OP275GSZ datasheet(7/12 Pages) AD

7 / 12 page

–6–

OP275

–7–

APPLICATIONS

Circuit Protection

OP275 has been designed with inherent short-circuit protection

to ground. An internal 30  resistor, in series with the output,

limits the output current at room temperature to ISC+ = 40 mA

and ISC– = –90 mA, typically, with ±15 V supplies.

However, shorts to either supply may destroy the device when

excessive voltages or currents are applied. If it is possible for a

user to short an output to a supply for safe operation, the output

current of the OP275 should be design-limited to ±30 mA, as

shown in Figure 1.

Total Harmonic Distortion

Total Harmonic Distortion + Noise (THD + N) of the OP275 is

well below 0.001% with any load down to 600 . However, this is

dependent upon the peak output swing. In Figure 2, the THD +

Noise with 3 V rms output is below 0.001%. In Figure 3, THD +

Noise is below 0.001% for the 10 k and 2 k loads but increases

to above 0.1% for the 600  load condition. This is a result of the

output swing capability of the OP275. Notice the results in Figure 4,

showing THD versus VIN (V rms). This figure shows that the THD

+ Noise remains very low until the output reaches 9.5 V rms. This

performance is similar to competitive products.

RFB

FEEDBACK

332 

VOUT

A1 = 1/2 OP275

–

Figure 1. Recommended Output Short-Circuit Protection

RL = 600, 2k, 10k

VS = 15V

VIN = 3V rms

AV = +1

0.010

0.001

0.0005

100

10k

20k

FREQUENCY – Hz

Figure 2.THD + Noise vs. Frequency vs. RLOAD

0.001

0.0001

100

10k

20k

FREQUENCY – Hz

AV = +1

VS = 18V

VIN = 10V rms

80kHz FILTER

600

2k

10k

0.1

0.010

Figure 3.THD + Noise vs. RLOAD; VIN =10 V rms

VS = 18V

RL = 600

0.010

0.001

0.0001

0.5

OUTPUT SWING – V rms

Figure 4. Headroom,THD + Noise vs. Output

Amplitude (V rms); RLOAD = 600  , VSUP = ±18 V

The output of the OP275 is designed to maintain low harmonic

distortion while driving 600  loads. However, driving 600 

loads with very high output swings results in higher distortion if

clipping occurs. A common example of this is in attempting to

drive 10 V rms into any load with ±15 V supplies. Clipping will

occur and distortion will be very high. To attain low harmonic

distortion with large output swings, supply voltages may be

increased. Figure 5 shows the performance of the OP275 driving

600  loads with supply voltages varying from ±18 V to ±20 V.

Notice that with ±18 V supplies the distortion is fairly high, while

with ±20 V supplies it is a very low 0.0007%.

SUPPLY VOLTAGE – V

0.0001

0.001

17

22

18

19

20

21

0.01

0.1

RL = 600

VOUT = 10V rms @ 1kHz

Figure 5.THD + Noise vs. Supply Voltage

Noise

The voltage noise density of the OP275 is below 7 nV/Hz from

30 Hz.This enables low noise designs to have good performance

throughout the full audio range. Figure 6 shows a typical OP275

with a 1/f corner at 2.24 Hz.

10Hz

0Hz

CH A: 80.0V FS

10.0V/DIV

MKR: 45.6V/ Hz

BW: 0.145Hz

MKR:

2.24Hz

Figure 6. 1/f Noise Corner, VS = ±15 V, AV = 1000

REV. C

OP275GSZ Scheda tecnica(PDF) 7 Page - Analog Devices

OP275GSZ Scheda tecnica(HTML) 7 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12

Scheda tecnica Scarica

Link URL