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参数资料
| 型号： | LTC4309CDE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 11/16页 |
| 文件大小： | 200K |
| 描述： | IC BUS BUFFER 2-WIRE 12-DFN |
| 产品培训模块： | LTC4310 - Hot-Swappable I²C Isolators |
| 标准包装： | 2,500 |
| 类型： | 热交换开关 |
| 应用： | 通用型缓冲器/总线扩展器 |
| 内部开关： | 是 |
| 电源电压： | 2.3 V ~ 5.5 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 12-WFDFN 裸露焊盘 |
| 供应商设备封装： | 12-DFN（4x3） |
| 包装： | 带卷 (TR) |
LTC4309
11
4309fa
If the rise time accelerators are enabled, the bus pull-up
supply can be greater than or equal to V
CC
for the output
busses and accordingly, the input pull-up supply can
be greater than or equal to V
CC2
for the input busses.
This ensures the LTC4309s rise time accelerators do
not source current through the pull-up resistors into the
pull-up supply. If the rise time accelerator circuitries are
disabled, the bus pull-up supply can be as low as 2V for
V
CC
e 2.9V and for V
CC
< 2.9V , the bus pull-up supply can
be as low as 1.7V . The bound on the lower supply limit
exists to ensure the bus signal range exceeds the logic
input threshold voltage, V
THR
.
Resistor Pull-Up Value Selection
To guarantee the rise time accelerators are activated during
a rising edge, the bus must rise on its own with a positive
slew rate of at least 0.8V/約. To achieve this, choose a
maximum resistor value R
PULLUP
using the formula:
R
PULLUP
(V
BUS(MIN)
0.8V)"1250
ns
V
C
BU
S
Where R
PULLUP
is the pull-up resistor value in kilo ohms,
V
BUS(MIN)
is the minimum bus pull-up supply voltage and
C
BUS
is the equivalent bus capacitance in pico-Farads
(pF).
To estimate the value of C
BUS
, use a general rule of 20pF
of capacitance per device on the bus (10pF for the device
and 10pF for interconnect).
In addition, R
PULLUP
must be strong enough to overcome
the precharge voltage and provide logic highs on SDAOUT
and SCLOUT for the start-up and connection circuitry to
connect the backplane to the card. Regardless of the bus
capacitance, always choose
R
PULLUP
V
BUS(MAX)
V
THR
100?/DIV>
A
to the pull-up impedance, multiple LTC4309 buffers can
be used in a single system. This allows the user to divide
the line and device capacitances into more sections with
buffering and meet rise and fall times.
The LTC4309 disconnects when both bus I/Os are above
0.48V and rising. In systems with large ground bounce,
if many devices are cascaded, the 0.48V threshold can be
exceeded, and the transients associated with the ground
bounce can appear to be a rising edge. Under this condition,
the LTC4309 with inputs above 0.48V may disconnect.
Level Shifting Applications
Systems requiring different supply voltages for the
backplane side and the card side can use the LTC4309
for bidirectional level shifting, as shown in Figure 6. The
LTC4309 can level shift between bus pull-up supplies as
low as 1.7V , with the accelerators disabled, to as high as
5.5V . Level shifting allows newer designs that require low
voltage supplies, such as EEPROMs and microcontrollers,
the capability to interface with legacy backplanes which
may be operating at higher supply voltages.
Systems with Supply Voltage Droop
In large 2-wire systems, the supply voltages seen by devices
at various points in the system can differ by a few hundred
millivolts or more. For proper operation, make sure that
the V
CC2(LTC4309)
is e 1.8V , and V
CC(LTC4309)
e 2.3V .
Additional Pull-Up Supply Options
In typical applications, a pull-up resistor connected from
the LTC4309s bus output pins to V
CC
and bus input pins
to V
CC2
or V
CC
, if V
CC2
is grounded, is suf cient. However,
for unique applications, additional exibility is available for
bus pull-up supplies other than V
CC
or V
CC2
. One example
is shown in Figure 8. The expanded bus pull-up range is
dependent on the user con guration of the rise time ac-
celerators and the supply voltage, V
CC
.
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| LTC4309CGN#PBF | 功能描述:IC BUS BUFFER 2-WIRE 16-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:119 系列:- 类型:热交换控制器 应用:通用型，PCI Express? 内部开关:无 电流限制:- 电源电压:3.3V，12V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:80-TQFP 供应商设备封装:80-TQFP（12x12） 包装:托盘 产品目录页面:1423 (CN2011-ZH PDF) |
| LTC4309CGN#TRPBF | 功能描述:IC BUS BUFFER 2-WIRE 16-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 标准包装:50 系列:- 类型:热交换控制器 应用:-48V 远程电力系统，AdvancedTCA ? 系统，高可用性 内部开关:无 电流限制:可调 电源电压:11.5 V ~ 14.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:10-TFSOP，10-MSOP（0.118"，3.00mm 宽） 供应商设备封装:10-MSOP 包装:管件 |
| LTC4309IDE#PBF | 功能描述:IC BUS BUFFER 2-WIRE 12-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
| LTC4309IDE#TRPBF | 功能描述:IC BUS BUFFER 2-WIRE 12-DFN RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
| LTC4309IGN#PBF | 功能描述:IC BUS BUFFER 2-WIRE 16-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 热交换 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:100 系列:- 类型:热插拔开关 应用:通用 内部开关:是 电流限制:可调 电源电压:9 V ~ 13.2 V 工作温度:-40°C ~ 150°C 安装类型:表面贴装 封装/外壳:10-WFDFN 裸露焊盘 供应商设备封装:10-TDFN-EP（3x3） 包装:管件 |
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