Analog Devices Inc./Maxim Integrated

The LTC4300 series hot swappable 2-wire bus buffers allow I/O card insertion into a live backplane without corruption of the data and clock busses. When the connection is made, the LTC4300-1/LTC4300-2 provide bidirectional buffering, keeping the backplane and card capacitances isolated. Rise-time accelerator circuitry* allows the use of weaker DC pull-up currents while still meeting rise-time requirements. During insertion, the SDA and SCL lines are precharged to 1V to minimize bus disturbances.The LTC4300-1 incorporates a CMOS threshold digital ENABLE input pin, which forces the part into a low current mode when driven to ground and sets normal operation when driven to VCC. It also includes an open drain READY output pin, which indicates that the backplane and card sides are connected together. The LTC4300-2 replaces the ENABLE pin with a dedicated supply voltage pin, VCC2, for the card side, providing level shifting between 3.3V and 5V systems. Both the backplane and card may be powered with supply voltages ranging from 2.7V to 5.5V, with no contraints on which supply voltage is higher. The LTC4300-2 also replaces the READY pin with a digital CMOS input pin, ACC, which enables and disables the rise-time accelerator currents.The LTC4300 is available in a small 8-pin MSOP package.*U.S. Patent No. 6,650,174ApplicationsHot Board InsertionServersCapacitance Buffer/Bus ExtenderDesktop Computer

The LTC4300A series hot swappable 2-wire bus buffers allow I/O card insertion into a live backplane without corruption of the data and clock busses. When the connection is made, the LTC4300A-1/LTC4300A-2 provide bidirectional buffering, keeping the backplane and card capacitances isolated. Rise-time accelerator circuitry* allows the use of weaker DC pull-up currents while still meeting rise-time requirements. During insertion, the SDA and SCL lines are precharged to 1V to minimize bus disturbances.The LTC4300A-1 incorporates a CMOS threshold digital ENABLE input pin, which forces the part into a low current mode when driven to ground and sets normal operation when driven to VCC. It also includes an open drain READY output pin, which indicates that the backplane and card sides are connected together. The LTC4300A-2 replaces the ENABLE pin with a dedicated supply voltage pin, VCC2, for the card side, providing level shifting between 3.3V and 5V systems. Both the backplane and card may be powered with supply voltages ranging from 2.7V to 5.5V, with no contraints on which supply voltage is higher. The LTC4300A-2 also replaces the READY pin with a digital CMOS input pin, ACC, which enables and disables the rise-time accelerator currents.The LTC4300A is available in a small 8-pin MSOP package.ApplicationsHot Board InsertionServersCapacitance Buffer/Bus ExtenderDesktop Computer

The LTC4300A series hot swappable 2-wire bus buffers allow I/O card insertion into a live backplane without corruption of the data and clock busses. When the connection is made, the LTC4300A-1/LTC4300A-2 provide bidirectional buffering, keeping the backplane and card capacitances isolated. Rise-time accelerator circuitry* allows the use of weaker DC pull-up currents while still meeting rise-time requirements. During insertion, the SDA and SCL lines are precharged to 1V to minimize bus disturbances.The LTC4300A-1 incorporates a CMOS threshold digital ENABLE input pin, which forces the part into a low current mode when driven to ground and sets normal operation when driven to VCC. It also includes an open drain READY output pin, which indicates that the backplane and card sides are connected together. The LTC4300A-2 replaces the ENABLE pin with a dedicated supply voltage pin, VCC2, for the card side, providing level shifting between 3.3V and 5V systems. Both the backplane and card may be powered with supply voltages ranging from 2.7V to 5.5V, with no contraints on which supply voltage is higher. The LTC4300A-2 also replaces the READY pin with a digital CMOS input pin, ACC, which enables and disables the rise-time accelerator currents.The LTC4300A is available in a small 8-pin MSOP package.ApplicationsHot Board InsertionServersCapacitance Buffer/Bus ExtenderDesktop Computer

The LTC4300A-3 hot swappable 2-wire bus buffer allows I/O card insertion into a live backplane without corruption of the data and clock busses. When the connection is made, the LTC4300A-3 provides bidirectional buffering, keeping the backplane and card capacitances isolated. Rise-time accelerator circuitry allows the use of weaker DC pull-up currents while still meeting rise-time requirements. During insertion, the SDA and SCL lines are precharged to 1V to minimize bus disturbances.The LTC4300A-3 provides level translation between 3.3V and 5V supplies. The backplane and card can both be powered with supplies ranging from 2.7V to 5.5V. The LTC4300A-3 also incorporates a CMOS threshold ENABLE pin which forces the part into a low current mode and isolates the card from the backplane. When driven to VCC, the ENABLE pin sets normal operation.The LTC4300A-3 is available in the MSOP and 3mm × 3mm DFN packages.*Patent pending.ApplicationsHot Board InsertionServersCapacitance Buffer/Bus ExtenderDesktop Computer

The LTC4301L hot swappable, 2-wire bus buffer allows I/O card insertion into a live backplane without corruption of the data and clock busses. In addition, the LTC4301L SDAIN and SCLIN pins are compatible with systems with pull-up voltages as low as 1V. Control circuitry prevents the backplane from being connected to the card until a stop bit or a bus idle is present. When the connection is made, the LTC4301L provides bidirectional buffering, keeping the backplane and card capacitances isolated.When driven low, the CS input pin allows the part to connect after a stop bit or bus idle occurs. Driving CS high breaks the connection between SCLIN and SCLOUT and between SDAIN and SDAOUT. A logic high on READY indicates that the backplane and card sides are connected together.The LTC4301L is offered in 8-pin DFN (3mm x 3mm) and MSOP packages.ApplicationsHot Board InsertionServersCapacitance Buffer/Bus ExtenderDesktop Computers

The LTC4303 hot swappable 2-wire Bus Buffer allows I/O card insertion into a live backplane without corruption of the data and clock busses. When a connection is made, the LTC4303 provides bidirectional buffering, keeping the backplane and card capacitances isolated. If SDAOUT or SCLOUT is low for ≥ 30ms (typ), the LTC4303 automatically breaks the data and clock bus connection. At this time the LTC4303 automatically generates up to 16 clock pulses on SCLOUT in an attempt to free the bus. A connection will be enabled automatically when the bus becomes free.Rise-time accelerator circuitry allows the use of larger pull-up resistors while still meeting rise-time requirements. During insertion, the SDA and SCL lines are precharged to 1V to minimize bus disturbances. When driven high, ENABLE allows the LTC4303 to connect after a stop bit or bus idle occurs. Driving ENABLE low breaks the connection between SDAIN and SDAOUT, SCLIN and SCLOUT. READY is an open drain output that indicates when the backplane and card sides are connected together.ApplicationsHot Board InsertionServersCapacitance Buffer/Bus ExtenderRAID Systems

The LTC4305 is a 2-channel, 2-wire bus multiplexer with bus buffers to provide capacitive isolation between the upstream bus and downstream buses. Through software control, the LTC4305 connects the upstream 2-wire bus to any desired combination of downstream channels. Each channel can be pulled up to a supply voltage ranging from 2.2V to 5.5V, independent of the LTC4305 supply voltage. The downstream channels are also provided with anALERT1-ALERT2inputs for fault reporting.Programmable timeout circuitry disconnects the downstream buses if the bus is stuck low. When activated, rise time accelerators source currents into the 2-wire bus pins to reduce rise time. Driving the ENABLE pin low restores all features to their default states. Three address pins provide 27 distinct addresses.The LTC4305 is available in 16-lead (4mm × 5mm) DFN and SSOP packages.ApplicationsNested Addressing5V/3.3V Level TranslatorCapacitance Buffer/Bus Extender