TLV2470, TLV2471, TLV2472, TLV2473, TLV2474, TLV2475, TLV247xA

FAMILY OF 600−

µA/Ch 2.8−MHz RAIL−TO−RAIL INPUT/OUTPUT

HIGH−DRIVE OPERATIONAL AMPLIFIERS WITH SHUTDOWN

SLOS232C - JUNE 1999 - REVISED AUGUST 2003

16

POST OFFICE BOX 655303

APPLICATION INFORMATION

general configurations

When receiving low-level signals, limiting the bandwidth of the incoming signals into the system is often

required. The simplest way to accomplish this is to place an RC filter at the noninverting terminal of the amplifier

(see Figure 44).

C1

+

-

R1

f

–3dB +

1

2

pR1C1

V

O

V

I

+

1

)

R

F

R

G

1

1

) sR1C1

Figure 44. Single-Pole Low-Pass Filter

If even more attenuation is needed, a multiple pole filter is required. The Sallen-Key filter can be used for this

task. For best results, the amplifier should have a bandwidth that is 8 to 10 times the filter frequency bandwidth.

Failure to do this can result in phase shift of the amplifier.

C2

R2

R1

C1

R1 = R2 = R

C1 = C2 = C

Q = Peaking Factor

(Butterworth Q = 0.707)

(

=

1

Q

2 -

)

_

+

f

–3dB +

1

2

pRC

Figure 45. 2-Pole Low-Pass Sallen-Key Filter

shutdown function

Three members of the TLV247x family (TLV2470/3/5) have a shutdown terminal for conserving battery life in

portable applications. When the shutdown terminal is tied low, the supply current is reduced to 350 nA/channel,

the amplifier is disabled, and the outputs are placed in a high impedance mode. To enable the amplifier, the

shutdown terminal can either be left floating or pulled high. When the shutdown terminal is left floating, care

should be taken to ensure that parasitic leakage current at the shutdown terminal does not inadvertently place

Therefore, when operating the device with split supply voltages (e.g.

±2.5 V), the shutdown terminal needs to