Sipex Corporation SPX2870T-5.0, SPX2870U, SPX2870U-2.5, SPX2870U-3.3, SPX2870U-5.0 Datasheet

6.5A Low Dropout Voltage Regulator
Adjustable & Fixed Output,

SPX2870

Fast Response

FEATURES

Adjustable Output Down To 1.2V

•

Fixed Output Voltages 2.5, 3.3 & 5.0V

•

Output Current of 6.5A

•

Low Dropout Voltage 1.1V Typ.

•

Extremely Tight Load And Line Regulation

•

Current & Thermal Limiting

•

Standard 3-Terminal Low Cost TO-220 & TO-263

•

PRODUCT DESCRIPTION

The SPX2870 are low power 6.5A adjustable and fixed voltage regulators that are very easy to use. It requires only 2 external resistors
to set the output voltage for adjustable version. The SPX2870 are designed for low voltage applications that offers lower dropout
voltage and faster transient response. This device is an excellent choice for use in powering low voltage microprocessor that require a
lower dropout, faster transient response to regulate from +2.5V to 3.8V supplies and as a post regulator for switching supplies
applications. The SPX2870 features low dropout of a maximum 1.5 volts.

The SPX2870 offers full protection against over-current faults, reversed input polarity, reversed load insertion, and positive and
negative transient voltage. On-Chip trimming adjusts the reference voltage to 1%. The I
increases efficiency.

The SPX2870 are offered in a 3-pin TO-220 and TO-263 packages compatible with other 3 terminal regulators. For a 8A low dropout
regulator refer to the SPX2880 data sheet.

APPLICATIONS

Powering VGA & Sound Card

•

Power PC Supplies

•

SMPS Post-Regulator

•

High Efficiency “Green” Computer Systems

•

High Efficiency Linear Power Supplies

•

Portable Instrumentation

•

Constant Current Regulators

•

Adjustable Power Supplies

•

Battery charger

•

of this device flows into the load, which

Q

PIN CONNECTIONS

TO-263-3 (T)

SPX2870

2

V

OUT

Top View

3

V

IN

ADJ/GND

1

ADJ/GND

TO-220-3 (U)

SPX2870

1

23

V

OUT

Front View

V

IN

Rev. 10/30/00

SPX2870

ABSOLUTE MAXIMUM RATINGS

Lead Temp. (Soldering, 10 Seconds) .............................. 300°C Input Voltage........................................................ 10V

Storage Temperature Range ............................ -65° to +150°C Input to Output Voltage Differential .................... 10V
Operating Junction Temperature Range

SPX2870 Control Section.......................... -45°C +125°C

SPX2870 Power Transistor.........................-45°C +150°C

ELECTRICAL CHARACTERISTICS

PARAMETER CONDITIONS Typ SPX2870A SPX2870 UNITS

Min Max Min Max

2.5V Version

3.3V Version

5.0V Version

SPX2870-5.0V, 0 ≤ I

(MAX)

REF

)

V

1.5V≤ (V

1.5V≤ (V

)) 2.75V≤VIN ≤7V, I

REF(VIN

(Note 3)
V

REF(IOUT

))

10mA≤I

0≤I

∆

I

VIN=7V 6 6.9 6.9 A Current Limit

1.4V ≤ (V

7V, P≤ P

≤

IN

IN

IN

≤7V, I

IN

OUT

OUT

≤5A, VIN=7V, TJ=25ºC (Note 2)

OUT

V

=1% I

REF

IN

All Voltage Options

Reference Voltage (V

Min. Load Current (Note 3)

Line Regulation (∆V

Load Regulation(∆V

Dropout Voltage

I

OUT

Long Term Stability TA=125ºC, 1000 Hrs. 0.3

(NOTE 1) at I

< 6.5A, 4.0V<VIN<7V 2.5

OUT

< 6.5A, 4.8V<VIN<7V 3.3

OUT

≤ 6.5A, 6.5V≤V

OUT

MAX

-V

)≤5.75V, 10mA≤I

OUT

–V

)≤5.75V

OUT

=10mA, TJ=25ºC

OUT

=0mA, TJ=25ºC (Note 2)

≤5A, (Vin-V

– V

OUT

)=3V, TJ=25ºC (Note 3)

OUT

OUT

OUT

) (Note3)

= 10mA, TA=25°C, unless otherwise specified.

OUT

7V

≤

IN

5 4.950 5.050 4.9 5.1 V Output Voltage (Note 2)

1.250 1.225 1.270 1.225 1.270

5A

≤

OUT

5 10 10

0.005 0.2 0.2

0.005 0.2 0.2

0.05 0.3 0.3

0.05 0.3 0.3

= 6.5A (Note 3)

1.5 1.5 V

< 6.5A (Note 2)

(Note 2)

2.475 2.525 2.45 2.55 V Output Voltage (Note 2) SPX2870-2.5V, 0 < I

2.45 2.55 2.425 2.575

3.267 3.333 3.234 3.366 V Output Voltage (Note 2) SPX2870-3.3V, 0 < I

3.234 3.366 3.069 3.399

4.900 5.100 4.65 5.15

V

V

%

%

1 1 %

Thermal Regulation
(∆V

OUT

(PWR))

Temperature Stability
(∆V

OUT

(T))

=25ºC, 20 ms pulse 0.01 0.020 0.020 %/W

T

A

0.25 %

Output Noise, RMS 10Hz to 10kHz Ta=25ºC 0.003 % VO

Thermal Resistance

Junction to Ambient

DD Package Junction to Tab
Junction to Ambient

The Bold specifications apply to the full operating temperature range.
Note 1: Changes in output voltage due to heating effects are covered under the specification for thermal regulation.
Note 2: Fixed Version Only
Note 3: Adjustable Version Only

3.0 3.0 3.0 TO-220 Junction to Tab

ºC/W

60 60 60

3.0 3.0 3.0

60 60 60

Rev. 10/30/00

SPX2870

APPLICATION HINTS

The SPX2870 incorporates protection against over-current
faults, reversed load insertion, over temperature operation, and
positive and negative transient voltage. However, the use of
an output capacitor is required in order to insure the stability
and the performances.

Stability

The output capacitor is part of the regulator’s frequency
compensation system. Either a 220µF aluminum electrolytic
capacitor or a 47µF solid tantalum capacitor between the
output terminal and ground guarantees stable operation for all
operating conditions.
However, in order to minimize overshoot and undershoot, and
therefore optimize the design, please refer to the section
‘Ripple Rejection’.

Ripple Rejection

Ripple rejection can be improved by adding a capacitor
between the ADJ pin and ground. When ADJ pin bypassing is
used, the value of the output capacitor required increases to its
maximum (220µF for an aluminum electrolytic capacitor, or
47µF for a solid tantalum capacitor). If the ADJ pin is not
bypass, the value of the output capacitor can be lowered to
100µF for an electrolytic aluminum capacitor or 15µF for a
solid tantalum capacitor.
However the value of the ADJ-bypass capacitor should be
chosen with respect to the following equation:
C = 1 / ( 6.28 * F

Where C = value of the capacitor in Farads (select an
equal or larger standard value),
F
R

= ripple frequency in Hz,

R

= value of resistor R1 in Ohms.

1

If an ADJ-bypass capacitor is use, the amplitude of the output
ripple will be independent of the output voltage. If an ADJ­bypass 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
Where M = multiplier for the ripple seen when the ADJ pin
is optimally bypassed.
V

REF

* R1 )

R

REF

= Reference Voltage

Reducing parasitic resistance and inductance

One solution to minimize parasitic resistance and inductance is
to connect in parallel capacitors. This arrangement will
improve the transient response of the power supply if your
system requires rapidly changing current load condition.

Thermal Consideration

Although the SPX2870 offers some limiting circuitry for
overload conditions, it is necessary not to exceed the
maximum junction temperature, and therefore to be careful
about thermal resistance. The heat flow will follow the lowest
resistance path, which is the Junction-to-case thermal
resistance. In order to insure the best thermal flow of the
component, a proper mounting is required. Note that the case
of the device is electrically connected to the output. In case
the case has to be electrically isolated, a thermally conductive
spacer can be used. However do not forget to consider its
contribution to thermal resistance.

Assuming:
V

= 10V, V

IN

θ

Heat Case

= 6°C/W,

OUT

= 5V, I

θ

Heat Case

= 1.5A, TA = 50°C/W,

OUT

= 0.5°C/W, θ JC = 3°C/W

Power dissipation under this condition
P

= (VIN – V

D

OUT

) * I

= 7.5W

OUT

Junction Temperature
T

= TA + PD * (

J

θ

Case – HS

+

+

θ

HS

)

θ

JC

For the Control Sections
T

= 50 + 7.5W*(0.5 +6=3) = 121.25°C

J

121.25°C < T

for the Control & Power Sections.

J(max)

In both case reliable operation is insured by adequate junction
temperature.

Rev. 10/30/00