®
SPX2810 / SP2810A
1A Low Dropout Positive Linear Regulator
FEATURES
■
Output Current of 1A
■
Accurate Output Voltage
■
Low Quiescent Current
■
Low Dropout Voltage of 1.1V at Full Load
■
0.2% Line and 0.3% Load Regulation
■
Adjustable Output Down to 1.2V
■
Overcurrent and Thermal Protection
■
Output Accuracy
■
SPX2810A = 1% Room Temp.
■
SPX2810 = 2% Room Temp.
■
Fixed Output Voltage: 1.5V, 2.5V, 3.0V,
3.3V and 5V (SOT223 only)
■
Available Packages: SOT-223,TO-252,
TO-220, and TO-263
SPX2810
3 Pin SOT-223
1
2
3
ADJ/GND V
OUT
V
IN
Now Available in Lead Free Packaging
APPLICATIONS
■
SCSI-II Active Terminator
■
Pocket PC/PDAs
■
Notebook Computers
■
Battery Chargers
■
Disk Drives
■
Portable Consumer Equipment
■
Portable Instrumentation
■
SMPS Post-Regulator
DESCRIPTION
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 1.5, 2.5V, 3.0V, 3.3V and 5.0V 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 10µF or larger, provides unconditionally
stability for most applications.
TYPICAL APPLICATION CIRCUITS
V
IN
4.7µF +
C
1
IN
SPX2810
ADJ
I
ADJ
50µA
OUT
C
2
V
REF
R
1
V
OUT
V
OUT
= V
REF
(1+R
2
/R
1
) +I
ADJ
R
2
R
2
Date: 9/8/04
SPX2810 1A Low Dropout Linear Regulator
© Copyright 2004 Sipex Corporation
1
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
ELECTRICAL CHARACTERISITCS
V
IN
=V
OUT
+ 1.5V, C
OUT
= 10µF, at I
OUT
= 10mA, T
A
= 25°C, unless otherwise specified. Limits in
Boldface
applies
over the full operating temperature range.
SPX2810A
PARAMETER
1.5V Version
Output Voltage
2.5V Version
Output Voltage
3.0V Version
Output Voltage
3.3V Version
Output Voltage
5.0V Version
Output Voltage
All Output Options
Reference Voltage
Min Load Current
Line Regulation
Load Regulation
Dropout Voltage
(Note 1)
Current Limit
Long Term Stability
Thermal Regulation
RMS Output Noise
Thermal Resistance
I
OUT
=10mA, V
IN
= V
OUT
+3V
10≤ I
OUT
≤
1A, 1.5V≤ (V
IN
-V
OUT
)≤ 5.75V
1.5≤(V
IN
- V
OUT
)≤5.75V
2.75≤V
IN
≤
7V, I
OUT
=T
J
=25°C (Note 2)
(V
IN
- V
OUT
)=3.0V, 10mA≤I
OUT
≤
1A,
T
J
=25°C (Note 2)
I
OUT
=1A
V
IN
=7V,1.4≤(V
IN
-V
OUT
)
T
A
=25°C, 1000Hrs
25°C, 20mS Pulse
T
A
=25°C, 10Hz≤f≤10kHz
TO-220 Junction to Tab
TO-220 Junction to Ambient
TO-220 Junction to Tab
TO-220 Juinction to Ambient
TO-220 Junction to Tab
TO-220 Junction to Ambient
SOT-223 Junction Tab
TO-220 Junction to Ambient
1.2
1.238
1.225
1.250
5
0.005
0.05
1.1
2.0
0.3
0.01
0.003
3.0
60
3.0
60
6
126
15
156
1.0
0.02
1.263
1.281
10
0.2
0.3
1.2
1.2
1.225
1.212
1.250
5
0.005
0.05
1.1
2.0
0.3
0.01
0.003
3.0
60
3.0
60
6
126
15
156
1.0
0.02
1.275
1.288
10
0.2
0.2
1.2
V
mA
%
%
V
A
%
%/Ω
%
°C/W
°C/W
°C/W
°C/W
°CW
°C/W
0
≤
I
OUT
= 1A, 6.5V
≤
V
IN
≤
12V
4.950
4.900
5.0
5.050
5.100
4.900
4.650
5.0
5.100
5.150
V
0
≤
I
OUT
= 1A, 4.8V
≤
V
IN
≤
10V
3.267
3.234
3.3
3.333
3.366
3.234
3.069
3.3
3.366
3.399
V
0
≤
I
OUT
= 1A, 4.5V
≤
V
IN
≤
10V
2.970
2.940
3.0
3.030
3.060
2.940
2.790
3.0
3.060
3.090
V
0
≤
I
OUT
= 1A, 4.0V
≤
V
IN
≤
10V
2.475
2.450
2.5
2.525
2.550
2.450
2.425
2.5
2.550
2.575
V
0
≤
I
OUT
= 1A, 3.3V
≤
V
IN
≤
10V
1.485
1.470
1.5
1.515
1.530
1.470
1.455
1.5
1.530
1.545
V
CONDITIONS
MIN
TYP
MAX
MIN
SPX2810
TYP
MAX
UNITS
NOTES:
Note 1: 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 2: 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.
Date: 9/8/04
SPX2810 / SPX2810A 1A Low Dropout Linear Regulator
© Copyright 2004 Sipex Corporation
2
TYPICAL PERFORMANCE CHARACTERISTICS
3.320
3.315
3.310
3.305
3.300
3.295
3.290
3.285
3.280
10
100
Output Current (A)
1000
Line Regulation at 25°C
Output Voltage (V)
3.330
Series 1
Series 2
Vout (V)
3.320
3.310
3.300
4.8
9.8
Vin (V)
14.8
Figure 1. Load Regulation for SPX2810M3-3.3;
V
IN
=4.8V, C
OUT
=2.2µF
Figure 2. Line Regulation for SPX2810M3--3.3;
V
IN
=4.8V, C
OUT
=2.2µF
Current Limit VS Temp
Dropout Voltage (V)
Current Limit (A)
1.3
1.2
1.1
1.0
0.9
100
200
300
400
500
600
700
800
900
1000
Output Current (mA)
2.00
1.50
1.00
0.50
0.00
-50
Series 1
Series 2
-25
0
25
50
75
100 125
Temp (°C)
Figure 3. Dropout Voltage vs Output Current for
SPX2810M3-3.3; V
IN
=4.89V, C
OUT
=10µF
Figure 4. Current Limit for SP1202M3-3.3; V
IN
=4.8V,
C
IN
=C
OUT
=1.0µF, I
OUT
pulsed from 10mA to Current
Limit
Output Devation
(mV)
100
0
125°C
22µF
-100
15
Indicating Current
Limit Starts
Output Current
(A)
10
0.5
0
V = 4.0V
V =3.3V Fixed
1 =10mA
C =1µF Ten Cap
C =2.2µF Ten Cap
IN
IN
O
IN
OUT
0
0.1
0.2
0.3
0.4 0.5 0.6
Time (ms)
0.7
0.8 0.9
1.0
Figure 5. Current Limit for SPX2810M3-3.3, Output
Voltage Deviation, (I
OUT
pulsed from 10mA to 1A).
Date: 9/8/04
SPX2810 1A Low Dropout Linear Regulator
© Copyright 2004 Sipex Corporation
3
APPLICATION INFORMATION
Output Capacitor
To ensure the stability of the SPX1202, an
output capacitor of at least 10µF (tantalum or
ceramic) or 50µF (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 0.5Ω or less. A
larger value of output capacitance (up to 100µF)
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 <137°C.
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.
50 X 50mm
35 X 17mm
16 X 10mm
Figure 7. Substrate Layout for SOT-223 for thermal
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
© Copyright 2004 Sipex Corporation
Date: 9/8/04
SPX2810 / SPX2810A 1A Low Dropout Linear Regulator
4
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 2.2µF 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
PC BOARD
AREA mm
2
TOPSIDE COPPER
AREA mm
2
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
BACKSIDE COPPER
AREA mm
2
THERMAL RESISTANCE
JUNCTION TO AMBIENT
°C/W
2500
2500
2500
2500
2500
1600
2500
2500
1600
900
900
2500
1250
950
2500
1800
600
1250
915
600
240
240
2500
2500
2500
0
0
1600
0
0
0
900
0
46
47
49
51
53
55
58
59
67
72
85
TYPICAL APPLICATION CIRCUITS
V
IN
4.7µF +
C
1
IN
SPX2810
ADJ
V
IN
OUT
C
2
R
1
IN
4.7µF +
C
1
SPX2810
ADJ
I
ADJ
50µA
OUT
C
2
V
REF
R
1
V
OUT
I
OUT
=
V
REF
R
1
I
OUT
LOAD
V
OUT
= V
REF
(1+R
2
/R
1
) +I
ADJ
R
2
R
2
Figure 8. 600mA Current Source
Date: 9/8/04
Figure 9. Typical Adjustable Regulator
SPX2810 1A Low Dropout Linear Regulator
© Copyright 2004 Sipex Corporation
5
