OPA690 datasheet(25/27 Pages) TI

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OPA2613

SBOS249D − JUNE 2003− REVISED APRIL 2004

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This total effective impedance should be set to match the

trace impedance. The high output voltage and current

capability of the OPA2613 allows multiple destination

devices to be handled as separate transmission lines,

each with their own series and shunt terminations. If the

6dB attenuation of a doubly-terminated transmission line

is unacceptable, a long trace can be series-terminated at

the source end only. Treat the trace as a capacitive load in

this case and set the series resistor value as shown in the

plot of RS vs Capacitive Load. However, this does not

preserve signal integrity as well as a doubly-terminated

line. If the input impedance of the destination device is low,

there is 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 OPA2613 is not

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

capacitance introduced by the socket can create an

extremely troublesome parasitic network, which can make

it almost impossible to achieve a smooth, stable frequency

response. Best results are obtained by soldering the

OPA2613 onto the board.

f) Use the −VS plane to conduct heat out of the PSO-8

power package (OPA2613H). This package attaches the

die directly to a metal slug in the bottom, which should be

soldered to the board. This slug needs to be connected

electrically to the same voltage plane as the most negative

supply applied to the OPA2613 (in Figure 6, this would be

ground), which must have a minimum area of 2

″ x 2″

(50mm x 50mm) to produce the

qJA values in the

specifications table.

INPUT AND ESD PROTECTION

The OPA2613 is built using a high-speed complementary

bipolar process. The internal junction breakdown voltages

are relatively low for these very small geometry devices

and are reflected in the absolute maximum ratings table.

All device pins have limited ESD protection using internal

diodes to the power supplies, as shown in Figure 15.

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 (for example,

in systems with

±15V supply parts driving into the

OPA2613), current-limiting series resistors should be

added into the two inputs. Keep these resistor values as

low as possible, because high values degrade both noise

performance and frequency response.

External

−V

Internal

Circuitry

Figure 15. Internal ESD Protection

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