LMH0031VS/NOPB National Semiconductor, LMH0031VS/NOPB Datasheet - Page 28

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LMH0031VS/NOPB

Manufacturer Part Number
LMH0031VS/NOPB
Description
IC DESER/DESCRAM DGTL VID 64TQFP
Manufacturer
National Semiconductor
Type
Descrambler/Deserializerr
Datasheet

Specifications of LMH0031VS/NOPB

Applications
SDTV/HDTV
Mounting Type
Surface Mount
Package / Case
64-TQFP, 64-VQFP
Input Voltage
3.3 V
Supply Voltage (max)
3.45 V
Supply Voltage (min)
3.15 V
Maximum Operating Temperature
+ 70 C
Minimum Operating Temperature
0 C
Mounting Style
SMD/SMT
For Use With
SD131EVK - BOARD EVALUATION LMH0031
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
*LMH0031VS
*LMH0031VS/NOPB
LMH0031VS

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LMH0031VS/NOPB
Manufacturer:
Texas Instruments
Quantity:
10 000
www.national.com
Pin Descriptions
Note: All LVCMOS inputs have internal pull-down devices except VCLK and ACLK.
Application Information
A typical application circuit for the LMH0031 is shown in the
Application Circuit diagram. This circuit demonstrates the
capabilities of the LMH0031 and allows its evaluation in a
native configuration. An assembled demonstration board is
available, part number SD131EVK. The board may be or-
dered through any of National’s sales offices. Complete
circuit board layouts and schematics for the SD131EVK are
available on National’s WEB site. For latest availability infor-
mation, please see: www.national.com/appinfo/interface.
PCB LAYOUT AND POWER SYSTEM BYPASS
RECOMMENDATIONS
Circuit board layout and stack-up for the LMH0031 should be
designed to provide noise-free power to the device. Good
layout practice also will separate high frequency or high-
level inputs and outputs from low-level inputs to minimize
unwanted stray noise pickup, feedback and interference.
Power system performance may be greatly improved by
using thin dielectrics (4 to 10 mils) for power/ground sand-
wiches. This increases the intrinsic capacitance of the PCB
power system which improves power supply filtering, espe-
cially at high frequencies, and makes the value and place-
ment of external bypass capacitors less critical. External
bypass capacitors should include both RF ceramic and tan-
talum electrolytic types. RF capacitors may use values in the
range 0.01 µF to 0.1 µF. Tantalum capacitors may be in the
range 2.2 µF to 10 µF. Voltage rating for tantalum capacitors
should be at least 5X the power supply voltage being used.
It is recommended practice to use two vias at each power pin
of the LMH0031 as well as all RF bypass capacitor termi-
nals. Dual vias reduce the interconnect inductance by up to
half, thereby extending the effective frequency range of the
bypass components.
The outer layers of the PCB may be flooded with additional
V
isolation as well as increase the intrinsic capacitance of the
power supply plane system. Naturally, to be effective, these
planes must be tied to the V
quent intervals with vias. Frequent via placement also im-
proves signal integrity on signal transmission lines by pro-
SS
Pin
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
(ground) plane. These planes will improve shielding and
V
V
V
R
R
V
SDI
SDI
V
V
XTALi/EXT CLK
XTALo
V
ANC/CTRL
RD/WR
CLK
DDPLL
SSPLL
SSSI
DDSI
SSIO
DDD
REF
BB
Name
SS
(Continued)
power supply plane at fre-
Parallel Video Data Clock Output
Positive Power Supply Input (2.5V supply, PLL)
Negative Power Supply Input (2.5V supply, PLL)
Current Reference Resistor
SDI Bias Supply Resistor
Negative Power Supply Input (3.3V supply, Serial Input)
Serial Data Complement Input
Serial Data True Input
Positive Power Supply Input (3.3V supply, Serial Input)
Negative Power Supply Input (3.3V supply, I/O)
Crystal or External 27MHz Clock Input
Crystal (Oscillator Output)
Positive Power Supply Input (2.5V supply, Digital Logic)
ancillary/Control Data Port Function Control Input
ancillary/Control Data Port Read/Write Control Input
28
viding short paths for image currents which reduces signal
distortion. The planes should be pulled back from all trans-
mission lines and component mounting pads a distance
equal to the width of the widest transmission line or the
thickness of the dielectric separating the transmission line
from the internal power or ground plane(s) whichever is
greater. Doing so minimizes effects on transmission line
impedances and reduces unwanted parasitic capacitances
at component mounting pads.
In especially noisy power supply environments, such as is
often the case when using switching power supplies, sepa-
rate filtering may be used at the LMH0031’s PLL and serial
input power pins. The LMH0031 was designed for this situ-
ation. The I/O, digital section, PLL and serial input power
supply feeds are independent (see pinout description table
and pinout drawing for details). Supply filtering may take the
form of L-section or pi-section, L-C filters in series with these
V
from several manufacturers. Device power supplies must be
either sequenced as described in Section POWER SUP-
PLIES, POWER-ON-RESET AND RESET INPUT and ide-
ally should be applied simultaneously as from a common
source.
MAINTAINING OUTPUT DATA INTEGRITY
The way in which the TRS and other video data characters
are specified and are therefore output in parallel form can
result in the simultaneous switching of many of the
LMH0031’s CMOS outputs. Such switching can lead to the
production of output high level droop or low level ground
bounce. Given in the specifications, V
LOW voltage or ground bounce and V
output HIGH voltage or output droop that may occur under
dynamic simultaneous output switching conditions. V
and V
Careful attention to PCB layout, power pin connections to
the power planes and timing of the output data clocking can
reduce these effects. Consideration must also be given to
the timing allocated to external circuits which sample the
outputs.
The effects of simultaneous output switching on output levels
may be minimized by adopting good PCB layout and data
DD
inputs. Such filters are available in a single package
OLP
are measured with respect to reference ground.
Description
OLP
OHV
is the peak output
is the lowest
OHV

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