1
Date: 5/25/04 SPX2810 1A Low Dropout Linear Regulator
Copyright 2004 Sipex Corporation
1A Low Dropout Positive Linear Regulator
SPX2810
FEATURES
Guaranteed 1A Output
Three Terminal Adjustable or Fixed
2.5V, 3.0V and 3.3V
Low Quiescent Current
Low Dropout Voltage of 1.1V at Full Load
0.2% Line and 0.3% Load Regulation
Voltage Temperature Stability 0.25%
Overcurrent and Thermal Protection
Available Packages: SOT-223,TO-252,
TO-220, and TO-263
The SPX2810 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 SPX2810 has a very low
quiescent current and a low dropout voltage of 1.1V at full load. As output current decreases,
quiescent current flows into the load, increasing efficiency. SPX2810 is available in adjustable
or fixed 2.5V, 3.0V and 3.3V output voltages.
The SPX2810 is offered in several industry standard 3-pin surface mount packages: SOT-223,
TO-252, TO-220 and TO-263. An output capacitor of 10
F or larger, provides unconditionally
stability for most applications.
DESCRIPTION
Now Available in Lead Free Packaging
TYPICAL APPLICATION CIRCUITS
APPLICATIONS
SCSI-II Active Terminator
Portable/Palm Top/Notebook
Computers
Battery Chargers
Disk Drives
Portable Consumer Equipment
Portable Instrumentation
SMPS Post-Regulator
SPX2810 is 2% Accuracy
SPX2810A is 1% Accuracy
IN
OUT
I
ADJ
SPX2810
C
1
R
1
R
2
V
OUT
V
IN
C
2
V
OUT
= V
REF
(1+R
2
/R
1
) +I
ADJ
R
2
V
REF
50
A
ADJ
4.7
F +
1
2
3
SPX2810
3 Pin TO-263
ADJ/GND
V
IN
V
OUT
2
Date: 5/25/04 SPX2810 1A Low Dropout Linear Regulator
Copyright 2004 Sipex Corporation
SPX2810A
SPX2810
PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
2.5V Version
Output Voltage
0
I
OUT
= 1A, 4.0V
V
IN
10V
2.475
2.500
2.525
2.450
2.500
2.550
V
(Note 2)
2.450
2.550
2.425
2.575
3.0V Version
Output Voltage
0
I
OUT
= 1A, 4.5V
V
IN
10V
2.970
3.000
3.030
2.940
3.000
3.060
V
(Note 2)
2.940
3.060
2.790
3.090
3.3V Version
Output Voltage
0
I
OUT
= 1A, 4.8V
V
IN
10V
3.267
3.300
3.333
3.234
3.300
3.366
V
(Note 2)
3.234
3.366
3.069
3.399
All Output Options
Reference Voltage
I
OUT
=10mA, V
IN
= V
OUT
+3V
1.238
1.250
1.263
1.225
1.250
1.275
V
10
I
OUT
1A, 1.5V
(V
IN
-V
OUT
)
5.75V
1.225
1.281
1.212
1.288
Min Load Current
1.5
(V
IN
- V
OUT
)
5.75V
5
10
10
mA
(Note 3)
Line Regulation
2.75
V
IN
7V, I
OUT
=T
J
=25
C (Note 2)
0.005
0.2
0.005
0.2
%
Load Regulation
(V
IN
- V
OUT
)=3.0V, 10mA
I
OUT
1A,
0.05
0.3
0.05
0.2
%
T
J
=25
C (Note 3)
Dropout Voltage
I
OUT
=1A (Note 3)
1.1
1.2
1.1
1.2
V
(Note 2)
I
OUT
=1A (Note 2)
1.05
1.15
Current Limit
V
IN
=7V,1.4
(V
IN
-V
OUT
)(Note 3)
1.2
2.0
1.2
A
Long Term Stability
T
A
=25
C, 1000Hrs (Note2)
0.03
1.0
1.0
%
Thermal Regulation
25
C, 20mS Pulse
0.01
0.02
0.01
0.02
%/
RMS Output Noise
T
A
=25
C, 10Hz
f
10kHz
0.003
0.003
%
Thermal Resistance
TO-220 Junction to Tab
3.0
3.0
C/W
TO-220 Junction to Ambient
60
60
TO-220 Junction to Tab
3.0
3.0
C/W
TO-220 Juinction to Ambient
60
60
TO-220 Junction to Tab
6
6
C/W
TO-220 Junction to Ambient
126
126
C/W
SOT-223 Junction Tab
15
15
CW
TO-220 Junction to Ambient
156
156
C/W
ABSOLUTE MAXIMUM RATINGS
Lead Temperature (soldering, 5 seconds) .................. 300
C
Storage Temperature Range ...................... -65
C to +150
C
Operating Junction Temperature Range ..... -40
C to +125
C
Input Supply Voltage ..................................................... +10V
NOTES:
Note 1: Output temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 2: Dropout voltage is defined as the input to output differential at which the output voltage drops 100mV below its nominal value measured at 1V differential at
very low values of programmed output voltage, the minimum input supply voltage of 2V ( 2.3V over temperature) must be taken into account.
Note 3: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied excluding load or line regulation effect.
V
IN
=V
OUT
+ 1.5V, C
OUT
= 10
F, at I
OUT
= 10mA, T
A
= 25
C, unless otherwise specified. Limits in Boldface applies
over the full operating temperature range.
ELECTRICAL CHARACTERISITCS
3
Date: 5/25/04 SPX2810 1A Low Dropout Linear Regulator
Copyright 2004 Sipex Corporation
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 1. Load Regulation for SPX2810M3-3.3;
Figure 2. Line Regulation for SPX2810M3--3.3;
V
IN
=4.8V, C
OUT
=2.2
F
V
IN
=4.8V, C
OUT
=2.2
F
Figure 3. Dropout Voltage vs Output Current for
SPX2810M3-3.3; V
IN
=4.89V, C
OUT
=10
F
Figure 5. Current Limit for SPX2810M3-3.3, Output
Voltage Deviation, (I
OUT
pulsed from 10mA to 1A).
3.280
3.285
3.290
3.295
3.300
3.305
3.310
3.315
3.320
10
100
1000
Output Current (A)
Output V
oltage (V)
3.300
3.310
3.320
3.330
4.8
9.8
14.8
Vin (V)
V
out (V)
Series 1
Series 2
Line Regulation at 25
C
0.9
1.0
1.1
1.2
1.3
100
200
300
400
500
600
700
800
900
1000
Output Current (mA)
Dropout V
o
ltage (V)
Figure 4. Current Limit for SP1202M3-3.3; V
IN
=4.8V,
C
IN
=C
OUT
=1.0
F, I
OUT
pulsed from 10mA to Current
Limit
Temp (
C)
-50
-25
0
25
50
75
100 125
2.00
1.50
1.00
0.50
0.00
Series 1
Series 2
Current Limit (A)
Current Limit VS Temp
125
C
22
F
Indicating Current
Limit Starts
V
IN
= 4.0V
V
IN
=3.3V Fixed
1
O
=10mA
C
IN
=1
F Ten Cap
C
OUT
=2.2
F Ten Cap
100
0
-100
15
10
0.5
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8 0.9
1.0
Time (ms)
Output Current
(A)
Output De
v
ation
(mV)
4
Date: 5/25/04 SPX2810 1A Low Dropout Linear Regulator
Copyright 2004 Sipex Corporation
Output Capacitor
To ensure the stability of the SPX1202, an
output capacitor of at least 10
F (tantalum or
ceramic) or 50
F (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. The
recommended value for ESR is 0.5
or less. A
larger value of output capacitance (up to 100
F)
can improve the load transient response.
SOLDERING METHODS
The SPX2810 SOT-223 package is designed to
be compatible with infrared reflow or vapor-
phase reflow soldering techniques. During sol-
dering, the non-active or mildly active fluxes
may be used. The SPX2810 die is attached to
the heatsink lead which exits opposite the input,
output, and ground pins.
Hand soldering and wave soldering should be
avoided since these methods can cause damage
to the device with excessive thermal gradients
on the package. The SOT-223 recommended
soldering method are as follows: vapor phase
reflow and infrared reflow with the component
preheated to within 65
C of the soldering tem-
perature range.
THERMAL CHARACTERISTICS
The thermal resistance of SPX2810 depends on
type of package and PC board layout as shown
in Table 1. The SPX2810 features the internal
thermal limiting to protect the device during
overload conditions. Special care needs to be
taken during continuous load conditions such
that the maximum junction temperature does
not exceed 125
C. Thermal protection is acti-
vated at >144
C and deactiviated at <137C.
Taking the FR-4 printed circuit board and 1/16
thick with 1 ounce copper foil as an experiment,
the PCB material is effective at transmitting
heat with the tab attached to the pad area and a
ground plane layer on the backside of the sub-
strate. Refer to table 1 for the results of the
experiment.
The thermal interaction from other components
in the application can effect the thermal resis-
tance of the SPX2810. The actual thermal resis-
tance can be determined with experimentation.
SPX2810 power dissipation is calculated as
follows:
P
D
= (V
IN
- V
OUT
)(I
OUT
)
Maximum Junction Temperature range:
T
J
= T
AMBIENT
(max) + P
D
* (Junction to ambient
Thermal Resistance)
Although the SPX2810 offers some limiting
circuitry for overload conditions, it is still nec-
essary to insure that maximum junction
tepmerature is not exceeded. Heat will flow
through the lowest resistance path, in this case
the junction to case. Therfore proper mounting
of the regulator to the board is critical. The case
of the device is electrically connected to the
output. If the case must be electrically isolated,
a thermal nonconductive spacer should be used
between the case and the board. It thermal resis-
tance must be taken into account.
For example:
V
IN
=10V, V
OUT
=5V. I
OUT
=1.5A and T
A
=50
C/W
Theta
JC
=3
C/W, theta
SinkCase
= 6
C/W
theta
Sink
=0.5
C/W
Power dissipation is calculated as
P
D
= (V
IN
-V
OUT
)* I
OUT
=7.5W
Junction Temperature will be
T
J
=T
A
+ P
D
*(theta
Case-Hs
+theta
Hs
+ theta
Jc
) or
T
J
= 50 + 7.5(0.5+6+3) = 121.25
C
Figure 7. Substrate Layout for SOT-223 for thermal
experiment.
50 X 50mm
35 X 17mm
16 X 10mm
APPLICATION INFORMATION
5
Date: 5/25/04 SPX2810 1A Low Dropout Linear Regulator
Copyright 2004 Sipex Corporation
PC BOARD
TOPSIDE COPPER BACKSIDE COPPER
THERMAL RESISTANCE
AREA mm
2
AREA mm
2
AREA mm
2
JUNCTION TO AMBIENT
C/W
2500
2500
2500
46
2500
1250
2500
47
2500
950
2500
49
2500
2500
0
51
2500
1800
0
53
1600
600
1600
55
2500
1250
0
58
2500
915
0
59
1600
600
0
67
900
240
900
72
900
240
0
85
Figure 8. 600mA Current Source
Figure 9. Typical Adjustable Regulator
Ripple Rejection
Ripple rejection can be improved by adding a
capacitor between the ADJ pin and ground as
shown in Figure 6. 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 10(F for an electrolytic aluminum
capacitor or 2.2
F for a solid tantalum capacitor
(Fig 10). However the value of the ADJ-bypass
capacitor should be chosen with respectto 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 R
1
in Ohms
If an ADJ-bypass capacitor is used, the
amplitude of the output ripple will be inde-
pendent 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
TYPICAL APPLICATION CIRCUITS
LOAD
ADJ
SPX2810
V
IN
C
1
OUT
IN
4.7
F
C
2
I
OUT
R
1
V
REF
R
1
I
OUT
=
+
IN
OUT
I
ADJ
SPX2810
C
1
R
1
R
2
V
OUT
V
IN
C
2
V
OUT
= V
REF
(1+R
2
/R
1
) +I
ADJ
R
2
V
REF
50
A
ADJ
4.7
F +
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