MAX9257/MAX9258
40 ______________________________________________________________________________________
Fully Programmable Serializer/Deserializer
with UART/I
2
C Control Channel
ADDRESS BITS DEFAULT NAME DESCRIPTION
7:6 10 PRATE
Pixel clock frequency range
00 = 5MHz to 10MHz
01 = 10MHz to 20MHz
10 = 20MHz to 40MHz (default)
11 = 40MHz to 70MHz
5:4 11 SRATE
Serial-data rate range
00 = 60Mbps to 100Mbps
01 = 100Mbps to 200Mbps
10 = 200Mbps to 400Mbps
11 = 400Mbps to 840Mbps (default)
3 0 PAREN Parity enable 0 = disabled (default), 1 = enabled
0
2:0 101 PWIDTH
Parallel data width
(includes HSYNC and VSYNC, excludes DCB, INV, and parity bits)
000 = 10 100 = 18
001 = 12 101 = 18 (default)
010 = 14 110 = 18
011 = 16 111 = 18
7:5 000 SPREAD
Spread-spectrum setting
For PRATE ranges 00, 01: all spread options possible
For PRATE ranges 10, 11: maximum spread is 2%
000 = Off (default) 100 = Off
001 = 1.5% 101 = 3%
010 = 1.75% 110 = 3.5%
011 = 2% 111 = 4%
1
4:0 11111 Reserved (set to 11111)
Control channel start timeout: (STO) times out if ECU does not start using control channel within this amount of time
after control channel session is enabled.
7:4 1010 STODIV
Control channel start timeout divider
Pixel clock is first divided by:
0000 = 16 1000 = 256
0001 = 16 1001 = 512
0010 = 16 1010 = 1024 (default)
0011 = 16 1011 = 2048
0100 = 16 1100 = 4096
0101 = 32 1101 = 8192
0110 = 64 1110 = 16,384
0111 = 128 1111 = 32,768
2
3:0 0000 STOCNT
Control channel start timeout counter
Divided pixel clock is used to count up to (STOCNT + 1)
MAX9257 Register Table
Choosing I
2
C Pullup Resistors
I
2
C requires pullup resistors to provide a logic-high level
to data and clock lines. There are tradeoffs between
power dissipation and speed, and a compromise must
be made in choosing pullup resistor values. Every device
connected to the bus introduces some capacitance even
when device is not in operation. I
2
C specifies 300ns rise
times to go from low to high (30% to 70%) for fast mode,
which is defined for a date rate up to 400kbps (see I
2
C
specifications for details). To meet the rise time require-
ment, choose the pullup resistors so the rise time
t
R
= 0.85R
PULLUP
x C
BUS
< 300ns. If the transition time
becomes too slow, the setup and hold times may not be
met and waveforms will not be recognized.
(1 Seiten)
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