OPA643 datasheet(15/16 Pages) TI1

15 / 16 page

OPA686

of RS vs Capacitive Load. This will not preserve signal

integrity as well as a doubly-terminated line. If the input

impedance of the destination device is low, there will be

some signal attenuation due to the voltage divider formed by

the series output into the terminating impedance.

e) Socketing a high speed part like the OPA686 is not

recommended. The additional lead length and pin-to-pin

capacitance introduced by the socket can create an ex-

tremely troublesome parasitic network which can make it

almost impossible to achieve a smooth, stable frequency

response. Best results are obtained by soldering the OPA686

onto the board.

INPUT AND ESD PROTECTION

The OPA686 is built using a very high speed complemen-

tary bipolar process. The internal junction breakdown volt-

ages are relatively low for these very small geometry de-

vices. These breakdowns are reflected in the Absolute Maxi-

mum Ratings table. All device pins are protected with

internal ESD protection diodes to the power supplies as

shown in Figure 9.

External

–V

Internal

Circuitry

FIGURE 9. Internal ESD Protection.

These diodes provide moderate protection to input overdrive

voltages above the supplies as well. The protection diodes

can typically support 30mA continuous current. Where higher

currents are possible (e.g., in systems with

±15V supply

parts driving into the OPA686), current-limiting series resis-

tors should be added into the two inputs. Keep these resistor

values as low as possible since high values degrade both

noise performance and frequency response.

OPA643 Datasheet(PDF) 15 Page - Texas Instruments