®
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 at 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 PC's 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
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: 5/17/04
SPX2815 1.5A Low Dropout Voltage Regulator
© Copyright 2004 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
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
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
%
%
(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
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
≤
3A, 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
≤
3A, 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
≤
3A, 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
≤
3A, 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
V
Date: 5/17/04
SPX2815 1.5A Low Dropout Voltage Regulator
© Copyright 2004 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 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
capacitance (up to 100µF) can improve the load
transient response.
Soldering Methods
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 effect 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
* thermal resistance
(junction-to-ambient)
Maximum junction temperature must not ex-
ceed the 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 the internal thermal lim-
iting to protect the device during overload con-
ditions. Special care needs to be taken during
Date: 5/17/04
SPX2815 1.5A Low Dropout Voltage Regulator
© Copyright 2004 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 capaci-
tor should be chosen with respect to the
following equation:
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
amplitude of the output ripple will be indepen-
dent 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
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 approxi-
mated 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 account, the formula becomes
V
OUT
= V
REF
(1+ (R
2
/R
1
)) + I
ADJ
* R
2
where
V
REF
=1.25V
Layout Considerations
Parasitic line resistance can degrade load
regulation. 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: 5/17/04
SPX2815 1.5A Low Dropout Voltage Regulator
© Copyright 2004 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
Date: 5/17/04
SPX2815 1.5A Low Dropout Voltage Regulator
© Copyright 2004 Sipex Corporation
5
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