MSM6688 Datasheet, PDF (28/159 Pages) OKI electronic componets – ADPCM Solid-State Recorder IC

¡ Semiconductor
MSM6688/6688L
FUNCTIONAL DESCRIPTION
Recording Time and Memory Capacity
The recording time depends on the memory capacity of the external serial registers, sampling
frequency, and ADPCM bit length, and is given by
Recording time = ^{1.024 ¥ memory capacity (K bits)}
(seconds)
sampling frequency (kHz) ¥ bit length (bits)
For example, if the sampling frequency is
4096
768
kHz (= 5.333 kHz), ADPCM bit length is 3 bits, and
four 8M bit serial registers are used, the recording time can be obtained as follows.
Recording time = ^{1.024 ¥ (8192 ¥ 4 – 64)} = 2093 seconds
5.333 ¥ 3
= 34 minutes 53 seconds
In the above equation, the memory capacity is obtained by subtracting the memory capacity (64
Kbits) for the channel index area from the total memory capacity.
Connection of an Oscillator
Connect a ceramic oscillator or a crystal oscillator to XT and XT pins as shown below. The optimal
load capacities when connecting ceramic oscillators from MURATA MFG. and KYOCERA
CORPORATION are shown below for reference.
MSM6688
XT
XT
C1
C2
Ceramic oscillator
Type
CSA4.00MG
CST4.00MGW
(with capacitor)
MURATA CSA6.00MG
MFG. _CST6.00MGW
(with capacitor)
CSA8.00MTZ
CST8.00MTW
(with capacitor)
KBR-4.0MSA
KBR-4.0MKS
(with capacitor)
PBRC4.00A
PBRC4.00B
KYOCERA _KBR-6.0MSA
CORPO-
RATION
KBR-6.0MKS
PBRC6.00A
(with capacitor)
PBRC6.00B
KBR-8.0M
PBRC8.00A
PBRC8.00B
Freq(MHz)
4.0
6.0
8.0
4.0
6.0
8.0
Optimal load capacity
C1(pF)
C2(pF)
30
30
33
33
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