MAX9240GTM+ Maxim Integrated, MAX9240GTM+ Datasheet - Page 34

• Manufacturer Part Number: MAX9240GTM+
• Description: Serializers & Deserializers - Serdes 28Bit GMSL Deserializer
• Manufacturer: Maxim Integrated

Specifications of MAX9240GTM+

• Rohs: yes

The serializer includes a PRBS pattern generator that
works with bit-error verification in the deserializer. To run
the PRBS test, set PRBSEN = 1 (0x04, D5) in the deserial-
izer and then in the serializer. To exit the PRBS test, set
PRBSEN = 0 (0x04, D5) in the serializer.
The deserializer includes an adjustable line equalizer to
further compensate cable attenuation at high frequen-
cies. The cable equalizer has 11 selectable levels of
compensation from 2.1dB to 13dB
powers up with the equalizer disabled. To select other
equalization levels, set the corresponding register bits
in the deserializer (0x05 D[3:0]). Use equalization in the
deserializer, together with preemphasis in the serializer,
to create the most reliable link for a given cable.
To reduce the EMI generated by transitions, the dese-
rializer output is programmable for spread spectrum. If
the serializer driving the deserializer has programmable
spread spectrum, do not enable spread for both at the
same time or their interaction will cancel benefits. The
programmable spread-spectrum amplitudes are Q2%
and Q4%
The deserializer includes a sawtooth divider to
control the spread-modulation rate. Autodetection of
the PCLKOUT operation range guarantees a spread-
Table 5. Cable Equalizer Boost Levels
*The equalizer is disabled at power-up.
Maxim Integrated
6.25MHz to 100MHz, 25-Bit GMSL Deserializer for
BOOST SETTING
(0x05 D[3:0])
(Table
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
6).
Coax or STP Cable With Line Fault Detect
TYPICAL BOOST GAIN
Spread Spectrum
(Table
Line Equalizer
Default*
(dB)
10.7
11.7
2.1
2.8
3.4
4.2
5.2
6.2
8.2
9.4
13
5). The device
7
PRBS Test
spectrum modulation frequency within 20kHz to 40kHz.
Additionally, manual configuration of the sawtooth divider
(SDIV: 0x03, D[5:0]) allows the user to set a modulation
frequency according to the PCLKOUT frequency. When
ranges are manually selected, program the SDIV value
for a fixed modulation frequency around 20kHz.
The modulation rate for the deserializer relates to the
PCLKOUT frequency as follows:
where:
f
DRS = DRS value (0 or 1)
f
MOD = Modulation coefficient given in
SDIV = 5-bit SDIV setting, manually programmed by
the FC
To program the SDIV setting, first look up the modula-
tion coefficient according to the desired bus-width and
spread-spectrum settings. Solve the above equation for
SDIV using the desired pixel clock and modulation fre-
quencies. If the calculated SDIV value is larger than the
maximum allowed SDIV value in
maximum value.
Table 6. Parallel Output Spread
Table 7. Modulation Coefficients and
Maximum SDIV Settings
M
PCLKOUT
= Modulation frequency
SETTING (%)
SPECTRUM
SPREAD-
SS
00
01
10
11
4
2
= PCLKOUT frequency
f
M
of the Spread-Spectrum Divider
=
No spread spectrum. Power-up default.
Q2% spread spectrum.
No spread spectrum.
Q4% spread spectrum.
(
1 DRS
MODULATION
COEFFICIENT
+
(dec)
208
208
)
MOD SDIV
Manual Programming
f
SPREAD (%)
PCLKOUT
Table
×
MAX9240
7, set SDIV to the
Table 7
SDIV UPPER
LIMIT (dec)
15
30
34