Datasheet LTC4300A-1, LTC4300A-2 (Analog Devices) - 10
| Manufacturer | Analog Devices |
| Description | Hot Swappable 2-Wire Bus Buffers |
| Pages / Page | 16 / 10 — APPLICATIONS INFORMATION. Resistor Pull-Up Value Selection. Live … |
| File Format / Size | PDF / 186 Kb |
| Document Language | English |
APPLICATIONS INFORMATION. Resistor Pull-Up Value Selection. Live Insertion and Capacitance Buffering Application
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LTC4300A-1/LTC4300A-2
APPLICATIONS INFORMATION Resistor Pull-Up Value Selection
In addition, regardless of the bus capacitance, always choose R ≤ 16k for V The system pull-up resistors must be strong enough to CC = 5.5V maximum, R ≤ 24k for V provide a positive slew rate of 1.25V/μs on the SDA and CC = 3.6V maximum. The start-up circuitry requires logic high voltages on SDAOUT and SCLOUT to connect SCL pins, in order to activate the boost pull-up currents the backplane to the card, and these pull-up values are during rising edges. Choose maximum resistor value R needed to overcome the precharge voltage. using the formula: R ≤ (VCC(MIN) – 0.6) (800,000) / C
Live Insertion and Capacitance Buffering Application
where R is the pull-up resistor value in ohms, VCC(MIN) Figures 3 through 6 illustrate the usage of the LTC4300A is the minimum VCC voltage and C is the equivalent bus in applications that take advantage of both its hot swap capacitance in picofarads (pF). controlling and capacitance buffering features. In all of BACKPLANE CONNECTOR BACKPLANE I/O PERIPHERAL CARD 1 POWER SUPPLY VCC HOT SWAP R3 C1 R1 R2 R4 R5 R6 10k 0.01μF 10k 10k CARD 10k 10k 10k ENABLE/DISABLE BD_SEL ENABLE VCC SDAOUT CARD_SDA U1 SDA SDAIN SCLOUT CARD_SCL LTC4300A-1 AGGERED CONNECTOR SCL SCLIN READY ST GND I/O PERIPHERAL CARD 2 POWER SUPPLY HOT SWAP R7 C3 R8 R9 R10 10k 0.01μF 10k 10k 10k CARD ENABLE/DISABLE ENABLE VCC SDAOUT CARD2_SDA U2 SDAIN SCLOUT CARD2_SCL LTC4300A-1 AGGERED CONNECTOR SCLIN READY GND ST ttt I/O PERIPHERAL CARD N POWER SUPPLY HOT SWAP R11 C5 R12 R13 R14 10k 0.01μF 10k 10k 10k CARD ENABLE/DISABLE ENABLE VCC SDAOUT CARDN_SDA U3 SDAIN SCLOUT CARDN_SCL LTC4300A-1 AGGERED CONNECTOR SCLIN READY GND ST 4300a12 F03
Figure 3. Inserting Multiple I/O Cards into a Live Backplane Using the LTC4300A-1 in a CompactPCI System
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APPLICATIONS INFORMATION Resistor Pull-Up Value Selection
In addition, regardless of the bus capacitance, always choose R ≤ 16k for V The system pull-up resistors must be strong enough to CC = 5.5V maximum, R ≤ 24k for V provide a positive slew rate of 1.25V/μs on the SDA and CC = 3.6V maximum. The start-up circuitry requires logic high voltages on SDAOUT and SCLOUT to connect SCL pins, in order to activate the boost pull-up currents the backplane to the card, and these pull-up values are during rising edges. Choose maximum resistor value R needed to overcome the precharge voltage. using the formula: R ≤ (VCC(MIN) – 0.6) (800,000) / C
Live Insertion and Capacitance Buffering Application
where R is the pull-up resistor value in ohms, VCC(MIN) Figures 3 through 6 illustrate the usage of the LTC4300A is the minimum VCC voltage and C is the equivalent bus in applications that take advantage of both its hot swap capacitance in picofarads (pF). controlling and capacitance buffering features. In all of BACKPLANE CONNECTOR BACKPLANE I/O PERIPHERAL CARD 1 POWER SUPPLY VCC HOT SWAP R3 C1 R1 R2 R4 R5 R6 10k 0.01μF 10k 10k CARD 10k 10k 10k ENABLE/DISABLE BD_SEL ENABLE VCC SDAOUT CARD_SDA U1 SDA SDAIN SCLOUT CARD_SCL LTC4300A-1 AGGERED CONNECTOR SCL SCLIN READY ST GND I/O PERIPHERAL CARD 2 POWER SUPPLY HOT SWAP R7 C3 R8 R9 R10 10k 0.01μF 10k 10k 10k CARD ENABLE/DISABLE ENABLE VCC SDAOUT CARD2_SDA U2 SDAIN SCLOUT CARD2_SCL LTC4300A-1 AGGERED CONNECTOR SCLIN READY GND ST ttt I/O PERIPHERAL CARD N POWER SUPPLY HOT SWAP R11 C5 R12 R13 R14 10k 0.01μF 10k 10k 10k CARD ENABLE/DISABLE ENABLE VCC SDAOUT CARDN_SDA U3 SDAIN SCLOUT CARDN_SCL LTC4300A-1 AGGERED CONNECTOR SCLIN READY GND ST 4300a12 F03
Figure 3. Inserting Multiple I/O Cards into a Live Backplane Using the LTC4300A-1 in a CompactPCI System
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