Datasheet LND5201-3.5, LND5201-3.3, LND5201-3.0, LND5201-2.85, LND5201-2.5 Datasheet (Linear Dimensions)

DATA SHEET

LND5201

GENERAL DESCRIPTION

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%.

1 A Low Dropout Positive Voltage Regulator

FEATURES

• 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

TYPICAL APPLICATION DATA

APPLICATIONS

2.5 V, 1 A Regulator

• High efficiency Linear Regulators

• Post Regulators for Switching

Supplies

• Adjustable Power Supply

V

= V

OUT

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel [phone] • fax [phone] •

(I+R2/R1) +I

REF

ADJ

R2

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LND5201

Package Information

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

Vpower

Vin
Vout
ADJ/GND

Absolute Maximum Rating

SYMBOL PARAMETER MAXIMUM UNITS

P

V

T

T

T

d

in

J

STG

LEAD

Power Dissipation Internally limited W

Input Voltage

Vpower

Vcontrol

Operating Junction Temperature range

Control Section

Power Transistor

Storage Temperature -65 to 150 ºC

Lead Temperature (Soldering, 10 sec) 300 ºC

7

13

0 to 125

0 to 150

Vcontrol
OUTPUT
ADJ/GND
SENSE

V

ºC

Device Selection Guide (note 1)

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 V

• Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel [phone] • fax [phone] •

=1.5v to 5.0V

out

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LND5201

Electrical Characteristics

At I

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

load

PARAMETER DEVICE TEST CONDITIONS MIN TYP MAX UNITS

V

=2.75V, V

Control

10mA

Reference Voltage LND5201

V

=2.7V to 12 V

Control

V

=3.3V to 5.5V, I

Power

1A
V

=4V, V

LND5201-1.5

V

Control

Control

=3V, V

to 1A
V

=5V, V

LND5201-2.5

V

Control

Control

=4V, V

to 1A
V

=5.35V, V

LND5201-2.85

V

Control

Control

=4.4V, V

=0mA to 1A
V

=5.5V, V

Output Voltage

LND5201-3.0

V

Control

Control

=4.5V, V

to 1A
V

=5.8V, V

Control

V

LND5201-3.3

Control

=4.8V, V

0mA to1A
V

=6V, V

Control

V

=5V, V

LND5201-3.5

Control

to 1A

=7.5V, V

V

Control

V

=6.5V V

LND5201-5.0

Line Regulation All

Load Regulation All

Minimum Load
Current(Note 2)

Control Pin Current(Note

3)

LND5201 V

All

LND5201-1.5/-

Ground Pin Current

2.5/-2.85/-3.0/-

3.3/-3.5/-5.0

Adjust Pin Current LND5201

Current Limit All (Vin-V

Ripple Rejection All

Control

to 1 A

I

=10mA, (1.5V+V

Load

≤12V, 0.8V ≤ ( V
V

=V

I

V
I

V
I

V
I

V
V

Load

Load

Load

Load

Control

Control

Control

Control

Control

Control

ripple

+2.5V, V

out

=10mA to 1A

=5V, V

=V

+2.5V, V

out

=10mA to 1A

=V

+2.5, V

out

=10mAto 1A

=2.75V, V

=10mA

)=3V * 1000 1500 mA

out

= V

Power

=1Vp.p, I

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

Dropout Voltage note 4

V

=V

Control Input All

Power Input
(V

power-Vout

)

All V

V

Power

Power

Control

= V

= V

+0.8, I

out

out

out

+0.8V I

+2.5V, I

= 2V, I

Power

Load

=2V

Power

=2.3V, I

Power

=3.3V

Power

=3.3V I

Power

=3.35V

Power

=3.7V, I

Power

3.5V

Power

3.8V, I

Power

=3.8V

Power

= 4.1V, I

Power

=4V

Power

=4.3V, I

Power

=5.5V

Power

=5.8V, I

Power

) ≤ V

out

-V

Power

out

Power

=3.3V, V

Power

Power

=V

Power

=2.05V

Power

=Vout+2.5V,

=500mA

Load

=10mA

Load

=1A

Load

=1A * 0.55 0.70 V

Load

=

Load

1.238

1.250

1.262

*

=10mA to

=0mA

Load

=0mA

Load

Load

=0mA

Load

=

Load

=0mA

Load

=0mA

Load

Control

) ≤ 5.5V

=V

+0.8V,

out

=0V * 1.7 5 mA

ADJ

=V

+0.8V,

out

+0.8V,

out

1.230

1.485

*

1.475

2.475

*

2.460

2.821

*

2.805

2.970

*

2.950

3.267

*

3.247

3.465

*

3.445

4.950

*

4.920

1.250

1.500

1.500

2.500

2.500

2.850

2.850

3.000

3.000

3.300

3.300

3.500

3.500

5.000

5.000

1.270

1.515

1.525

2.525

2.540

2.879

2.895

3.030

3.050

3.333

3.353

3.535

3.555

5.050

5.080

* 0.04 0.20 %

* 0.08 0.40 %

*20mA

*510mA

* 50 120 µA

60 75 dB

*

1.00

1.15

1.15

1.30

V

V

V

V

V

V

V

V

V

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)

V

LND 5201

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.

BLOCK DIAGRAM

(Pin 5): This pin is the collector

power

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.

V

(pin 4): This pin is the supply

control

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

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APPLICATIONS INFORMATION

LND5201

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

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1: Conventional Load Sensing 2: Remote Load Sensing

( Iout ) (Rp)

Vout

A

Figure 1

LND5201

Vout
Figure 2

Iout

Time

3 : Remote sensing improves Load Regulation

B

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LND5201

Ag

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.

V

OUT

= V

(I+R2/R1) +I

REF

ADJ

R2

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 power­input pin will protect the control input pin.

Figure 4. Setting Output Voltage

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 junction­to-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.

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Figure 5. Optional Clamp Diodes Protect

ainst Input Crowbar Circuits.

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