DS90UB927-Q1 Datasheet, PDF (18/56 Pages) Texas Instruments – 5MHz - 85MHz 24-bit Color FPD-Link III Serializer with Bidirectional Control Channel

DS90UB927-Q1, DS90UB927Q, DS90UB927Q-Q1
SNLS416B – JUNE 2012
EMI REDUCTION FEATURES
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LVCMOS V_DDIO OPTION
The 1.8V or 3.3V LVCMOS inputs and outputs are powered from separate VDDIO supply pins to offer
compatibility with external system interface signals. Note: When configuring the V_DDIO power supplies, all the
single-ended control input pins for device need to scale together with the same operating V_DDIO levels. If V_DDIO is
selected to operate in the 3.0V to 3.6V range, V_DDIO must be operated within 300mV of V_DD33.
POWER DOWN (PDB)
The Serializer has a PDB input pin to ENABLE or POWER DOWN the device. This pin may be controlled by an
external device, or through V_DDIO, where V_DDIO = 3.0V to 3.6V or V_DD33. To save power, disable the link when the
display is not needed (PDB = LOW). Ensure that this pin is not driven HIGH before V_DD33 and V_DDIO have
reached final levels. When PDB is driven low, ensure that the pin is driven to 0V for at least 1.5ms before
releasing or driving high. In the case where PDB is pulled up to V_DDIO = 3.0V to 3.6V or V_DD33 directly, a 10kΩ
pull-up resistor and a >10µF capacitor to ground are required (See Figure 29).
Toggling PDB low will POWER DOWN the device and RESET all control registers to default. During this time,
PDB must be held low for a minimum period of time. See AC Electrical Characteristics for more information.
REMOTE AUTO POWER DOWN MODE
The DS90UB927Q serializer features a Remote Auto Power Down mode. This feature is enabled and disabled
through the register bit 0x01[7] (Table 5). 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 16:
Enable
Set reg_0x01[7]=1
Back Channel IDLE
Normal Operation
Remote Auto Power
Down Enabled
Forward-channel
OFF
Sleep
Disable
Set reg_0x01[7]=0
Back Channel ACTIVE
Figure 16. Remote Auto Power Down Sleep/Wake Cycle
To resume normal operation, the Remote Auto Power Down feature must be disabled in the device control
register. This may be accomplished from a local I2C controller by writing reg_0x01[7]=0 (Table 5). To disable
from a remote I2C controller located at the deserializer, perform the following procedure to complete the wake-up
process:
1. Power up remote deserializer (back channel must be active)
2. Enable I2C PASS-THROUGH ALL by setting deserializer register reg_0x05[7]=1
3. Enable I2C AUTO ACK by setting deserializer register reg_0x03[2]=1
4. Disable Remote Auto Power Down by setting serializer register reg_0x01[7]=0
5. Disable I2C AUTO ACK by setting deserializer register reg_0x03[2]=0
6. Disable I2C PASS-THROUGH ALL by setting deserializer register reg_0x05[7]=0
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