Datasheet LTC4301 (Analog Devices) - 9

ManufacturerAnalog Devices
DescriptionSupply Independent Hot Swappable 2-Wire Bus Buffer
Pages / Page12 / 9 — APPLICATIO S I FOR ATIO. Figure 5. Inserting Multiple I/O Cards into a …
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APPLICATIO S I FOR ATIO. Figure 5. Inserting Multiple I/O Cards into a Live Backplane Using the LTC4301 in a PCI System

APPLICATIO S I FOR ATIO Figure 5 Inserting Multiple I/O Cards into a Live Backplane Using the LTC4301 in a PCI System

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LTC4301
U U W U APPLICATIO S I FOR ATIO
BACKPLANE CONNECTOR BACKPLANE I/O PERIPHERAL CARD 1 VCC 0.01µF 0.1µF R4 R5 R6 10k 10k V 10k CC2 R1 R2 R3 CS VCC SDAOUT CARD_SDA 10k 10k 100k SDA SDAIN LTC4301 SCLOUT CARD_SCL SCL SCLIN READY GND I/O PERIPHERAL CARD 2 0.01µF R8 R9 R10 0.1µF 10k 10k 10k V R7 CC SDAOUT CARD2_SDA CS 100k SDAIN LTC4301 SCLOUT CARD2_SCL SCLIN READY GND 4301 F05 • • •
Figure 5. Inserting Multiple I/O Cards into a Live Backplane Using the LTC4301 in a PCI System
filter to prevent the LTC4301 from becoming activated system to meet rise- and fall-time requirements. In this until the transients associated with live insertion have situation, the differential ground voltage between the two settled. Connect the capacitor between VCC and CS, and systems may limit the allowed distance, because valid the resistor from CS to GND. logic low voltage with respect to the ground at one end of the system may violate the allowed VOL specification with
Repeater/Bus Extender Application
respect to the ground at the other end. In addition, the Users who wish to connect two 2-wire systems separated connection circuitry offset voltages of the back-to-back by a distance can do so by connecting two LTC4301s LTC4301s add together, directly contributing to the same back-to-back as shown in Figure 6. The I2C specification problem. allows for 400pF maximum bus capacitance, severely
Systems with Supply Voltage Droop
limiting the length of the bus. The SMBus specification places no restriction on bus capacitance, but the limited In large 2-wire systems, the VCC voltages seen by devices impedances of devices connected to the bus require at various points in the system can differ by a few hundred systems to remain small if rise- and fall-time specifica- millivolts or more. This situation is well modelled by a series tions are to be met. Using the LTC4301 allows the capaci- resistor in the VCC line as shown in Figure 7. For proper tance to be isolated into smaller sections, enabling the operation, make sure that the VCC(LTC4301) is ≥ 2.7V. 4301fb 9
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