TI SN65LVDS308ZQCR

SN65LVDS308
www.ti.com
SLLS835 – MAY 2007
PROGRAMMABLE 27-BIT PARALLEL-TO-SERIAL RECEIVER
FEATURES
•
•
•
•
•
•
•
•
•
•
•
FlatLink 3G Serial Interface Technology
Compatible With FlatLink™ 3G Transmitters
Such as SN65LVDS307
Supports Video Interfaces up to 24-Bit RGB
Data and 3 Control Bits Received Over Two
Differential Data Lines
SubLVDS Differential Voltage Levels
Up to 810-Mbps Data Throughput
Three Operating Modes to Conserve Power
– Active mode VGA 60 fps: 17 mW
– Typical Shutdown: 0.7 µW
– Typical Standby Mode: 67 µW Typical
ESD Rating > 4 kV (HBM)
Pixel-Clock Range of 8 MHz–30 MHz
Failsafe on all CMOS Inputs
4-mm × 4-mm MicroStar Junior™µBGA®
Package With 0,5-mm Ball Pitch
Very Low EMI
When receiving, the PLL locks to the incoming clock,
CLK, and generates an internal high-speed clock at
the line rate of the data lines. The data is serially
loaded into a shift register using the internal
high-speed clock. The deserialized data is presented
on the parallel output bus with a recreation of the
pixel clock, PCLK, generated from the internal
high-speed clock. If no input CLK signal is present,
the output bus is held static with PCLK and DE held
low, while all other parallel outputs are pulled high.
The F/S control input selects between a slow CMOS
bus output rise time for best EMI and power
consumption and a fast CMOS output for increased
speed or higher-load designs.
Flatlinkä3G
LCD
Driver
LVDS308
CLK
APPLICATIONS
•
•
•
Small Low-Emission Interface Between
Graphics Controller and LCD Display
Mobile Phones and Smart Phones
Portable Multimedia Players
DESCRIPTION
The SN65LVDS308 receiver deserializes FlatLink
3G-compliant serial input data to 27 parallel data
outputs. The SN65LVDS308 receiver contains one
shift register to load 30 bits from two serial inputs
and latches the 24 pixel bits and 3 control bits out to
the parallel CMOS outputs after checking the parity
bit. If a parity error is detected, the data output bus
disregards the newly received pixel. Instead, the last
data word is held on the output bus for another clock
cycle.
DATA
LVDS307
1
2
3
4
5
6
7
8
9
*
0
#
Application
Processor
with
RGB
Video
Interface
M0056-03
The serial data and clock are received via
sub-low-voltage differential signalling (SubLVDS)
lines. The SN65LVDS308 supports three operating
power modes (shutdown, standby, and active) to
conserve power.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
FlatLink, MicroStar Junior are trademarks of Texas Instruments.
µBGA is a registered trademark of Tessera, Inc.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2007, Texas Instruments Incorporated
SN65LVDS308
www.ti.com
SLLS835 – MAY 2007
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
DESCRIPTION (CONTINUED)
The RXEN input can be used to put the SN65LVDS308 in a shutdown mode. The SN65LVDS308 enters an
active standby mode if the common-mode voltage of the CLK input becomes shifted to VDDLVDS (e.g., the
transmitter releases the CLK output into high-impedance). This minimizes power consumption without the need
of switching an external control pin. The SN65LVDS308 is characterized for operation over ambient air
temperatures of –40°C to 85°C. All CMOS and SubLVDS signals are 2-V tolerant with VDD = 0 V. This feature
allows powering up I/Os before VDD is stabilized.
FUNCTIONAL BLOCK DIAGRAM
VDDLVDS
RBBDC
iPCLK
D0+
50
Parity
Check
SubLVDS
50
F/S
AND
D0–
8
50
SubLVDS
D1–
27-Bit Parallel
Register
D1+
50
R[0:7]
8
G[0:7]
0
Output Buffer
VDDLVDS
Serial-to-Parallel Conversion
RBBDC
1
RGB = 1
HS = VS = 1
DE = 0
VDDLVDS
8
B[0:7]
HS
VS
Standby or
Pwr Down
DE
RBBDC
CLK+
´15
50
50
PLL
Multiplier
SubLVDS
CLK–
´1
0
PCLK
1
Standby
Vthstby
RXEN
Glitch
Suppression
Control
B0177-03
2
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PINOUT – TOP VIEW
ZQC PACKAGE
(TOP VIEW)
1
2
3
4
5
6
7
B4
B6
B7
G1
G3
G5
GND
B2
B3
B5
G2
G4
G7
R0
B0
GND
G0
G6
R1
VDD
GNDPLLD
VDD
VDDPLLD
B1
R3
R5
R2
D1+
D1–
VDDPLLA
RXEN
PCLK
R7
R4
TST
CLK–
D0+
VS
HS
R6
GNDPLLA
D0–
DE
VDD
F/S
A
B
C
D
E
F
GNDLVDS
(Tie to GND)
G
VDDLVDS
CLK+
P0063-02
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SN65LVDS308
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PINOUT – TOP VIEW (continued)
Table 1. Numeric Terminal List
TERMINAL
4
SIGNAL
TERMINAL
SIGNAL
TERMINAL
SIGNAL
TERMINAL
SIGNAL
A1
B4
B7
R0
D6
R5
F5
VS
A2
B6
C1
B0
D7
R2
F6
HS
A3
B7
C2
GND
E1
D1+
F7
R6
A4
G1
C3
–
E2
D1–
G1
VDDLVDS
A5
G3
C4
G0
E3
VDDPLLA
G2
CLK+
A6
G5
C5
G6
E4
RXEN
G3
GNDPLLA
A7
GND
C6
R1
E5
PCLK
G4
D0–
B1
B2
C7
VDD
E6
R7
G5
DE
B2
B3
D1
GNDPLLD
E7
R4
G6
VDD
B3
B5
D2
VDD
F1
GNDLVDS
G7
F/S
B4
G2
D3
VDDPLLD
F2
TST
B5
G4
D4
B1
F3
CLK–
B6
G7
D5
R3
F4
D0+
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Table 2. TERMINAL FUNCTIONS
NAME
I/O
D0+, D0–
D1+, D1–
DESCRIPTION
SubLVDS data link
SubLVDS in
SubLVDS data link
CLK+, CLK–
SubLVDS input pixel clock; polarity is fixed.
R0–R7
Red-pixel data (8)
G0–G7
Green-pixel data (8)
B0–B7
HS
Blue-pixel data (8)
CMOS out
Horizontal sync
VS
Vertical sync
DE
Data enable
PCLK
Output pixel clock (rising clock polarity)
Disables the CMOS Drivers and Turns Off the PLL, putting device in shutdown mode
1 – Receiver enabled
0 – Receiver disabled (shutdown)
RXEN
CMOS in
Note: The RXEN input incorporates glitch suppression logic to avoid unwanted switching. The input
must be pulled low for longer than 10 µs continuously to force the receiver to enter shutdown. The input
must be pulled high for at least 10 µs continuously to activate the receiver. An input pulse shorter than
5 µs is interpreted as a glitch and becomes ignored. At power up, the receiver is enabled immediately if
RXEN = H and disabled if RXEN = L.
CMOS bus rise time select
F/S
1 – fast-output rise time
0 – slow-output rise time
TST
Test – this input is used for TI internal test purposes only and must be tied permanently to VSS.
VDD
Supply voltage
GND
Supply ground
VDDLVDS
SubLVDS I/O supply voltage
GNDLVDS
VDDPLLA
Power supply
SubLVDS ground
PLL analog supply voltage
GNDPLLA
PLL analog GND
VDDPLLD
PLL digital supply voltage
GNDPLLD
PLL digital GND
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SN65LVDS308
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FUNCTIONAL DESCRIPTION
The SN65LVDS308 receives payload data over two SubLVDS data pairs, D0 and D1. The PLL locks to the
SubLVDS clock input and internally multiplies the clock by a factor of 15. The internal high-speed clock is used
to shift in the data payload on D0 and D1 and to deserialize 15 bits of data from each pair. Figure 1 illustrates
the timing and the mapping of the data payload into the 30-bit frame. The internal high-speed clock is divided by
a factor of 15 to recreate the pixel clock, and the data payload with pixel clock is presented on the output bus.
The reserved bits and parity bit are not output.
CLK–
CLK +
D0+/– Channel CP R7 R6 R5 R4 R3 R2 R1 R0 G7 G6 G5 G4 VS res CP R7 R6
D1+/– Channel res G3 G2 G1 G0 B7 B6 B5 B4 B3 B2 B1 B0 HS DE res G3 G2
T0162-01
Figure 1. Data and Clock Input
POWER-DOWN MODES
The SN65LVDS308 receiver has two power-down modes to facilitate efficient power management.
Shutdown Mode
A low input signal on the RXEN pin puts the SN65LVDS308 into shutdown mode. This turns off most of the
receiver circuitry, including the SubLVDS receivers, PLL, and deserializers. The SubLVDS differential-input
resistance remains 100 Ω, and any input signal is ignored. All outputs hold a static output pattern:
R[0:7] = G[0:7] = B[0:7] = VS = HS = high; DE = PCLK = low.
The current draw in shutdown mode is nearly zero if the SubLVDS inputs are left open or pulled high.
Standby Mode
The SN65LVDS308 enters the standby mode when the SN65LVDS308 is not in shutdown mode but the
clock-input common-mode voltage on the SubLVDS clock input is above 0.9 × VDDLVDS. The CLK input
incorporates pullup circuitry. This circuit shifts the SubLVDS clock-input common-mode voltage to VDDLVDS in
the absence of an input signal. All circuitry except the SubLVDS clock-input standby monitor is shut down. The
SN65LVDS308 also enters the standby mode when the input clock frequency on the CLK input is less than 500
kHz. The SubLVDS input resistance remains 100 Ω, and any input signal on data inputs D0 and D1 is ignored.
All outputs hold a static output pattern:
R[0:7] = G[0:7] = B[0:7] = VS = HS = high; DE = PCLK = low.
The current draw in standby mode is very low.
ACTIVE MODES
A high input signal on RXEN combined with a CLK input signal switching faster than 3 MHz and VICM smaller
than 0.9 VDD forces the SN65LVDS308 into the active mode. Current consumption in the active mode depends
on operating frequency and the number of data transitions in the data payload. CLK-input frequencies between 3
MHz and 8 MHz activate the device, but proper PLL functionality is not assured.
Acquire Mode (PLL Approaches Lock)
When the SN65LVDS308 is enabled and a SubLVDS clock input is present, the PLL pursues lock to the input
clock. While the PLL pursues lock, the output data bus holds a static output pattern:
R[0:7] = G[0:7] = B[0:7] = VS = HS = high; DE = PCLK = low.
6
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FUNCTIONAL DESCRIPTION (continued)
For proper device operation, the pixel clock frequency must fall within the valid fPCLK range specified under
recommended operating conditions. If the pixel clock frequency is larger than 3 MHz but smaller than fPCLK(min),
the SN65LVDS308 PLL is enabled. Under such conditions, it is possible for the PLL to lock temporarily to the
pixel clock, causing the PLL monitor to release the device into active receive mode. If this happens, the PLL
may or may not be properly locked to the pixel clock input, potentially causing data errors, frequency oscillation,
and PLL deadlock (loss of VCO oscillation).
Receive Mode
After the PLL achieves lock the device enters the normal receive mode. The output data bus presents the
deserialized data. The PCLK output pin outputs the recovered pixel clock.
PARITY ERROR DETECTION AND HANDLING
The SN65LVDS308 receiver performs error checking on the basis of a parity bit that is transmitted across the
SubLVDS interface from the transmitting device. Once the SN65LVDS308 detects the presence of the clock and
the PLL has locked onto PCLK, then the parity is checked. Parity-error detection ensures detection of all
single-bit errors in one pixel and 50% of all multibit errors.
The parity bit covers the 27-bit data payload consisting of 24 bits of pixel data plus VS, HS, and DE. Odd-parity
bit signalling is used. If the sum of the 27 data bits and the parity bit is an odd number, the receive data are
assumed to be valid. If the sum equals an even number, parity error is declared.
If a parity error is detected, then the data on that PCLK cycle is not output. Instead, the last valid data from a
previous PCLK cycle is repeated on the output bus. This is to prevent any bit error that occurs on the LVDS link
from causing perturbations in VS, HS, or DE that might be visually disruptive to a display.
The reserved bits are not covered in the parity calculations.
R[0:7], G[0:7],
B[0:7], HS, VS, DE
PCLK
When a parity error is
detected, the receiver outputs
the previous pixel on the
bus. Hence, no data transitions
occur.
T0163-02
Figure 2. Output Response When Parity Error Is Detected
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SN65LVDS308
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FUNCTIONAL DESCRIPTION (continued)
STATUS-DETECT AND OPERATING-MODES FLOW DIAGRAM
The SN65LVDS308 switches between the power saving and active modes in the following way:
Power Up
RXEN = 1
CLK Input Inactive
RXEN Low
for > 10 ms
Power Up
RXEN = 0
Shutdown
Mode
Standby
Mode
RXEN High
for > 10 ms
VICM(CLK) > 0.9 VDDLVDS
RXEN Low
for > 10 ms
VICM(CLK) > 0.9 VDDLVDS
or fCLK < 500 kHz
CLK Input Active
Power Up
RXEN = 1
CLK Active
RXEN Low
for > 10 ms
Receive
Mode
PLL Achieved Lock
Acquire
Mode
F0017-01
Figure 3. Operating Modes Flow Diagram
Table 3. Status Detect and Operating Modes Descriptions
MODE
CONDITIONS
Least amount of power consumption (most circuitry turned
off); all outputs held static:
R[0:7] = G[0:7] = B[0:7] = VS = HS = high; DE = PCLK =
low
RXEN is set low for longer than 10 µs.
Standby mode
Low power consumption (standby monitor circuit active;
PLL is shut down to conserve power);
All outputs held static:
R[0:7] = G[0:7] = B[0:7] = VS = HS = high;
DE = PCLK = low
RXEN is high for longer than 10 µs and both CLK inputs
are common-mode, VICM(CLK) is above 0.9 × VDDLVDS, or
CLK inputs are floating (2)
Acquire mode
PLL pursues lock; all outputs held static:
R[0:7] = G[0:7] = B[0:7] = VS = HS = high; DE = PCLK =
low
RXEN is high; CLK input monitor detected clock input
common mode and woke up receiver from standby
mode.
Receive mode
Data transfer (normal operation);
receiver deserializes data and provides data on parallel
output
RXEN is high and PLL is locked to incoming clock.
(1)
(2)
8
CHARACTERISTICS
Shutdown mode
(1) (2)
In shutdown mode, all SN65LVDS308 internal switching circuits (e.g., PLL, serializer, etc.) are turned off to minimize power
consumption. The input stage of any input pin remains active.
Leaving inputs unconnected can cause random noise to toggle the input stage and potentially harm the device. All CMOS inputs must
be tied to a valid logic level, VIL or VIH, during shutdown or standby mode. Exceptions are the SubLVDS inputs CLK and Dx, which can
be left unconnected while not in use.
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Table 4. Operating Mode Transitions
MODE TRANSITION
USE CASE
Shutdown → standby
Drive RXEN high to enable
receiver.
TRANSITION SPECIFICS
1. RXEN high > 10 µs
2. Receiver enters standby mode.
a. R[0:7] = G[0:7] = B[0:7] = VS = HS remain high and DE = PCLK low
b. Receiver activates clock input monitor.
Standby → acquire
Transmitter activity
detected
1. CLK input monitor detects clock input activity.
2. Outputs remain static.
3. PLL circuit is enabled.
Acquire → receive
Link is ready to receive
data.
1. PLL is active and approaches lock.
2. PLL achieves lock within twakeup.
3. First data word is recovered.
4. Parallel output bus turns on switching from a static output pattern to output the
first valid data word.
Receive → standby
Transmitter requested to
enter standby mode by
input common-mode
voltage VICM > 0.9
VDDLVDS (e.g., transmitter
output clock enters
high-impedance state)
1. Receiver disables outputs within tsleep.
2. RX input monitor detects VICM > 0.9 VDDLVDS.
3. R[0:7] = G[0:7] = B[0:7] = VS = HS transition to high and DE = PCLK to low on
next falling PLL clock edge.
4. PLL shuts down.
5. Clock activity input monitor remains active.
Receive/standby →
shutdown
Turn off receiver.
1. RXEN pulled low for > tpwrdn.
2. Receiver switches all outputs to high-impedance state.
3. Most IC circuitry is shut down for least power consumption.
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SN65LVDS308
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ABSOLUTE MAXIMUM RATINGS (1)
Supply voltage range,
VDD (2),
VDDPLLA, VDDPLLD, VDDLVDS
Voltage range at any input When VDDx > 0 V
or output terminal
When VDDx ≤ 0 V
V
±4
Charged-device model (4) (all pins)
±1500
Machine model (5) (all pins)
±200
V
kV
V
See Dissipation Ratings Table
±5
Ouput current, IO
(2)
(3)
(4)
(5)
–0.3 to 2.175
–0.5 to VDD + 2.175
Continuous power dissipation
(1)
UNIT
–0.5 to 2.175
Human body model (3) (all pins)
Electrostatic discharge
VALUE
mA
Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute maximum-rated conditions for extended periods may affect device reliability.
All voltage values are with respect to the GND terminals.
In accordance with JEDEC Standard 22, Test Method A114-B
In accordance with JEDEC Standard 22, Test Method C101
In accordance with JEDEC Standard 22, Test Method A115-A
DISSIPATION RATINGS
(1)
(2)
PACKAGE
CIRCUIT
BOARD MODEL
TA < 25°C
DERATING FACTOR (1)
ABOVE TA = 25°C
TA = 85°C
POWER RATING
ZQC
Low-K (2)
496 mW
6.21 mW/°C
124 mW
This is the inverse of the junction-to-ambient thermal resistance when board-mounted and with no air
flow.
In accordance with the low-K thermal metric definitions of EIA/JESD51-2.
DEVICE POWER DISSIPATION
PARAMETER
PD
10
Device power
dissipation
TEST CONDITIONS
VDDx = 1.8 V, TA = 25°C, all outputs terminated with 10 pF, fCLK at 8 MHz
VDDx = 1.95 V, TA = –40°C, all outputs terminated with 10 pF, fCLK at 30 MHz
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TYP
MAX
11.5
72.2
UNIT
mW
SN65LVDS308
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RECOMMENDED OPERATING CONDITIONS
VDD
VDDPLLA
VDDPLLD
VDDLVDS
(1)
Supply voltages
VDDn(PP)
Supply voltage noise magnitude
TA
Operating free-air temperature
MIN
TYP
MAX
UNIT
1.65
1.8
1.95
V
Test setup shown in Figure 5;
f(noise) = 1Hz to 2 GHz
100
f(noise) = 1Hz to 1MHz
100
f(noise) > 1MHz
mV
40
–40
85
°C
CLK+ and CLK–
fCLK±
Input pixel clock frequency
tDUTCLK
CLK input duty cycle
See Figure 1
8
30
MHz
500
kHz
35
65
%
|VD0+ – VD0-|, |VD1+– VD1-|,
|VCLK+ – VCLK-| during normal operation
70
200
mV
Receive or acquire mode
0.6
1.2
Standby mode (2), see Figure 14
D0+, D0–, D1+, D1–, CLK+, and CLK–
|VID|
Magnitude of differential input voltage
VICM
Input voltage common mode range
∆VICM
Input voltage common mode variation VICM(n) – VICM(m) with n = D0, D1, or CLK
among all SubLVDS inputs
and m = D0, D1, or CLK
∆VID
Differential input voltage amplitude
variation among all SubLVDS inputs
VID(n) – VID(m) with n = D0, D1, or CLK and
m = D0, D1, or CLK
tr/f
Input rise and fall times
RXEN at VDD; see Figure 8
∆tr/f
Input rise or fall time mismatch
among all SubLVDS inputs
tr(n) – tr(m) and tf(n) – tf(m) with n = D0, D1, or
CLK and m = D0, D1, or CLK
Standby mode
V
0.9
VDDLVDS
–100
100
mV
–10
10
%
800
ps
–100
100
ps
0.7 VDD
VDD
V
0
0.3 VDD
RXEN, F/S
VICMOSH
High-level input voltage
VICMOSL
Low-level input voltage
tinRXEN
RXEN input pulse duration
V
µs
10
R[7:0], G[7:0], B[7:0], VS, HS, PCLK
CL
(1)
(2)
Output load capacitance
10
pF
Unused single-ended inputs must be held high or low to prevent them from floating.
PCLK input frequencies lower than 500 kHz force the SN65LVDS308 into standby mode. Input frequencies between 500 kHz and 3
MHz may or may not activate the SN65LVDS308. Input frequencies beyond 3 MHz activate the SN65LVDS308. Input frequencies
between 500 kHz and 4 MHz are not recommended, and can cause PLL malfunction.
DEVICE ELECTRICAL CHARACTERISTICS
over recommended operating conditions (unless otherwise noted)
PARAMETER
Alternating 1010 test pattern (seeTable 8***); all CMOS outputs terminated with 10
pF; F/S and RXEN at VDD; VIH = VDD, VIL = 0 V; VDD = VDDPLLA = VDDPLLD =
VDDLVDS
ID
D
RMS supply
current
Typical power test pattern (see Table 6); VID = 70 mV, all CMOS outputs
terminated with 10 pF; F/S at GND and RXEN at VDD; VIH = VDD, VIL = 0 V; VDD
= VDDPLLA = VDDPLLD = VDDLVDS
CLK and Dx inputs are left open; all control inputs held static high or low;
All CMOS outputs terminated with 10 pF;
VIH = VDD, VIL = 0 V; VDD = VDDPLLA = VDDPLLD = VDDLVDS
(1)
TYP (1)
MAX
14.3
19.4
fPCLK = 22 MHz
25
33
fPCLK = 30 MHz
26.8
37
fPCLK = 8 MHz
6.4
fPCLK = 22 MHz
13.7
fPCLK = 30 MHz
18.3
Standby mode;
RXEN = VIH
15
100
Shutdown
mode;
RXEN = VIL
0.4
10
TEST CONDITIONS
MIN
fPCLK = 8 MHz
UNIT
mA
mA
µA
All typical values are at 25°C and with 1.8-V supply, unless otherwise noted.
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INPUT ELECTRICAL CHARACTERISTICS
over operating free-air temperature range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP (1)
MAX
UNIT
D0+, D0–, D1+, D1–, CLK+, and CLK–
Vthstby
Input voltage common mode threshold to
switch between receive/acquire mode and RXEN at VDD
standby mode
1.3
VTHL
Low-level differential input voltage
threshold
–40
VTHH
High-level differential input voltage
threshold
II+, II–
Input leakage current
VDD = 1.95 V; VI+ = VI–;
VI = 0.4 V or VI = 1.5 V
IIOFF
Power-off input current
VDD = GND; VI = 1.5 V
RID
Differential input termination resistor value
CIN
Input capacitance
∆CIN
Input capacitance variation
VD0+– VD0–, VD1+– VD1–,
VCLK+– VCLK–
78
0.9 VDDLVDS
mV
100
Measured between input terminal
and GND
40
mV
75
µA
–75
µA
122
Ω
1
pF
Within one signal pair
0.2
Between all signals
RBBDC Pullup resistor for standby detection
V
1
21
30
39
pF
kΩ
RXEN, F/S
VIK
Input clamp voltage
IICMOS Input current (2)
II = –18 mA, VDD = VDD(min)
–1.2
V
0 V ≤ VDD ≤ 1.95 V; VI = GND
or VI = 1.95 V
100
nA
CIN
Input capacitance
IIH
High-level input current
VIN = 0.7 VDD
–200
200
IIL
Low-level input current
VIN = 0.3 VDD
–200
200
VIH
High-level input voltage
0.7 VDD
VDD
VIL
Low-level input voltage
0
0.3 VDD
(1)
(2)
2
pF
nA
V
All typical values are at 25°C and with 1.8-V supply unless otherwise noted.
Do not leave any CMOS input unconnected or floating to minimize leakage currents. Every input must be connected to a valid logic
level, VIH or VOL, while power is supplied to VDD.
OUTPUT ELECTRICAL CHARACTERISTICS
over operating free-air temperature range (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
0.8 VDD
VDD
V
0
0.2 VDD
V
R[0:7], G[0:7], B[0:7], VS, HS, PCLK
VOH
High-level output current
VOL
Low-level output current
IOH
High-level output current
IOL
Low-level output current
12
F/S = L, IOH = –500 µA
F/S = H, IOH = –2 mA
F/S = L, IOL = 500 µA
F/S = H, IOL = 2 mA
F/S = L
–500
F/S = H
–2000
µA
F/S = L
500
F/S = H
2000
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SWITCHING CHARACTERISTICS
over recommended operating conditions (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP (1)
MAX
UNIT
800
ps
–100
100
ps
F/S = L
4
8
F/S = H
1
2
D0+, D0–, D1+, D1–, CLK+, and CLK–
tr/f
Input rise and fall times
RXEN at VDD; see Figure 8
∆tr/f
Input rise or fall time
mismatch between all
SubLVDS inputs
tr(n) – tr(m) and tf(n) – tf(m) with n = D0, D1, or CLK and m
= D0, D1, or CLK
R[7:0], G[7:0], B[7:0], VS, HS, PCLK
CL = 10 pF (3); see
Figure 7
tr/f
Rise and fall time
20%–80% of VDD
tOUTP
PCLK output duty cycle
48%
tOSK
Output skew between PCLK
and R[0:7], G[0:7], B[0:7], HS, See Figure 7.
VS, and DE
–500
(2)
53%
ns
59%
500
ps
2.5/fPCLK
s
3.8
µs
INPUT-TO-OUTPUT RESPONSE TIME
tPD(L)
Propagation delay time from
CLK+ input to PCLK output
RXEN at VDD, VIH = VDD, VIL = GND, CL = 10 pF,
see Figure 12
tGS
RXEN glitch suppression
pulse width (4)
VIH = VDD, VIL = GND, RXEN toggles between VIL and
VIH; see Figure 13 and Figure 14.
tpwrup
Enable time from power down
(↑RXEN)
Time from RXEN pulled high to data outputs enabled and
transmit valid data; see Figure 14.
2
ms
tpwrdn
Disable time from active
mode (↓RXEN)
RXEN is pulled low during receive mode; time
measurement until all outputs held static: R[0:7] = G[0:7] =
B[0:7] = VS = HS = high, DE = PCLK = low and PLL is
shut down; see Figure 14.
11
µs
twakeup
Enable time from standby
(↑↓CLK)
RXEN at VDD; device is in standby; time measurement
from CLK input start of switching until PCLK and data
outputs enabled and transmitting valid data; see Figure 15.
2
ms
tsleep
Disable time from active
mode (CLK transitions to
high-impedance)
RXEN at VDD; device is receiving data; time measurement
from CLK input signal stops (input open or input common
mode VICM exceeds threshold voltage Vthstby) until all
outputs held static:
R[0:7] = G[0:7] = B[0:7] = VS = HS = high;
DE = PCLK = low and PLL is shut down;
see Figure 15.
3
µs
fBW
PLL bandwidth (5)
Tested from CLK input to PCLK output; fPCLK = 22 MHz
(1)
(2)
(3)
(4)
(5)
1.4/fPCLK
0.087 fPCLK
1.9/fPCLK
MHz
All typical values are at 25°C and with 1.8-V supply, unless otherwise noted.
tr/f depends on the F/S setting and the capacitive load connected to each output. Some application information of how to calculate tr/f
based on the output load and how to estimate the timing budget to interconnect to an LCD driver are provided in the application section
near the end of this data sheet.
The output rise and fall times are optimized for an output load of 10 pF. The rise and fall times can be adjusted by changing the output
load capacitance.
The RXEN input incorporates glitch-suppression logic to disregard short input pulses. tGS is the duration of either a high-to-low or
low-to-high transition that is suppressed.
When using the SN65LVDS308 receiver in conjunction with the SN65LVDS307 transmitter in one link, the PLL bandwidth of the
SN65LVDS308 receiver always exceeds the bandwidth of the SN65LVDS307 transmit PLL. This ensures stable PLL tracking under all
operating conditions and maximizes the receiver skew margin.
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12
10.0
11
10
9
8 MHz
9%
PLL – Bandwidth – %
PLL BW [% of PCLK Frequency]
9.5
RX PLL BW
9%
8.5%
8.2%
8
7.7%
7
6
9.0
Spec Limit
8.5
8.0
30 MHz
8.1 %
TX PLL BW
7.5
5
7.0
4
0
100
200
300
0
400
5
10
PLL Frequency − MHz
15
20
25
30
35
40
PCLK – Frequency – MHz
G001
Figure 4. SN65LVDS308 PLL Bandwidth (Also Showing the SN65LVDS307 PLL Bandwidth)
TIMING CHARACTERISTICS
PARAMETER
tRSKMx
(1) (2)
(1)
(2)
(3)
(4)
(5)
Receiver input skew
margin; See (3) and
Figure 30
TEST CONDITIONS
MIN
fCLK = 30 MHz (4)
x = 0..14,
fPCLK =30 MHz
RXEN at VDD, VIH = VDD, VIL =
GND, RL = 100 Ω, test setup as
in Figure 6, test pattern as in
Table 9
MAX
fCLK = 8 MHz to 30 MHz (5)
1
- 480 ps
2 · 15 · fCLK
ps
Receiver input skew margin (tRSKM) is the timing margin available for transmitter output pulse position (tPPOS), interconnect skew, and
interconnect inter-symbol interference. tRSKM represents the remainder of the serial bit time not taken up by the receiver strobe
uncertainty. tRSKM assumes a bit error rate better than 10–12.
tRSKM is inversely proportional to the internal setup and hold time uncertainty, ISI and duty cycle distortion from the front end receiver,
the skew missmatch between CLK and data D0 and D1, as well as the PLL cycle-to-cycle jitter.
This includes the receiver internal setup and hold time uncertainty, all PLL-related high-frequency random and deterministic jitter
components that impact the jitter budget, ISI and duty cycle distortion from the front-end receiver, and the skew between CLK and data
D0 and D1; the pulse position minimum/maximum variation is given with a bit error rate target of 10–12; measurements of the total jitter
are taken over >1012 samples.
The minimum and maximum limits are based on statistical analysis of the device performance over process, voltage, and temperature
ranges.
These minimum and maximum limits are simulated only.
PARAMETER MEASUREMENT INFORMATION
1
Noise
Generator
100 mV
VDDPLLA
2
1
SN65LVDS308
VDDPLLD
VDD
10 mF
VDDLVDS
GND
Note: The generator regulates the
noise amplitude at point 1 to the
target amplitude given under the table
Recommended Operating Conditions
1.8-V
Supply
S0216-04
Figure 5. Power-Supply Noise Test Setup
14
UNIT
630
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PARAMETER MEASUREMENT INFORMATION (continued)
To measure tRSKM CLK is advanced or delayed with respect to data until errors are observed at the receiver outputs. The advance
or delay is then reduced until there are no data errors observed over 10
tRSKM
Programmable Delay
–12
serial bit times. The magnitude of the advance or delay
CLK
CLK and Data
Pattern
Generator
D1
DUT:
SN65LVDS308
D2
Bit Error
Detector
D3
Ideal Receiver Strobe Position
tPG_ERROR
tRSKM(p)
tRSKM(n)
C
tbit
tRSKM
– is the smaller of the two measured values tRSKM(p) and tRSKM(n)
tPG_ERROR – Test equipment (pattern generator) intrinsic output pulse position timing uncertainty
tbit
– serial bit time
C
– LVDS308 set-up and hold-time uncertainty
Note: C can be derived by subtracting the receiver skew margin tRSKM(p) + tRSKM(p) from one serial bit time
T0164-03
Figure 6. Receiver Jitter-Budget Test Setup
tf
t setup
80% (VOH -V OL )
R[7:0], G[7:0],
B[7:0], HS, VS, DE
20% (VOH -V OL )
t hold
t OSK
tr
VOH
80% (VOH -V OL )
PCLK
50% (VOH
- –VOL)
20% (VOH -VOL )
VOL
tf
tr
Note:
The Set-up and Hold-time of CMOS outputs R[7:0], G[7:0],
B[7:0], HS, VS, and DE in relation to PCLK can be
calulated by:
1
tS&H =
2 -rPCLK -tREF - tOSK - DtDUTP
T0256-01
Figure 7. Output Rise/Fall, Setup/Hold Time
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PARAMETER MEASUREMENT INFORMATION (continued)
VD+ – VD– , VCLK+ – VCLK–
tf
80%(VID)
100%(VIC)
tr
0V
20%(VID)
0%(VID)
T0167-01
Figure 8. SubLVDS Differential Input Rise and Fall Time Defintion
CLK+, Dx+
VDDLVDS
RID/2
RBBDC
Gain
Stage
RID/2
CLK–, Dx–
Standby
Detection
Line End
Termination
ESD
S0224-02
Figure 9. Equivalent Input Circuit Design
16
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PARAMETER MEASUREMENT INFORMATION (continued)
IICMOS
RXEN, F/S
CMOS Input
(VI+ + VI–)/2
II+
VICMOS
CLK+, Dx+
VID
RGB, VS,
HS, PCLK
IO
II–
CLK–, Dx–
VICM
VI+
VO
VI–
SubLVDS Input
CMOS Output
S0217-03
Figure 10. I/O Voltage and Current Definition
RGB, VS,
HS, PCLK
VO
SN65LVDS308
CL=10 pF
S0218-03
Figure 11. CMOS Output Test Circuit, Signal, and Timing Definition
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PARAMETER MEASUREMENT INFORMATION (continued)
Pixel(n–1)
R7(n–1)
R7(n–2)
D0+
R7 R6 R5 R4
Pixel(n)
Pixel(n+1)
R7(n)
R7(n+1)
CP R7
CP R7
CLK–
CLK+
tPD(L)
VDD/2
PCLK
Pixel(n–1)
CMOS Data Out
R7
R7(n–3)
R7(n–1)
R6
R6(n–3)
R6(n–1)
T0168-02
Figure 12. Propagation Delay, Input to Output
VDD/2
RXEN
tGS
CLK
tPLL
VCO Internal Signal
PLL Approaches Lock
tpwrup
PCLK
R[7:0], G[7:0], B[7:0], VS, HS
DE
T0257-01
Figure 13. Receiver Phase-Locked Loop Set TIme and Receiver Enable Time
18
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PARAMETER MEASUREMENT INFORMATION (continued)
3 ms
<20 ns
Glitch Shorter
Than tGS Will Be
Ignored
2 ms
Less Than 20 ns
Spike Will be
Rejected
Glitch Shorter
Than tGS Will Be
Ignored
RXEN
tpwrup
tpwrdn
CLK+
tGS
ICC
tGS
PCLK
Receiver Disabled
(OFF)
Receiver Aquires Lock
Receiver Enabled
(ON)
Receiver
Turns OFF
Receiver
Disabled
(OFF)
T0254-01
Figure 14. Receiver Enable/Disable Glitch Suppression Time
CLK
twakeup
tsleep
PCLK
R[7:0], G[7:0], B[7:0], VS, HS,
Receiver Disabled
(OFF)
Receiver Aquires Lock,
Outputs Still Disabled
RX Enabled
Output Data Valid
RX Enabled;
Output Data
Invalid
RX
Disabled
(OFF)
T0255-01
Figure 15. Standby Detection
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PARAMETER MEASUREMENT INFORMATION (continued)
POWER CONSUMPTION TESTS
Table 5 shows an example test pattern word.
Table 5. Example Test Pattern Word
WORD
R[7:4], R[3:0], G[7:4], G[3:0], B[7:4], B[3:0], 0, VS, HS, DE
1
7
0x7C3E1E7
C
3
E
1
R7 R6 R5 R4 R3 R2 R1 R0 G7 G6 G5 G4 G3 G2 G1 G0 B7
0
1
1
1
1
1
0
0
0
0
1
1
1
1
1
0
E
7
B6
B5
B4
B3
B2
B1
B0
0
0
0
1
1
1
1
0
0
0
VS HS DE
1
1
1
TYPICAL IC POWER-CONSUMPTION TEST PATTERN
Typical power-consumption test patterns consist of eight 30-bit transmit words. The pattern repeats itself
throughout the entire measurement. It is assumed that every possible transmit code on RGB inputs has the
same probability to occur during typical device operation.
Table 6. Typical IC Power-Consumption Test Pattern
WORD
20
TEST PATTERN:
R[7:4], R[3:0], G[7:4], G[3:0], B[7:4], B[3:0], 0, VS, HS, DE
1
0x0000001
2
0x03F03F1
3
0xBFFBFF1
4
0x1D71D71
5
0x4C74C71
6
0xC45C451
7
0xA3aA3A5
8
0x5555553
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MAXIMUM POWER-CONSUMPTION TEST PATTERN
The maximum (or worst-case) power consumption of the SN65LVDS308 is tested using the two different test
patterns shown in Table 7. Test patterns consist of eight 30-bit transmit words. The pattern repeats itself
throughout the entire measurement. It is assumed that every possible transmit code on the RGB inputs has the
same probability to occur during typical device operation.
Table 7. Worst-Case Power-Consumption
Test Pattern 1
WORD
TEST PATTERN:
R[7:4], R[3:0], G[7:4], G[3:0], B[7:4], B[3:0], 0, VS, HS, DE
1
0x0000000
2
0xFFFFFF7
Table 8. Worst-Case Power-Consumption
Test Pattern 2
WORD
TEST PATTERN:
R[7:4], R[3:0], G[7:4], G[3:0], B[7:4], B[3:0], 0, VS, HS, DE
1
0x0000000
2
0xFFFFFF7
OUTPUT SKEW PULSE POSITION and JITTER PERFORMANCE
The following test pattern is used to measure the output skew pulse position and the jitter performance of the
SN65LVDS308. The jitter test pattern stresses the interconnect, particularly to test for ISI, using very long
run-lengths of consecutive bits, and incorporating very high and low data rates, maximizing switching noise. The
pattern is self-repeating for the duration of the test.
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Table 9. Transmit Jitter Test Pattern
WORD
22
TEST PATTERN:
R[7:4], R[3:0], G[7:4], G[3:0], B[7:4], B[3:0], 0, VS, HS, DE
1
0x0000001
2
0x000FFF3
3
0x8008001
4
0x0030037
5
0xE00E001
6
0x00FF001
7
0x007E001
8
0x003C001
9
0x0018001
10
0x1C7E381
11
0x3333331
12
0x555AAA5
13
0x6DBDB61
14
0x7777771
15
0x555AAA3
16
0xAAAAAA5
17
0x5555553
18
0xAAA5555
19
0x8888881
20
0x9242491
21
0xAAA5571
22
0xCCCCCC1
23
0xE3E1C71
24
0xFFE7FF1
25
0xFFC3FF1
26
0xFF81FF1
27
0xFE00FF1
28
0x1FF1FF1
29
0xFFCFFC3
30
0x7FF7FF1
31
0xFFF0007
32
0xFFFFFF1
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TYPICAL CHARACTERISTIC CURVES
Some of the plots in this section show more than one curve representing various device pin relationships. Taken together,
they represent a working range for the tested parameter.
SUPPLY CURRENT vs TEMPERATURE
QUIESCENT SUPPLY CURRENT vs TEMPERATURE
100.0
30
22 MHz (VGA), F/S = 1
25
STANDBY
11 MHz (HVGA), F/S = 1
10.0
IDDQ - mA
IDD - mA
20
22 MHz (VGA), F/S = 0
15
11 MHz (HVGA), F/S = 0
10
1.0
POWERDOWN
5
0.1
-50
0
-50
-30
-10
10
30
Temperature - °C
50
70
90
-30
-10
10
30
50
Temperature - °C
Figure 16.
90
Figure 17.
SUPPLY CURRENT vs FREQUENCY
RECEIVER STROBE POSITION vs TEMPERATURE
450
40
Limit With RSKM = 130 ps
400
35
F/S = 1, typ pwr
350
30
F/S = 1, jitter test
FL3G Limit
300
t(RSPOS)
25
IDD - mA
70
20
15
22 MHz (VVGA)
250
200
150
10
100
F/S = 0, jitter test
5
50
F/S = 0, typ pwr
0
0
5
10
15
20
f - Frequency - MHz
25
30
0
-40
Figure 18.
-20
0
20
40
Temperature - °C
60
80
Figure 19.
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TYPICAL CHARACTERISTIC CURVES (continued)
PLL BANDWIDTH
PCLK CYCLE-TO-CYCLE OUTPUT JITTER
12
900
800
Spec Limit
8 Mhz: 9%
700
8
600
Spec Limits
CC Jitter - ps
PLL Bandwidth - %
10
6
4
500
400
300
200
2
100
0
0
0
10
20
Frequency - MHz
30
40
0
Figure 20.
RSKM vs BIT RATE
Output Voltage Amplitude - mV
225 ps
0
225 ps
Trskm - Tppos
-1000
190
Bit width
Trskm
Time - ps
40
VGA OUTPUT WAVEFORM
Trskm - Tppos
1000
Trskm
0
f(PCLK) = 22 MHz
–190
Bit width
-1500
-2000
120
30
250
1500
-500
20
Frequency - MHz
Figure 21.
2000
500
10
–250
170
220
270
320
dR - Mbps
370
500 ps/div
Response Over 8-inch FR-4 + 1m Coax Cable
420
Figure 22.
Figure 23.
VGA OUTPUT WAVEFORM
INPUT COMMON-MODE NOISE REJECTION vs
FREQUENCY
0.0
249
-2.0
-4.0
-6.0
0
CMNR - dB
Output Voltage Amplitude - mV
190
f(PCLK) = 22 MHz
-8.0
-10.0
-12.0
-14.0
-16.0
–190
-18.0
–251
500 ps/div
Response Over 80-inch FR-4 + 1m Coax Cable
-20.0
0
Figure 24.
24
200 400 600 800 1000 1200 1400 1600 1800 2000
Frequency - MHz
Figure 25.
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TYPICAL CHARACTERISTIC CURVES (continued)
INPUT RETURN LOSS
INPUT DIFFERENTIAL CROSSTALK vs FREQUENCY
0.0
0.0
-10.0
Differential Xtalk - dB
Differential S11 - dB
-10.0
-20.0
-30.0
-40.0
-20.0
-30.0
-40.0
-50.0
-60.0
-50.0
-70.0
-60.0
-80.0
0
200 400 600 800 1000 1200 1400 1600 1800 2000
Frequency - MHz
0
Figure 26.
200 400 600 800 1000 1200 1400 1600 1800 2000
Frequency - MHz
Figure 27.
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APPLICATION INFORMATION
PREVENTING INCREASED LEAKAGE CURRENTS IN CONTROL INPUTS
A floating (left open) CMOS input allows leakage currents to flow from VDD to GND. Do not leave any CMOS
input unconnected or floating. Every input must be connected to a valid logic level, VIH or VIL, while power is
supplied to VDD. This also minimizes the power consumption of standby and power-down modes.
POWER-SUPPLY DESIGN RECOMMENDATION
For a multilayer PCB, it is recommended to keep one common GND layer underneath the device and connect all
ground terminals directly to this plane.
SN65LVDS308 DECOUPLING RECOMMENDATION
The SN65LVDS308 was designed to operate reliably in a constricted environment with other digital switching
ICs. In cell phone designs, the SN65LVDS308 often shares a power supply with various other ICs. The
SN65LVDS308 can operate with power-supply noise as specified in the Recommended Operating Conditions.
To minimize the power-supply noise floor, provide good decoupling near the SN65LVDS308 power pins. The
use of four ceramic capacitors (two 0.01-µF and two 0.1-µF) provides good performance. At the very least, it is
recommended to install one 0.1-µF and one 0.01-µF capacitor near the SN65LVDS308. To avoid large current
loops and trace inductance, the trace length between the decoupling capacitors and IC power input pins must be
minimized. Placing the capacitor underneath the SN65LVDS308 on the bottom of the PCB is often a good
choice.
VGA APPLICATION
Figure 28 shows a possible implementation of a standard 640 × 480 VGA display. The SN65LVDS307 interfaces
to the SN65LVDS308, which is the corresponding receiver device, to deserialize the data and drive the display
driver. The pixel clock rate of 22 MHz assumes ~10% blanking overhead and 60-Hz display refresh rate. The
application assumes 24-bit color resolution. Also shown is how the application processor provides a power-down
(reset) signal for both the serializer and the display driver. The signal count over the flexible printed circuit board
(FPC) could be further decreased by using the standby detection feature of the SN65LVDS307 and
SN65LVDS308 and pulling RXEN high.
2 ´ 0.01 mF
1.8 V
GND
GND
D1+
D1–
330 Mbps
LS
If no RESET signal is available,
TXEN and RXEN can also be
pulled high permanently with 1.8 V
a pull-up resistor to VDD
Serial Port Interface
(3-Wire IF)
R[7:0]
G[7:0]
B[7:0]
HS, VS, DE
SN65LVDS308
TXEN
LS
SPI
RESET
SN65LVDS307
D1+
D1–
22 MHz
PCLK
27
LCD With VGA
Resolution
330 Mbps
CLK+
CLK–
D0+
D0–
ENABLE
R[7:0]
G[7:0]
B[7:0]
HS, VS, DE
22 MHz
Video Mode Display
Driver
SPI
27
2.7 V
1.8 V
RXEN
PCLK
D[23:0]
HS, VS, DE
2.7 V
CLK+
CLK–
D0+
D0–
22 MHz
Pixel CLK
2 ´ 0.1 mF
GND
2 ´ 0.01 mF
VDDx
Application
Processor
(e.g. OMAP)
GND
FPC
VDDx
GND
GND
2 ´ 0.1 mF
1.8 V
If FPC wire count is critical, replace this
connection with a pull-up resistor at RXEN
3
B0178-03
Figure 28. Typical VGA Display Application
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APPLICATION INFORMATION (continued)
TYPICAL APPLICATION FREQUENCIES
The SN65LVDS308 supports pixel clock frequencies from 8 MHz to 30 MHz over two data pairs. Table 10
provides a few typical display resolution examples and shows the number of data pairs necessary to connect the
SN65LVDS308 with the display. The blanking overhead is assumed to be 20%. Often, blanking overhead is
smaller, resulting in a lower data rate. Furthermore, the examples in the table assumes a display frame refresh
rate of 60 Hz. The actual refresh rate may differ, depending on the application-processor clock implementation.
Table 10. Typical Application Data Rates and Serial Pair Usage
Display Screen
Resolution
Visible Pixel
Count
Blanking
Overhead
Display
Refresh Rate
[Hz]
Pixel Clock Frequency [MHz]
Data Rate on
D0 and D1
[Mbps]
90
8.3
124
240 × 320 (QVGA)
76,800
640 × 200
128,000
9.2
138
352 × 416 (CIF+)
146,432
10.5
158
352 × 440
154,880
11.2
167
320 × 480 (HVGA)
153,600
11.1
166
800 × 250
200,000
14.4
216
640 x 320
204,800
14.7
221
640 × 480 (VGA)
307,200
11.1
166
640 × 480 (VGA)
307,200
22.1
332
1024 × 320
327,680
23.6
354
854 × 480 (WVGA)
409,920
29.5
443
800 × 600 (SVGA)
480,000
17.3
259
1024 × 768 (XGA)
786,432
28.3
425
60
20%
30
60
30
Submit Documentation Feedback
27
SN65LVDS308
www.ti.com
SLLS835 – MAY 2007
CALCULATION EXAMPLE: HVGA DISPLAY
Display resolution:
480 × 320
Frame refresh rate:
58.4 Hz
Vertical visible pixels:
320 lines
Vertical front porch:
10 lines
Vertical sync:
5 lines
Vertical back porch:
3 lines
Horizontal visible pixels:
480 columns
Horizontal front porch:
20 columns
Horizontal sync:
5 columns
Horizontal back porch:
3 columns
Hsync = 5
HBP
The following calculation shows an example for a half-VGA display with the following parameters:
Visible Area = 480 Column
Vsync = 5
VBP = 3
Visible Area
= 320 Lines
VFP = 10
Visible Area
Entire Display
M0086-01
Figure 29. HVGA Display
Calculation of the total number of pixels and blanking overhead:
Visible area pixel count:
480 × 320 = 153,600 pixels
Total frame pixel count:
(320 + 10 + 5 + 3) × (480 + 20 + 5 + 3) = 171,704 pixels
Blanking overhead:
(171,704 – 153,600) ÷ 153,600 ≈ 11.8%
The application requires the following serial-link parameters:
Pixel clock frequency:
171,704 × 58.4 Hz = 10 MHz
Serial data rate:
10 MHz × 15 bits/channel = 150 Mbps
28
HFP = 20
Submit Documentation Feedback
SN65LVDS308
www.ti.com
SLLS835 – MAY 2007
HOW TO DETERMINE INTERCONNECT SKEW AND JITTER BUDGET
Designing a reliable data link requires examining the interconnect skew and jitter budget. The sum of all
transmitter, PCB, connector, FPC, and receiver uncertainties must be smaller than the available serial bit time.
The highest pixel clock frequency defines the available serial bit time. The transmitter timing uncertainty is
defined by tPPOS in the transmitter data sheet. For a bit-error-rate target of ≤ 10–12, the measurement duration for
tPPOS is ≥ 1012. The SN65LVDS308 receiver can tolerate a maximum timing uncertainty defined by tRSKM. The
interconnect budget is calculated by:
tinterconnect = tRSKM– tPPOS
Example:
fPCLK(max) = 23 MHz (VGA display resolution, 60 Hz)
Transmission mode: 2-ChM; tPPOS(SN65LVDS307) = 330 ps
Target bit error rate: 10–12
tRSKM(SN65LVDS308) = 1/(2 × 15 × fPCLK) – 480 ps = 969 ps
The interconnect budget for cable skew and ISI must be smaller than:
tinterconnect = tRSKM– tPPOS = 639 ps
Ideal TPPosn data transition
Serial bit width (1/dR)
D0, D1
TPPosn(min)
TPPosn(max)
Ideal receiver strobe position
tinterconnect
tinterconnect
RX internal sampling clock
tRSPosn(min)
tRSPosn(max)
Tppos: Transmitter output pulse position (min and max)
RSKM: Receiver Skew Margin
RSPosn: Receiver input strobe position (min and max)
TPPosx(max) -TPPosx(min) = TJ TXPLL(non-trackable) + tTXskew + tTXDJ
RSKM = SKEW PCB + XTALK PCB + ISIPCB
RSPosn(max) - RSPosn(min) = SkewRX + S&HRX + TJ (RXPLL(non-trackable)
TJTXPLL(non-trackable): : non-trackable TX PLL jitter; this is
mainly cycle-to-cycle PLL jitter, which can not be
compensated for at the R PLL
tTXskew: : transmitter output skew (skew between CLK
and data)
tTXIDJ Transmitter Deterministic Jitter of TX output
stage (includes TX Intersymbol Interference ISI)
SKEWPCB: : PCB induced Skew
(trace + connector);
XTALKPCB: : PCB induced cross-talk;
SkewRX: Receiver input skew (skew between CLK and Dx input)
S&HRX: Receiver input latch Sample & Hold uncertainty
TJ(RXPLL(non-trackable): : Intrinsic RX PLL jitter above RX PLL
bandwidth; PLLTJ > f(BWRX); TJ=RJ[ps-rms]*14 + DJ[ps]
ISIPCB: : Inter-symbol interference of PCB;
is dependent on interconnect frequency
loss; may be zero for short interconnects.
T0165-03
Figure 30. Jitter Budget
Submit Documentation Feedback
29
SN65LVDS308
www.ti.com
SLLS835 – MAY 2007
F/S-PIN SETTING AND CONNECTING THE SN65LVDS308 TO AN LCD DRIVER
NOTE:
Receiver PLL tracking: To maximize the design margin for the interconnect, good
RX PLL tracking of the TX PLL is important. FlatLink3G requires the RX PLL to have
a bandwidth higher than the bandwidth of the TX PLL. The SN65LVDS308 PLL
design is optimized to track the SN65LVDS307 PLL particularly well, thus providing a
very large receiver skew margin. A FlatLink3G-compliant link must provide at least
±225 ppm of receiver skew margin for the interconnect.
It is important to understand the tradeoff between power consumption, EMI, and maximum speed when selecting
the F/S signal. It is beneficial to choose the slowest rise time possible to minimize EMI and power consumption.
Unfortunately, a slower rise time also reduces the timing margin left for the LCD driver. Hence, it is necessary to
calculate the timing margin to select the correct F/S pin setting.
The output rise time depends on the output driver strength and the output load. An LCD driver typical capacitive
load is assumed with ~10 pF. The higher the capacitive load, the slower is the rise time. Rise time of the
SN65LVDS308 is measured as the time duration it takes the output voltage to rise from 20% of VDD to 80% of
VDD, and fall time is defined as the time for the output voltage to transition from 80% of VDD down to 20% of
VDD.
The rise time of the output stage is fixed and does not adjust to the pixel frequency. Only setting F/S changes
the output rise time. Due to the short bit time at very fast pixel clock speeds and the real capacitive load of the
display driver, the output amplitude might not reach VDD and GND saturation fully. To ensure sufficient signal
swing and verify the design margin, it becomes necessary to determine that the output amplitude under any
circumstance reaches the display driver’s input stage logic threshold (usually 30% and 70% of VDD).
Figure 31 shows a worst-case rise time simulation assuming an LCD driver load of 16 pF at VGA display
resolution. PCLK is the fastest-switching output. With F/S set to GND (Figure 31-b), the PCLK output voltage
amplitude is significantly reduced. The voltage amplitude of the output data RGB[7:0], VS, HS, and DE shows
less amplitude attenuation because these outputs carry random data patterns and toggle at half of the PCLK
frequency or less. It is necessary to determine the timing margin between the SN65LVDS308 output and LCD
driver input.
RX rise/fall time
Application: VGA (2-channel mode); F/S set to GND; Display driver load ~16 pF
RX rise/fall time
2.0V
1.8V
1.8V
1.6V
1.6V
1.4V
1.4V
1.2V
1.2V
VOD
VOD
Application: VGA (2-channel mode); F/S set to VDD; Display driver load ~16 pF
2.0V
(
1.0V
0.8V
0.6V
0.6V
0.4V
0.4V
0.2V
0.2V
0.0V
100ns
150ns
200ns
250ns
300ns
350ns
clk 22 MHz, F/S=1, CL=16 pF
400ns
450ns
500ns
550ns
600ns
The data signal has a slower maximum switching
frequency, and therefore drives a larger amplitude
than the clock signal
1.0V
0.8V
0.0V
100ns
150ns
200ns
250ns
300ns
350ns
clk 22 MHz, F/S=0, CL=16 pF
data 22 Mbps, F/S=1, CL=16 pF
400ns
450ns
500ns
data 22 Mbps, F/S=0, CL=16 pF
(b)
(a)
Figure 31. Output Amplitude as a Function of Output Toggling Frequency,
Capacitive Load, and F/S Setting
30
Submit Documentation Feedback
550ns
600ns
SN65LVDS308
www.ti.com
SLLS835 – MAY 2007
HOW TO DETERMINE THE LCD DRIVER TIMING MARGIN
To determine the timing margin, it is necessary to specify the frequency of operation, identify the setup and hold
times of the LCD driver, and specify the output load of the SN65LVDS308 as a combination of the LCD driver
input parasitics plus any capacitance caused by the connecting PCB trace. Furthermore, the setting of pin F/S
and the SN65LVDS308 output skew impact the margin. The total remaining design margin calculates as follows:
t rise(max) C LOAD
1
t DM +
* t DUTP(max_error) *
* Ťt OSKŤ
2 ƒ PCLK
10 pF
(3)
where:
tDM – Design margin
fPCLK – Pixel clock frequency
tDUTP(max_error) – maximum duty cycle error
trise(max) – maximum rise or fall time; see tr/f under switching characteristics
CLOAD – parasitic capacitance (sum of LCD driver input parasitics + connecting PCB trace)
tskew – clock to data output skew of the SN65LVDS308
Example:
At a pixel clock frequency of 11 MHz (HVGA), and an assumed LCD driver load of 15 pF, the remaining timing
margin is:
Ť
Ť
t
(max) * 50
t DUTP(max_error) + DUTP
100%
t DM +
2
1
* 4.5ns *
11 MHz
t PCLK + 5%
100%
16ns (FńS+GND)
10 pF
1
+ 4.5 ns
11 MHz
15pF
* 500 ps + 16 ns
As long as the setup and hold times of the LCD driver are each less than 16 ns, the timing budget is met
sufficiently.
Submit Documentation Feedback
31
PACKAGE OPTION ADDENDUM
www.ti.com
18-May-2007
PACKAGING INFORMATION
Orderable Device
Status (1)
SN65LVDS308ZQCR
ACTIVE
BGA MI
CROSTA
R JUNI
OR
ZQC
48
2500 Green (RoHS &
no Sb/Br)
SNAGCU
Level-3-260C-168 HR
SN65LVDS308ZQCT
ACTIVE
BGA MI
CROSTA
R JUNI
OR
ZQC
48
250
SNAGCU
Level-3-260C-168 HR
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
Green (RoHS &
no Sb/Br)
Lead/Ball Finish
MSL Peak Temp (3)
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
Addendum-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
17-May-2007
TAPE AND REEL INFORMATION
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
Device
17-May-2007
Package Pins
Site
Reel
Diameter
(mm)
Reel
Width
(mm)
A0 (mm)
B0 (mm)
K0 (mm)
P1
(mm)
W
Pin1
(mm) Quadrant
SN65LVDS308ZQCR
ZQC
48
TAI
330
12
4.3
4.3
1.5
12
12
PKGORN
T1TR-MS
P
SN65LVDS308ZQCT
ZQC
48
TAI
330
12
4.3
4.3
1.5
12
12
PKGORN
T1TR-MS
P
TAPE AND REEL BOX INFORMATION
Device
Package
Pins
Site
Length (mm)
Width (mm)
Height (mm)
SN65LVDS308ZQCR
ZQC
48
TAI
342.9
336.6
20.64
SN65LVDS308ZQCT
ZQC
48
TAI
342.9
336.6
20.64
Pack Materials-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
17-May-2007
Pack Materials-Page 3
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