GS1528 Gennum Corporation, GS1528 Datasheet - Page 4

• Manufacturer Part Number: GS1528
• Description: Multi-rate Dual Slew-rate Cable Driver For HD-SDI, Sd-sdi & DVB-ASI. 3.3V Supply.
• Manufacturer: Gennum Corporation

DETAILED DESCRIPTION
DETAILED DESCRIPTION
DETAILED DESCRIPTION
DETAILED DESCRIPTION
INPUT INTERFACING
SDI/SDI are high impedance differential inputs. (See Figure 1
for equivalent input circuit).
Several conditions must be observed when interfacing to
these inputs:
1. The differential input signal amplitude must be between
2. The common mode voltage range must be as specified
3. For input trace lengths longer than approximately 1cm,
The GS1528 inputs are self-biased, allowing for simple AC
coupling to the device. For serial digital video, a minimum
capacitor value of 4.7µF should be used to allow coupling
of pathological test signals. A tantalum capacitor is
recommended.
SD/HD
The GS1528 SDO rise and fall times can be set to comply
with both SMPTE 259M/344M and SMPTE 292M. For all
SMPTE 259M standards, or any data rate that requires
longer rise and fall time characteristics, the SD/HD pin must
be set to a HIGH INPUT. For SMPTE 292M standards and
signals which require faster rise and fall times, this pin
should be set to a LOW INPUT.
OUTPUT INTERFACING
The GS1528 outputs are current mode, and will drive 800mV
into a 75Ω load. These outputs are protected from accidental
static damage with internal static protection diodes.
The SMPTE 292M, SMPTE 344M and SMPTE 259M
standards requires that the output of a cable driver have a
source impedance of 75Ω and a return loss of at least 15dB
between 5MHz and 1.485GHz.
In order for an SDI output circuit using the GS1528 to meet
this specification, the output circuit shown in the Typical
Application Circuit is recommended.
The value of L
with a typical value of 5.6nH (see the Application Information
section in this data sheet for further details). A 4.7µF
capacitor is used for AC coupling the output of the GS1528.
This value is chosen to ensure that pathological signals can
be coupled without a significant DC component occurring.
GENNUM CORPORATION
300 and 2000mVpp.
in the DC Characteristics Table.
the inputs should be terminated as shown in the Typical
Application Circuit.
COMP
will vary depending on the PCB layout,
4
When measuring return loss at the GS1528 output, it is
necessary to take the measurement for both a logic high
and a logic low output condition. This is because the output
protection diodes act as a varactor (voltage controlled
capacitor) as shown in Figure 6.
Consequently, the output capacitance of the GS1528 is
dependent on the logic state of the output.
Tek Stopped:
Tek Running: Normal
Fig. 5 Output signal for 1.485Gb/s input
Fig. 4 Output signal for 270Mb/s input
8110 Acquisitions
16632 - 2