Datasheet

32 Maxim Integrated
Gigabit Multimedia Serial Link with Spread
Spectrum and Full-Duplex Control Channel
MAX9259/MAX9260
Interrupt Control
The INT of the MAX9259 is the interrupt output and the
INT of the MAX9260 is the interrupt input. The interrupt
output on the MAX9259 follows the transitions at the
interrupt input of the MAX9260. This interrupt function
supports remote-side functions such as touch-screen
peripherals, remote power-up, or remote monitoring.
Interrupts that occur during periods where the reverse
control channel is disabled, such as link startup/shut-
down, are automatically resent once the reverse control
channel becomes available again. Bit D4 of register
0x06 in the MAX9260 also stores the interrupt input state.
Writing to the SETINT register bit also sets the INT output
of the MAX9259. In addition, the FC sets the INT output
of the MAX9259 by writing to the SETINT register bit. In
normal operation, the state of the interrupt output chang-
es when the interrupt input on the MAX9260 toggles.
Preemphasis Driver
The serial line driver in the MAX9259 employs current-
mode logic (CML) signaling. The driver generates
an adjustable preemphasized waveform according to
the cable length and characteristics. There are 13
preemphasis settings, as shown in Table 4. Negative
preemphasis levels are deemphasis levels in which the
preemphasized swing level is the same as normal swing,
but the no-transition data is deemphasized. Program the
preemphasis levels through register 0x05 D[3:0] of the
MAX9259. This preemphasis function compensates the
high-frequency loss of the cable and enables reliable
transmission over longer link distances. Additionally, a
lower power drive mode can be entered by program-
ming CMLLVL bits (0x05 D[5:4]) to reduce the driver
strength down to 75% (CMLLVL = 10), or 50% (CMLLVL
= 01) from 100% (CMLLVL = 11, default).
Line Equalizer
The MAX9260 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 (Table 5). The EQS
input selects the default equalization level at power-up.
The state of EQS is latched upon power-up or when
resuming from power-down mode. To select other
equalization levels, set the corresponding register bits
in the MAX9260 (0x05 D[3:0]). Use equalization in the
MAX9260, together with preemphasis in the MAX9259 to
create the most reliable link for a given cable.
Table 4. MAX9259 CML Driver Strength (Default Level, CMLLVL = 11)
*Negative preemphasis levels denote deemphasis.
PREEMPHASIS LEVEL
(dB)*
PREEMPHASIS SETTING
(0x05, D[3:0])
I
CML
(mA)
I
PRE
(mA)
SINGLE-ENDED VOLTAGE SWING
MAX
(mV)
MIN
(mV)
-6.0 0100 12 4 400 200
-4.1 0011 13 3 400 250
-2.5 0010 14 2 400 300
-1.2 0001 15 1 400 350
0 0000 16 0 400 400
1.1 1000 16 1 425 375
2.2 1001 16 2 450 350
3.3 1010 16 3 475 325
4.4 1011 16 4 500 300
6.0 1100 15 5 500 250
8.0 1101 14 6 500 200
10.5 1110 13 7 500 150
14.0 1111 12 8 500 100