參數(shù)資料
型號(hào)： MAX4455ECQ
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 畫(huà)面疊加
英文描述： Triple Differential Transceivers 20-SOIC -40 to 85
中文描述： ON-SCREEN DISPLAY IC, PQFP100
封裝： 14 X 14 MM, 1 MM HEIGHT, TQFP-100
文件頁(yè)數(shù)： 8/30頁(yè)
文件大小： 663K
代理商： MAX4455ECQ
M
Arbitrary Graphics On-Screen Display
Video Generator
8
_______________________________________________________________________________________
Detailed Description
The MAX4455 provides 4-bit gray-scale graphics video
to eight simultaneous independent composite video
inputs. The bit-mapped approach allows an arbitrary
message to be inserted into the camera video when
used in conjunction with the MAX4356/MAX4358 video
crosspoint switch or discrete fast mux switch. The
inserted graphics can include camera location, date,
time, company logo, or warning prompts.
The graphics palette for each of the eight video channels
in the MAX4455 is logically organized into 1024 pixels by
512 lines. This memory arrangement facilitates easy
row/column pixel addressing by the host processor. The
actual displayed area is 712
×
484 NTSC (712
×
512 PAL)
pixels. The remaining 312 logical pixels per line are
blanked. The remaining 28 NTSC (0 PAL) horizontal lines
are also blanked as shown in Figure 4.
The MAX4455 controls a 16Mb SDRAM (such as
MT48LC1M16A) that stores video graphics insertion data.
The MAX4455 performs all SDRAM support functions,
including refresh, RAS/CAS timing, video addressing, and
CPU access cycles for host processor read/write support.
Since the SDRAM is organized as a 16-bit wide
×
1 mil-
lion deep array, each SDRAM memory location holds 4
pixels (based on the fact that a pixel is 4 bits and mem-
ory is 16 bits wide). The host processor thus accesses
pixels four at a time. The host processor interface is 8
bits wide so the 16 bit wide SDRAM data is written into
(or read from) the pixel data register as two separate
8-bit bytes.
The MAX4455 establishes a video raster time base by
sensing the video signal on either the output of the
Maxim crosspoint switch, or the output buffer of the fast
mux switch. The MAX4455 uses this raster timing to
produce an OSD image signal that can be inserted into
the camera video by controlling the OSDKEY input to
the Maxim crosspoint switch or fast mux switch. The
OSD image is inserted wherever the OSD video level
pixel code has a nonzero value, and the crosspoint
switch or discrete fast mux is made to pass the original
video wherever the OSD video level pixel code is zero.
When the OSD video level is nonzero, it represents a
gray-level code such that level 1 is near black and
code 15 (the maximum possible with a 4-bits-per-pixel
code) is maximally white (Table 1). The host computer
fills the external OSD frame memory with a bit-mapped
image such that each pixel has a value between zero
and 15, controlling both insertion locations and the
brightness levels within an inserted video image. There
are eight channels in the MAX4455 that share memory
resources but are logically completely independent.
Writing/reading image data to/from any channel
’
s mem-
ory does not disrupt other channels.
The MAX4455 features a memory-sharing function
where the even channels or the odd channels can be
updated simultaneously by writing to a designated
source channel. The memory-sharing function mini-
mizes the number of memory writes by the host proces-
sor. This is useful for updating information that changes
rapidly (i.e., time stamp).
Video Inputs
The MAX4455
’
s eight VIDIN_ inputs include circuitry to
extract video timing from each asynchronous video
channel for proper display of the OSD specific to that
channel. Each VIDIN_ time-base circuitry includes a
horizontal sync detector, vertical sync detector, vertical
interval detector, horizontal line counter, and even/odd
field counter. The VIDIN_ inputs sense a standard 1V
P-P
video signal at the output of the crosspoint switch, or
fast mux buffer in order to make video timing insensitive
to delays through the switch/mux. AC-couple the input
with a 0.1μF capacitor.
OSDFILL_ Video Outputs
The MAX4455 has eight independent current output
video DACs that provide 7 IRE to 100 IRE video levels
(R
RSET
= 11.75k
) when terminated with 75
to
AGND. Connect OSDFILL_ to either the OSDFILL_
input of the Maxim crosspoint switch (MAX4356/
MAX4358) or to one of the inputs of the fast mux switch.
OSDKEY Control Outputs
Each OSD channel has an OSDKEY_ logic output that
drives low when OSDFILL_ output video is to be multi-
plexed into the active video. The OSDKEY_ output
interfaces directly to the OSDKEY_ inputs of the
MAX4356/MAX4358 or control inputs of the fast mux
switch to allow pixel-by-pixel OSD insertion. The V
K1
supply sets the OSDKEY_ logic output voltage levels.
Pin Description (continued)
PIN
NAME
FUNCTION
93
RSET
OSDFILL Reference Voltage. Connect a resistor (typically 11.75k
) from RSET to AGND to
set the full-scale output current of all eight OSDFILL_ outputs.
94
AGND
Analog Ground
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參數(shù)描述
MAX4455ECQ+D 功能描述:視頻開(kāi)關(guān) IC RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)數(shù)量:4 開(kāi)啟電阻（最大值）:12 Ohms 傳播延遲時(shí)間: 開(kāi)啟時(shí)間（最大值）: 關(guān)閉時(shí)間（最大值）: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:WQFN-42 封裝:Reel
MAX4455ECQ+TD 功能描述:視頻開(kāi)關(guān) IC Integrated Circuits (ICs) RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)數(shù)量:4 開(kāi)啟電阻（最大值）:12 Ohms 傳播延遲時(shí)間: 開(kāi)啟時(shí)間（最大值）: 關(guān)閉時(shí)間（最大值）: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:WQFN-42 封裝:Reel
MAX4455ECQ-T 功能描述:視頻開(kāi)關(guān) IC RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)數(shù)量:4 開(kāi)啟電阻（最大值）:12 Ohms 傳播延遲時(shí)間: 開(kāi)啟時(shí)間（最大值）: 關(guān)閉時(shí)間（最大值）: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:WQFN-42 封裝:Reel
MAX4455EVKIT 制造商:Maxim Integrated Products 功能描述:ARBITRARY GRAPHICS ON-SCREEN DISPLAY VIDEO GE - Bulk
MAX4455EVSYS 制造商:Maxim Integrated Products 功能描述:ARBITRARY GRAPHICS ON-SCREEN DISPLAY VIDEO GE - Bulk 制造商:Rochester Electronics LLC 功能描述:
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