11

®

OPA623

reduce the internal thermal rise, resulting in cooler, more

reliable operation. At extreme temperatures and under full

load conditions a heat sink is necessary. The internal power

dissipation is given by the equation P

dissipation in the output stage due to the load). Although the

when a signal is applied. For high-speed op amps, a more

precise approach to determine power consumption is to

measure the average total quiescent current for several

typical load conditions. The power consumption of the

OPA623 is influenced by the kind of signal, the applied

signal frequency, the output voltage, load resistor, and the

repetition rate of the signal transitions. Figure 8 shows the

average supply current versus the frequency of an applied

sine wave for various output voltages. Figure 9 illustrates the

average supply current versus the repetition frequency of an

applied square wave signal.

50

40

30

20

10

0

–10

–20

–30

Frequency (Hz)

100k

1M

10M

100M

1G

300

Ω

150

Ω

27

Ω

1M

10M

100M

1G

Frequency (Hz)

FREQUENCY RESPONSE vs C

LOAD

G

10pF

22pF

47pF

100k

2pF

51

Ω

DUT

50

Ω

R

2

C

L

R

1

3

2

6

R

1

300

Ω

270

Ω

240

Ω

120

Ω

R

2

300

Ω

270

Ω

240

Ω

120

Ω

C

L

2pF

10pF

22pF

47pF

10k

100k

1M

10M

100M

1G

Frequency (Hz)

50

45

40

35

30

25

20

15

10

5

0

Sine Curve

R

G = +2V/V

C

5.0Vp-p

2.8Vp-p

1.4Vp-p

0.2Vp-p

FIGURE 8. Average Supply Current vs Frequency

(sinewave).

FIGURE 6. Optimum Frequency Response vs Closed-Loop

Gain.

20

15

10

5

0

–5

–10

–15

–20

–25

–30

Frequency (Hz)

100k

1M

10M

100M

1G

+10V/V

+2V/V

+1V/V

–1V/V

25

20

15

10

5

0

10k

100k

1M

10M

100M

Frequency (Hz)

5.0Vp-p

2.8Vp-p

1.4Vp-p

0.2Vp-p

G = +2V/V

C

R

FIGURE 9. Average Supply Current vs Frequency

(squarewave).