DS90UB928Q-Q1 Datasheet, PDF (33/69 Pages) Texas Instruments – 5 MHz to 85 MHz 24-bit Color FPD-Link III to FPD-Link Deserializer With Bidirectional Control Channel

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DS90UB928Q-Q1
SNLS417C – MARCH 2013 – REVISED JULY 2016
8.4.3 Low Frequency Optimization (LFMODE)
The LFMODE is set via register (Table 8) or by the LFMODE Pin. This mode optimizes device operation for
lower input data clock ranges supported by the serializer. If LFMODE is Low (LFMODE=0, default), the
TxCLKOUT± PCLK frequency is between 15 MHz and 85 MHz. If LFMODE is High (LFMODE=1), the
TxCLKOUT± frequency is between 5 MHz and <15 MHz. Note: when the device LFMODE is changed, a PDB
reset is required. When LFMODE is high (LFMODE=1), the line rate relative to the input data rate is multiplied by
four. Thus, for the operating range of 5 MHz to <15 MHz, the line rate is 700 Mbps to <2.1 Gbps with an effective
data payload of 175 Mbps to 525 Mbps. Note: for Backwards Compatibility Mode (BKWD=1), the line rate relative
to the input data rate remains the same.
8.4.4 Mode Select (MODE_SEL)
Device configuration may be done via the MODE_SEL pin or via register (Table 7). A pullup resistor and a
pulldown resistor of suggested values may be used to set the voltage ratio of the MODE_SEL input (VR4) and
V_DD33 to select one of the 9 possible selected modes. See Figure 30 and Table 6.
V_DD33
R₃
VR4
R₄
MODE_SEL
Deserializer
Copyright © 2016, Texas Instruments Incorporated
Figure 30. MODE_SEL Connection Diagram
Table 6. Configuration Select (MODE_SEL)
NO.
Ideal Ratio
(V_R4/V_DD33)
Ideal
V_R4 (V)
Suggested
Resistor R₃
(kΩ, 1% tol)
Suggested
Resistor R₄
(kΩ, 1% tol)
1
0
0
OPEN
40.2
2
0.120
0.397
29.4
4.02
3
0.164
0.540
25.5
4.99
4
0.223
0.737
26.7
7.68
5
0.286
0.943
25.5
10.2
6
0.365
1.205
22.6
13.0
7
0.446
1.472
20.5
16.5
8
0.541
1.786
16.2
19.1
9
0.629
2.075
12.4
21.0
REPEAT
L
L
H
H
L
L
H
H
L
BKWD
L
L
L
L
L
L
L
L
H
I2S_B
L
H
L
H
L
H
L
H
L
LCBL
L
L
L
L
H
H
H
H
L
8.4.5 Repeater Configuration
The supported Repeater application provides a mechanism to extend transmission over multiple links to multiple
display devices.
For the repeater application, this document refers to the DS90UB927Q-Q1 or DS90UB925Q-Q1 as the
Transmitter (TX), and refers to the DS90UB928Q-Q1 or DS90UB926Q-Q1 as the Receiver (RX). shows the
maximum configuration supported for Repeater implementations. Two levels of Repeaters are supported with a
maximum of three Transmitters per Receiver.
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