Pin Descriptions (Continued)
Pin Description
FS
R
Receive Frame Sync input. Normally a pulse
or squarewave with an 8 kHz repetition rate is
applied to this input to define the start of the
receive time slot assigned to this device
(non-delayed data timing mode), or the start of
the receive frame (delayed data timing mode
using the internal time-slot assignment
counter).
BCLK Bit clock input used to shift PCM data into and
out of the D
R
and D
X
pins. BCLK may vary
from 64 kHz to 4.096 MHz in 8 kHz
increments, and must be synchronous with
MCLK.
MCLK Master clock input used by the switched
capacitor filters and the encoder and decoder
sequencing logic. Must be 512 kHz, 1.536
MHz, 1.544 MHz, 2.048 MHz or 4.096 MHz
and synchronous with BCLK.
VF
X
I The Transmit analog high-impedance input.
Voice frequency signals present on this input
are encoded as an A-law or µ-law PCM bit
stream and shifted out on the selected D
X
pin.
VF
R
O The Receive analog power amplifier output,
capable of driving load impedances as low as
300Ω(depending on the peak overload level
required). PCM data received on the assigned
D
R
pin is decoded and appears at this output
as voice frequency signals.
D
X
0
D
X
1D
X
1 is available on the TP3070 only; D
X
0is
available on all devices. These Transmit Data
TRI-STATE®outputs remain in the high
impedance state except during the assigned
transmit time slot on the assigned port, during
which the transmit PCM data byte is shifted
out on the rising edges of BCLK.
TS
X
0
TS
X
1TS
X
1 is available on the TP3070 only; TS
X
0is
available on all devices. Normally these
open-drain outputs are floating in a high
impedance state except when a time-slot is
active on one of the D
X
outputs, when the
appropriate TS
X
output pulls low to enable a
backplane line-driver.
D
R
0
D
R
1D
R
1 is available on the TP3070 only; D
R
0is
available on all devices. These receive data
inputs are inactive except during the assigned
receive time slot of the assigned port when
the receive PCM data is shifted in on the
falling edges of BCLK.
CCLK Control Clock input. This clock shifts serial
control information into or out from CI/O or CI
and CO when the CS input is low, depending
on the current instruction. CCLK may be
asynchronous with the other system clocks.
Pin Description
CI/O This is the Control Data I/O pin which is
provided on the TP3071. Serial control
information is shifted to or read from COMBO
II on this pin when CS is low. The direction of
the data is determined by the current
instruction as defined in
Table 1
.
CI This is a separate Control Input, available only
on the TP3070. It can be connected to CO if
required.
CO This is a separate Control Output, available
only on the TP3070. It can be connected to CI
if required.
CS Chip Select input. When this pin is low, control
information can be written to or read from
COMBO II via the CI/O pin (or CI and CO).
IL5–IL0 IL5 through IL0 are available on the TP3070.
IL4 through IL0 are available on the TP3071.
Each Interface Latch I/O pin may be
individually programmed as an input or an
output determined by the state of the
corresponding bit in the Latch Direction
Register (LDR). For pins configured as inputs,
the logic state sensed on each input is latched
into the Interface Latch Register (ILR)
whenever control data is written to COMBO II,
while CS is low, and the information is shifted
out on the CO (or CI/O) pin. When configured
as outputs, control data written into the ILR
appears at the corresponding IL pins.
MR This logic input must be pulled low for normal
operation of COMBO II. When pulled
momentarily high (at least 1 µsec.), all
programmable registers in the device are reset
to the states specified under “Power-On
Initialization”.
NC No Connection. Do not connect to this pin. Do
not route traces through this pin.
Functional Description
POWER-ON INITIALIZATION
When power is first applied, power-on reset circuitry initial-
izes the COMBO II and puts it into the power-down state.
The gain control registers for the transmit and receive gain
sections are programmed to OFF (00000000), the hybrid
balance circuit is turned off, the power amp is disabled and
the device is in the non-delayed timing mode. The Latch Di-
rection Register (LDR) is pre-set with all IL pins programmed
as inputs, placing the SLIC interface pins in a high imped-
ance state. The CI/O pin is set as an input ready for the first
control byte of the initialization sequence. Other initial states
in the Control Register are indicated in Section 2.0.
Areset to these same initial conditions may also be forced by
driving the MR pin momentarily high. This may be done ei-
ther when powered-up or down. For normal operation this
pin must be pulled low. If not used, MR should be hard-wired
to ground.
The desired modes for all programmable functions may be
initialized via the control port prior to a Power-up command.
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