AM79C32A Advanced Micro Devices, AM79C32A Datasheet - Page 7

• Manufacturer Part Number: AM79C32A
• Description: Digital Subscriber Controller (DSC) Circuit
• Manufacturer: Advanced Micro Devices

RD
Read (Input)
The active Low read signal is conditioned by CS and in-
dicates that internal information is to be transferred
onto the data bus. A number of internal registers are
user accessible. The contents of the accessed register
are transferred onto the data bus after the High to Low
transition of the RD input.
WR
Write (Input)
The active Low write signal is conditioned by CS and
indicates that external information on the data bus is to
be transferred to an internal register. The contents of
the data bus are loaded on the Low to High transition of
the WR input.
Oscillator (OSC)
MCLK
Master Clock (Output)
The MCLK output is available for use as the system
clock for the microprocessor. MCLK is derived from the
12.288-MHz crystal via a programmable divider in the
Am79C30A/32A which provides the following MCLK
output frequencies: 12.288, 6.144, 4.096, 3.072, 1.536,
0.768, and 0.384 MHz.
XTAL1, XTAL2
External Crystal (Output, Input)
XTAL1 and XTAL2 are connected to an external parallel
resonant crystal for the on-chip oscillator. XTAL2 can
also be connected to an external source instead of a
crystal, in which case XTAL1 should be left discon-
nected. The frequency must be 12.288 MHz, ± 80 ppm.
Peripheral Port (PP)
SBIN
Serial Data (Input/Output)
When the Peripheral Port is programmed to SBP mode,
SBIN operates as an input for serial data. When the Pe-
ripheral Port is programmed to IOM-2 mode, SBIN
functions as the data input except in the special case of
IOM-2 Slave mode, when it becomes an open-drain
output during part or all of the IOM-2 frame, or when
deactivated.
SBOUT
Serial Data (Input/Output)
When the Peripheral Port is programmed to SBP mode,
SBOUT operates as an output for serial data. When the
Am79C30A/32A Data Sheet
Peripheral Port is programmed to IOM-2 mode, SBOUT
functions as the data output except in the special case
of IOM-2 Slave mode when it becomes an input during
part or all of the IOM-2 frame.
SCLK
Serial Data Clock (Input/Output)
When the PP is programmed to SBP mode, SCLK out-
puts a 192-kHz data clock, which may be inverted
under software control. When the PP is programmed to
IOM-2 Master mode, SCLK outputs a 1.536-MHz 2X
data clock. In IOM-2 Slave mode, SCLK functions as
the clock input. The SCLK pin defaults to a high-imped-
ance state upon reset, but becomes active after any
MUX connection is made or if the PP is programmed to
IOM-2 Master mode.
SFS
Serial Frame Sync (Input/Output)
In SBP mode, SFS outputs an 8-kHz frame synchroni-
zation signal. SFS is an output in IOM-2 Master mode,
and an input in IOM-2 Slave mode. As an output, SFS
is active for 8-bit periods. The SFS pin defaults to a
high-impedance state upon reset, but becomes active
after any MUX connection is made or if the PP is pro-
grammed to IOM-2 Master mode. For SBP mode, the
active signal state is Low during Idle and 8 kHz in Ac-
tive Data Only and Active Voice and Data modes.
BCL/CH2STRB
Bit Clock/SBP Channel 2 Strobe
(Output, Three-state)
In SBP mode, this pin provides a strobe during the 8-bit
times of the second 64-kbit/s data channel. In IOM-2
Master mode, this pin provides a 768-kHz bit clock to
aid in the connection of non-IOM-2 devices to the port.
In IOM-2 Slave mode, this pin is high-impedance.
Power Supply Pins
PLCC/TQFP Packages
AV
AV
DV
DV
Note:
For best performance, decoupling capacitors should be in-
stalled between V
Do not use separate supplies for analog and digital power
and ground connections.
CC
SS
SS
CC
+5-V analog power supply, ±5%
Analog ground
Digital ground
+5-V digital power supply, ±5%
CC
and V
SS
as close to the chip as possible.
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