BAYLI B1585T-ADJ, B1585T-5, B1585T-3.3, B1585T-3.0, B1585T-2.5 Datasheet

Bay Linear, Inc

2478 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

5.0A Low Dropout Voltage Regulator

B1585

Adjustable & Fix Output

Pin Connection

Ordering Information

Devices Package Temp.

B1585T TO-220

0 °C to 70 °C

B1585S TO-263

0 °C to 70 °C

B1585j LPDD

0 °C to 70 °C

PLDD (J)

Description

The Bay Linear B1585 is Monolithic low power 5.0A
Adjustable and fixed NPN voltage regulator that are easy to
use with minimum external components. It is suitable for
applications requiring a well-regulated positive output voltage
with low input-output differential voltage requirements and
output voltage 1.5V, 2.5V, 3.0V, 3.3V, or 5V.

The B1585 Outstanding features include full power usage up
to 5.0Amp of load current internal current limiting and thermal
shutdown. Other fixed versions are also available consult with
factory.

The B1585 is offered in 3-pin TO-220, LPDD & TO-263
packages compatible with other 3 terminal regulators. For 7A
Low dropout Regulator refer to the B1584 data sheet.

Features

• Adjustable Output Down to 1.2V

• Fixed Output Voltages 2.5V, 3.0V 3.3V,

and 5.0V

• Output Current of 5.0A

• Low Dropout Voltage 1.1V Typ.

• Current & Thermal Limiting

• Standard 3-Terminal Low Cost TO-220,

LPDD, & D

2

Packages

•

Similar to industry Standard
LT1084/LT1585

Applications

• 3.3V to 2.5V for Pentium Processor

• SMPS Post Regulator

• High Efficiency “Green” Computer

Systems

• High Efficiency Linear Power Supplies

• 5V to 3.XXV fro Pentium Processor

• Battery Charger

Top View

TO - 263 - 3 (S)

1

Bay Linear

2

3

Top View

TO - 263 -

1

Bay Linear

2

3

Bay Linear

Bay LinearBay Linear

Bay Linear

Inspire the Linear Power

Inspire the Linear PowerInspire the Linear Power

Inspire the Linear Power

Bay Linear, Inc

2478 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

B1585

Absolute Maximum Rating

Parameter Symbol Value Unit

Maximum Input Voltage V

IN

7 V

Power Dissipation P

O

Internally Limited W

Thermal Resistance Junction to Case

θ

JC

3

Thermal Resistance Junction to
Ambient

θ

JA

50

°

C/W

Operating Junction
Temperature Range
Control Section
Power Transistor

T

J

0 to 125
0 to 150

Storage Temperature Range T

STG

-65 to 150

Lead Temperature (Soldering 10
Sec.)

T

LEAD

260

°

C

Electrical Characteristics

(VIN = 4.75V to 5.25V; IO = 10mA to 5.0Amp, unless otherwise specified)

Parameter Symbol Conditions MIN TYP MAX UNIT

1.485 1.515

0<I

OUT

<5A, 3.3V<VIN<7V, T= 25 °C

0<I

OUT

<5A, 3.3V<VIN<7V, Over Temp.

1.475

1.5

1.525

2.475 2.525

0<I

OUT

<5A, 4.0V<VIN<7V, T= 25 °C

0<I

OUT

<5A, 4.0V<VIN<7V, Over Temp.

2.460

2.5

2.540

2.970 3.030

0<I

OUT

<5A, 4.5V<VIN<7V, T= 25 °C

0<I

OUT

<5A, 4.5V<VIN<7V, Over Temp.

2.950

3.0

3.050

3.267 3.333

0<I

OUT

<5A, 4.8V<VIN<7V, T= 25 °C

0<I

OUT

<5A, 4.8V<VIN<7V, Over Temp.

3.247

3.3

3.353

4.950 5.050

Output Voltage V

O

0<I

OUT

<5A, 6.5V<VIN<7V, T= 25 °C

0<I

OUT

<5A, 6.5V<VIN<7V, Over Temp.

4.920

5.0

5.080

V

1.238 1.262 Reference Voltage V

ref

VIN<7V, 1.5V<VIN<5.75, 10mA<I

out

<5Amp

1.230

1.250

1.270

V

Line Regulation (1) REG

(line)

IO = 10mA, VIN =5V, T= 25 °C

0.04 0.2

0.08 0.40 Load Regulation (1) REG

(LOAD)

IO = 10mA, VIN =5V, T= 25 °C

%

1.0 Dropout Voltage V

D

T= 25 °C
Over Temperature

1.1 1.3

V

Minimum load Cu rrent I

min

5.0 10 mA

Current Limit I

S

(Vin-V

out

)=3V 5.5 6.8 A

Ground Pin Current I

Q

VIN =5V 6 10 mA

Temperature Stability T

S

IO = 10mA, VIN =5V 0.5 %

Thermal Regulation

T= 25 °C, 30ms pulse

0.003 %/W

Ripple Rejection R

A

T= 25 °C, VIN =5V

60 80 dB

Thermal Resistance - TO-220 Junction to Tab

Junction to Ambient
DD Package Junction to Tab
Junction to Ambient

3.0
60

3.0
60

3.0
60

3.0
60

°

C/W

Note:

Output Switch tests are performed under pulsed conditions to minimize power dissipation

Bay Linear, Inc

2478 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone] www.baylinear.com

B1585

APPLICATION HINTS

The Bay Linear B1585 incorporates protection against
over-current faults, reversed load insertion, over
temperature operation, and positive and nega t ive
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

R

* R1 )

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 use, 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

= 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 B1585 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

IN

= 7V, V

OUT

= 5V, I

OUT

= 5A, TA = 90°C,

θ

CASE

=

1°C/W (no external heat sink, no wind)

Power dissipation under these conditions
P

D

= (VIN – V

OUT

) * I

OUT

= 15W

Junction Temperature
T

J

= TA + PD * (

θ

CASE

+

θ

JC

)

For the Control Section
T

J

= 90°C + 15W*(1°C/W + 0.6°C/W) = 114°C

114°C < T

JUNCTION MAX

for the control section.

For the Power Section
T

J

= 90°C + 15W*(1°C/W + 1.6°C/W) = 129°C

129°C < T

JUNCTION MAX

for the power transistor.

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