Table 4-2: Slew Rate Selection
SD/HD
Rise/Fall Time
0
1
SMPTE 424M & 292M compliant
SMPTE 259M compliant
Floating
SMPTE 259M compliant
4.4 Output Disable
The GS2988 supports an output disable function for the serial data differential output.
Control of this function is determined by the setting of the DISABLE control pin.
The serial output disable (DISABLE), disables power to the entire device. When asserted
LOW, the SDO/SDO output driver is powered-down.
Table 4-3: Output Disable
DISABLE
SDO/SDO
0
1
All Chip Power Down
Operational
Floating
Operational
4.5 Output Signal Presence Indicator (OSP)
The GS2988 supports an output signal presence indicator function.
The output signal presence pin (OSP) is an active-low output that indicates when a valid
output signal has been detected at the pre-driver output.
The output signal presence function measures signal-edge energy to indicate that the
pre-driver to the serial data outputs is toggling.
Table 4-4: Output Signal Presence Indicator
Pre-Driver Output
OSP Pin
Valid signal present
0
1
No valid signal present
4.6 Output Amplitude (RSET)
The output amplitude of the GS2988 can be adjusted by changing the value of the RSET
resistor as shown in Figure 4-1. For an 800mVp-p output with a nominal ±7% tolerance,
a value of 750Ω is required. A ±1% SMT resistor should be used.
GS2988 Dual-Slew-Rate, Cable Driver with 3Gb/s
10 of 17
Capability
Data Sheet
52131 - 4
December 2010
GENNUM [ GENNUM CORPORATION ]
