Setting Up The Evaluation Board; Input Configuration; Shutdown Mode; Gain Configuration - Analog Devices UG-373 User Manual

Evaluation Board User Guide

SETTING UP THE EVALUATION BOARD

INPUT CONFIGURATION

Four of the 2-pin headers (J1, J2, J5, and J6) feed the stereo
differential audio signal into the board (see Figure 1). If the
input audio signal is a single-ended stereo audio input, an
audio jack, J3, (3.5 mm) can be used. To configure the board
for single-ended stereo audio input, connect LINP and RINP
to ground by inserting jumpers across J1 and J2. Audio signals
are then connected to J5 (LINN) and J6 (RINN) or via a 3.5 mm
jack to J3.

SHUTDOWN MODE

amplifier is controlled by the SD (J4)
Shutdown of the SSM2932
pin. If a logic low is applied to the pin by inserting a jumper
from the center pin of J4 to GND (low), the amplifier becomes
inactive and draws only minimal current from the supply. To
activate the amplifier, insert a jumper across the center pin of
J4 to PVDD (high).

GAIN CONFIGURATION

The SSM2932 amplifier gain can be set to either 0 dB or 6 dB
by applying a logic level to the GAIN pin, as shown in Table 1.
J10 is used to configure the SSM2932
and to insert a jumper across the center pin of J10 and PVDD
(high). To configure the SSM2932
a jumper across the center pin of J10 and GND (low).
Table 1. Amplifier Gain
Amplifier Gain
0 dB
6 dB

HIGH OUTPUT IMPEDANCE

The SSM2932 has a HI-Z control pin that mutes the amplifier
and sets the output to a high impedance. If both HI-Z and SD
are set to PVDD (high), the amplifier remains in a high-
impedance mode. This feature allows the headphone output
jack to be shared for other functions such as video output
or data transmission. J9 is used to configure the
amplifier gain to high impedance output mode and to insert
a jumper across the center pin of J9 and PVDD (high). To
configure the SSM2932 amplifier output to normal operational
mode, insert a jumper across the center pin of J9 and GND (low).
amplifier gain to 6 dB
amplifier gain to 0 dB, insert
GAIN Pin Logic Level
Low (≤0.5 V)
High (≥1.2 V)
SSM2932

OUTPUT CONFIGURATION

The output connector, J8 can be connected to a set of head-
phones with a minimum impedance of 16 Ω. J8 is a standard
3.5 mm 3-terminal connector (left, right, and ground).
Alternatively, for direct access to the outputs, the user
can connect test loads to J12 (OUTL) and J13 (OUTR)
for testing on an audio analyzer.

GROUND SENSE

SGND is a headphone ground sense pin and must be connected
directly to the common headphone jack. When the headphone
jack is connected to a device or board, there is ground differ-
ence between the headphone jack's ground pin and audio
amplifier. SGND is used to detect this ground difference,
which reduces audible noise due to ground loop currents. This
also reduces output offset voltage and turn-on pop noise. On
the board, SGND is connected to the board GND by placing a
jumper across J11.

POWER SUPPLY CONFIGURATION

An external power supply connected to PVDD is required for
the SSM2932 to operate. PVDD and GND must be connected
by the 2-pin header, J7.
Be sure to connect the dc power supplies with correct polarity
and voltage. PVDD must be connected to a supply voltage in
the acceptable range, between 2.5 V and 3.6 V. Reverse polarity
or overvoltage may damage the board permanently.
Rev. 0 | Page 3 of 8
UG-373