March 26, 2021

CONFIDENTIAL Rev. 3.6

ES9018K2M Datasheet

21

ESS TECHNOLOGY, INC. 109 Bonaventura Drive, San Jose, CA 95134, USA. Tel (408) 643-

8800 • www.esstech.com

Register #23-22: 2nd Harmonic Compensation Coefficients

16 bit, Read-Write Register, Default = 0x0000 (no compensation). Register #23 is MSB. See Register #13 for more details.

Bits

[15:0]

Mnemonic

Thd_comp_c2

Default

16’d0

Register #25-24: 3rd Harmonic Compensation Coefficients

16 bit, Read-Write Register, Default = 0x0000 (no compensation). Register #25 is MSB. See Register #13 for more details.

Bits

[15:0]

Mnemonic

Thd_comp_c3

Default

16’d0

The THD Compensation registers are signed integer values split into two memory locations each.

THD Compensation Coefficient

MSB

LSB

x^3 (third harmonic)

Register 25

Register 24

x^2 (second harmonic)

Register 23

Register 22

Table 1: THD Compensation Registers

1. Configure the output stage gain for the maximum desired output level. If any component values are later changed on

the output audio signal path you will need to re-tune the THD Compensation to achieve peak performance.

2. Set the input level, ES9018K2M Volume and Master Trim for the maximum desired output level.

If the output level is later increased beyond this level you will need to re-tune the THD Compensation to achieve

peak performance.

3. Adjust registers 0x23 and 0x25 to achieve peak THD performance. Use the I2C interface or the ES9018K2M GUI to make

the adjustments while watching the THD+N measurement.

In the GUI, adjust the THD Compensation sliders as shown in figure 1. The sliders are linked to the MSB of the THD

Compensation registers so they are somewhat coarse.

Both channels are tuned simultaneously; keep an eye on both measurements.

Typical register values are very close to zero.

4. For finer adjustments use registers 0x22 and 0x24. Use the I2C interface or the ES9018K2M GUI to make large changes

of 50 or so while watching the THD+N measurement. Switch to smaller increments when you're close to peak

performance.

In the GUI, open the register listing (see figure 2) and click Update Registers to make sure the most up-to-date values are

displayed. There are no sliders for the fine-adjust registers (see figure 3).

The ES9018K2M GUI is available for download from the ESS website at:

64-Bit: http://www.esstech.com/software/Sabre2M_signed_x64.zip

32-Bit: http://www.esstech.com/software/Sabre2M_signed_x86.zip