Datasheet

LTC4313-1/LTC4313-2/
LTC4313-3
14
4313123f
applicaTions inForMaTion
The LTC4313-2 on only one of the shelf managers is
enabled at any given time. The hot insertion logic on the
LTC4313-3 allows the FRUs to be plugged or unplugged
from a live backplane. The features mentioned previously
provide noise immunity and allow timing specifications to
be met for a wide range of backplane loading conditions.
In the 6 × 4 radial configuration shown in Figure 8, the
LTC4314s on the shelf managers and the LTC4313-2s on
the FRUs drive the large backplane capacitance while the
I
2
C slave devices on the FRUs only drive the small input
capacitance of the LTC4313-2s. The LTC4314s on only
one of the shelf managers are enabled at a given time. All
the benefits provided by the LTC4313-2 in Figure 7 apply
to Figure 8 as well.
Cascading and Interoperability with Other LTC Buffers
and Non-Compliant I
2
C Devices
Multiple LTC4313s can be cascaded or the LTC4313 can be
cascaded with other LTC bus buffers. Cascades often exist
in large I
2
C systems, where multiple I/O cards having bus
buffers connect to a common backplane bus. Two issues
need to be considered when using such cascades – the
additive nature of the buffer logic low offset voltages and the
impact of the RTA-buffer interaction on the noise margin.
Figure 8. LTC4313-2 Used in a Radially Connected Telecommunication System in a 6 × 4 Arrangement.
Only the Clock Path is Shown for Simplicity. The Data Pathway is Identical
SHELF MANAGER #1
IPMB-A(X24)
IPMB-B(X24)
SCL1
SCL24
SCL1
SCL24
3.3V
R2
10k
LTC4314#1
V
CC
V
CC2
SCLOUT1
SCLOUT2
SCLOUT3
SCLOUT4
SCLIN
ENABLE1
ENABLE2
ENABLE3
ENABLE4
ACC
ENABLE1A
ENABLE2A
ENABLE3A
ENABLE4A
ENABLE21A
ENABLE22A
ENABLE23A
ENABLE24A
R1
10k
µP
3.3V
3.3V
IPMB-B DETAILS (NOT SHOWN) ARE IDENTICAL TO IPMB-A
IPMB-B
R5
10k
LTC4314#6
V
CC
V
CC2
SCLOUT1
SCLOUT2
SCLOUT3
SCLOUT4
SCLIN
ENABLE1
ENABLE2
ENABLE3
ENABLE4
ACC
3.3V
4313123 F08
BACKPLANE
IPMB-B
SCL24
3.3V
IPMB-A
SCL1
IPMB-A
SCL24
IPMB-B
SCL1
FRU #1
LTC4313-2
I
2
C
DEVICE
3.3V
SCLOUT
V
CC
SCLIN
R3
10k
R4
10k
LTC4313-2
SCLOUT
V
CC
SCLIN
FRU #24
3.3V
LTC4313-2
I
2
C
DEVICE
3.3V
SCLOUT
V
CC
SCLIN
R6
10k
R7
10k
LTC4313-2
SCLOUT
V
CC
SCLIN
SHELF MANAGER #2
IDENTICAL TO SHELF MANAGER #1
• • • • • •
• • •
• • •
• • •