Bay Linear
Inspire the Linear Power
4.0A Low Dropout Voltage Regulator |
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B1587 |
Adjustable & Fix Output |
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Description
The Bay Linear B1587 is Monolithic low power 4.0A 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 B1587 Outstanding features include full power usage up to 4.0Amp of load current internal current limiting and thermal shutdown. Other fixed versions are also available consult with factory. The B1587 is offer in a new LPDD (Low Profile TO263) package from 4.47 mm (DD) thickness down to only 1.27 mm (LPDD) total thickness.
Features
•Adjustable Output Down to 1.2V
•Fixed Output Voltages 2.5V, 3.0V 3.3V, and 5.0V
•Output Current of 4.0A
•Low Dropout Voltage 1.1V Typ.
•Current & Thermal Limiting
•Standard 3-Terminal Low Cost TO-220, D2, D Packages
•Similar to industry Standard LT1085/LT1587/LT1585
The B1587 is offered in a 3-pin TO-220, TO-263 & TO-252 packages compatible with other 3 terminal regulators. For 5A Low dropout Regulator refer to the B1585 data sheet.
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 for Pentium Processor
•Battery Charger
Pin Connection |
Ordering Information |
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Devices |
Package |
Temp. |
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B1587T |
TO-220 |
0 ° C to 70 ° C |
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B1587S |
TO-263 |
0 ° C to 70 ° C |
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B1587D |
TO-252 |
0 ° C to 70 ° C |
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B1587J |
LPDD |
0 ° C to 70 ° C |
TO-263-3 (S) |
TO-252 (D) |
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Bay Linear
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ADJ/
V OU V
GND T IN
Front View
Top View
LPDD (J)
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 606-5950, Fax: (925) 940-9556 |
www.baylinear.com |
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B1587 |
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Absolute Maximum Rating |
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Parameter |
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Symbol |
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Value |
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Unit |
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Maximum Input Voltage |
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VIN |
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7 |
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V |
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Power Dissipation |
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PO |
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Internally Limited |
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W |
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Thermal Resistance Junction to Case |
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θ JC |
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3 |
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° C/W |
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Thermal Resistance Junction to |
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θ JA |
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50 |
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Ambient |
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Operating Junction |
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TJ |
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° C |
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Temperature Range |
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Control Section |
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0 to 125 |
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Power Transistor |
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0 to 150 |
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Storage Temperature Range |
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TSTG |
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-65 to 150 |
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Lead Temperature (Soldering 10 |
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TLEAD |
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260 |
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Sec.) |
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Electrical Characteristics |
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(VIN = 4.75V to 5.25V; IO = 10mA to 4.0Amp, unless otherwise specified) |
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Parameter |
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Symbol |
Conditions |
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MIN |
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TYP |
MAX |
UNIT |
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Output Voltage |
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VO |
0<IOUT<4A, 3.3V<VIN<7V, T= 25 ° C |
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1.485 |
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1.5 |
1.515 |
V |
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0<IOUT<4A, 3.3V<VIN<7V, Over Temp. |
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1.475 |
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1.525 |
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0<IOUT<4A, 4.0V<VIN<7V, T= 25 ° C |
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2.475 |
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2.5 |
2.525 |
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0<IOUT<4A, 4.0V<VIN<7V, Over Temp. |
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2.460 |
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2.540 |
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0<IOUT<4A, 4.5V<VIN<7V, T= 25 ° C |
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2.970 |
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3.0 |
3.030 |
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0<IOUT<4A, 4.5V<VIN<7V, Over Temp. |
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2.950 |
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3.050 |
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0<IOUT<4A, 4.8V<VIN<7V, T= 25 ° C |
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3.267 |
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3.3 |
3.333 |
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0<IOUT<4A, 4.8V<VIN<7V, Over Temp. |
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3.247 |
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3.353 |
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0<IOUT<4A, 6.5V<VIN<7V, T= 25 ° C |
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4.950 |
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5.0 |
5.050 |
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0<IOUT<4A, 6.5V<VIN<7V, Over Temp. |
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4.920 |
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5.080 |
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Reference Voltage |
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Vref |
VIN<7V, 1.5V<VIN<5.75, 10Ma<Iout<4Amp |
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1.238 |
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1.250 |
1.262 |
V |
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1.230 |
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1.270 |
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Line Regulation (1) |
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REG (line) |
IO = 10mA, VIN =5V, T= 25 ° C |
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0.04 |
0.2 |
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Load Regulation (1) |
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REG (LOAD) |
IO = 10mA, VIN =5V, T= 25 ° C |
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0.08 |
0.40 |
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Dropout Voltage |
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VD |
T= 25 ° C, IOUT=3A |
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1.0 |
1.1 |
V |
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T= 25 ° C, IOUT=4A |
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1.1 |
1.3 |
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Minimum load Current |
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Imin |
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5 |
10 |
mA |
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Current Limit |
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IS |
(Vin-Vout)=3V |
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3 |
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5 |
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A |
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Ground Pin Current |
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IQ |
VIN =5V |
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5 |
10 |
mA |
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Temperature Stability |
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TS |
IO = 10mA, VIN =5V |
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0.5 |
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% |
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Thermal Regulation |
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T= 25 ° C, 30ms pulse |
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0.003 |
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%/W |
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Ripple Rejection |
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RA |
T= 25 ° C, VIN =5V |
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60 |
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75 |
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dB |
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Thermal Resistance |
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- |
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TO-220 |
Junction to Tab |
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3.0 |
3.0 |
° C/W |
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Junction to Ambient |
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60 |
60 |
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DD Package |
Junction to Tab |
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3.0 |
3.0 |
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Junction to Ambient |
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60 |
60 |
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Note: Output Switch tests are performed under pulsed conditions to minimize power dissipation
Bay Linear, Inc 2478 Armstrong Street, Livermore, CA 94550 Tel: (925) 606-5950, Fax: (925) 940-9556 |
www.baylinear.com |
APPLICATION HINTS
The Bay Linear B1587 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), |
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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
B1587
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 B1587 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 = 10V, VOUT = 5V, IOUT = 4A, 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: (925) 606-5950, Fax: (925) 940-9556 |
www.baylinear.com |