LT1965

7

1965f

TIME (μs)

0

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

80

20

40

60

100

70

10

30

50

90

1965 G26

OUTPUT

SHDN

0

0.0

–100

–50

0

50

100

0.5

1.0

1.5

10

20

30

40

50

60

70

80

1965 G25

TIME (μs)

PIN FUNCTIONS

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.

ADJ (Pins 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.

⎯S⎯H⎯D⎯N (Pin 6 / 6 / 1 / 1): Shutdown. Pulling the ⎯S⎯H⎯D⎯N pin

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

output off. Drive the ⎯S⎯H⎯D⎯N 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 ⎯S⎯H⎯D⎯N pin current,

typically less than 6μA. If unused, connect the ⎯S⎯H⎯D⎯N pin

if the ⎯S⎯H⎯D⎯N pin is not connected. The ⎯S⎯H⎯D⎯N pin cannot

be driven below GND unless it is tied to the IN pin. If the

⎯S⎯H⎯D⎯N pin is driven below GND while IN is powered, the

output will turn on. ⎯S⎯H⎯D⎯N 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.

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

Transient Response

⎯S⎯H⎯D⎯N Transient Response

TYPICAL PERFORMANCE CHARACTERISTICS