Solved by
SPX1587
TM
3A Low Dropout Voltage Regulator
FEATURES
■
Guaranteed 3A Output Current
■
Three Terminal Adjustable or Fixed
1.5V, 1.8V, 2.5V, 3.3V and 5.0V
■
Low Quiescent Current
■
Low Dropout Voltage: 1.1V at 3A
■
Line Regulation: 0.1%
■
Load Regulation: 0.1%
■
Stable with 10uF Ceramic Capacitor
■
Overcurrent and Thermal Protection
■
Available Packages: TO-252,
TO-220, and TO-263
■
Similar to Industry Standard LT1085/
LT1585
SPX1587
3 Pin TO-263
SPX1587
3 Pin TO-220
1
2
3
1
2
3
ADJ/GND V
OUT
V
IN
Now Available in Lead Free Packaging
APPLICATIONS
■
■
■
■
■
■
■
Desktop PC's Servers
Powering VGA and Sound Cards
Cordless Phones
Battery Chargers
Adjustable Power Supplies
Portable Instrumentation
SMPS Post-Regulator
ADJ/GND V
OUT
V
IN
The SPX1587 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 SPX1587 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. SPX1587 is available in adjustable or fixed 1.5V, 1.8V, 2.5V, 3.3V and 5.0V output voltages.
The SPX1587 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.
DESCRIPTION
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
Jan8-07 Rev C
SPX587 Low-Dropout Voltage Regulator
© 2007 Sipex Corporation
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
ABSOLUTE MAXIMUM RATINGS
Specifications are at V
IN
=V
OUT
+ 1.5V, T
A
= 25°C, C
IN
= C
OUT
= 10µF, I
OUT
=10mA, unless otherwise specified. The
the specifications which apply full operating temperature range -40°C to +85°C, unless otherwise specified.
PARAMETER
1.5V Version
Output Voltage
1.8V Version
Output Voltage
2.5V Version
Output Voltage
3.3V Version
Output Voltage
5.0V Version
Output Voltage
All Voltage Options
Reference Voltage
Output Voltage
Temperature Stability
Line Regulation
1.238
1.225
1.250
0.3
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
1.00
1.05
1.10
4
4
50
3.2
60
5
0.01
75
0.03
0.003
3
29.4
3
31.4
6
50
0.1
60
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.3
0.3
0.3
1.2
10
10
120
3.2
1.262
1.275
1.225
1.212
1.250
0.5
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
1.00
1.05
1.10
4
4
50
5
0.01
75
0.03
0.003
3
29.4
3
31.4
6
50
0.1
0.2
0.2
0.2
0.2
0.2
0.3
0.3
0.3
0.3
0.3
1.2
10
10
120
A
%/W
dB
%
%
°C/W
(V
IN
-V
OUT
)=2V
25°C, 30mS pulse
mA
mA
µA
Fixed voltage versions
1.275
1.287
V
%
%
3.0V V
IN
10V,V
OUT
=1.5V
3.3V V
IN
10V,V
OUT
=1.8V
4.25V V
IN
10V,V
OUT
=2.5V
4.75V V
IN
10V,V
OUT
=3.3V
6.50V V
IN
10V,V
OUT
=5.0V
10mA
10mA
10mA
10mA
10mA
I
OUT
I
OUT
I
OUT
I
OUT
I
OUT
3A, V
OUT
=1.5V
3A, V
OUT
=1.8V
3A, V
OUT
=2.5V
3A, V
OUT
=3.3V
3A, V
OUT
=5.0V
4.950
4.900
5.000
5.050
5.100
4.900
4.850
5.000
5.100
5.150
V
3.267
3.234
3.300
3.333
3.366
3.234
3.201
3.300
3.366
3.399
V
2.475
2.450
2.500
2.525
2.550
2.450
2.425
2.500
2.550
2.575
V
1.782
1.764
1.800
1.818
1.836
1.764
1.746
1.800
1.836
1.854
V
1.485
1.470
MIN
TYP
SPX1587A
1.500
1.515
1.530
1.470
1.455
MAX
MIN
TYP
SPX1587
1.500
1.530
1.545
V
MAX
UNITS
CONDITIONS
ELECTRICAL CHARACTERISTICS
denotes
I
OUT
= 10mA, V
IN
=3.5V
10mA I
OUT
3A, 3.0V V
IN
10V
I
OUT
= 10mA, V
IN
=3.8V
10mA I
OUT
3A, 3.3V V
IN
10V
I
OUT
= 10mA, V
IN
=4.5V
10mA I
OUT
3A, 4.25V V
IN
10V
I
OUT
= 10mA, V
IN
=5V
10mA I
OUT
3A, 4.75V V
IN
10V
I
OUT
=10mA, V
IN
=7V
10mA I
OUT
3A, 6.50V V
IN
10V
I
OUT
=10mA, (V
IN
- V
OUT
)= 2V
10mA I
OUT
3A, 1.5V (V
IN
-V
OUT
) 10V
Load Regulation
%
Dropout Voltage
(Note 2)
Minimum Load Current
(Note 4)
Quiescent Current
Adjust Pin Current
Current Limit
Thermal Regulation
Ripple Rejection
Long Term Stability
RMS Output Noise
Thermal Resistance
V
I
OUT
=1A
I
OUT
=2A
I
OUT
=3A
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
Jan8-07 Rev C
SPX587 Low-Dropout Voltage Regulator
© 2007 Sipex Corporation
2
ELECTRICAL CHARACTERISTICS: Continued (Notes)
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.
Note 4: Adjustable Version Only.
TYPICAL PERFORMANCE CHARACTERISTICS
3.325
1.275
1.27
1.25v Adj
3.320
1.265
1.26
Vout (V)
Vout (V)
3.315
1.255
1.25
1.245
1.24
3.310
3.305
1.235
1.23
3.300
4.5
6.5
8.5
10.5
Vin (V)
12.5
14.5
1.225
-50
-30
-10
10
30
Temp (C)
50
70
90
110
130
Figure 1. Line Regulation for SPX1587U-3.3; I
OUT
=10mA
Figure 2. V
OUT
vs Temperature, V
IN
=2.5V, I
OUT
=10mA
2.55
2.54
2.53
Vout (V)
3.38
2.5v Adj
2.5v Fixed
3.36
3.34
3.32
3.3
3.28
3.26
-50
3.3v Adj
3.3v Fixed
2.52
Vout (V)
2.51
2.5
2.49
2.48
2.47
2.46
2.45
-50
-30
-10
10
30
50
70
90
110 130
-30
-10
10
30
50
70
90
110 130
Temp (°C)
Temp (C)
Figure 3. V
IN
=4.0V, I
OUT
=10mA
Jan8-07 Rev C
Figure 4. V
IN
=5.0V, I
OUT
=10mA
SPX587 Low-Dropout Voltage Regulator
© 2007 Sipex Corporation
APPLICATION INFORMATION
Output Capacitor
To ensure the stability of the SPX1587, 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 applica-
tions to guarantee stability. The recommended value
for ESR is 0.5 or less. A larger value of output
capacitance (up to 100µF) can improve the load
transient response.
Soldering Methods
The SPX1587 die is attached to the heatsink lead which
exits opposite the input, output, and ground pins.
Thermal Characteristics
The SPX1587 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 tempera-
ture 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 resistance of
the SPX1587. The actual thermal resistance can be
determined with experimentation.
SPX1587 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
*
JA
(junction-to-ambient thermal resistance)
Maximum junction temperature must not exceed 125°C.
Ripple Rejection
Ripple rejection can be improved by adding a capaci-
tor 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 maxi-
mum. 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).
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.
© 2007 Sipex Corporation
However the value of the ADJ-bypass capacitor
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 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
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 de-
pending 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
Jan8-07 Rev C
SPX587 Low-Dropout Voltage Regulator
APPLICATION INFORMATION: Continued
0
-10
-20
Ripple Rejection, Db
-30
-40
-50
-60
-70
-80
-90
10
V
IN
4.7µF +
C
1
IN
SPX1587
ADJ
OUT
C
2
R
1
I
OUT
LOAD
V
OUT
I
OUT
=
V
REF
R
1
100
1000
10000
100000
1000000
Frequency, Hz
Figure 5. Ripple Rejection; Vin=3.3V, Vout=1.8V (adj.),
Iload=200mA
Figure 6. Current Source
(Note A)
V
IN
SPX1587
IN
OUT
ADJ
5V
V
IN
4.7µF + C
1
IN
SPX1587
ADJ
I
ADJ
50µA
2
OUT
V
REF
R
1
V
OUT
C
2
4.7µF
+
R
1
330
1%
V
OUT
10µF
V
OUT
= V
REF
(1+R
2
/R
1
) +I
ADJ
R
R
2
*C
1
improves ripple rejection.
Z
C
should be ~ R1 at ripple frequency
R
2
1k ,
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
V
IN
(Note A)
+
4.7µF
1K
SPX1587
IN
ADJ
OUT
5V
330W
1%
+
V
IN
ADJ
R
P
Parasitic Line
Resistance
SPX1587
V
OUT
10µF
TTL
Input
2N3904
1k
1k
1%
Connect R to
Case of Regulator R
1
Connect R
2
to Load
R
2
R
L
Note A: V
IN(MIN)
= (Intended V
OUT
) + (V
)
DROPOUT (MAX)
Figure 9. 5V Regulator with Shutdown
Jan8-07 Rev C
Figure 10. Recommended Connections for Best Results
SPX587 Low-Dropout Voltage Regulator
© 2007 Sipex Corporation
5
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