ad6437

Manufacturer Part Numberad6437
DescriptionAnalog Front End For Adsl
ManufacturerAnalog Devices, Inc.
ad6437 datasheet
 
1
Page 1
2
Page 2
3
Page 3
4
Page 4
5
Page 5
6
Page 6
7
Page 7
8
Page 8
9
Page 9
10
Page 10
11
12
Page 1/12

Download datasheet (122Kb)Embed
Next
a
FEATURES
Complete Analog Front End for ADSL Modems
Part of ADI ADSL Chipset (AD20msp910)
Designed to ANSI T1.413/ETSI TR238/ITU G.adsl
Performance
e.g., 6.1 Mbps Downstream Over 12K Ft.
Suitable for CO or Residence (ATU-C and ATU-R)
Includes Transmit and Receive Signal Paths:
DAC: 20 MSPS 12-Bit Current Output
ADC: 10 MSPS 12-Bit
PGA: 0 dB–25 dB of Gain with 1 dB Steps
Programmable Filters
Auxiliary DAC for Timing Recovery
Interface to 3.3 V or 5 V Digital Logic
Low Power Consumption (485 mW)
80-Lead PQFP
–40 C to +85 C Operation
GENERAL DESCRIPTION
The AD6437 is a complete analog front-end IC (AD6437) for
ADSL systems. Although part of the Analog Devices DMT
chipset, it is suitable for use with digital implementations from
other suppliers.
As part of the AD20msp910 chipset, it complements the
AD6435, the AD6436 and ADSP-2183; together with the AD816
driver and an external filter, they make a complete ADSL
datapump, designed to comply with ANSI and ETSI standards
for DMT-based ADSL.
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
This Material Copyrighted By Its Respective Manufacturer
Analog Front End for ADSL
FUNCTIONAL BLOCK DIAGRAM
IOUT
TXLPFIN
14
12-BIT
ANALOG
TX[13:0]
DAC
FILTER
AD6437
3
CONTROL
CPORT
LOGIC
ANALOG
FILTER
7-BIT
VCXO
DAC
12
12-BIT
RX[11:0]
ADC
RX_ADC
LOW PASS
FILTER OUT
The AD6437 includes both transmit and receive paths. These
include the DAC (up to 20 MSPS, allowing for oversampling of
the downstream transmit signal), ADC (up to 10 MSPS), low
noise PGA and filters. The filters are software configurable for
both the CO and RT modes. There is an auxiliary 7-bit auxiliary
DAC (e.g., for timing recovery).
The AD6437 has been designed to be versatile, and most blocks
can be used or externally bypassed.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 1997
AD6437
TO
DRIVER
LOOPBACK
FROM
PGA
HYBRID

ad6437 Summary of contents

  • Page 1

    ... PGA and filters. The filters are software configurable for both the CO and RT modes. There is an auxiliary 7-bit auxiliary DAC (e.g., for timing recovery). The AD6437 has been designed to be versatile, and most blocks can be used or externally bypassed. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. ...

  • Page 2

    ... AD6437–SPECIFICATIONS Parameter TRANSMIT CHANNEL SNR THD DAC Resolution Sample Rate Data Format Output Compliance Range TRANSMIT FILTER Input Voltage Range Input Impedance Output Voltage Range CO Mode 3 dB Frequency Stopband Rejection @ 16 MHz Passband Passband Gain RT Mode 3 dB Frequency Stopband Rejection @ 2.07 MHz ...

  • Page 3

    ... ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD6437 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality ...

  • Page 4

    ... Digital Output (Receive) Data from ADC. ADC Clock Input Sampled on Positive Edge. PIN CONFIGURATION PIN 1 2 IDENTIFIER TX13 7 TX12 8 TX11 9 AD6437 TX10 10 TOP VIEW TX9 11 (Not to Scale) TX8 12 TX7 13 TX6 14 TX5 15 TX4 16 TX3 17 TX2 18 TX1 19 ...

  • Page 5

    ... B). Typically, it will then be connected to TXLPF for the on-chip reconstruction filter (4th order Butterworth active filter). However, this filter can be bypassed if a different filter is required (e.g., to use the AD6437 in a non- standard application). The filter can be switched between two corner frequencies, for use in CO mode or RT mode. For downstream operation (CO mode), the band ends at 1.1 MHz and the filter’ ...

  • Page 6

    ... The filter capacitors shown in Figure 2 are used to decouple the internal reference voltages of the ADC. A buffer is required after the filters, at the input to the ADC. This must be able to drive the 30 pF input capacitance of the ADC, with the desired bandwidth and distortion properties. A typical part is the AD8042. AD6437 0 ...

  • Page 7

    ... SFRAME are clocked into the DSP Interface block on a falling edge of SCLK. The DSP interface decodes the first three bits of the incoming data word to determine if the AD6437 is being addressed. If the DSP has selected the AD6437, the next 10 bits are accepted. The first two bits decode one of four inter- nal data registers (Reg A, Reg B, Reg C, and Reg D), and the following eight bits used as data to be loaded into that register ...

  • Page 8

    ... AD6437 SDATA [2:0] Determines if AD6437 is selected, Addr 101 is assigned for AD6437. NOTE Data is transmitted in 13-bit words: SDATA 0, LSB, transmitted first; SDATA 12, MSB, transmitted last. TIMING RECEIVE INTERFACE The analog input is sampled every the rising edge of the ADC clock (RX_CLK), with digital data (RX11:RX0) being valid on each falling edge of RX_CLK ...

  • Page 9

    ... CONNECTION AND APPLICATION INFORMATION Decoupling All the internal bias points of the AD6437 DAC and ADC are decoupled as shown in Figures 2 and 3. All AD6437 power pins should be decoupled with tantalum capacitor and a parallel 0.1 F ceramic chip cap. The 0.1 F capacitors should be placed as closely as possible to the device pins. This configuration ensures a low impedance power source over a wide band of frequencies. ...

  • Page 10

    ... AD6437 This Material Copyrighted By Its Respective Manufacturer OUTLINE DIMENSIONS Dimensions shown in inches and (mm). 80-Lead Plastic Quad Flatpack (PQFP) (S-80A) 0.690 (17.45) 0.667 (16.95) 0.555 (14.10) 0.134 (3.40) MAX 0.547 (13.90) 0.486 (12.35) BSC 0.041 (1.03) 0.029 (0.73 SEATING PLANE TOP VIEW (PINS DOWN) 0.004 (0.10) 20 MAX 21 0.010 (0.25) MIN 0.026 (0.65) ...

  • Page 11

    This Material Copyrighted By Its Respective Manufacturer –11– ...

  • Page 12

    This Material Copyrighted By Its Respective Manufacturer –12– ...