LMC662: LMC662 600ohm drive

Hello Kai,

A 600 Ohm load resistance is commonly specified for op amps used in, or designated for, audio applications. If you see a 600 Ohm load specified with output voltage and THD+ Noise specifications, one of its intended applications is audio.

One of our high performance audio op amps that has a cost similar to the LMC662, is the OPA1652. You can see references to a 600 Ohm load, and others, in the datasheet Typical Characteristics curves. You can view the datasheet here:

Regards, Thomas

Precision Amplifiers Applications Engineering

Hi Thomas and Kai,

To add more possible low cost devices (CM to ground, < 22nV/RtHz noise, > 1MHz, 20mA output current, dual), here they are:

Device	RR Out?	CM to ground?	Cost (1k units) $
LMC6032	Yes	Yes	0.35
LMV722	Yes	Yes	0.39
TL3414A	No	Yes	0.31
TLV2314	Yes	Yes	0.32
TLV2316	Yes	Yes	0.36
OPA1652	No	No	0.65

Regards,

Hooman

Dear Thomas / Hooman

Beside Audio application ,have any end-equipment will use this kind of OP ??
We want to instead MC33202 of On-semi ,if you have best solution ,please kindly let me know or I will check above table)


Thanks

Hello Kai and Thomas,

LMC662 and other similar devices, do not need to be restricted to audio applications. Any other "higher" output drive application is included.

The 600ohm output drive capability is a qualification which shows that despite the device's relatively low power consumption (400uA / amplifier typical supply current), it is still capable to drive a 600ohm load (which may be out of the capability of some other "low power" OPA's).

What is the load that you need to drive in your application? Please keep in mind that the output voltage swing capability is a parameter that is strongly influenced if you have a "heavy" load. For example, with the LMC662 plot shown below, if you are driving a 600ohm load tied to ground and operating with a single supply of 5V, you'd need about 8.3mA (= 5V/ 600ohm) of output source current. From Figure 7 shown below, with this current, output voltage swing is going to be typically limited to about 1V from the top rail (or ~4V) from the y-axis:

For comparison, with the MC33202 plot shown below, under the same condition it can swing to a higher voltage (~0.18V of VCC) or about 4.82V:

This is only important if you need to drive a heavy load and swing close to the rails. Not otherwise!

If you specify your needs (supply voltage, output swing capability, load to ground or to mid-rail?, etc.), and other important specs, we'll be able to direct you to the most cost competitive solution to match your needs.

Regards,

Hooman

Dear Hoomen

Thanks for your explain
So you mean ,if the power rail is 5V and load is 600ohm ,drive current is 8.3mA
In this condition ,MC33202 can have a bigger swing 4.82V than our 4V ,is it right??

Thanks

Hi Kai,
What I showed you was just an example. I don't know your operating conditions.

If you tell me what you're trying to do / drive with the LMC662 / MC33202, then I can help you better to let you know whether you are in anyway limited by the output drive current or not?

Regards,
Hooman