VersaLogic VL-ADR-01 Reference Manual

VL-ADR-01

USB to Audio Adapter

Reference
Manual

DOC. REV. 03/13/2015

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VL-ADR-01 Reference Manual ii

The VL-ADR-01 is a USB-to-audio adapter board. The board uses a Texas Instruments



The stereo line level output is limited to driving a 10 kΩ impedance load. This output should be

connected to an external amplifier to drive either headphones or speakers.

PCM2906C codec to bring audio capabilities to embedded single board computers lacking audio
capabilities. As shown in Figure 3, the board provides the following controls and outputs:

 Three volume control switches (Volume Up, Volume Down, and Mute)
 Two 3.5 mm line-level audio connectors (stereo line input and stereo line output)
 One 12-pin (2x6) 2 mm connector for off-board routing of controls, inputs, and outputs

Integrator’s Note:

Ordering Information

 VL-ADR-01S, temperatur e range of -25 ºC to +85 ºC

Accessories

The board connects to a host using a 0.5 m, USB 2.0 A plug to Micro-B plug cable, VersaLogic
part number VL-CBR-0503.

Dimensions

Overview

Figure 1 shows the dimensions of the VL-ADR-01.

Operating System Support

The VL-ADR-01 is compatible with standard USB audio driver code, typically embedded within an
operating system. No additional driver software is needed or supplied with the VL-ADR-01.

Figure 1. Board Dimensions

VL-ADR-01 Reference Manual 1

Audio Signaling Characteristics

ADR01_02

TVS Devices

Ground

Audio Output Right Channel

Audio Output Left Channel

Audio Input Right Channel

Audio Input Left Channel

Table 1 lists the characteristics of the audio line-level signals on the audio jacks as well as the
auxiliary connector. For information on the audio characteristics of the PCM2906C codec, refer
to the following datasheet: http://www.ti.com/product/PCM2906C.

Table 1: Line-Level Signal Characteristics

Parameter Description

Audio input signal level 2 Vp-p (typical)

Input Impedance 30 kΩ (typical)

Output voltage level 2 Vp-p (typical)

Minimum output load impedance 10 kΩ

Transient Voltage Suppression (TVS) Devices

The ADR-01 circuitry is protected from spike and surge damage by on-board Transient Voltage
Suppression (TVS) devices on the audio line input and audio line output signals. Figure 2
provides a schematic view of the connection of the TVS devices.

VL-ADR-01 Reference Manual 2

Figure 2. Schematic of TVS Circuitry

Connectors and Switches

Reference

Designator

12-pin (2x6) 2 mm connector

Figure 3 shows the locations of the connectors and switches.

Integration

Figure 3. VL-ADR-01 Connectors and Switches

Table 2: VL-ADR-01 Connectors

Connector Description

J1 Auxiliary

J2 USB Micro-B Connects the ADR-01 to a host/CPU board through a USB interface
J3 Line Input Stereo line-level input
J4 Line Output Stereo line-level output

Can be used for remote cabling of audio in/out signals and volume control
switches. Refer to Table 4 and Figure 4 for additional information.

Table 3: VL-ADR-01 Switches

Reference Designator Silkscreen Legend Description

S1 MUTE Mute
S2 VOL UP Volume up
S3 VOL DW N Volume down

VL-ADR-01 Reference Manual 3

Table 4: Auxiliary Connector Pin Description

Notes:

button switch or an open-drain driver.

Pin Signal Pin Signal

1 Mute switch (Note 1) 2 Mute input to codec (Note 2)
3 Volume Up switch (Note 1) 4 Volume Up input to codec (Note 2)
5 Volume Down switch (Note 1) 6 Volume Down input to codec (Note 2)
7 GND 8 Line input left
9 Line input right 10 GND

11 Line output right 12 Line output left

1. This signal connects to a 1.5 kΩ pull-up resistor to either 3.3 V (when operating) or to 0 V (in USB
suspend mode.

2. The optional inputs to pins 2, 4, and 6 must be pulled up to 3.3 V using a 1.5 kΩ resistor (pins 1, 3,
and 5 are intended for this use but are not required to be used). They connect directly to the HID0,
HID1 and HID2 inputs on the PCM2906C. These inputs are intended to be driven by either a push-

VL-ADR-01 Reference Manual 4

Figure 4. Pin Orientation of J1 Auxiliary Connector