AD1812

REV. 0

–12–

Power Supplies

Pin Name

P/TQFP

I/O

Description

51, 61, 72

I

Analog Supply Voltage (+5 V).

GNDA

52, 62, 74

I

Analog Ground.

6, 17, 28, 91,

I

Digital Supply Voltage (+5 V).

94, 104, 107,

116, 126, 132,

135, 140, 146,

149, 154

GNDD

5, 16, 27, 34, 82,

I

Digital Ground.

83, 86, 92, 93,

105, 106, 117,

127, 133, 134,

141, 147, 148,

155

ADVDD

80

I

ADGND

79

I

Analog/Digital Ground. Connect to analog ground plane.

50

I

GNDG

45

I

Game Port Digital Ground. Connect to the digital ground plane.

(continued from Page 1)

HOST PC INTERFACE

All necessary ISA bus interface logic is completely contained on-

chip. This includes address decoding for all onboard resources,

control and signal interpretation, DMA selection and control

logic, IRQ selection and control logic, and all interface configu-

ration logic (see Table IV).

The AD1812 supports a DMA request/grant architecture for

transferring data with the ISA bus. One, two, or three DMA

channels can be supported. Programmed I/O (PIO) mode is

also supported for control register accesses and for applications

lacking DMA control. The AD1812 includes dual DMA count

registers for full-duplex operation enabling simultaneous capture

and playback on separate DMA channels.

The AD1812 is fully configurable according to the Plug and

Play ISA specification. In a non-Plug and Play environment, the

built in Plug and Play protocol can be disabled. When Plug and

Play is disabled, the AD1812 operates under a fixed address

space.

Table IV. Emulated Logical Devices

Logical

PnP

Device

Emulated

Compatible

Number

Device

Device

0

Windows Sound System

—

1

Sound Blaster Pro v. 2.01

PNPB002

2

OPL3 Music Synthesizer

PNPB020

3

MIDI MPU-401 Port

PNPB006

4

Game/Joystick Port

PNPB02F

5*

Modem

PNP0501

*If MODEM_EN is asserted.

WSS COMPATIBLE CODEC

The AD1812 contains the AD1845 SoundPort Stereo Codec for

business audio support and multimedia applications. The codec

includes stereo audio converters, complete on-chip filtering,

MPC Level-2 compliant analog mixing, programmable gain and

attenuation, a variable sample frequency generator, and FIFOs

buffering the ISA bus.

The codec includes a stereo pair of

∑∆ analog-to-digital con-

verters and a stereo pair of

∑∆ digital-to-analog converters. In-

puts to the ADC can be selected from four stereo pairs of analog

signals: line (LINE), microphone (MIC), auxiliary line #1

(AUX1), and post-mixed DAC output. In addition, an analog

mixer allows a mono input (MONO_IN), MIC, AUX1, LINE

and auxiliary line #2 (AUX2) to be mixed with the DACs’ out-

put. A software-controlled programmable gain stage allows in-

dependent gain for each channel going into the ADC. The

ADCs’ output can be digitally mixed with the DACs’ input.

The pair of 16-bit outputs from the ADCs are available over a

16-bit bidirectional interface that also supports 16-bit digital in-

put to the DACs and control information. The codec can accept

and generate 16-bit twos-complement PCM linear (big endian

or little endian) digital data, 4-bit IMA-ADPCM compatible

digital data, 8-bit unsigned magnitude PCM linear data, and

8-bit

µ-law or A-law companded digital data.

The AD1812 includes a variable sample frequency generator,

which allows the codec to instantaneously change sample rates

from 5.5 kHz to 50 kHz with a resolution of 1 Hz. This is a su-

perb way to create special audio effects.