Specifications

26 SAM0023-122898 ESS Technology, Inc.
ES1869 DATA SHEET
PERIPHERAL INTERFACING
For support of mixer master volume control, a write to
mixer registers 22h or 32h translates automatically into
writes to the master volume registers. Since register 22h
only has 3-bit resolution per channel, and register 32h only
has 4-bit resolution per channel, a translation circuit is
included in the ES1869 that translates 3- or 4-bit volume
values into the 6-bit volume + mute that is used in the
master volume registers. Support of these mixer registers
can be defeated under software control.
Reading master volume registers 22h or 32h also requires
a translation circuit to translate 6-bit + mute master
volumes into 3- or 4-bit master volume numbers for
registers 22h or 32h.
PC Speaker
The PC Speaker is supported with a 1-bit DAC with
volume control. The analog output pin PCSPKO is
intended to be externally mixed at the external amplifier.
PC Speaker Volume Control
When the PCSPKI signal is high, a resistive path to analog
ground is enabled. The value of the resistor is selected
from among 7 choices to control the amplitude of the
output signal.
Figure 17 PC Speaker Volume Circuitry
With the external circuit shown in Figure 17, the amplitude
of a square wave output on pin PCSPKO should be
approximately VDDA/2 for maximum volume, i.e., the
internal resistor is approximately 500 ohms (± 30%). The
other levels are relative to this amplitude as follows:
mute, -24dB, -21dB, -18dB, -15dB, -12dB, -9dB, -6dB
The purpose of the circuit, beyond volume control of the
speaker, is to prevent digital noise from the PC speaker
signal being mixed into the analog signal. This circuit
provides a clean analog signal. The output can be either
mixed with the AOUT_L and AOUT_R pins externally or it
can be used to drive a simple transistor amplifier to drive
an 8 ohm speaker dedicated to producing beeps.
PCSPKI
VDDD
PCSPKO
.01 µF
.1 µF
500
GNDA