Modem User Manual

LZT 123 1834 53
Parameter Conditions Min Typ Max Unit
max input gain 14 16 18 mVrms
Input voltage full scale
min input gain 45 50 56 mVrms
Frequency response -3dB cut-off 300 3400 Hz
Output dc bias level 2.16 2.4 2.64 V
5.9.4 Speaker Signals (EARP, EARN)
EARP and EARN are the speaker output signals. These are differential-mode outputs.
With a full-scale PCM input to the CODEC, 0 dB audio output gain setting, and a
differential load RL = 30Ω, the output voltage between EARP and EARN is 1.5 V rms.
For load resistances less than 30Ω, the full-scale output needs is limited using the
modules internal programmable gain attenuator.
The electrical characteristics are given in the table below.
Parameter Conditions Min Typ Max Unit
RL = 30 1.34 1.5 1.68 Vrms
RL = 16  1.41 Vrms
Input voltage full scale
RL = 8

1.24 Vrms
Frequency response -3dB cut-off 300 3400 Hz
5.10 PCM Digital Audio (SSP)
Pin Name Direction Function
48 SSPDFM Output Serial PCM data from module to host
47 SSPDTM Input Serial PCM data to module from host
51 SSPFS In/Out Serial PCM frame synchronization
52 SSPCLK In/Out Serial PCM clock
The SSP (Synchronous Serial Port) digital interface is configured to provide a PCM
(digital) audio interface. This interface can be used to process PCM digital audio
signals as an alternative to routing signals to the CODECs through the analogue
uplink and downlink chains.
5.10.1 PCM Data Format
The PCM digital audio interface for GR64 is based upon the Texas Instruments SSI
standard. The SSP is a versatile interface which can be programmed for different
clock rates and data frame sizes between 4 to 16 bits.