DC995A Datasheet DC995A | P1-P3

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 995A

ADJUSTABLE LDO LINEAR REGULATOR

LT3080EDD

DESCRIPTION

Demonstration circuit 995A is an adjustable 1.1A lin-

ear regulator featuring LT

3080. Architected as a

precision current source and voltage follower, it al-

lows this new regulator to be used in many applica-

tions requiring high current, adjustability to zero out-

put, and no heat sink. Also the device brings out the

collector of the pass transistor to allow low dropout

operation when used with multiple supplies.

A key feature of the LT3080 is the capability to sup-

ply a wide output voltage range. By using a reference

current through a single resistor, the output voltage

can be programmed to any level between zero and

36V. The DC995A has a reduced input voltage 25V

due to input capacitor voltage rating. And DC995A is

capable of delivering up to 1.1A output current.

Therefore, the DC995A can be used as a high current

linear regulator, post regulator for switching supply,

variable voltage supply or low output voltage power

supply.

Internal protection circuitry includes current limiting

and thermal limiting.

LT3080 regulator is offered in 8-lead MSOP (with an

Exposed Pad for better thermal characteristics), a

3mm × 3mm DFN, 5-lead TO-220 and a simple-to-

use 3-lead SOT-223 version.

The LT3080 datasheet gives a complete description

of the part, operation and application information.

The datasheet should be read in conjunction with this

quick start guide for working on or modifying the

demo circuit 995A.

If more output current is required or heat-spreading

is needed, LT3080 can be easily paralleled. See

DC1294A for details.

Design files for this circuit board are available.

Call the LTC factory.

, LTC and LT are registered trademarks of Linear Technology Corporation.

Table 1.

Performance Summary ( T

= 25

C )

PARAMETER CONDITION VALUE

Minimum Vin Voltage Vout=1.8V 2.3V

Maximum Vin Voltage 25V

Minimum Vcontrol Voltage Vout=1.8V 3.4V

Maximum Vcontrol Voltage 25V

Output Voltage JP1, Vout=1.8V

JP1, Vout=0V-5V

1.8V ±3%

0V-5V±3%

Minimum Output Current 1mA

Maximum Output Current Vin-Vout<3.5V 1.1A

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 995A

ADJUSTABLE LDO LINEAR REGULATOR

QUICK START PROCEDURE

The DC995A is easy to set up to evaluate the per-

formance of the LT3080. Refer to Figure 1. for proper

measurement equipment setup and following the

procedures below:

1. Before proceeding to test, use VOUT Select

jumper JP1 for the desired output voltage

(1.8V or 0V-5V). If the output voltage is dif-

ferent from the above values, use the USER

option and install R3. Select R3 according to

the following equation:

OUT

2. Assume 1.8V is the desired output. Apply

2.3V across Vin (to Gnd), and 3.4V across

Vcontrol. Draw 1.1A of load current. The

measured Vout should be 1.8V ± 3% (1.766V

to 1.875V).

3. Vary Vin from 2.3V to 25V, Vcontrol from

3.4V to 25V and the load current from 1mA to

1.1A. Vout should measure 1.8V ± 3%

(1.766V to 1.875V).

Note: Make sure the power dissipation is limited be-

low the thermal limit.

Figure 1. Proper Measurement Equipment Setup

Figure 2. Measuring Input or Output Ripple

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 995A

ADJUSTABLE LDO LINEAR REGULATOR

INPUT VOLTAGE RANGE

The guaranteed Vin dropout voltage is 0.5V at 1.1A,

the guaranteed Vcontrol dropout voltage is 1.6V at

1.1A. The maximum Vin and maximum Vcontrol is

reduced to 25V due to the input capacitor voltage rat-

ing.

DUAL SUPPLY OR SINGLE SUPPLY

Use two separate supplies for Vin and Vcontrol, a low

dropout voltage can be achieved on the Vin pin and the

power dissipation is minimized. Alternatively, Tying the

Vcontrol to Vin through a zero ohm jump resistor on

board, a single supply is sufficient to drive the demo

circuit 995A.

AVOID USING A LONG WIRE TO TIE

VCONTROL AND VIN

OUTPUT CURRENT

The output current will decrease at high input-to-output differential. The actual current output is further limited by the

thermal shutdown function, which is related to the board thermal dissipation. A typical curve is provided using the

demo circuit 995A at room temperature.

DO NOT CONTINUOUSLY OPERATE THE LT3080 TO THE THERMAL LIMIT,

WHICH MAY IMPAIR THE DEVICE RELIABILITY. MAXIMUM JUNCTION TEMPERATURE IS 125

Thermal Limit & Current Limit

0.2

0.4

0.6

0.8

1.2

1.4

0 5 10 15 20 25 30

Vin - Vout (V)

LOAD CURRENT (mA)

Thermal Limit

Current Limit

P1-P3 P4-P5

DC995A

Mfr. #:

Buy DC995A

Manufacturer:

Analog Devices Inc.

Description:

Power Management IC Development Tools LT3080EDD - 1.1A Adjustable, Single resi

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DC995A