Document
GS1674
GS1674 Adaptive Cable Equalizer
The GS1674 is a high-speed BiCMOS integrated circuit designed to equalize and restore signals received over 75Ω coaxial cable. The device is optimized for performance at 270Mb/s and 1.485Gb/s, and features DC restoration to compensate for the DC content of SMPTE pathological test patterns.
The Carrier Detect output pin (CD) indicates whether a valid input signal has been detected. It can be connected directly to the MUTE pin to mute the output on loss of carrier. The sensitivity of the carrier detect can be easily programmed to allow the GS1674 to distinguish between low-amplitude SDI signals and noise at the input of the device. The equalizing and DC restore stages are disengaged when the BYPASS pin is HIGH. No equalization occurs in Bypass mode.
The GS1674 is footprint and drop-in compatible with existing GS1574A and LMH0044 designs, with no additional application changes required.
Key Features
• Replaces the LMH0044
• SMPTE 292M, SMPTE 344M and SMPTE 259M compliant
• Automatic cable equalization
• Performance optimized for 270Mb/s and 1.485Gb/s. Typical equalized length of Belden 1694A cable:
220m at 1.485Gb/s
400m at 270Mb/s
• Supports DVB-ASI at 270Mb/s
• Manual bypass (useful for low data rates with slow rise/fall times)
• Programmable carrier detect with squelch threshold adjustment
• Standard EIA/JEDEC logic control and status signal levels
• Single 3.3V power supply operation
• 195mW power consumption (typical)
• Wide temperature range of -40ºC to +85ºC
• Small footprint QFN package (4mm x 4mm)
• Drop-in compatible with the GS1574A. Forward compatible with Gennum's 3G EQ products.
• Pb-free and RoHS compliant
Typical Application Circuit
CD
MUTE VCC VCC
6.8nH* SDI
75Ω
10nF
1µF 1µF
16 15 14 13
VCC_A CD
MUTE VCC_D
1 VEE_A
2 SDI 3
SDI
GS1674
VEE_D 12 11
SDO 10
SDO
10nF
75Ω 37.4Ω
4 VEE_A
9 VEE_D
4.7µF +
+ 4.7µF
AGC AGC BYPASS SQ_ADJ
56
78
1µF
SQ_ADJ BYPASS
NOTE: All resistors in Ohms, capacitors in Farads, and inductors in Henrys, unless otherwise noted. * Value dependent on layout
GS1674 Adaptive Cable Equalizer
Data Sheet
54168 - 2
September 2012
www.semtech.com
SDO SDO
1 of 16
Contents
Key Features ........................................................................................................................................................1 Typical Application Circuit.............................................................................................................................1 1. Pin Out...............................................................................................................................................................3
1.1 GS1674 Pin Assignment .................................................................................................................3 1.2 GS1674 Pin Descriptions ................................................................................................................3 2. Electrical Characteristics ............................................................................................................................5 2.1 Absolute Maximum Ratings ..........................................................................................................5 2.2 DC Electrical Characteristics ........................................................................................................5 2.3 AC Electrical Characteristics ........................................................................................................6 2.4 Typical Performance Curves ........................................................................................................7 3. Detailed Description.....................................................................................................................................8 3.1 Serial Data Inputs .............................................................................................................................8 3.2 Cable Equalization ...........................................................................................................................8 3.3 Programmable Squelch Adjust (SQ_ADJ) .................................................................................9 3.4 Mute and Carrier Detect .................................................................................................................9 3.5 Output Rise/Fall Times ................................................................................................................ 10 4. Application Information .......................................................................................................................... 11 4.1 High-Gain Adaptive Cable Equalizers .................................................................................... 11 4.2 PCB Layout ....................................................................................................................................... 11 4.3 Typic.