ST70134-ST70135A STMICROELECTRONICS [STMicroelectronics], ST70134-ST70135A Datasheet - Page 3

• Manufacturer Part Number: ST70134-ST70135A
• Description: ASCOT ADSL MODEM CHIP SET FOR CPE
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

ASCOT ICs
ASCOT consists of an Analog Front End
(ST70134) and a Discrete Multitone Modem
(ST70135A)
produced by STMicroelectronics.
Here below we will briefly go through the main
topics of both the ICs (see Figure 2 and Figure 3).
Analog Front End (ST70134)
HCMOS5A (0.5 m) mixed digital and analog
technology has been chosen to produce this
component that embodies the analog functions of
the ASCOT.
Automatic gain control amplifiers, placed at the
analog interface of transmit and receive paths,
allow to keep acceptable level of the signal ADC’s
and DAC’s resolution, that is 12-bit wide with
8.8MHz sampling rate.
A built-in driver allows for external clock
generation using a VCXO.
Figure 2 : Analog Front End block diagram
TRANSMIT-SIDE
RECEIVE-SIDE
4
4
integrated
MUX
MUX
circuits
12 Bits / 8.8MHz
12 Bits / 8.8MHz
DAC
DAC
which
are
138KHz
1.1MHz
VCODAC
ST70134 Analog Front End’s main features:
– Rx low noise amplifier (0-31dB in 1dB steps
– Tx pre-driver amplifier (-15dB -0)
– Two input ports allow selection of RX signals,
– Programmable low pass and band pass filters
– 12-bit DAC and ADC, sampling at 8.832MHz
– Xtal: 35.328MHz, 50ppm, the accuracy of the
– Direct connection to ST70135A DMT modem
– Error correction on ADC output
– Analog and digital loop back modes
– Single 3.3V supply, or 3.3V analog and 3.0V
– Power dissipation 0.4W
– Power-down mode 0.1W
– TQFP64 (10 x 10mm body, 0.5mm pitch)
e.g. with or without external attenuation
frequency is determined by the External XTAL
digital supplies
LPF
LPF
XTAL DRIVER
G = 0...31dB
STEP 1dB
LNA
G = -15...0dB
ST70134 - ST70135A
STEP 1dB
3/8