MAX14982 Datasheet, PDF (9/12 Pages) Maxim Integrated Products – Test Equipment

MAX14982
All-In-One Ruggedized 5GT/s 2:1/1:2 PCIe Mux and
Redriver with Equalization
Detailed Description
The MAX14982 is an active 2:1/1:2 multiplexer designed
to equalize and redrive PCIe signals up to 5.0GT/s. The
device features PCIe-required electrical idle and receiver
detection on each channel, and improves signal integrity
at the receiver through independent programmable input
equalization and output deemphasis.
Enable Input (EN)
The MAX14982 features an active-high enable input
(EN). EN has an internal pulldown resistor of 60kΩ (typ).
When EN is driven low or left unconnected, the IC enters
reduced power standby mode and the redrivers are dis-
abled. Drive EN high for normal operation.
Active Input/Output Select (SEL1, SEL2)
SEL1 selects the active output for channel 1 and SEL2
selects the active input for channel 2. Drive SEL1 or
SEL2 low or leave unconnected to activate A inputs or
outputs. Drive SEL1 or SEL2 high to activate B inputs or
outputs. SEL1 and SEL2 have internal pulldown resistors
of 60kΩ (typ).
Table 1. Output Deemphasis
ODE_1
0
0
1
1
ODE_0
0
1
0
1
OUTPUT DEEMPHASIS
(dB)
0, low swing
0, full swing
3.5, full swing
6, full swing
Table 2. Input Equalization
INEQ_1
INEQ_0
INPUT EQUALIZATION
(dB)
0
X
0
1
0
3.5
1
1
6
X = Don’t Care
Table 3. Receiver Detection
Programmable Output Deemphasis
(ODE_0, ODE_1)
The MAX14982 features independent programmable
output deemphasis capable of providing 0dB, 3.5dB, or
6dB deemphasis on any channel. When both ODE_0 and
ODE_1 are driven low or left unconnected, the output is
in low-swing mode (750mV typ) (see Table 1). ODE0,
ODE1, ODEA0, ODEA1, ODEB0, and ODEB1 have inter-
nal pulldown resistors of 60kΩ (typ).
Programmable Input Equalization
(INEQ_0, INEQ_1)
The MAX14982 features independent programmable
input equalization capable of providing 0dB, 3.5dB, or
6dB of high-frequency equalization on any channel (see
Table 2.) INEQ0, INEQ1, INEQA0, INEQA1, INEQB0, and
INEQB1 have internal pulldown resistors of 60kI (typ).
Receiver Detection (RX_DET)
The MAX14982 features receiver detection on each
channel. Receiver detection initializes on the rising edge
of EN, or upon initial power-up if EN is high. Receiver
detection can also be initiated on a rising or falling edge
of the RX_DET, SEL1, or SEL2 inputs when EN is high.
During this time, the part remains in reduced power
standby mode and the outputs are squelched, despite the
logic-high state of EN. Once started, receiver detection
repeats indefinitely on each channel. Once a receiver is
detected on one of the channels, up to 2¹⁶ more attempts
are made on the other channel. Upon receiver detection,
channel output and electrical idle detection are enabled
(see Table 3). RX_DET has an internal pulldown resistor
of 60kΩ (typ).
Electrical Idle Detection
The IC features electrical idle detection to prevent
unwanted noise from being redriven at the output. If the
MAX14982 detects that the differential input has fallen
below V_{TX-IDLE-THRESH}, the MAX14982 squelches the
output. For differential input signals that are above
V_{TX-IDLE-THRESH}, the MAX14982 turns on the output
and redrives the signal.
RX_DET/
SEL1/SEL2
X
0
Rising or falling edge
1
X = Don’t Care
EN
DESCRIPTION
0
Receiver detection inactive
1
Following a rising or falling edge; indefinite retry until receiver detected
1
Initiate receiver detection
1
Following a rising or falling edge; indefinite retry until receiver detected
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