QLX4270-DP_10 Datasheet, PDF (5/7 Pages) Intersil Corporation – DisplayPort Lane Extender

QLx4270-DP
Electrical Characteristics V_DD = 1.2V, T_A = +25°C, and V_IN = 800mV_P-P, unless otherwise noted. (Continued)
PARAMETER
SYMBOL
CONDITION
MIN TYP MAX UNITS NOTES
Output Return Loss
(Com. to Diff.
Conversion)
S_DC22 50MHz to 1.35GHz
20
dB
5
Output Residual Jitter
2.7Gb/s; Up to 2m 38AWG standard twin-axial
cable (11.5dB loss)
0.15 0.2
UI 4, 6, 7
Output Transition Time
Lane-to-Lane Skew
t_r, t_f
20% to 80%
30 60 100 ps
8
50
ps
Propagation Delay
From IN[k] to OUT[k]
500 ps
NOTES:
4. After channel loss, differential amplitudes at QLx4270-DP inputs must meet the input voltage range specified in “Absolute
Maximum Ratings” on page 4.
5. Temperature = +25°C, V_DD = 1.2V.
6. Output residual jitter is the difference between the total jitter at the lane extender output and the total jitter of the transmitted
signal (as measured at the input to the channel). Total jitter (TJ) is DJ_pp + 14.1 x RJ_RMS.
7. Measured using a PRBS 2⁷-1 pattern. Deterministic jitter at the input to the lane extender is due to frequency-dependent,
media-induced loss only.
8. Rise and fall times measured using a 1GHz clock with a 20ps edge rate.
Control Pin Boost Setting
The voltages at the CP pins are used to determine the
boost level of each channel of QLx4270-DP. For each of
the four channels, k, the [A], [B], and [C] control pins
(CP[k]) are associated with a 3-bit non binary word.
While [A] can take one of two values, ‘LOW’ or ‘HIGH’,
[B] and [C] can take one of three different values: ‘LOW’,
‘MIDDLE’, or ‘HIGH’. This is achieved by changing the
value of a resistor connected between VDD and the CP
pin, which is internally pulled low with a 25kΩ resistor.
Thus, a ‘HIGH’ state is achieved by using a 0Ω resistor,
‘MIDDLE’ is achieved with a 25kΩ resistor, and ‘LOW’ is
achieved with an open resistance. Table 1 defines the
mapping from the 3-bit CP word to the 18 out of 32
possible levels available via the serial interface on the
Evaluation Board kit.
TABLE 1. MAPPING BETWEEN CP-SETTING RESISTOR
AND QLx4270-DP BOOST LEVELS
RESISTANCE BETWEEN CP PIN
AND V_DD
CP[A]
CP[B]
CP[C]
SERIAL BOOST
LEVEL
Open
Open
Open
0
Open
Open
25kΩ
2
Open
Open
0Ω
4
Open
25kΩ
Open
6
Open
25kΩ
25kΩ
8
Open
25kΩ
0Ω
10
Open
0Ω
Open
12
Open
0Ω
25kΩ
14
Open
0Ω
0Ω
15
0Ω
Open
Open
16
TABLE 1. MAPPING BETWEEN CP-SETTING RESISTOR
AND QLx4270-DP BOOST LEVELS (Continued)
RESISTANCE BETWEEN CP PIN
AND V_DD
CP[A]
CP[B]
CP[C]
SERIAL BOOST
LEVEL
0Ω
Open
25kΩ
17
0Ω
Open
0Ω
19
0Ω
25kΩ
Open
21
0Ω
25kΩ
25kΩ
23
0Ω
25kΩ
0Ω
24
0Ω
0Ω
Open
26
0Ω
0Ω
25kΩ
28
0Ω
0Ω
0Ω
31
If all four channels are to use the same boost level, then
a minimum number of board resistors can be realized by
tying together like CP[k][A,B,C] pins across all channels
k. For instance, all four CP[k][A] pins can be tied to the
same resistor running to VDD. Consequently, only three
resistors are needed to control the boost of all four
channels. If the CP Pins are tied together and the 25kΩ is
used, the value changes to a 3.125kΩ resistor because
the 25kΩ is divided by 4.
Channel Power-Down
The IS[k] pin powers down the equalizer channel when
pulled low. This feature allows individually to power down
unused channels and to minimize power consumption.
Example: for DisplayPort applications with 1 or 2 links,
the unused channels may be powered down to save
power. The current draw for a channel is reduced from
50mA to 3.8mA when powered down.
5
FN6972.2
March 3, 2010