LT1965IDD-1.8-PBF(RevA) Ver la hoja de datos (PDF) - Linear Technology

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LT1965IDD-1.8-PBF
(Rev.:RevA)

1.1A, Low Noise, Low Dropout Linear Regulator

Linear Technology 

LT1965 Series

PIN FUNCTIONS (DFN/MSOP/DD-PAK/TO-220)

OUT (Pins 1, 2 / 1, 2 / 4 / 4): Output. This pin supplies

power to the load. Use a minimum output capacitor of

10μF to prevent oscillations. Large load transient applica-

tions require larger output capacitors to limit peak volt-

age transients. See the Applications Information section

for more information on output capacitance and reverse

output characteristics.

SENSE (Pin 3 / 3 / 5 / 5): Sense. For fixed voltage ver-

sions of the LT1965 (LT1965-1.5/LT1965-1.8/ LT1965-2.5/

LT1965-3.3), the SENSE pin is the input to the error ampli-

fier. Optimum regulation is obtained when the SENSE pin

is connected to the OUT pin of the regulator. In critical ap-

plications, small voltage drops are caused by the resistance

(RP) of PCB traces between the regulator and the load.

These drops may be eliminated by connecting the SENSE

pin to the output at the load as shown in Figure 1 (Kelvin

Sense Connection). Note that the voltage drop across

the external PCB traces will add to the dropout voltage

of the regulator. The SENSE pin bias current is 100μA at

the nominal rated output voltage. The SENSE pin can be

pulled below ground (as in a dual supply system where

the regulator load is returned to a negative supply) while

still allowing the device to start and operate.

+

VIN

IN

OUT

LT1965

SHDN SENSE

GND

RP

+

LOAD

RP

1965 F01

Figure 1. Kelvin Sense Connection

ADJ (Pin 3 / 3 / 5 / 5): Adjust. This pin is the input to the

error amplifier. It has a typical bias current of 1.3μA that

flows into the pin. The ADJ pin voltage is 1.20V referenced

to ground.

GND (Pins 4, 5 / 4, 5 / 3 / 3): Ground. For the adjustable

LT1965, connect the bottom of the resistor divider, setting

output voltage, directly to GND for optimum regulation.

SHDN (Pin 6 / 6 / 1 / 1): Shutdown. Pulling the SHDN

pin low puts the LT1965 into a low power state and turns

the output off. Drive the SHDN pin with either logic or an

open collector/drain with a pull-up resistor. The resistor

supplies the pull-up current to the open collector/drain

logic, normally several microamperes and the SHDN pin

current, typically less than 5.5μA. If unused, connect the

SHDN pin to VIN. The SHDN pin cannot be driven below

GND unless it is tied to the IN pin. If the SHDN pin is

driven below GND while IN is powered, the output will

turn on. SHDN pin logic cannot be referenced to a nega-

tive supply rail.

IN (Pins 7, 8 / 7, 8 / 2 / 2): Input. This pin supplies power

to the device. The LT1965 requires a bypass capacitor at IN

if located more than six inches from the main input filter

capacitor. Include a bypass capacitor in battery-powered

circuits as a battery’s output impedance generally rises with

frequency. A bypass capacitor in the range of 1μF to 10μF

suffices. The LT1965’s design withstands reverse voltages

on the IN pin with respect to ground and the OUT pin. In

the case of a reversed input, which occurs if a battery is

plugged in backwards, the LT1965 behaves as if a diode

is in series with its input. No reverse current flows into

the LT1965 and no reverse voltage appears at the load.

The device protects itself and the load.

Exposed Pad (Pin 9 / 9, DFN and MSOP Packages Only):

Ground. Tie this pin directly to Pins 4 and 5 and the PCB

ground. This pin provides enhanced thermal performance

with its connection to the PCB ground. See the Applica-

tions Information section for thermal considerations and

calculating junction temperature.

1965fa

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