LT1965T-1.8 View Datasheet(PDF) - Linear Technology

Part Name

Description

Manufacturer

LT1965T-1.8

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 voltage

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 versions

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

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

plifier. Optimum regulation is obtained when the SENSE

pin is connected to the OUT pin of the regulator. In criti-

cal applications, 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.

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 sup-

plies 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 negative 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.

+

VIN

IN

OUT

LT1965

SHDN SENSE

GND

RP

+

LOAD

RP

1965 F01

Figure 1. Kelvin Sense Connection

For more information www.linear.com/LT1965

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