DS90UB921-Q1 Datasheet, PDF (17/57 Pages) Texas Instruments – 5 - 96 MHz 24-bit Color FPD-Link III Serializer with Bidirectional Control Channel

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Feature Description (continued)
DS90UB921-Q1
SNLS488 – MARCH 2016
PCLK
IN
HS/VS/DE
IN
Latency
PCLK
OUT
HS/VS/DE
OUT
Pulses 1 or 2
PCLKs wide
Filetered OUT
Figure 14. Video Control Signal Filter Waveform
7.3.5 EMI Reduction Features
7.3.5.1 Input SSC Tolerance (SSCT)
The DS90UB921-Q1 serializer is capable of tracking a triangular input spread spectrum clocking (SSC) profile up
to ±2.5% amplitude deviations (center spread), up to 35 kHz modulation at 5–96 MHz, from a host source.
7.3.6 LVCMOS VDDIO Option
1.8 V or 3.3 V Inputs and Outputs are powered from a separate VDDIO supply to offer compatibility with external
system interface signals.
NOTE
When configuring the VDDIO power supplies, all the single-ended data and control input
pins for device need to scale together with the same operating VDDIO levels.
7.3.7 Power Down (PDB)
The Serializer has a PDB input pin to ENABLE or POWER DOWN the device. This pin can be controlled by the
host or through the VDDIO, where VDDIO = 3.0V to 3.6V or VDD33. To save power disable the link when the
display is not needed (PDB = LOW). When the pin is driven by the host, make sure to release it after VDD33 and
VDDIO have reached final levels; no external components are required. In the case of driven by the VDDIO =
3.0V to 3.6V or VDD33 directly, a 10 kohm resistor to the VDDIO = 3.0V to 3.6V or VDD33 , and a >10uF
capacitor to the ground are required (See Figure 26).
7.3.8 Remote Auto Power-Down Mode
The DS90UB921-Q1 serializer features a Remote Auto Power Down mode. This feature is enabled and disabled
through the register bit 0x01[7] (Table 7). When the back channel is not detected, either due to an idle or
powered-down deserializer, the serializer enters remote auto power down mode. Power dissipation of the
serializer is significantly reduced in this mode. The serializer automatically attempts to resume normal operation
upon detection of an active back channel from the deserializer. To complete the wake-up process and reactivate
forward channel operation, the remote power-down feature must be disabled by either a local I²C host, or by an
auto-ACK I²C transaction from a remote I²C host located at the deserializer. The Remote Auto Power Down
Sleep/Wake cycle is shown below in Figure 15:
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