LND5201 - Linear Dimensions Semiconductor

LND5201

1 A Low Dropout Positive Voltage Regulator

2.5 V, 1 A Regulator

DATA

SHEET

GENERAL DESCRIPTION

• Adjustable or fixed Output

• Output Current of 1A

• Low Dropout, 700mV at 1A Output

Current

• 0.04% Line Regulation

• 0.1% Load Regulation

• 100% Thermal Limit Burn-In

• Fast Transient Response

• Remote Sense

FEATURES

The LND5201 series of positive adjustable and

fixed regulators are designed to provide 1A with

higher efficiency than currently available

devices. All internal circuitry are designed to

operate down to 700mV input to output

differential and the dropout voltage is fully

specified as a function of load current. Dropout

voltage of the device is 100mV at light loads and

rising to 700mV at maximum output current. A

second low current input is required to achieve

this dropout. The LND5201 can also be used as

a single supply device (3-pin version). On-chip

trimming adjusts the reference voltage to 1%.

• High efficiency Linear Regulators

• Post Regulators for Switching

Supplies

• Adjustable Power Supply

TYPICAL APPLICATION DATA APPLICATIONS

LND5201

VOUT = VREF (I+R2/R1) +IADJ R2

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

SYMBOL PARAMETER MAXIMUM UNITS

PdPower Dissipation Internally limited W

Vin Input Voltage

Vpower

Vcontrol

TJOperating Junction Temperature range

Control Section

Power Transistor

0 to 125

0 to 150

ºC

TSTG Storage Temperature -65 to 150 ºC

TLEAD Lead Temperature (Soldering, 10 sec) 300 ºC

DEVICE OUTPUT VOLTAGE

LND5201 Adj.

LND5201-1.5 1.5V

LND5201-2.5 2.5V

LND5201-2.85 2.85V

LND5201-3.0 3.0V

LND5201-3.3 3.3V

LND5201-3.5 3.5V

LND5201-5.0 5.0V

Note 1: Other fixed versions are available Vout =1.5v to 5.0V

Absolute Maximum Rating

Device Selection Guide (note 1)

LND5201

Package Information

Vin

Vout

ADJ/GND

3 LEAD To –220 (Front view) 5 LEAD To –220 (Front View)

Vpower

Vcontrol

OUTPUT

ADJ/GND

SENSE

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

LND5201

PARAMETER DEVICE TEST CONDITIONS MIN TYP MAX UNITS

Reference Voltage LND5201

VControl=2.75V, VPower = 2V, ILoad=

10mA

VControl =2.7V to 12 V

VPower =3.3V to 5.5V, ILoad =10mA to

1.238

1.230

1.250

1.262

1.270

VControl =4V, VPower =2V

VControl =3V, VPower =2.3V, ILoad =0mA

to 1A

*1.485

1.475

1.500

1.515

1.525 V

VControl =5V, VPower =3.3V

VControl =4V, VPower =3.3V ILoad =0mA

to 1A

*2.475

2.460

2.500

2.525

2.540 V

VControl =5.35V, VPower =3.35V

VControl =4.4V, VPower =3.7V, ILoad

=0mA to 1A

*2.821

2.805

2.850

2.879

2.895 V

VControl =5.5V, VPower 3.5V

VControl =4.5V, VPower 3.8V, ILoad =0mA

to 1A

*2.970

2.950

3.000

3.030

3.050 V

VControl =5.8V, VPower =3.8V

VControl =4.8V, VPower = 4.1V, ILoad =

0mA to1A

*3.267

3.247

3.300

3.333

3.353 V

VControl =6V, VPower =4V

VControl =5V, VPower =4.3V, ILoad =0mA

to 1A

*3.465

3.445

3.500

3.535

3.555 V

Output Voltage

LND5201-1.5

LND5201-2.5

LND5201-2.85

LND5201-3.0

LND5201-3.3

LND5201-3.5

LND5201-5.0

VControl =7.5V, VPower =5.5V

VControl =6.5V VPower =5.8V, ILoad =0mA

to 1 A

*4.950

4.920

5.000

5.050

5.080 V

Line Regulation All ILoad =10mA, (1.5V+Vout) ≤ VControl

≤12V, 0.8V ≤ ( VPower -Vout) ≤ 5.5V * 0.04 0.20 %

Load Regulation All VControl =Vout+2.5V, VPower =Vout +0.8V,

ILoad =10mA to 1A * 0.08 0.40 %

Minimum Load

Current(Note 2) LND5201 VControl =5V, VPower =3.3V, VADJ =0V * 1.7 5 mA

Control Pin Current(Note

3) All VControl =Vout+2.5V, VPower =Vout+0.8V,

ILoad =10mA to 1A *20mA

Ground Pin Current

LND5201-1.5/-

2.5/-2.85/-3.0/-

3.3/-3.5/-5.0

VControl =Vout+2.5, VPower =Vout+0.8V,

ILoad =10mAto 1A *510mA

Adjust Pin Current LND5201 VControl =2.75V, VPower =2.05V

ILoad =10mA * 50 120 µA

Current Limit All (Vin-Vout)=3V * 1000 1500 mA

Ripple Rejection All VControl = VPower =Vout+2.5V,

Vripple=1Vp.p, ILoad =500mA 60 75 dB

Thermal Regulation LND5201 TA=25ºC,30ms pulse 0.003 %/W

Dropout Voltage note 4

Control Input All VPower =Vout+0.8, ILoad =10mA

VPower = Vout+0.8V ILoad =1A *1.00

1.15

1.30 V

Power Input

(Vpower-Vout)All VControl = Vout+2.5V, ILoad =1A * 0.55 0.70 V

Electrical Characteristics

At I load = 0mA and TJ = + 25 °C unless otherwise specified

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

The* denotes the specifications which apply over the full temperature range.

Note 1: Unless otherwise specified Vout=Vsense. For LND5201 (adj.) Vadj=0V

Note 2: For the adjustable device the minimum load current is the minimum current required to maintain regulation.

Normally the current in the resistor divider used to set the output voltage is selected to meet the minimum load current

requirement.

Note 3: The control pin current is the drive current required for the output transistor. This current will track output with

a ratio of about 1:100.

Note 4: The dropout voltage for the LND5201 is caused by either minimum control voltage or minimum power voltage.

The specifications represent the minimum input/output voltage required to maintain 1% regulation.

PIN FUNCTIONS

(

5-LEAD

)

Sense (Pin 1): This pin is the positive

side of the reference voltage. With this

pin it is possible to Kelvin sense the

output voltage at the load.

Adjust (Pin 2): This pin is the negative

side of the reference voltage. Adding a

small bypass capacitor from the Adjust

pin to ground improves the transient

response. For fixed voltage devices the

Adjust pin is also brought out to allow

the user to add a bypass capacitor.

GND (Pin 2): For fixed voltage devices

this is the bottom of the resistor divider

that sets the output voltage.

power (Pin 5): This pin is the collector

of the power transistor. The output

load current is supplied through this

pin. The voltage at this pin must be

0.7V greater than the output voltage

for the device to regulate.

Vcontrol (pin 4): This pin is the supply

pin for the control circuitry. The

current flow into this pin will be about

1% of the output current. The voltage

at this pin must be 1.3V greater than

the output voltage for the device to

regulate.

Output (Pin 3): This is the power

output of the device.

LND 5201

BLOCK DIAGRAM

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

APPLICATIONS INFORMATION

The LND5201 series of adjustable and fixed

regulators are designed to power the new

generation of microprocessors. The LND5201 is

designed to make use of multiple power

supplies, present in most systems, to reduce the

dropout voltage. One of the advantages of the

two supply approach is maximizing the

efficiency.

The second supply is at least 1V greater than

output voltage and is providing the power for the

control circuitry and supplies the drive current to

the NPN output transistor. This allows the NPN

output transistor to be driven into saturation. For

the control voltage the current requirement is

small equal to about 1% of the output current.

This drive current becomes part of the output

current. The maximum voltage on the Control

pin is 12V. The maximum voltage at the Power

pin is 7V. By tying the control and power inputs

together the LND5201 can also be operated as

a single supply device. In single supply

operation the dropout will be determined by the

minimum control voltage.

Both fixed and adjustable versions have remote

sense pins, permitting very accurate regulation

of output voltage. As a result, over an output

current range of 100mA to 1A, the typical load

regulation is less than 1mV. For the fixed

voltages the adjust pin is brought out allowing

the user to improve transient response by

bypassing the internal resistor divider. Optimum

transient response is provided using a capacitor

in the range of 0.1µF to 1µF for bypassing the

Adjust pin. In addition to the enhancements

mentioned, the reference accuracy has been

improved by a factor of two with a guaranteed

initial tolerance of ±1% at 25ºC and 1.6%

accuracy over the full temperature and load

current range.

Typical applications for the LND5201 include

3.3V to 2.5V conversion with a 5V control

supply, 5V to 4.2V conversion with a 12V

control supply. The device is fully protected

against overcurrent and overtemperature

conditions.

Grounding and Output Sensing

The LND5201 allows true Kelvin sensing for

both the high and low side of the load. As a

result the voltage regulation at the load can be

easily optimized. Voltage drops due to

parasitic resistance’s between the regulator

and the load can be placed inside the

regulation loop. The advantages of remote

sensing are illustrated in figures 1 through 3.

Figure 1 shows the device connected as a

convential 3 terminal regulator with the sense

lead connected directly to the output of the

device. Rp is the parasitic resistance of the

connections between the device and the load.

Trace A of figure 3 illustrates the effect of Rp.

Figure 2 shows the device connected to take

advantage of the remote sense feature. The

Sense pin and the top of the resistor divider

are connected to the top of the load. The

bottom of the resistor divider is connected to

the bottom of the load. The effect on output

regulation can be seen in trace B of figure 3.

It is important to note that the voltage drops

due to Rp are not eliminated. They will add to

the dropout voltage of the regulator regardless.

The LND5201 can control the voltage at the

load as long as the input-output voltage is

greater than the total of the dropout voltage of

the device plus the voltage drop across Rp.

Stability

The circuit design used in the LND5201 series

requires the use of an output capacitor as part

of the device frequency compensation. The

addition of 150µF aluminnum electrolytic or a

22µF solid tantalum on the output will ensure

stability for all operating conditions

LND5201

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

LND5201

1: Conventional Load Sensing 2: Remote Load Sensing

( Iout ) (Rp)

Time

Iout

Vout

Figure 2

Vout

Figure 1

3 : Remote sensing improves Load Regulation

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •

Output Voltage

The LND5201 (adjustable version)

develops a 1.25V reference voltage

between the Sense pin and the Adjust

pin (Figure 4). Placing a resistor

between these two terminals causes a

constant current to flow through R1 and

down though R2 to set the output

voltage. In general R1 is chosen so that

this current is the specified minimum

load current of 5mA. The current out of

the Adjust pin is small, typically 50µA

and it adds to the current from R1. For

the best regulation the top of the resistor

divider should be connected directly to

the Sense pin.

Protection Diodes

In normal operation LND5201 family does

not need any protection diodes between

the adjustment pin and the output to the

input to prevent die overstresses. Internal

resistors are limiting the internal current

paths on the ADJ pin. Therefore even

with bypass capacitors on the adjust pin

no protection diode is needed to ensure

device safety under short-circuit

conditions. The adjust pin can be driver

on a transient basis ±7V with respect to

the output with out any device

degradation. A protection diode between

the Output pin and Vpower pin is not

usually needed. Microsecond surge

currents of 50A to 100A can be handled

by the internal diode between the Output

pin and Vpower pin of the device. In

normal operations it is difficult to get those

values of surge currents even with the

use of large output capacitance. Only

with high value output capacitors, such as

1000 to 5000µF and the Vpower pin are

instantaneously shorted to ground,

damage can occur. A diode from output

to input is recommended (Figure 5).

If LND5201 is connected as a single

supply device with the control and power

input pins shorted together the internal

diode between the output and the power-

input pin will protect the control input pin.

Thermal Considerations

The LND5201 series have internal power

and thermal-limiting circuitry designed to

protect the device under overload

conditions. However, maximum junction

temperature ratings should not be

exceeded under continuous normal load

conditions. Careful consideration must be

given to all sources of thermal resistance

from junction ambient, including junction-

to-case, case to-heat sink interface and

heat sink resistance itself.

Junction temperature of the control

section can run up to 125ºC. Junction

temperature of the Power section can run

up to 150ºC.

LND5201

Figure 4. Setting Output Voltage

Figure 5. Optional Clamp Diodes Protect

ainst In

ut Crowbar Circuits.

LND5201

VOUT = VREF (I+R2/R1) +IADJ R2

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •