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

Bay Linear

Inspire the Linear Power

5.0A Low Dropout Voltage Regulator		B1585
Adjustable & Fix Output

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, & D2 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

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

TO-263-3 (S)

Bay Linear

1 2 3

PLDD (J)

Top View

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

VIN

7

V

Power Dissipation

PO

Internally Limited

W

Thermal Resistance Junction to Case

θ JC

3

° C/W

Thermal Resistance Junction to

θ JA

50

Ambient

Operating Junction

TJ

° C

Temperature Range

Control Section

0 to 125

Power Transistor

0 to 150

Storage Temperature Range

TSTG

-65 to 150

Lead Temperature (Soldering 10

TLEAD

260

Sec.)

Electrical Characteristics

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

Parameter

Symbol

Conditions

MIN

TYP

MAX

UNIT

Output Voltage

VO

0<IOUT<5A, 3.3V<VIN<7V, T= 25 ° C

1.485

1.5

1.515

V

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

1.475

1.525

0<IOUT<5A, 4.0V<VIN<7V, T= 25 ° C

2.475

2.5

2.525

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

2.460

2.540

0<IOUT<5A, 4.5V<VIN<7V, T= 25 ° C

2.970

3.0

3.030

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

2.950

3.050

0<IOUT<5A, 4.8V<VIN<7V, T= 25 ° C

3.267

3.3

3.333

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

3.247

3.353

0<IOUT<5A, 6.5V<VIN<7V, T= 25 ° C

4.950

5.0

5.050

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

4.920

5.080

Reference Voltage

Vref

VIN<7V, 1.5V<VIN<5.75, 10mA<Iout<5Amp

1.238

1.250

1.262

V

1.230

1.270

Line Regulation (1)

REG (line)

IO = 10mA, VIN =5V, T= 25 ° C

0.04

0.2

%

Load Regulation (1)

REG (LOAD)

IO = 10mA, VIN =5V, T= 25 ° C

0.08

0.40

Dropout Voltage

VD

T= 25 ° C

1.0

V

Over Temperature

1.1

1.3

Minimum load Current

Imin

5.0

10

mA

Current Limit

IS

(Vin-Vout)=3V

5.5

6.8

A

Ground Pin Current

IQ

VIN =5V

6

10

mA

Temperature Stability

TS

IO = 10mA, VIN =5V

0.5

%

Thermal Regulation

T= 25 ° C, 30ms pulse

0.003

%/W

Ripple Rejection

RA

T= 25 ° C, VIN =5V

60

80

dB

Thermal Resistance

-

TO-220

Junction to Tab

3.0

3.0

° C/W

Junction to Ambient

60

60

DD Package

Junction to Tab

3.0

3.0

Junction to Ambient

60

60

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

APPLICATION HINTS

The Bay Linear B1585 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 220µ F aluminum electrolytic capacitor or a 47µ F 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 (220µ F for an aluminum electrolytic capacitor, or 47µ F for a solid tantalum capacitor). If the ADJ pin is not bypass, the value of the output capacitor can be lowered to 100µ F for an electrolytic aluminum capacitor or 15µ F 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 * FR * R1 )

Where C	= value of the capacitor in Farads (select
an equal or larger standard value),
FR	= ripple frequency in Hz,
R1	= 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 = VOUT / VREF

Where M = multiplier for the ripple seen when the ADJ pin is optimally bypassed.

VREF = Reference Voltage

B1585

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:

VIN = 7V, VOUT = 5V, IOUT = 5A, TA = 90° C, θ CASE= 1° C/W (no external heat sink, no wind)

Power dissipation under these conditions PD = (VIN – VOUT) * IOUT = 15W

Junction Temperature

TJ = TA + PD * (θ CASE+ θ JC)

For the Control Section

TJ = 90° C + 15W*(1° C/W + 0.6° C/W) = 114° C 114° C < TJUNCTION MAX for the control section.

For the Power Section

TJ = 90° C + 15W*(1° C/W + 1.6° C/W) = 129° C 129° C < TJUNCTION MAX for the power transistor.

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

Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: [phone], Fax: [phone]

www.baylinear.com