Rainbow Electronics DS3150 - Manual (Page 13)

DS3150
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2. SIGNAL DESCRIPTIONS
Table 2A below lists all signals on the DS3150 and their function. The signals are listed in alphabetical
order. Section 4 shows the signal pin assignments for each package option.
Table 2A. SIGNAL DESCRIPTIONS
SIGNAL
NAME
I/O DESCRIPTION
DM* O Driver Monitor (Active Low, Open Drain). This signal reports the status of the transmit
driver monitor. When the transmit driver monitor detects a faulty transmitter, this pin is
pulled low. This pin should have an external pullup to V
DD
. This signal is not bonded out
in the PLCC package.
EFE I3
Enhanced Feature Enable. This signal enables the enhanced DS3150 features (PRBS
generation/detection, transmit driver monitor, and transmission of patterns, including all
ones, T3 AIS, or the 1010… pattern).
0 = Enhanced Features Disabled: TDS0 and TDS1 ignored and PRBS three-stated
1 = Enhanced Features Enabled: TDS0, TDS1, and PRBS active
Float = Test Mode Enabled: TDS0, TDS1, LBO, LOS* redefined as test pins
ICE I3
Invert Clock Enable. This signal determines on which RCLK edge RPOS/RNRZ and
RNEG/RLCV are updated and on which TCLK edge TPOS/TNRZ and TNEG are
sampled.
0 = Normal RCLK/Normal TCLK: update RPOS/RNRZ and RNEG/RLCV on falling
edge of RCLK; sample TPOS/TNRZ and TNEG on rising edge of TCLK
1 = Normal RCLK/Inverted TCLK: update RPOS/RNRZ and RNEG/RLCV on falling
edge of RCLK; sample TPOS/TNRZ and TNEG on falling edge of TCLK
Float = Inverted RCLK/Inverted TCLK: update RPOS/RNRZ and RNEG/RLCV on rising
edge of RCLK; sample TPOS/TNRZ and TNEG on falling edge of TCLK
LBKS* I3 Loopback Select. This input determines if either the Analog Loopback or the Remote
Loopback is enabled. See the Block Diagram in Section 1 for details.
0 = Analog Loopback Enabled
1 = No Loopback Enabled
Float = Remote Loopback Enabled
LBO I
Line Build-Out. This input indicates cable length for waveform shaping in DS3 and STS-
1 modes. LBO is ignored for E3 mode.
0 = Cable length greater than or equal to 225ft.
1 = Cable length less than 225ft.
LOS* O
Loss Of Signal (Active Low). This signal will be asserted upon detection of 175
± 75
consecutive zeros. Signals lower than 21dB below nominal are squelched. LOS* is
deasserted when there are no Excessive Zero occurrences over a span of 175
± 75 clock
periods. An Excessive Zero occurrence is defined as three or more consecutive zeros in
the T3 and STS-1 modes or four or more zeros in the E3 mode. Governing Specifications
are ANSI T1.231 and ITU G.775.
MCLK I
Master Clock. The clock input at this signal is used by the clock and data recovery
machine. A T3 (44.736MHz
± 20ppm), E3 (34.368MHz ± 20ppm), or STS-1 (51.840MHz
± 20ppm) clock should be applied at this signal. Tying this pin high or leaving it floating
forces the device to use the clock applied at the TCLK input for the receive side clock and
data recovery. Tying this pin low enables an internal oscillator. The frequency of this
oscillator is determined by a resistor placed between OFSEL and V
SS
. MCLK has an
internal 15kΩ pullup resistor to V
DD
.