LTC1563-2IGN 查看數據表（PDF） - Linear Technology

零件编号

产品描述 (功能)

生产厂家

LTC1563-2IGN

Active RC, 4th Order Lowpass Filter Family

Linear Technology 

LTC1563-2/LTC1563-3

PIN FUNCTIONS

LP (Pin 1): Low Power. The LTC1563-X has two operating

modes: Low Power and High Speed. Most applications will

use the High Speed operating mode. Some lower fre-

quency, lower gain applications can take advantage of the

Low Power mode. When placed in the Low Power mode,

the supply current is nearly an order of magnitude lower

than the High Speed mode. Refer to the Applications

Information section for more information on the Low

Power mode.

The LTC1563-X is in the High Speed mode when the

LP input is at a logic high level or is open-circuited. A small

pull-up current source at the LP input defaults the

LTC1563-X to the High Speed mode if the pin is left open.

The part is in the Low Power mode when the pin is pulled

to a logic low level or connected to V –.

SA, SB (Pins 2, 11): Summing Pins. These pins are a

summing point for signals fed forward and backward.

Capacitance on the SA or SB pin will cause excess peaking

of the frequency response near the cutoff frequency. The

three external resistors for each section should be located

as close as possible to the summing pin to minimize this

effect. Refer to the Applications Information section for

more details.

NC (Pins 3, 5, 10, 12, 14): These pins are not connected

internally. For best performance, they should be con-

nected to ground.

INVA, INVB (Pins 4, 13): Inverting Input. Each of the INV

pins is an inverting input of an op amp. Note that the INV

pins are high impedance, sensitive nodes of the filter and

very susceptible to coupling of unintended signals.

Capacitance on the INV nodes will also affect the fre-

quency response of the filter sections. For these reasons,

printed circuit connections to the INV pins must be kept as

short as possible.

LPA, LPB (Pins 6, 15): Lowpass Output. These pins are

the rail-to-rail outputs of an op amp. Each output is

designed to drive a nominal net load of 5kΩ and 20pF.

Refer to the Applications Information section for more

details on output loading effects.

AGND (Pin 7): Analog Ground. The AGND pin is the

midpoint of an internal resistive voltage divider developing

a potential halfway between the V+ and V– pins. The

equivalent series resistance is nominally 10kΩ. This serves

as an internal ground reference. Filter performance will

reflect the quality of the analog signal ground. An analog

ground plane surrounding the package is recommended.

The analog ground plane should be connected to any

digital ground at a single point. Figures 1 and 2 show the

proper connections for dual and single supply operation.

V–, V+ (Pins 8, 16): The V– and V+ pins should be

bypassed with 0.1µF capacitors to an adequate analog

ground or ground plane. These capacitors should be

connected as closely as possible to the supply pins. Low

noise linear supplies are recommended. Switching sup-

plies are not recommended as they will decrease the

filter’s dynamic range. Refer to Figures 1 and 2 for the

proper connections for dual and single supply operation.

EN (Pin 9): ENABLE. When the EN input goes high or is

open-circuited, the LTC1563-X enters a shutdown state

and only junction leakage currents flow. The AGND pin, the

LPA output and the LPB output assume high impedance

states. If an input signal is applied to a complete filter

circuit while the LTC1563-X is in shutdown, some signal

will normally flow to the output through passive compo-

nents around the inactive part.

A small internal pull-up current source at the EN input

defaults the LTC1563 to the shutdown state if the EN pin

is left floating. Therefore, the user must connect the EN pin

to V– (or a logic low) to enable the part for normal

operation.

156323fa

8

Share Link: