Page updated: 4 Mar 2002

CONTENTS.

• Introduction.
• Specs.
• Fig 1. THD versus level, no load.
• Fig 2. THD versus load.

INTRODUCTION.
The TL052 from by Texas Instruments is designed to be an enhancement of the TL072, and so is naturally compared with it. Most of the improvements are in the DC specifications, which are of limited interest for audio use. The distortion however IS important, and this is worse rather than better.

• The JFET input devices give their best noise performance at medium impedances, in the range 1K - 10K. It has very high-impedance inputs, with effectively zero bias and offset currents.
• The common-mode range of the inputs does not extend all the way between the rails, and has the same sort of asymmetrical limits as the TL072. If the common mode voltage gets to within a couple of volts of the V- rail, the op-amp phase inverts; the inputs swap their polarities. This must be guarded against as it causes dire troubles. There may be really horrible clipping, where the output hits the bottom rail and then shoots up to hit the top one, or the stage may simply latch up until the power is turned off. Cures for both problems will be described below.
• THD-performance is rather disappointing. The unloaded THD is low, as shown in Fig 1, in series feedback mode. As usual, practical distortion depends very much on how heavily the outout is loaded. Fig 2 below shows that it deteriorates badly for loads of less than 4K7. The maximum loading is a matter of opinion, usually being a tradeoff between quality and circuit economy. 2 KOhm would be my upper limit. This is not an opamp to use for quality audio unless the high input impedance, low price, or modest power consumption are important factors.
• Offset voltage is 0.65 mV typ, 1.5 mV max, compared with the TL072's 3mV typ, 10mV max. It has half the bias current of the TL072. Very praiseworthy, but not not of much relevance to audio.
• Higher power consumption: typically 2.3mA per opamp section, which is almost twice that of the 072.
• Relatively relaxed about supply rail decoupling.
• Slew rate is higher than the TL072, (18 V/us against 13 V/us) but the lower figure is more than adequate for a full-range output at 20 kHz, so this enhancement is of little use.
• At the time of writing it costs more than twice as much as the TL072.

SPECS.
Here are the vital statistics of the cheapest version. All typical values, for +/-15V supply rails.

Supply voltage	+/-18V abs max
Output range	+/-12V typ (2K load)
CM range	+15.6 -12.3V
en	19 nV/rtHz typ 1 kHz
in	0.01 pA/rtHz typ
Ibias	30 pA typ
Slew rate:	18 V/us
Supply current	4.6 mA total
Unity gain stable	YES
Cost	111p RS Aug 2000

Fig 1: Distortion versus fequency at two output levels for the TL052CP, with no load. Series feedback.

TL072 opamps are not very critical in their decoupling requirements, though they will sometimes show very visible oscillation if they are at the end of very long and thin supply tracks. One or two rail-to-rail decouplers (eg 100nF) per board is usually sufficient to deal with this. Whether this is true of the TL052 is harder to say. I don't have much experience with it.

Fig 4 Distortion of the TL052 at 5 Vrms output with various loads. At 1K and 2K2 loading the residual is all crossover distortion at 1 kHz. Gain 3.2x, non-inverting. (Series feedback)