Date: 5/14/04
SPX1583
1.5A Ultra Low Dropout Voltage Regulator
Fast Response, Adjustable & Fixed
FEATURES APPLICATIONS
Low Dropout Voltage 500mV at 1.5A Full Load Current
3.3V to 2.8V ATX Power Supplies
Adjustable Output Down to 1.2V from ATX Power Supply 3.3V to 2.9V for Portable PENTIUM
Processor
Fixed Output Voltages of 3.3V, 2.8V, 2.5V, and 1.5V
5V to 3.5V VRE Supply
Extremely Tight Voltage and Line Regulation
High Efficiency "Green" Computer Systems
Standard 5-Terminal Low Cost TO-220 & TO-263
PRODUCT DESCRIPTION
The SPX1583 is a 1.5A 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 SPX1583 features a low dropout of less than 400mV(typ.) and offers fast transient response. This device is
suitable for Pentium applications requiring 2.8V or 2.5V from 3.3V ATX power supplies, where a 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 SPX1583 is also an excellent choice as a post regulator for switching supplies applications.
The SPX1583 offers full protection against over-current faults, reversed input polarity, over temperature operation and positive and
negative transient voltage.
The SPX1583 is offered in a 5 pin TO-220 and TO-263 compatible with industry standard 5-terminal regulators. For 7A, 5A and 3A
ultra low dropout versions refer to SPX1580, SPX1581 and SPX1582 data sheets respectively.
PIN CONNECTIONS
TO-263-5 (T)
Top View
4 5
SPX1583
1 2 3
1. SENSE
2. ADJ or FIXED
3. V
OUT
4. V
CTRL
5. V
IN
TO-220-5 (U)
Front View
5
4
3
2
1
SPX1583
1. SENSE
2. ADJ or FIXED
3. V
OUT
4. V
CTRL
5. V
IN
Date: 5/14/04
SPX1583
ABSOLUTE MAXIMUM RATINGS
Power Dissipation.................................................... Internally Limited
Input Supply Voltage ..........................................................6V
Lead Temp (soldering, 10 seconds)........................................... 300
C
V
CTRL
Input Voltage ..........................................................13V
Storage Temperature Range ...................................... -65C to +150C
Operating Junction Temperature Range
SPX1583 Control Section .............................................0C to +125C
SPX1583 Power Transistor ...........................................0C to +150C
ELECTRICAL CHARACTERISTICS
at V
S
=14V, T
A
=25
C, Io=10mA, C2=100F, unless otherwise specified. (Note 1)
(Boldface applies over full temperature range).
Parameters Conditions
SPX1583
Min Typ Max
Units
2.5V Version
Output Voltage
V
CTRL
=6.0V to 12V, V
IN
=3.0V to 5.0V, I
O
=10mA
I
O
=10mA to 1.5A
2.450
2.400
2.500 2.550
2.600
V
2.8V Version
Output Voltage
V
CTRL
=6.3V to 12V, V
IN
=3.3V to 12V, I
O
=10mA
I
O
=10mA to 1.5A
2.744
2.688
2.800 2.856
2.912
V
3.3V Version
Output Voltage
V
CTRL
=6.3V to 12V, V
IN
=3.3V to 12V, I
O
=10mA
I
O
=10mA to 1.5A
3.234
3.168
3.300 3.366
3.432
V
All Voltage Options
Reference Voltage
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
1.5A
1.237
1.250 1.263
V
Line Regulation
V
CTRL
=2.5V to 12V, V
IN
=1.75V to 5.5V, I
O
=10mA
V
ADJ
=0V
1.0
3.0
mV
Load Regulation (Note1)
V
CTRL
=2.75V, V
IN
=2.1V, I
O
=10mA to 1.5A,V
ADJ
=0V 1.0 5.0 mV
Dropout Voltage Minimum V
CTRL
(Note2)
(V
CTRL
V
OUT
)
V
ADJ
=0V
V
IN
=2.05V, I
O
=1A
1.00 1.15 V
Dropout Voltage Minimum
V
IN
(Note2)
(V
IN
- V
OUT
)
V
ADJ
=0V
V
IN
=2.75V, I
O
=1.5A
0.40
0.50
V
Current Limit
V
CTRL
=2.75V, V
IN
=2.05V,dV
O
=100mV,V
ADJ
=0V
1.6 A
Minimum Load Current
V
CTRL
=5V, V
IN
=3.3V,V
ADJ
=0V
5 10 mA
Thermal Regulation
30ms Pulse
0.002
0.02
%W
Ripple Rejection
V
CTRL
=3.75V V
IN
=3.75V, I
O
=2.1.5A,V
ADJ
=0V
T
J
=25, V
RIPPLE
=1Vpp at 120Hz
60 80 dB
Control Pin Current
V
ADJ
=0V
V
CTRL
=2.75V, V
IN
=2.05V, I
O
=1.5A
60 120
mA
Adjustable Pin Current
V
CTRL
=2.75V, V
IN
=2.05V,V
ADJ
=0V I
O
=10mA
50 90
A
Junction to Case (
JC
)
3
C/W
TO-220-5
Junction to Ambient (
JA
)
50
C/W
Junction to Case (
JC
)
3
C/W
Thermal Resistance
TO-263-5
Junction to Ambient (
JA
)
60
C/W
The Bold specifications applying to the over full operating temperature range.
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
99% Nominal V
OUT.
Note 3: V
REF
is measured across Adjust pin to Sense pin.
Date: 5/14/04
SPX1583
BLOCK DIAGRAM
APPLICATIONS NOTES
The SPX1583 is designed as a high performance and low cost
solution for application requiring a lower dropout than
traditional NPN regulators.
The SPX1583 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 added benefit this will reduce the heat dissipation, and
lower heatsink and cooling fan cost. A typical application
would use 5V for Vin and 3.3V for V
CTRL
from a motherboard
power supply to provide a nominal 2.5V output. Using the
sense pin allows to Kelvin measure the output, reducing
resistive-associated errors.
The SPX1583 can power the 2.5V core voltage for
microprocessors such as Pentium
, P55C, AMD5k86
and K6
and the IBM PowerPC 603EV and 604EV
processors.
*The reduction of heat dissipation is a result of the increase of the regulator
efficiency (efficiency = V
OUT
/ V
IN
).
Adjustable Regulator Design
1.25V reference voltage is being developed between the
SENSE pin and the ADJ pin of the SPX1583. 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 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 typically 50
A. This ADJ pin
contributes to the final VOUT but is usually neglected.
Connecting the sense pin to the top of the resistor divider will
improve load regulation.
Lowering Noise
Using the SENSE pin to Kelvin the load will increase accuracy
of the output voltage during load regulation. For the fixed
voltage devices, adding a capacitor at the GND pin will
improve transient response. This capacitor is chosen in the
range of 1
F to 0.1F and will depend on the amount of
output capacitance in the system.
PIN DESCRIPTION
1. Sense = Allows Kelvin sense of V
OUT
at the load. (Positive side of the reference voltage of the
device).
2. ADJ = 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.
3. V
OUT
= Power output of the device.
4. V
CTRL
= 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.
5. V
IN
= Output load current is supplied through this pin. V
IN
must be between 0.1V and 0.8V
greater than the output voltage for the device to regulate.
(4) V
CTRL
V
IN
(5)
S.O.A
V
OUT
(3)
LIMIT
SENSE
CURRENT
LIMIT
AMPLIFIER
THERMAL OVERLOAD
VOLTAGE
REGULATION
AMPLIFIER
V
REF
SENSE (1)
ADJ (2)
Date: 5/14/04
SPX1583
TYPICAL APPLICATION
SPX1583
SENSE
ADJ
V
IN
V
CTRL
R1
124
C4
2 X 330uF
C2
10uF
C1
330uF
5V
V
CTRL
3.3V
V
IN
C3
.033uF
(1) V
CTRL
needed when V
IN
< 5V.
(2) V
OUT
= V
REF
(1 + R2/ R1) + I
ADJ
R2.
(3) V
REF
is measured across adjust to sense.
2.5V
V
OUT
R2
124
V
OUT
Fig. 1 Adjustable Regulator
SPX1583
SENSE
GND
V
IN
V
CTRL
C4
2 X 330uF
C2
10uF
C1
330uF
5V
V
CTRL
3.3V
V
IN
(1) V
CTRL
is needed when V
IN
<5V.
Fig.2 Typical Fixed Regulator
2.5V
V
OUT
V
OUT
Date: 5/14/04
SPX1583
ORDERING INFORMATION
Ordering No.
Precision
Output Voltages
Packages
SPX1583U 0.6% Adj
5 Lead TO-220
SPX1583U-1.5 0.6% 1.5V
5 Lead TO-220
SPX1583U-2.5 0.6% 2.5V
5 Lead TO-220
SPX1583U-3.0 0.6% 3.0V
5 Lead TO-220
SPX1583U-3.3 0.6% 3.3V
5 Lead TO-220
SPX1583T 0.6% Adj
5 Lead TO-263
SPX1583T-1.5 0.6% 1.5V
5 Lead TO-263
SPX1583T-2.5 0.6% 2.5V
5 Lead TO-263
SPX1583T-3.0 0.6% 3.0V
5 Lead TO-263
SPX1583T-3.3 0.6% 3.3V
5 Lead TO-263
ANALOG EXCELLENCE
Sipex Corporation
Headquarters and Main Offices:
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 935-7600
FAX: (408) 934-7500
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described
hereing; neither does it convey any license under its patent rights nor the rights of others.
Corporation
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