NSC DS90CF388AVJD

DS90C387A/DS90CF388A
Dual Pixel LVDS Display Interface / FPD-Link
General Description
The DS90C387A/DS90CF388A transmitter/receiver pair is
designed to support dual pixel data transmission between
Host and Flat Panel Display up to QXGA resolutions. The
transmitter converts 48 bits (Dual Pixel 24-bit color) of
CMOS/TTL data and 3 control bits into 8 LVDS (Low Voltage
Differential Signalling) data streams. At a maximum dual
pixel rate of 112MHz, LVDS data line speed is 784Mbps,
providing a total throughput of 5.7Gbps (714 Megabytes per
second).
The LDI chipset is improved over prior generations of
FPD-Link devices and offers higher bandwidth support and
longer cable drive. To increase bandwidth, the maximum
pixel clock rate is increased to 112 MHz and 8 serialized
LVDS outputs are provided. Cable drive is enhanced with a
user selectable pre-emphasis feature that provides additional output current during transitions to counteract cable
loading effects.
The DS90C387A transmitter provides a second LVDS output
clock. Both LVDS clocks are identical. This feature supports
backward compatibility with the previous generation of
FPD-Link Receivers - the second clock allows the transmitter to interface to panels using a ’dual pixel’ configuration of
two 24-bit or 18-bit FPD-Link receivers.
This chipset is an ideal means to solve EMI and cable size
problems for high-resolution flat panel applications. It pro-
vides a reliable interface based on LVDS technology that
delivers the bandwidth needed for high-resolution panels
while maximizing bit times, and keeping clock rates low to
reduce EMI and shielding requirements. For more details,
please refer to the “Applications Information” section of this
datasheet.
Features
n
n
n
n
n
n
n
n
n
n
n
Supports SVGA through QXGA panel resolutions
32.5 to 112/170MHz clock support
Drives long, low cost cables
Up to 5.7 Gbps bandwidth
Pre-emphasis reduces cable loading effects
Dual pixel architecture supports interface to GUI and
timing controller; optional single pixel transmitter inputs
support single pixel GUI interface
Transmitter rejects cycle-to-cycle jitter
5V tolerant on data and control input pins
Programmable transmitter data and control strobe select
(rising or falling edge strobe)
Backward compatible with FPD-Link
Compatible with ANSI/TIA/EIA-644-1995 LVDS Standard
Generalized Transmitter Block Diagram
10132002
TRI-STATE ® is a registered trademark of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation
DS101320
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DS90C387A/DS90CF388A Dual Pixel LVDS Display Interface / FPD-Link
October 2002
DS90C387A/DS90CF388A
Generalized Receiver Block Diagram
10132003
Generalized Block Diagrams
10132001
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2
Package Derating:
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (VCC)
18.2mW/˚C above +25˚C
DS90C387A
−0.3V to +5.5V
CMOS/TTL Output
Voltage
18.2mW/˚C above +25˚C
DS90CF388 A
ESD Rating:
−0.3V to +4V
CMOS/TTL Input Voltage
DS90C387 A
> 6 kV
> 300 V
(HBM, 1.5kΩ, 100pF)
(EIAJ, 0Ω, 200pF)
−0.3V to (VCC + 0.3V)
DS90CF388A
LVDS Receiver Input
Voltage
−0.3V to +3.6V
LVDS Driver Output
Voltage
−0.3V to +3.6V
LVDS Output Short
Circuit Duration
Continuous
Recommended Operating
Conditions
Junction Temperature
+150˚C
Min Nom
Max
Units
Storage Temperature
−65˚C to +150˚C
Supply Voltage (VCC)
3.0
3.3
3.6
V
Operating Free Air
Temperature (TA)
−10
+25
+70
˚C
> 2 kV
> 200 V
(HBM, 1.5kΩ, 100pF)
(EIAJ, 0Ω, 200pF)
Lead Temperature
(Soldering, 4 sec.)
+260˚C
Maximum Package Power Dissipation Capacity @ 25˚C
Receiver Input Range
100 TQFP Package:
0
Supply Noise Voltage (VCC)
DS90C387A
2.8W
DS90CF388A
2.8W
2.4
V
100
mVp-p
Electrical Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
VCC
V
0.8
V
CMOS/TTL DC SPECIFICATIONS (Tx inputs, Rx outputs, control inputs and outputs)
VIH
High Level Input Voltage
VIL
Low Level Input Voltage
VOH
High Level Output Voltage
2.0
GND
IOH = −0.4 mA
2.7
2.9
V
IOH = −2 mA
2.7
2.85
V
VOL
Low Level Output Voltage
IOL = 2 mA
VCL
Input Clamp Voltage
ICL = −18 mA
IIN
Input Current
VIN = 0.4V, 2.5V or VCC
VIN = GND
IOS
Output Short Circuit Current
−15
0.1
0.3
V
−0.79
−1.5
V
+1.8
+15
µA
0
VOUT = 0V
µA
−120
mA
450
mV
35
mV
LVDS DRIVER DC SPECIFICATIONS
VOD
Differential Output Voltage
∆VOD
Change in VOD between
Complimentary Output States
VOS
Offset Voltage
∆VOS
Change in VOS between
Complimentary Output States
IOS
Output Short Circuit Current
IOZ
TRI-STATE ®
Output
RL = 100Ω
250
1.125
Current
VOUT = 0V, RL = 100Ω
PD = 0V, VOUT = 0V or VCC
345
1.25
1.375
V
35
mV
−3.5
−10
mA
±1
± 10
µA
+100
mV
LVDS RECEIVER DC SPECIFICATIONS
VTH
Differential Input High Threshold
VTL
Differential Input Low Threshold
IIN
Input Current
VCM = +1.2V
−100
VIN = +2.4V, VCC = 3.6V
VIN = 0V, VCC = 3.6V
3
mV
± 10
± 10
µA
µA
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DS90C387A/DS90CF388A
Absolute Maximum Ratings
DS90C387A/DS90CF388A
Electrical Characteristics
(Continued)
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
Conditions
Min
Typ
Max
Units
RL = 100Ω, CL = 5 f = 32.5 MHz
pF,
f = 65 MHz
Worst Case
Pattern
f = 85 MHz
(Figures 1, 3),
DUAL=High
f = 112 MHz
(48-bit RGB)
115
160
mA
145
200
mA
165
230
mA
210
260
mA
100Ω, CL = 5 pF,
16 Grayscale
Pattern
(Figures 2, 3),
DUAL=High
(48-bit RGB)
f = 32.5 MHz
92
140
mA
f = 65 MHz
100
150
mA
f = 85 MHz
110
170
mA
f = 112 MHz
130
190
mA
4.8
50
µA
TRANSMITTER SUPPLY CURRENT
ICCTW
Transmitter Supply Current
Worst Case
Transmitter Supply Current
16 Grayscale
ICCTZ
Transmitter Supply Current
Power Down
PD = Low
Driver Outputs in TRI-STATE under
Powerdown Mode
RECEIVER SUPPLY CURRENT
ICCRW
ICCRG
ICCRZ
Receiver Supply Current
Worst Case
Receiver Support Current
16 Grayscale
Receiver Supply Current
Power Down
CL = 8 pF,
Worst Case
Pattern
(Figures 1, 4),
DUAL = High
(48-bit RGB)
f = 32.5 MHz
100
140
mA
f = 65 MHz
150
200
mA
f = 85 MHz
170
220
mA
f = 112 MHz
185
240
mA
CL = 8 pF,
16 Grayscale
Pattern
(Figures 2, 4),
DUAL = High
(48-bit RGB)
f = 32.5 MHz
45
80
mA
f = 65 MHz
60
110
mA
f = 85 MHz
85
130
mA
f = 112 MHz
110
160
mA
255
300
µA
PD = Low
Receiver Outputs stay low
during Powerdown mode.
Note 1: “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. They are not meant to imply that the device
should be operated at these limits. The tables of “Electrical Characteristics” specify conditions for device operation.
Note 2: Typical values are given for VCC = 3.3V and T A = +25˚C.
Note 3: Current into device pins is defined as positive. Current out of device pins is defined as negative. Voltages are referenced to ground unless otherwise
specified (except VOD and ∆VOD).
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Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Parameter
TCIT
TxCLK IN Transition Time (Figure 5)
TCIP
TxCLK IN Period (Figure 6)
DUAL=Gnd or Vcc
DUAL=1/2Vcc
Min
Typ
Max
Units
1.0
2.0
3.0
ns
ns
1.0
1.5
1.7
DUAL=Gnd or Vcc
8.928
T
30.77
ns
DUAL=1/2Vcc
5.88
15.38
ns
ns
TCIH
TxCLK in High Time (Figure 6)
0.35T
0.5T
0.65T
TCIL
TxCLK in Low Time (Figure 6)
0.35T
0.5T
0.65T
ns
TXIT
TxIN Transition Time
6.0
ns
1.5
Transmitter Switching Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified.
Typ
Max
Units
LLHT
Symbol
LVDS Low-to-High Transition Time (Figure 3), PRE = 0.75V
(disabled)
Parameter
Min
0.14
0.7
ns
LVDS Low-to-High Transition Time (Figure 3), PRE = Vcc (max)
0.11
0.6
ns
LHLT
LVDS High-to-Low Transition Time (Figure 3), PRE = 0.75V
(disabled)
0.16
0.8
ns
0.11
0.7
LVDS High-to-Low Transition Time (Figure 3), PRE = Vcc (max)
1/7 TCIP
ns
TBIT
Transmitter Output Bit Width
DUAL=Gnd or Vcc
TPPOS
Transmitter Pulse Positions - Normalized
f = 33 to 70 MHz
−250
0
+250
ps
f = 70 to 112 MHz
−200
0
+200
ps
DUAL=1/2Vcc
ns
2/7 TCIP
ns
TCCS
TxOUT Channel to Channel Skew
TSTC
TxIN Setup to TxCLK IN (Figure 6)
2.7
100
ps
ns
THTC
TxIN Hold to TxCLK IN (Figure 6)
0
ns
TJCC
Transmitter Jitter Cycle-to-cycle (Figures
13, 14) (Note 5), DUAL=Vcc
f = 112 MHz
85
100
ps
f = 85 MHz
60
75
ps
f = 65 MHz
70
80
ps
f = 56 MHz
100
120
ps
f = 32.5 MHz
75
110
ps
TPLLS
Transmitter Phase Lock Loop Set (Figure 8)
10
ms
TPDD
Transmitter Powerdown Delay (Figure 10)
100
ns
5
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DS90C387A/DS90CF388A
Recommended Transmitter Input Characteristics
DS90C387A/DS90CF388A
Receiver Switching Characteristics
Over recommended operating supply and temperature ranges unless otherwise specified.
Symbol
Typ
Max
Units
CLHT
CMOS/TTL Low-to-High Transition Time (Figure 4), Rx data out
Parameter
1.52
2.0
ns
CMOS/TTL Low-to-High Transition Time (Figure 4), Rx clock out
0.5
1.0
ns
CHLT
CMOS/TTL High-to-Low Transition Time (Figure 4), Rx data out
1.7
2.0
ns
CMOS/TTL High-to-Low Transition Time (Figure 4), Rx clock out
0.5
1.0
ns
T
30.77
ns
RCOP
RxCLK OUT Period (Figure 7)
RCOH
RxCLK OUT High Time (Figure 7)(Note 4)
Min
8.928
f = 112 MHz
3.5
f = 85 MHz
4.5
ns
ns
3.5
ns
RCOL
RxCLK OUT Low Time (Figure 7)(Note 4)
f = 112 MHz
f = 85 MHz
4.5
ns
RSRC
RxOUT Setup to RxCLK OUT (Figure 7)(Note 4)
f = 112 MHz
2.4
ns
f = 85 MHz
3.0
ns
RHRC
RxOUT Hold to RxCLK OUT (Figure 7)(Note 4)
f = 112 MHz
3.4
ns
f = 85 MHz
4.75
RPLLS
Receiver Phase Lock Loop Set (Figure 9)
10
ms
RPDD
Receiver Powerdown Delay (Figure 11)
1
µs
RSKM
Receiver Skew Margin (Figure 12) (Notes 4, 6),
ns
f = 112 MHz
170
f = 100 MHz
170
240
ps
ps
f = 85MHz
300
350
ps
f = 66MHz
300
350
ps
Note 4: The Minimum and Maximum Limits are based on statistical analysis of the device performance over voltage and temperature ranges. This parameter is
functionally tested on Automatic Test Equipment (ATE). ATE is limited to 85MHz. A sample of characterization parts have been bench tested at 112MHz to verify
functional performance.
Note 5: The limits are based on bench characterization of the device’s jitter response over the power supply voltage range. Output clock jitter is measured with a
cycle-to-cycle jitter of ± 3ns applied to the input clock signal while data inputs are switching (see figures 15 and 16). A jitter event of 3ns, represents worse case jump
in the clock edge from most graphics VGA chips currently available. This parameter is used when calculating system margin as described in AN-1059.
Note 6: Receiver Skew Margin is defined as the valid data sampling region at the receiver inputs. This margin takes into account transmitter output pulse positions
(min and max) and the receiver input setup and hold time (internal data sampling window - RSPOS). This margin allows for LVDS interconnect skew, inter-symbol
interference (both dependent on type/length of cable) and clock jitter.
RSKM ≥ cable skew (type, length) + source clock jitter (cycle to cycle).
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DS90C387A/DS90CF388A
AC Timing Diagrams
10132010
FIGURE 1. “Worst Case” Test Pattern
10132011
FIGURE 2. “16 Grayscale” Test Pattern (Notes 7, 8, 9)
Note 7: The worst case test pattern produces a maximum toggling of digital circuits, LVDS I/O and CMOS/TTL I/O.
Note 8: The 16 grayscale test pattern tests device power consumption for a “typical” LCD display pattern. The test pattern approximates signal switching needed
to produce groups of 16 vertical stripes across the display.
Note 9: Figures 1, 2 show a falling edge data strobe (TxCLK IN/RxCLK OUT).
7
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DS90C387A/DS90CF388A
AC Timing Diagrams
(Continued)
10132012
FIGURE 3. DS90C387A (Transmitter) LVDS Output Load and Transition Times
10132013
FIGURE 4. DS90CF388A (Receiver) CMOS/TTL Output Load and Transition Times
10132014
FIGURE 5. DS90C387A (Transmitter) Input Clock Transition Time
10132015
FIGURE 6. DS90C387A (Transmitter) Setup/Hold and High/Low Times (Falling Edge Strobe)
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DS90C387A/DS90CF388A
AC Timing Diagrams
(Continued)
10132016
FIGURE 7. DS90CF388A (Receiver) Setup/Hold and High/Low Times
10132019
FIGURE 8. DS90C387A (Transmitter) Phase Lock Loop Set Time
10132020
FIGURE 9. DS90CF388A (Receiver) Phase Lock Loop Set Time
9
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DS90C387A/DS90CF388A
AC Timing Diagrams
(Continued)
10132021
FIGURE 10. Transmitter Power Down Delay
10132022
FIGURE 11. Receiver Power Down Delay
10132025
C — Setup and Hold Time (Internal data sampling window) defined by RSPOS (receiver input strobe position) min and max
TPPOS — Transmitter output pulse position (min and max)
RSKM ≥ Cable Skew (type, length) + LVDS Source Clock Jitter (cycle to cycle) + ISI (Inter-symbol interference)
j Cable Skew — typically 10 ps to 40 ps per foot, media dependent
j TJCC — Cycle-to-cycle LVDS Output jitter (TJCC) is less than 100 ps (worse case estimate).
j ISI is dependent on interconnect length; may be zero
See Applications Informations section for more details.
FIGURE 12. Receiver Skew Margin
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DS90C387A/DS90CF388A
AC Timing Diagrams
(Continued)
10132027
FIGURE 13. TJCC Test Setup - DS90C387A
10132028
FIGURE 14. Timing Diagram of the Input Cycle-to-Cycle Clock Jitter
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DS90C387A/DS90CF388A
DS90C387A Pin Description — FPD Link Transmitter
Pin Name
I/O
No.
Description
Rn, Gn, Bn,
DE, HSYNC,
VSYNC
I
51
TTL level input. This includes: 16 Red, 16 Green, 16 Blue, and 3 control
lines HSYNC, VSYNC, DE (Data Enable).(Note 10)
AnP
O
8
Positive LVDS differential data output.
AnM
O
8
Negative LVDS differential data output.
CLKIN
I
1
TTL level clock input.
R_FB
I
1
Programmable data strobe select. Rising data strobe edge selected when
input is high. (Note 10)
R_FDE
I
1
Programmable control (DE) strobe select. Tied high for data active when DE
is high. (Note 10)
CLK1P
O
1
Positive LVDS differential clock output.
CLK1M
O
1
Negative LVDS differential clock output.
PD
I
1
TTL level input. Assertion (low input) tri-states the outputs, ensuring low
current at power down. (Note 10)
PLLSEL
I
1
PLL range select. This pin must be tied to VCC for auto-range. NC or tied to
Ground is reserved for future use. Typical shift point is between 55 and 68
MHz. (Notes 10, 11)
PRE
I
1
Pre-emphasis level select. Pre-emphasis is active when input is tied to VCC
through external pull-up resistor. Resistor value determines pre-emphasis
level (see table in application section). For normal LVDS drive level (No
pre-emphasis) leave this pin open (do not tie to ground).(Note 10)
DUAL
I
1
Three-mode select for dual pixel, single pixel, or single pixel input to dual
pixel output operation. Single pixel mode when input is low (only LVDS
channels A0 thru A3 and CLK1 are active) for power savings. Dual mode is
active when input is high. Single in - dual out when input is at 1/2 Vcc. (Note
10)
VCC
I
4
Power supply pins for TTL inputs and digital circuitry.
GND
I
6
Ground pins for TTL inputs and digital circuitry.
PLLVCC
I
2
Power supply pin for PLL circuitry.
PLLGND
I
3
Ground pins for PLL circuitry.
LVDSVCC
I
3
Power supply pin for LVDS outputs.
LVDSGND
I
4
Ground pins for LVDS outputs.
CLK2P/NC
O
1
Additional positive LVDS differential clock output. Identical to CLK1P. No
connect if not used.
CLK2M/NC
O
1
Additional negative LVDS differential clock output. Identical to CLK1M. No
connect if not used.
Note 10: Inputs default to “low” when left open due to internal pull-down resistor.
Note 11: The PLL range shift point is in the 55 - 68 MHz range, typically the shift will occur during the lock time.
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Pin Name
I/O
No.
Description
AnP
I
8
AnM
I
8
Negative LVDS differential data inputs.
Rn, Gn, Bn,
DE, HSYNC,
VSYNC
O
51
TTL level data outputs. This includes: 16 Red, 16 Green, 16 Blue, and 3
control lines — HSYNC (LP), VSYNC (FLM), DE (Data Enable).
RxCLK INP
I
1
Positive LVDS differential clock input.
RxCLK INM
I
1
Negative LVDS differential clock input.
RxCLK OUT
O
1
TTL level clock output. The falling edge acts as data strobe.
R_FDE
I
1
Programmable control (DE) strobe select. Tied high for data active when DE
is high. (Note 10)
PLLSEL
I
1
PLL range select. This pin must be tied to VCC for auto-range. NC or tied to
Ground is reserved for future use. Typical shift point is between 55 and 68
MHz. (Notes 10, 11)
PD
I
1
TTL level input. When asserted (low input) the receiver data outputs are low
and clock output is high. (Note 10)
STOPCLK
O
1
Indicates receiver clock input signal is not present with a logic high. With a
clock input present, a low logic is indicated.
VCC
I
6
Power supply pins for TTL outputs and digital circuitry.
GND
I
10
Ground pins for TTL outputs and digital circuitry
PLLVCC
I
1
Power supply for PLL circuitry.
PLLGND
I
2
Ground pin for PLL circuitry.
Positive LVDS differential data inputs.
LVDSVCC
I
2
Power supply pin for LVDS inputs.
LVDSGND
I
3
Ground pins for LVDS inputs.
2
No Connect. Make NO Connection to these pins - leave these pins open, do
not tie to ground or VCC.
CNTLE,
CNTLF
Note 12: These receivers have input fail-safe bias circuitry to guarantee a stable receiver output for floating or terminated receiver inputs. Under test conditions
receiver inputs will be in a HIGH state. If the clock input is floating/terminated, outputs will remain in the last valid state.
13
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DS90C387A/DS90CF388A
DS90CF388A Pin Description — FPD Link Receiver
DS90C387A/DS90CF388A
LVDS Interface / TFT Data (Color) Mapping
Different color mapping options exist. See National Application Notes 1127 and 1163 for details.
only. Also, the DE signal is mapped to two LVDS sub symbols. The DS90CF388A only samples the DE bit on channel
A2. Two FPD-Link receivers may also be used in place of the
DS90CF388A, since the DS90C387A provides two LVDS
clocks. If this is the case, the FPD-Link receiver datasheet
needs to be consulted for recovery mapping information. In
this application, it is possible to recover two signals of: DE,
B17 and B27 from the transmitter.
There are two reserved bits (RES). The DS90CF388A ignores these bits. If using separate FPD-Link receivers, the
corresponding receiver outputs for these two bits should be
left open (NC).
The LVDS Clock waveshape is shown in Figure 15. Note that
the rising edge of the LVDS clock occurs two LVDS sub
symbols before the current cycle of data. The clock is compose of a 4 LVDS sub symbol HIGH time and a 3 LVDS sub
symbol LOW time. The respective pin (transmitter and receiver) names are show in Figure 15. As stated above these
names are not the color mapping information (MSB/LSB) but
pin names only.
Inputs B17 and B27 are double wide bits. If using the
DS90CF388A, this bits are sampled in the back half of the bit
10132026
FIGURE 15. TTL Data Inputs Mapped to LVDS Outputs 387A/388A
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14
How to configure the DS90C387A and DS90CF388A for
most common application:
Transmitter Features:
The transmitter is designed to reject cycle-to-cycle jitter
which may be seen at the transmitter input clock. Very low
cycle-to-cycle jitter is passed on to the transmitter outputs.
This significantly reduces the impact of jitter provided by the
input clock source, and improves the accuracy of data sampling.
The transmitter is offered with programmable edge data
strobes for convenient interface with a variety of graphics
controllers. The transmitter can be programmed for rising
edge strobe or falling edge strobe through a dedicated pin. A
rising edge transmitter will inter-operate with a falling edge
receiver without any translation logic.
Pre-Emphasis:
1. To configure for single input pixel-to-dual pixel output
application, the DS90C387 “DUAL” pin must be set to 1/2
Vcc=1.65V. This may be implemented using pull-up and
pull-down resistors of 10kΩ. In this configuration, the input
signals (single pixel) are split into odd and even pixel (dual
pixels) starting with the odd (first) pixel outputs A0-to-A3 the
next even (second) pixel outputs to A4-to-A7. The splitting of
the data signal also starts with DE (data enable) transitioning
from logic low to high indicating active data. The ’R_FDE’ pin
must be set high in this case. The number of clock cycles
during blanking must be an EVEN number. This configuration will allow the user to interface to an LDI receiver
(DS90CF388A) or to two FPD-Link ’notebook’ receivers
(DS90CF384A or DS90CF386).
2. To configure for single pixel or dual pixel application using
the DS90C387A/DS90CF388A, the “DUAL” pin must be set
to Vcc (dual) or Gnd (single). In dual mode, the
transmitter-DS90C387A has two LVDS clock outputs enabling an interface to two FPD-Link ’notebook’ receivers
(DS90CF384A or DS90CF386). In single mode, outputs
A4-to-A7 and CLK2 are disabled which reduces power dissipation.
The DS90CF388A is able to support single or dual pixel
interface up to 112MHz operating frequency. This receiver
may also be used to interface to a VGA controller with an
integrated LVDS transmitter.
Pre-Emphasis adds extra current during LVDS logic transition to reduce the cable loading effects. Pre-emphasis
strength is set via a DC voltage level applied from min to max
(0.75V to Vcc) at the “PRE” pin. A higher input voltage on the
”PRE” pin increases the magnitude of dynamic current during data transition. The “PRE” pin requires one pull-up resistor (Rpre) to Vcc in order to set the DC level. There is an
internal resistor network, which cause a voltage drop. Please
refer to the tables below to set the voltage level.
TABLE 1. Pre-emphasis DC voltage level with (Rpre)
Rpre
Resulting PRE Voltage
Effects
1MΩ or NC
0.75V
Standard LVDS
50kΩ
1.0V
9kΩ
1.5V
3kΩ
2.0V
1kΩ
2.6V
100Ω
Vcc
50% pre-emphasis
100% pre-emphasis
TABLE 2. Pre-emphasis needed per cable length
Frequency
PRE Voltage
Typical cable length
112MHz
1.0V
2 meters
112MHz
1.5V
5 meters
80MHz
1.0V
2 meters
80MHz
1.2V
7 meters
65MHz
1.5V
10 meters
56MHz
1.0V
10 meters
Note 13: This is based on testing with standard shield twisted pair cable. The amount of pre-emphasis will vary depending on the type of cable, length and operating
frequency.
RSKM - Receiver Skew Margin
RSKM is a chipset parameter and is explained in AN-1059 in
detail. It is the difference between the transmitter’s pulse
position and the receiver’s strobe window. RSKM must be
greater than the summation of: Interconnect skew, LVDS
Source Clock Jitter (TJCC), and ISI (if any). See Figure 12.
Interconnect skew includes PCB traces differences, connector skew and cable skew for a cable application. PCB trace
and connector skew can be compensated for in the design of
the system. Cable skew is media type and length dependant.
Power Down:
Both transmitter and receiver provide a power down feature.
When asserted current draw through the supply pins is
minimized and the PLLs are shut down. The transmitter
outputs are in TRI-STATE when in power down mode. The
receiver outputs are forced to a active LOW state when in
the power down mode. (See Pin Description Tables). The PD
pin should be driven HIGH to enable the device once VCC is
stable.
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DS90C387A/DS90CF388A
Applications Information
DS90C387A/DS90CF388A
Applications Information
cycle-to-cycle basis, is also provided to reduce ISI
(Inter-Symbol Interference). With pre-emphasis and DC balancing, a low distortion eye-pattern is provided at the receiver end of the cable. A cable deskew capability has been
added to deskew long cables of pair-to-pair skew of up to
+/−1 LVDS data bit time (up to 80 MHz Clock Rate). These
three enhancements allow cables 5+ meters in length to be
driven depending upon media and clock rate.
(Continued)
DS90C387/DS90CF388:
The DS90C387A/CF388A chipset is electrically similar to the
DS90C387/CF388. The DS90C387/CF388 is intended for
improved support of longer cable drive. Cable drive is enhanced with a user selectable pre-emphasis feature that
provides additional output current during transitions to counteract cable loading effects. Optional DC balancing on a
Configuration Table
TABLE 3. Transmitter / Receiver configuration table
Pin
R_FB (Tx only)
R_FDE (both Tx and Rx)
DUAL (Tx only)
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Condition
Configuration
R_FB = VCC
Rising Edge Data Strobe
R_FB = GND
Falling Edge Data Strobe
R_FDE = VCC
Active data DE = High
R_FDE = GND
Active data DE = Low
DUAL=VCC
48-bit color (dual pixel) support
DUAL=1/2VCC
Single-to-dual support
DUAL=Gnd
24-bit color (single pixel) support
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DS90C387A/DS90CF388A
Pin Diagram
Transmitter-DS90C387A
10132006
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DS90C387A/DS90CF388A
Pin Diagram
Receiver-DS90CF388A
10132007
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DS90C387A/DS90CF388A Dual Pixel LVDS Display Interface / FPD-Link
Physical Dimensions
inches (millimeters)
unless otherwise noted
Dimensions show in millimeters
Order Number DS90C387AVJD and DS90CF388AVJD
NS Package Number VJD100A
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