bt8375kpf Conexant Systems, Inc., bt8375kpf Datasheet - Page 157

• Manufacturer Part Number: bt8375kpf
• Description: Single Chip Transceivers For T1/e1 And Integrated Service Digital Network Isdn Primary Rate Interfaces Systems
• Manufacturer: Conexant Systems, Inc.

Bt8370/8375/8376
Fully Integrated T1/E1 Framer and Line Interface
RST_LIU
SQUELCH
FORCE_VGA
RDIGI
ATTN[1:0]
N8370DSE
020— LIU Configuration (LIU_CR)
RST_LIU
7
NOTE:
SQUELCH
Reset RLIU—Writing a 1 to RST_LIU resets the RLIU, reinitializes the receive equalizer, and
re-attempts signal acquisition. The processor must reset the RLIU after changing ATTN, or
after changing equalizer coefficients [EQ_DAT; addr 025]. Optionally, it can be reset in
response to an extended alarm condition.
Enable Squelch—Data slicer outputs from RLIU are forced to 0 until EYEOPEN [addr 021] =
1. SQUELCH is useful for long haul applications when near-end crosstalk may be of sufficient
magnitude to prevent accurate loss of signal detection.
FORCE VGA—Internal Variable Gain Amplifier (VGA) is set to equal the value programmed
in VGA_MAX register (addr 024). This bit is used for test purposes only.
Enable Receive Digital Inputs—When set, RDIGI bypasses RLIU and enables
RPOSI/RNEGI/RCKI inputs provided by an external line interface; otherwise, bipolar
RTIP/RRING inputs are enabled, RCKI input is ignored, and RPLL recovers the received
clock.
Bridge Attenuation—The receive equalizer can automatically compensate for signal level
attenuation caused by placement of bridge resistors in series with the normal receive
termination resistance. Bridge compensation scales the equalizer coefficients because they are
loaded from internal ROM; therefore, any change to the ATTN setting must be followed by an
RLIU reset command (RST_LIU).
6
Bits 0 and 1 are reserved and should be written to the values shown.
FORCE_VGA
5
ATTN
00
01
10
11
0 = normal
1 = reset RLIU (self clears)
0 = no effect
1 = squelch data slicer output
0 = normal operation
1 = force VGA to VGA_MAX (test mode only)
0 = RTIP/RRING inputs enabled
1 = RPOSI/RNEGI/RCKI inputs enabled
RDIGI
4
Bridge Attenuation
Conexant
–10 dB
–20 dB
–30 dB
0 dB
ATTN[1]
3
ATTN[0]
Bridge Resistance
2
1000
1500
300
None
3.7 Receive LIU Registers
1
0
0
1
3-39