SPX1582
3A Ultra Low Dropout Voltage Regulator
Fast Response, Adjustable & Fixed
FEATURES
■
Low Dropout Voltage 500mV at 3A Full Load Current
■
Adjustable Ouput Down to 1.25V from ATX Power Supply
■
Fixed Output Voltages of 3.3V and 2.5V
■
Extremely Tight Load and Line Regulation
■
Standard 5-Terminal Low Cost TO-220 and TO-263
ADJ OR FIXED
SENSE
V
CNTRL
V
OUT
V
IN
SPX1582
5 Pin TO-263
SPX1582
5 Pin TO-220
1 2 3 4 5
1 2 3 4 5
APPLICATIONS
■
3.3V to 2.8V ATX Power Supplies
■
3.3V to 2.9V for Portable PENTIUM
TM
Processor
■
5V to 3.5V VRE Supply
■
High efficiency "Green" Computer Systems
ADJ OR FIXED
SENSE
Now Available in Lead Free Packaging
DESCRIPTION
The SPX1582 is a 3A Low Dropout Regulator with extremely low dropout voltage. The adjustable version requires only
two external resistors to set the output voltage. The fixed version has a preset output of 3.3V, 2.8V or 2.5V and does
not require any external resistors. The SPX1582 features a low dropout of 400mV(Typ.) and offers fast transient
response. This device is suitable for Pentium applications requiring 2.8V, 2.5V from 3.3V ATX power supplies, where
low current input voltage 1V greater than the output voltage is needed. With an external sense pin the load regulation
is less than 1mV. This device is an excellent choice for the use in powering low voltage microprocessors that require
a lower dropout, fast transient response to regulate from 3.3V and 5V supplies. The SPX1582 is also an excellent choice
as a post regulator for switching supply applications.
The SPX1582 offers protection against over-current faults, reversed input polarity, over temperature operation and
positive or negative transient voltages.
The SPX1582 is offered in a 5 pin TO-220 and TO-263 compatible with industry standard 5-terminal regulators. For
5A, 3A and 1.5A ultra low dropout versions refer to SPX1581, SPX1582 and SPX1583 data sheets respectively.
TYPICAL APPLICATIONS CIRCUIT
3.3V
V
IN
5V
V
CTRL
V
IN
C1
330μF
V
CTRL
5
SPX1582
4
2
ADJ
C2
10μF
C3
.033μF
R2
124Ω
1
SENSE
R1
124Ω
C4
2x330μF
5V
V
CTRL
3
V
OUT
2.5V
V
OUT
3.3V
V
IN
V
IN
C1
330μF
V
CTRL
5
SPX1582
4
2
3
1
V
OUT
V
CNTRL
V
OUT
V
IN
2.5V
V
OUT
SENSE
GND
C2
10μF
C4
2x330μF
(1) V
CTRL
needed when V
IN
< 5V.
(2) V
OUT
= V
REF
(1+R
2
/R
1
)+I
ADJ
R
2
.
(3) V
REF
is measured across adjust to sense.
(1) V
CTRL
needed when V
IN
< 5V.
Adjustable Regulator
Typical Fixed Regulator
Jun 17-06 Rev F
SPX1582 3A Ultra Low Dropout Voltage Regulator
© 2006 Sipex Corporation
1
ABSOLUTE MAXIMUM RATINGS
Power Dissipation ..................................... Internally Limited
Storage Temperature Range ..................... -65°C to +150°C
Operating Junction Temperature Range
SPX1582 Control Section ............................. 0°C to +125°C
SPX1582 Power Transistor .......................... 0°C to +150°C
Input Supply Voltage ................................................ 6V
V
CTRL
Input Voltage ....................................................... 13V
ELECTRICAL CHARACTERISTICS
Electrical characteristics at V
OUT
= V
SENSE
, V
ADJ
= 0V, T
A
=25°C, C
CTL
= C
PWR
= C
OUT
= 33μF tantalum cap unless
otherwise specified. The
♦
denotes the specifications which apply over full temperature range -40°C to +85°C, unless
otherwise specified.
PARAMETER
2.5V Version
Output Voltage
2.8V Version
Output Voltage
3.3V Version
Output Voltage
All Voltage Options
Reference Voltage
Line Regulation
Load Regulation (Note 1)
0V
Dropout Voltage Min. V
CTRL
(Note 2) (V
IN
- V
OUT
)
Dropout Voltage Min. V
IN
(Note 2) (V
IN
- V
OUT
)
Current Limit
Minimum Load Current
Thermal Regulation
Ripple Rejection
Control Pin Current
Adjustble Pin Current
Thermal Resistance
TO-220-5
Thermal Resistance
TO-263-5
3.1
5
0.002
80
60
50
120
3
29.3
3
31.2
10
0.02
1.0
1.0
3.0
5.0
MIN
2.450
2.400
2.744
2.688
3.234
3.168
1.238
TYP
2.5
MAX
2.550
2.600
2.856
2.912
3.366
3.432
1.263
UNITS
V
CONDITIONS
V
CTRL
= 6.0V to 12V, V
IN
= 3.0V to 5.0V, I
O
=10mA
♦
I
O
= 10mA to 3A
V
CTRL
= 6.3V to 12V, V
IN
=3.3V + 0.8V, I
O
=10mA
♦
I
O
= 10mA to 3A
V
CTRL
= 6.3V to 12V, V
IN
= 3.3V + 0.8V, I
O
=10mA
♦
I
O
= 10mA to 3A
V
CTRL
= 2.75V, V
IN
= 2.00V, I
O
= 10mA
V
CTRL
=2.7V to 12V,V
IN
= 2.05V to 5.5V,I
O
=10mA to 7A
V
CTRL
= 2.5V to 12V, V
IN
= 1.75 to 5.5V, I
O
=10mA
♦
V
ADJ
= 0V
♦
V
CTRL
= 2.75V, V
IN
= V
OUT +
1.5V, I
O
=10mA to 3A, V
ADJ
=
2.8
V
3.3
3.3
1.25
V
V
mV
mV
1.05
0.40
1.18
0.50
V
V
A
mA
%/W
dB
mA
μA
°C/W
°C/W
°C/W
°C/W
V
ADJ
= 0V
V
IN
= 2.05V, I
O
= 1A
V
ADJ
= 0V
V
IN
= 2.75V, I
O
= 3A
V
CTRL
= 2.75V, V
IN
= 2.05V,
Δ
V
OUT
= 100mV, V
ADJ
= 0V
♦
V
CTRL
= 5V, V
IN
=3.3V, V
ADJ
=0V
30ms Pulse
V
CTRL
= 3.75V, V
IN
= 3.75V, I
O
= 2.3A, V
ADJ
=0V
T
J
=25, V
RIPPLE
=1Vpp at 120Hz
♦
V
ADJ
= 0V
V
CTRL
= 2.75V, V
IN
= 2.05V, I
O
= 3A
V
CTRL
= 2.75V, V
IN
= 2.05V, V
ADJ
=0V, I
O
= 10mA
♦
Junction to Case
(θ
JC
)
Junction to Ambient (θ
JA
)
Junction to Case (θ
JC
)
Junction to Ambient (θ
JA
)
60
120
Note 1:
Low duty cycle pulse testing with Kelvin connections is required to order to maintain accurate data.
Note 2:
Dropout voltage is defined as the minimum differential between V
IN
and V
OUT
or V
CTRL
and V
OUT
required to
maintain regulation at V
OUT
95% Nominal V
OUT
.
Note 3:
V
REF
is measured across Adjust pin to Sense pin.
Jun 17-06 Rev F
SPX1582 3A Ultra Low Dropout Voltage Regulator
© 2006 Sipex Corporation
2
PIN DESCRIPTION
PIN NUMBER
1
2
PIN NAME
SENSE
ADJ
DESCRIPTION
Allows Kelvin sense of V
OUT
at the load. (Positive side of the
reference voltage of the device).
Negative side of the reference voltage for the device. Adding a small
bypass capacitor from the ADJ pin to ground will improve the transient
response.
Power output of the device.
Supply pin for the control circuitry of the device. The current flow into this
pin will be about 1% of the output current. V
CTRL
must be between 1.0V
and 1.3V greater than the output voltage for the device to regulate.
Output load current is supplied through this pin. V
IN
must be between 0.1V
and 0.8V greater than the output voltage for this device to regulate.
3
4
V
OUT
V
CTRL
5
V
IN
Note that TAB is internally connected to Pin 3.
FUNCTIONAL DIAGRAM
(4) V
CTRL
V
IN
(5)
CURRENT
LIMIT
AMPLIFIER
LIMIT
SENSE
V
OUT
(3)
THERMAL OVERLOAD
SENSE (1)
VOLTAGE
REGULATION
AMPLIFIER
V
REF
ADJ (2)
Jun 17-06 Rev F
SPX1582 3A Ultra Low Dropout Voltage Regulator
© 2006 Sipex Corporation
3
APPLICATION INFORMATION
The SPX1582 is designed as a high performance
and low cost solution for applications requiring
a lower dropout than traditional NPN regulators.
The SPX1582 uses a separate input voltage V
CTRL
( V
CTRL
≥
V
OUT
+ 1.3V) to minimize the dropout
voltage. This allows the 2.5V power for the load
to come from a 3.3V system supply. As an added
benefit this will reduce the heat dissipation*, and
lower heatsink and cooling fan costs.
The SPX1582 can power the 2.5V core voltage
for microprocessors such as a PentiumPC
TM
,
P55C
TM
, AMD5k86
TM
and K6
TM
and the IBM
PowerPC
TM
603EV and 604EV processors.
A typical application would use 3.3V for V
IN
and
5.0V for V
CTRL
from a motherboard power sup-
ply to provide a nominal 2.5V output. Using the
sense pin provides a Kelvin measurement of
output for reducing resistance-associated errors.
Power Up Sequencing
The SPX1582 requires a power up sequence in
that V
IN
must be applied before V
CTRL
to prevent
a latchup condition. If this is not possible, then a
10Ω series resistor should be added to the V
CTRL
input to prevent the device from entering into
latchup if V
CTRL
is applied before V
IN
.
Adjustable Regulator Design
1.25V reference voltage is being developed be-
tween the SENSE pin and the ADJ pin of the
SPX1582. Adding two external resistors (see fig
1.) will allow setting the output voltage from
1.25V to 6V. R
1
is chosen so that this current is
specified at a minimum load current of 10mA.
R
2
is given by the formula:
V
OUT
= V
REF
(1+ R
2
/R
1
) + I
ADJ
(R
2
).
The current flowing from the ADJ pin is typicaly
50μA. This ADJ pin contributes to the final
V
OUT
but is usually neglected. Connecting the
sense pin to the top of the resistor divider will
improve load regulation.
Lowering Noise
For the fixed voltage device, adding a capacitor
at the GND pin will improve transient response.
This capacitor is chosen in the range of 1μF to
0.1μF and will depend on the amount of output
capacitance in the system.
Jun 17-06 Rev F
SPX1582 3A Ultra Low Dropout Voltage Regulator
© 2006 Sipex Corporation
4
PACKAGE: 5 Pin TO-220
Controlling Dimension is Inches
Jun 17-06 Rev F
SPX1582 3A Ultra Low Dropout Voltage Regulator
© 2006 Sipex Corporation
5
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