MAX3816ACUE Просмотр технического описания (PDF) - Maxim Integrated
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MAX3816ACUE Datasheet PDF : 18 Pages
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I2C 2-Wire Extender for DDC in DVI,
HDMI, and VGA Interfaces
Locally, connect a 47kΩ pullup resistor from CLOCK_C
and DATA_C to VCC. This assumes that a 1.65kΩ
pullup resistor resides at the opposite end of each
channel.
Display Drivers
The display drivers (Figure 11) are typical open-drain
pulldown devices capable of discharging up to 400pF
of capacitive load within the I2C fall-time limits.
Locally, connect a 2.2kΩ pullup resistor from CLOCK_D
and DATA_D to VDD for VDD = 3.3V, or a 3.3kΩ pullup
resistor to VDD for VDD = 5V.
Level Sense
The MAX3816A’s level-sensing circuitry monitors the
incoming data for state transitions. When the CLOCK or
DATA signal is high and drops below VTRIGIH, the con-
troller ramps the outputs low. When the DATA and
CLOCK are low and both rise above VTRIGIL, refer-
enced to GND_REF on the source side or VSS on the
display side, the output drives the level high.
HIGH
STATE
CLOCK_C “OR” CLOCK_D < 75%
1
SENSE ON
DRIVERS OFF
HOLDOFF TIMER ≥ 2.5μs
“AND”
CLOCK_C “AND” CLOCK_D > 85%
6
SENSE OFF
DRIVERS OFF
LOW
STATE
HOLDOFF TIMER = START
2
SENSE OFF
DRIVERS ON
RAMP
DOWN
HOLDOFF TIMER = 1.75μs
3
SENSE OFF
(NOTE 3)
HOLDOFF TIMER = 1.75μs
HOLDOFF TIMER = 2.5μs
RAMP
UP
5
SENSE OFF
DRIVERS ON
4
SENSE ON
(NOTE 3)
HOLDOFF TIMER = START
CLOCK_D > 17.5% AND CLOCK_C > 12.5%
NOTES:
1) STATE CHANGE CONDITIONS ARE IN ITALICS. TRANSITION ACTIONS ARE UNDERLINED.
2) THE DATA CHANNEL STATE MACHINE IS IDENTICAL AND SYMMETRIC, EXCEPT THAT HOLDOFF TIME IS 2.0μs INSTEAD OF 2.5μs.
ALSO, IN ADDITION TO THE 85% CONDITION TO EXIT STATE 6, DATA HAS AN ADDITIONAL EXIT: DATA_C “OR” DATA_D < 60%.
3) DEPENDENT ON MODE PIN 16: MODE = LOW FOR SERIAL OPERATION (DRIVERS HOLD); MODE = HIGH FOR PARALLEL OPERATION (DRIVERS OFF).
Figure 1a. Clock State Machine Diagram
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