SPX2815
1.5A Low Dropout Voltage Regulator
FEATURES
■
Guaranteed 1.5A Output Current
■
Three Terminal Adjustable or Fixed
2.5V, 3.3V and 5.0V
■
Low Quiescent Current
■
Low Dropout Voltage of 1.1V @ 1.5A
■
0.1% Line and 0.1% Load Regulation
■
Stable with 10uF Ceramic Capacitor
■
Overcurrent and Thermal Protection
■
Available Packages: TO-252,
TO-220, and TO-263
■
Similar to Industry Standard LT1086/
LT1586
APPLICATIONS
■
Desktop PCs, Servers
■
Powering VGA and Sound Cards
■
Cordless Phones
■
Battery Chargers
■
Adjustable Power Supplies
■
Portable Instrumentation
■
SMPS Post-Regulator
■
Constant Current Regulators
■
Disk Drives
Refer to Page 5 for Pinouts
Now Available in Lead Free Packaging
DESCRIPTION
The SPX2815 is a low power positive-voltage regulator designed to satisfy moderate power
requirements with a cost effective, small footprint solution. This device is an excellent choice for
use in battery-powered applications and portable computers. The SPX2815 features very low
quiescent current and a low dropout voltage of 1.1V at a full load. As output current decreases,
quiescent current flows into the load, increasing efficiency. SPX2815 is available in adjustable
or fixed 2.5V, 3.3V and 5.0V output voltages.
The SPX2815 is offered in several 3-pin surface mount packages: TO-252, TO-220 and TO-263.
An output capacitor of 10μF ceramic or tantalum provides unconditional stability.
FUNCTIONAL DIAGRAM (Adjustable)
V
IN
Current Limit
+
-
V
OUT
I
CL
_
AMP
+ 1.25V
Thermal Limit
+
–
V
REF
ADJ/GND
I
ADJ
~ 50μA
–
I
TL
Date: 6/21/06 Rev C
SPX2815 1.5A Low Dropout Voltage Regulator
© 2006 Sipex Corporation
1
ABSOLUTE MAXIMUM RATINGS
Power Dissipation.......................................Internally Limited
Lead Temperature (soldering, 5 seconds) ...............260°C
Storage Temperature Range.......................-65°C to +150°C
Operating Junction Temperature Range.....-40°C to +125°C
Input Supply Voltage .................................................... +10V
Input to Output Voltage ................................................ +8.8V
ESD Rating .............................................................. 2kV min
ELECTRICAL CHARACTERISTICS
at V
IN
=V
OUT
+ 1.5V, T
A
= 25°C, C
IN
= C
OUT
= 10μF, I
OUT
=10mA, unless otherwise specified. The
Boldface
applies over the
full operating temperature range.
PARAMETER
2.5V Version
Output Voltage
3.30V Version
Output Voltage
5.0V Version
Output Voltage
All Voltage Options
Reference Voltage
Output Voltage
Temperature Stability
Line Regulation
1.238 1.250
1.225
0.3
0.1
0.1
0.1
0.1
0.1
0.1
1.00
1.10
4
50
2.5
0.01
60
75
0.03
0.003
3
29.3
3
31.4
6
50
0.1
60
0.2
0.2
0.2
0.3
0.3
0.3
1.2
10
120
2.5
0.01
75
0.03
0.003
3
29.3
3
31.4
6
50
0.1
1.262 1.225 1.250
1.275 1.212
0.5
0.1
0.1
0.1
0.1
0.1
0.1
1.00
1.10
4
50
0.2
0.2
0.2
0.3
0.3
0.3
1.2
10
120
mA
μA
A
%/W
dB
%
%
°C/W
(V
IN
-V
OUT
)=5V
25°C, 30mS pulse
f
RIPPLE
=120Hz, (V
IN
-V
OUT
)=2V,
V
RIPPLE
=1V
PP
125°C, 1000Hrs
% of V
OUT
, 10Hz≤f≤10kHz
TO-220 Junction to Case, at Tab
TO-220 Junction to Ambient
TO-263 Junction to Case, at Tab
TO-263 Junction to Ambient
TO-252 Junction to Case, at Tab
TO-252 Junction to Ambient
1.275
1.287
V
%
%
4.25V≤V
IN
≤
10V,V
OUT
=2.5V,I
OUT
=10mA
4.75V≤V
IN
≤
10V,V
OUT
=3.3V,I
OUT
=10mA
6.50V≤V
IN
≤
10V,V
OUT
=5.0V,I
OUT
=10mA
10mA≤I
OUT
≤
1.5A, V
OUT
=2.5V
10mA≤I
OUT
≤
1.5A, V
OUT
=3.3V
10mA≤I
OUT
≤
1.5A, V
OUT
=5.0V
I
OUT
=0.5A
I
OUT
=1.5A
Fixed voltage versions
I
OUT
=10mA, (V
IN
- V
OUT
)= 2V
10mA≤I
OUT
≤
1.5A, 1.5V≤(V
IN
-V
OUT
)≤ 10V
4.950 5.000
4.900
5.050 4.900 5.000
5.100 4.850
5.100
5.150
V
I
OUT
=10mA, V
IN
=7V
10mA
≤
I
OUT
≤
1.5A, 6.50V
≤
V
IN
≤
10V
3.267 3.300
3.234
3.333 3.234 3.300
3.366 3.201
3.366
3.399
V
I
OUT
= 10mA, V
IN
=5V
10mA
≤
I
OUT
≤
1.5A, 4.75V
≤
V
IN
≤
10V
MIN
TYP
SPX2815A
2.475 2.500
2.450
MAX
MIN
TYP
SPX2815
2.525 2.450 2.500
2.550 2.425
2.550
2.575
V
I
OUT
= 10mA, V
IN
=4.5V
10mA
≤
I
OUT
≤
1.5A, 4.25V
≤
V
IN
≤
10V
MAX
UNITS
CONDITIONS
Load Regulation
%
Dropout Voltage
(Note 2)
Quiescent Current
Adjust Pin Current
Current Limit
Thermal Regulation
Ripple Rejection
Long Term Stability
RMS Output Noise
Thermal Resistance
V
Date: 6/21/06 Rev C
SPX2815 1.5A Low Dropout Voltage Regulator
© 2006 Sipex Corporation
2
TYPICAL PERFORMANCE CHARACTERISTICS
3.325
3.320
1.275
1.27
1.265
1.26
1.255
1.25
1.245
1.24
1.235
1.23
1.225
-50
1.25v Adj
Vout (V)
3.315
3.310
3.305
3.300
4.5
6.5
8.5
10.5
Vin (V)
12.5
14.5
Vout (V)
-30
-10
10
30
50
70
90
110
130
Temp (C)
Figure 1. Line Regulation for SPX2815U-3.3; I
OUT
=10mA
Figure 2. V
OUT
vs Temperature, V
IN
=2.5V, I
OUT
=10mA
2.55
2.54
2.53
2.52
2.51
2.5
2.49
2.48
2.47
2.46
2.45
-50
3.38
2.5v Adj
2.5v Fixed
3.36
3.34
Vout (V)
3.3v Adj
3.3v Fixed
Vout (V)
3.32
3.3
3.28
-30
-10
10
30
50
Temp (C)
70
90
110
130
3.26
-50
-30
-10
10
30
50
70
90
110
130
Temp (C)
Figure 3. V
IN
=4.0V, I
OUT
=10mA
Figure 4. V
IN
=5.0V, I
OUT
=10mA
APPLICATION INFORMATION
Output Capacitor
To ensure the stability of the SPX2815, an
output capacitor of at least 10μF (ceramic or
tantalum) or 22μF (aluminum) is required. The
value may change based on the application
requirements of the output load or temperature
range. The value of Equivalent Series Resis-
tance (ESR) can vary based on the type of
capacitor used in the applications to guarantee
stability. The recommended value for ESR is
0.5Ω or less. A larger value of output capaci-
tance (up to 100μF) can improve the load tran-
sient response.
Soldering Methods
tions. Special care needs to be taken during
continuous load conditions such that the maxi-
mum junction temperature does not exceed
125°C. Thermal protection is activated at >179°C
and deactiviated at <165°C.
The thermal interaction from other components
in the application can affect the thermal resis-
tance of the SPX2815. The actual thermal
resistance can be determined with experimenta-
tion.
SPX2815 power dissipation is calculated as
follows:
P
D
= (V
IN
- V
OUT
)(I
OUT
)
Maximum Junction Temperature range:
T
J
= T
A
(max) + P
D
*
θ
JA
(thermal resistance,
junction-to-ambient)
Maximum junction temperature must not ex-
ceed 125°C.
The SPX2815 die is attached to the heatsink lead
which exits opposite the input, output, and ground
pins.
Thermal Characteristics
The SPX2815 features internal thermal limiting
to protect the device during overload condi-
Date: 6/21/06 Rev C
SPX2815 1.5A Low Dropout Voltage Regulator
© 2006 Sipex Corporation
3
APPLICATION INFORMATION: Continued
Ripple Rejection
Ripple rejection can be improved by adding a
capacitor between the ADJ pin and ground as
shown in Figure 8. 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 7). However, the value of the ADJ-bypass
capacitor should be chosen with respect to the
following equation:
Ripple rejection for the adjustable version is
shown in Figure 5.
Output Voltage
The output of the adjustable regulator can be set
to any voltage between 1.25V and 15V. The
value of V
OUT
can be quickly approximated using
the formula
V
OUT
=1.25 *(R
1
+ R
2
)/R
1
A small correction to this formula is required
depending on the values of resistors R
1
and R
2
,
since the adjustable pin current (approx 50μA)
flows through R
2
. When I
ADJ
is taken into ac-
count, the formula becomes
V
OUT
= V
REF
(1+ (R
2
/R
1
)) + I
ADJ
* R
2
where
V
REF
=1.25V
C=
_______1______-_
( 6.28 * F
R
* R
1
)
Where
C = value of the capacitor in Farads
(select an equal or larger standard value),
F
R
= ripple frequency in Hz,
R
1
= value of resistor R1 in Ohms.
If an ADJ-bypass capacitor is used, the ampli-
tude of the output ripple will be 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:
M = V
OUT
/ V
REF
Where M = multiplier for the ripple seen when
the ADJ pin is optimally bypassed.
V
REF
=1.25V
Layout Considerations
Parasitic line resistance can degrade load regu-
lation. In order to avoid this, connect R
1
directly
to V
OUT
as illustrated in Figure 13. For the same
reason, R
2
should be connected to the negative
side of the load.
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
10
100
1000
10000
100000
1000000
Frequency, Hz
Ripple Rejection, Db
V
IN
4.7μF +
C
1
IN
SPX2815
ADJ
OUT
C
2
R
1
V
OUT
I
OUT
=
V
REF
R
1
I
OUT
LOAD
Figure 5. Ripple Rejection; Vin=3.3V, Vout=1.8V (adj.),
Iload=200mA
Figure 6. Current Source
Date: 6/21/06 Rev C
SPX2815 1.5A Low Dropout Voltage Regulator
© 2006 Sipex Corporation
4
APPLICATION INFORMATION: Continued
(Note A)
V
IN
SPX2815
IN
OUT
5V
V
OUT
R
1
330Ω
1%
10μF
V
IN
4.7μF +
C
1
IN
SPX2815
ADJ
I
ADJ
50μA
OUT
C
2
V
REF
R
1
V
OUT
+
4.7μF
ADJ
V
OUT
= V
REF
(1+R
2
/R
1
) +I
ADJ
R
2
R
2
*C
1
improves ripple rejection.
Z
C
should be ~ R1 at ripple frequency
R
2
1kΩ,
1%
+
C
1
10μF*
Note A: V
IN(MIN)
= (Intended V
OUT
) + (V
DROPOUT (MAX)
)
Figure 7. Typical Adjustable Regulator
Figure 8. Improving Ripple Rejection
SPX2815
V
IN
(Note A)
ADJ
IN
OUT
5V
330W
1%
+
R
P
Parasitic Line
Resistance
V
IN
SPX2815
V
OUT
+
4.7μF
TTL
Input
1K
2N3904
1k
ADJ
10μF
Connect R to
Case of Regulator
1kΩ
1%
R
1
Connect R
2
to Load
R
L
R
2
Note A: V
IN(MIN)
= (Intended V
OUT
) + (V
)
DROPOUT (MAX)
Figure 9. 5V Regulator with Shutdown
Figure 10. Recommended Connections for Best Results
PINOUTS
TO-252 (R)
TO-220-3 (U)
TO-263-3 (T)
1
2
3
1
2
3
1
2
3
ADJ/GND
V
OUT
V
IN
ADJ/GND
V
OUT
V
IN
Front View
ADJ/GND
V
OUT
V
IN
Top View
Front View
Note: Tab is connected to Pin 2 (Vout)
Date: 6/21/06 Rev C
SPX2815 1.5A Low Dropout Voltage Regulator
© 2006 Sipex Corporation
5
