LTC4312

13

4312f

APPLICATIONS INFORMATION

the LTC4312 can be cascaded with the LTC4303 and

LTC4307 if the LTC4312’s RTA turn-on voltage is set to be

0.8V (ACC low). The LTC4312 can be cascaded with the

LTC4301 and LTC4301L under all ACC settings as these

devices do not have RTAs. The LTC4312 can be cascaded

with the LTC4302, LTC4304, LTC4305 and LTC4306 if the

LTC4312’s RTAs are set to turn on at 0.8V (ACC low) or

under all ACC settings if the RTAs on the other bus buf-

fers are disabled. Finally, two LTC4312s can be cascaded

if their ACC pins are tied to the same state, HIGH, LOW

or open or if the ACC pin of one LTC4312 is tied high and

the other is left open.

Radial Telecommunications

Figure 6 shows the use of the LTC4312 in a radial telecom-

munications application. Two Shelf Managers are wired to

Shelf Manager can have as many LTC4312s as required

depending on the number of boards in the system and

the desired radial/star configuration. The ENABLE pins of

the LTC4312s inside only one Shelf Manager are asserted

high at any time. For simplicity, in Figure 6 only the SDA

pathway is shown. The SCL pathway is identical.

Figure 6. LTC4312s Configured for a Radially Connected Redundant Telecommunications Shelf Manager Application

in a 12 × 2 Arrangement. The ENABLE Pins on Only One of the Shelf Managers Are High at Any Time. Only the SDA

Path Is Shown for Simplicity

LTC4312 #1

GND

3.3V

SHMC #1

SHMC #2

(IDENTICAL TO SHMC#1)

4312 F06

SDAOUT1

SDAOUT2

SDAIN

ENABLE1

ENABLE2

ACC

ENABLE1A

ENABLE2A

μP

R1

10k

BACKPLANE

IPMB-A

SDA1

IPMB-A

SDA24

IPMB-B

SDA1

SDA24

SDA1

FRU #1

FRU #24

3.3V

R2

10k

3.3V

LTC4312 #12

GND

3.3V

SDAOUT1

SDAOUT2

SDAIN

ENABLE1

ENABLE2

ACC

ENABLE23A

ENABLE24A

R3

10k

3.3V

IPMB-A (×24)

IPMB-B (×24)

IPMB-B (×24)

IPMB-B

SDA24

SDA24

SDA1