ES9039Q2M datasheet(47/107 Pages) ESS

47 / 107 page

VERSION 0.2.2

ESS TECHNOLOGY, INC. 109 Bonaventura Drive, San Jose, CA 95134, USA Tel (408) 643-8800 • WWW.ESSTECH.COM

ES9039Q2M Product Datasheet

Analog Features

Calibration Resistor

The ES9039Q2M features a ~50kΩ integrated resistor that is used for calibration of DAC voltage supplies AVCC_DAC1

and AVCC_DAC2. This calibration is required to maintain output level from device to device with the process varying DAC

output impedance. The calibration resistor is accessible through GPIO8 (Pin 28) and terminated to ground as shown in the

below figure.

To calibrate the AVCC_DAC1 and AVCC_DAC2 voltage supplies, a circuit is required to generate the voltage supply based

on the resistor value. This can be done by generating a constant current and using that current through the internal

calibration resistor to generate the reference voltage. This voltage is then buffered for the AVCC_DACx supply.

The ultra low noise ESS ES9312 voltage regulator features a calibration mode that can be paired with the ES9039Q2M

AVCC_DAC1 and AVCC_DAC2 supplies. The ES9312 connects to the ES9039Q2M integrated calibration resistor, on

GPIO8, and adjusts the DAC output supplies to maintain a tighter distribution on the output level. See Recommended

Power Supply for connections.

By default, the switch is closed (CAL_RES_ENB = 1’b0), Register 42[7] = 1’b0 (input disabled), and Register 41[7]

GPIO8_OE = 1’b0 (tristated).

Figure 17 - GPIO8 Digital I/O with Calibration Resistor

ES9039Q2M Datasheet(PDF) 47 Page - ESS Technology,Inc