I
account, the formula becomes
Where
V
L
Parasitic line resistance can degrade load
regulation. In order to avoid this, connect R1
directly to V
the same reason, R2 should be connected to
the negative side of the load.
3
3
REF
REF
AYOUT
UTPUT
A
A
=1.25V
=1.25V
L
L
o
o
w
w
C
V
ONSIDERATIONS
OLTAGE
D
D
of
OUT
r
r
o
o
OUT
p
as illustrated in Figure 13. For
p
the
o
o
can be quickly approximated
u
u
1.25
t
t
1
output
V
V
o
o
l
l
t
t
a
a
ADJ
g
g
ripple
e
e
S
is taken into
S
R
R
P
P
e
e
X
X
g
g
Rev. 2.0.0
u
will
1
u
1
l
l
5
5
a
a
8
t
8
t
o
o
be
7
7
r
r