ucb1200 NXP Semiconductors, ucb1200 Datasheet - Page 11

• Manufacturer Part Number: ucb1200
• Description: Advanced Modem/audio Analog Front-end
• Manufacturer: NXP Semiconductors

Philips Semiconductors
TELECOM CODEC
The telecom codec contains an input channel, built up from a 64 times oversampling sigma delta analog to digital
converter (ADC) with digital decimation filters, programmable attenuation and built-in sidetone suppression circuit.
The output path consist of a digital up sample filter, a 64 time oversampling 4 bit digital to analog converter (DAC) circuit
followed by a differential output driver, capable of directly driving a 600
a mute function. The telecom codec also incorporates a loopback mode, in which codec output path and the input path
are connected in series.
The telecom sample rate (f
interface. The telecom sample rate is given by the following formula:
For example, a SIBCLK of 9.216 MHz, with a divisor of 40, results in a telecom sample rate of 7.2 kHz. Both the rising
and the falling edges of the SIBCLK are used in case TEL_DIV[n] is set to an odd number. In that case a 50% duty cycle
of the SIBCLK signal is mandatory to obtain time equidistant sampling.
The input path of the telecom codec has a programmable attenuation. It also implements a voice band filter, which
consists of an digital low pass filter, which is a part of the decimation filter. Therefore the pass band of the voice band
1998 Jul 22
TOUTP
TOUTN
Advanced modem/audio analog front-end
f
st
=
------------------------------------------------- -
64 TEL_DIV[n]
TINP
TINN
2 F
SIBCLK
TEL_SIDE_ENA
SUPPRESSION
SIDETONE
CIRCUIT
st
) is derived from the SIB interface clock pin (SIBCLK) and is programmable through the SIB
(15 < TEL_DIV[n] <128)
Fig.7 Telecom codec block diagram.
TEL_MUTE
TEL_LOOP
11
TEL_ATT
isolation transformer. The output path includes
4bit DAC
1bit ADC
DIGITAL
DECIMATION
FILTER
DIGITAL
NOISE
SHAPER
Product specification
UCB1200
TEL_OUT_ENA
TEL_IN_ENA
14
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