ETC5064 - ETC5064-X - ETC5067 - ETC5067-X
FUNCTIONAL DESCRIPTION
POWER-UP
Each FSX pulse begins the encoding cycle and the
PCM data from the previous encode cycle is shift out
of the enabled DX output on the positive edge of
BCLKX. After 8 bit clock periods, the TRISTATE DX
outputis returnedto a high impedancestate. With an
FSR pulse, PCM data is latched via the DR input on
thenegativeedgeof BCLKX (or on BCKLR if running).
FSX and FSR must be synchronous with MCLKX/R.
When poweris first applied, power-on resetcircuitry
initializes the device and places it into the power-
down mode. All non-essential circuits are deacti-
vated and the DX and VFRO outputsare put in high
impedancestates.To power-upthe device,a logical
low level or clock must be applied to the
MCLKR/PDN pin and FSX and/or FSR pulses must
be present. Thus 2 power-down control modes are
available. The first is to pull the MCLKR/PDN pin
high; the alternative is to hold both FSX and FSR in-
puts continuouslylow. The device will power-down
approximately 2 ms after the last FSX pulse. The
TRI-STATE PCM data output, DX, will remain in the
high impedance state until the second FSX pulse.
ASYNCHRONOUS OPERATION
For asynchronousoperation,separate transmit and
receive clocks may be applied. MCLKX and MCLKR
must be 2.048MHz for the ETC5067 or 1.536MHz,
1.544 MHz for the ETC5064, and need not be syn-
chronous.For best transmissionperformance,how-
ever, MCLKR shouldbe synchronouswith MCLKX,
which is easily achievedby applyingonly staticlogic
levels to theMCLKR/PDNpin.Thiswill automatically
connectMCLKX toall internalMCLKR functions(see
pin description). For 1.544 MHz operation, the de-
vice automaticallycompensates for the 193rd clock
pulse each frame. FSX starts each encoding cycle
and must be synchronous with MCLKX and BCLKX.
FSR starts each decoding cycle and must be syn-
chronous with BCLKR. BCLKR must be a clock, the
logic levels shown in Table 1 are not valid in asyn-
chronous mode. BCLKX and BCLKR may operate
from 64kHz to 2.048 MHz.
SYNCHRONOUS OPERATION
For synchronous operation, the same master clock
and bit clock should be used for both the transmit
and receive directions.In thismode,a clockmust be
applied to MCLKX and the MCLKR/PDN pin can be
used as a power-down control. A low level on
MCLKR/PDN powers up the device and a high level
powersdown the device. In either case, MCLKX will
be selectedas the master clock for boththe transmit
and receive circuits. A bit clock mustalso be applied
to BCLKX and theBCLR/CLKSELcan be usedto se-
lect the proper internal divider for a master clock of
1.536 MHz, 1.544 MHz or 2.048 MHz. For 1.544
MHz operation, the device automatically compen-
sates for the 193 rd clock pulse each frame.
SHORT FRAME SYNC OPERATION
The device can utilize either a short frame sync
pulse ora longframe sync pulse.Uponpowerinitiali-
zation, the device assumes a short frame mode. In
this mode, both frame sync pulses. FSX and FSR,
must be one bit clock period long, with timing rela-
tionships specified in figure 2. With FSX high during
a falling edge of BCLKR, the next rising edge of
BCLKX enables the DX TRI-STATE output buffer,
which willoutputthesignbit. Thefollowingsevenris-
ing edges clock out the remaining seven bits, and
the next falling edge disables the DX output. With
FSR high during a falling edge of BCLKR (BCLKX in
synchronousmode), the nextfalling edgeof BCLKR
latches in the sign bit. The following seven falling
edges latch in the seven remaining bits. Both de-
vices may utilize the short frame sync pulse in syn-
chronous or asynchronousoperating mode.
With a fixed level onthe BCLKR/CKSEL pin, BCLKX
will be selected as the bit clock for both the transmit
and receive directions. Table 1 indicates the fre-
quencies of operation which can be selected, de-
pendingon the state ofBCLKR/CLKSEL.In thissyn-
chronousmode, the bit clock, BCLKX, may be from
64 kHz to2.048 MHz, but must be synchronouswith
MCLKX.
Table 1: Selection of Master Clock Frequencies.
Master Clock
Frequency Selected
BCLKR/CLKSEL
ETC5067
ETC5064
ETC5067-X
ETC5064-X
Clocked
2.048MHz
1.536MHz or
1.544MHz
LONG FRAME SYNC OPERATION
To use the long frame mode, both the frame sync
pulses, FSX andFSR, mustbethree ormorebit clock
periods long, with timing relationships specified in
figure 3. Based on the transmit frame sync FSX, the
device will sense whether short or long frame sync
0
1.536MHz or
1.544MHz
2.048MHz
1 (or open circuit)
2.048MHz
1.536MHz or
1.544MHz
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