MAX3845 Maxim Integrated Products, MAX3845 Datasheet - Page 11

• Manufacturer Part Number: MAX3845
• Description: DVI/HDMI 2:4 TMDS Fanout Switch and Cable Driver
• Manufacturer: Maxim Integrated Products

Pin 14, TEMP, allows the on-die temperature to be
sensed as an analog voltage output. To sense the die
temperature, measure the DC voltage at TEMP. The
approximate die temperature can be determined using
the following equation:
Also see the Typical Operating Characteristics section
for more information.
The power-down inputs (PWRDWN_1 and PWRDWN_2)
reduce power consumption by powering down the cho-
sen input and all outputs that are selected to that input.
For example, when output channels 1 and 4 are select-
ed to transmit input channel 2, and channel 2 is pow-
ered down, both outputs 1 and 4 are also powered
down.
Table 1. Output Levels With and Without Back Termination
Table 2. Output Enable Requirements
PREEMPHx = LOW, OUT_LEVEL = LOW (Output Drive Current = 11mA)
No back termination
PREEMPHx = LOW, OUT_LEVEL = HIGH (Output Drive Current = 14mA)
Differential 200
Differential 300
Single-ended, 2x 100
OUTPUT x
INPUT 1
INPUT 2
STATE
T
back terminations (DC-coupled)
back terminations (DC-coupled)
J
= (V
______________________________________________________________________________________
CONDITION
IN_SELx
CONDITIONS
back terminations (AC-coupled)
DVI/HDMI 2:4 TMDS Fanout Switch and
TEMP
HIGH
LOW
- 0.93) x 297
Temperature Sense
CONDITION
HOTPLUGx
Power-Down
HIGH
HIGH
PWRDWN_1
CONDITION
Don’t care
VOLTAGES AT THE INPUT OF THE TMDS RECEIVER (TYPICAL)
LOW
1100mV
1050mV
950mV
950mV
V
Each output channel has a HOTPLUGx detection pin
associated with it. This pin is designed to detect
whether a monitor’s hotplug connection is attached. If
HOTPLUGx is low (less than 1.5V), the associated out-
put is powered down. If HOTPLUGx is higher than
V
ered down.
Several things must occur for an output to be active.
Table 2 lists the required inputs to enable an output.
Good quality cable is recommended for good perfor-
mance. Deterministic jitter (DJ) can be caused by dif-
ferential-to-common-mode conversion (or vice versa)
within a twisted pair (STP or UTP), usually a result of
cable twist or dielectric imbalance. Refer to Application
Note HFAN-4.5.4: ‘Jitter Happens’ when a Twisted Pair
is Unbalanced for more information.
DIFF
CC
P-P
P-P
P-P
P-P
- 0.2V, up to 5.5V, the associated output is pow-
PWRDWN_2
CONDITION
Don’t care
V
V
V
LOW
CC
CC
CC
V
- 275mV
- 350mV
- 350mV
V
CM
CC
CONDITION
Cable Driver
Don’t care
V
V
V
CC
LOS 1
CC
Activating an Output
CC
LOW
+ 240mV
V
- 120mV
V
- 90mV
CC
H
Cable Selection
Hotplug Detect
CONDITION
V
V
V
V
Don’t care
CC
CC
CC
CC
LOS 2
LOW
- 550mV
- 585mV
- 615mV
- 240mV
V
L
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