- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄385505 > LTC1694 (Linear Technology Corporation) SMBus/I 2 C Accelerator(SMBus/I 2 C加速器) PDF資料下載
參數(shù)資料
| 型號： | LTC1694 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | SMBus/I 2 C Accelerator(SMBus/I 2 C加速器) |
| 中文描述： | 的SMBus /的I 2 C加速器（的SMBus /的I 2 C加速器） |
| 文件頁數(shù)： | 5/8頁 |
| 文件大?。?/td> | 149K |
| 代理商： | LTC1694 |
5
LTC1694
SMBus Overview
SMBus communication protocol employs open-drain
drivers with resistive or current source pull-ups. This
protocol allows multiple devices to drive and monitor the
bus without bus contention. The simplicity of resistive or
fixed current source pull-ups is offset by the slow rise
times they afford when bus capacitance is high. Rise
times can be improved by using lower pull-up resistor
values or higher fixed current source values, but the
additional current increases the low state bus voltage,
decreasing noise margins. Slow rise times can seriously
impact data reliability, enforcing a maximum practical
bus speed well below the established SMBus maximum
transmission rate.
Theory of Operation
The LTC1694 overcomes these limitations by using bilevel
hysteretic current sources as pull-ups. During positive
SMBus line transitions, the pull-up current sources typi-
cally provide 2.2mA to quickly slew any parasitic bus
capacitance. Therefore, rise time is dramatically improved,
especially with maximum SMBus loading conditions.
The LTC1694 has separate but identical circuitry for each
SMBus output pin. The circuitry consists of a positive edge
slew rate detector and a voltage comparator.
The LTC1694 nominally sources only 275
μ
A of pull-up
current to maintain good V
OL
noise margin. The 2.2mA
boosted pull-up current is only turned on if the voltage on
the SMBus line voltage is greater than the 0.65V compara-
tor threshold voltage and the positive slew rate of the
SMBus line is greater than the 0.2V/
μ
s threshold of the
slew rate detector. The boosted pull-up current remains on
until the voltage on the SMBus line is within 0.5V of V
CC
and/or the slew rate drops below 0.2V/
μ
s.
Auto Detect Standby Mode
The LTC1694 enters standby mode if the voltage on both
the SCL and SDA lines is high (idle state). In standby mode,
the pull-up currents drop to 100
μ
A, thereby lowering the
system power consumption.
Maximum R
S
Considerations
For ESD protection of the SMBus lines, a series resistor R
S
(Figure 2) is sometimes added to the open-drain driver of
the bus agents. This is especially common in SMBus-
controlled smart batteries. The maximum value of R
S
is
limited by the low state noise margin and timing require-
ments of the SMBus specification. The maximum value for
R
S
is 700
if resistive pull-ups or fixed value current
sources are used.
In general, an R
S
of 100
to 200
is sufficient for ESD
protection while meeting both the low state noise margin
and fall time requirement. If a larger value of R
S
is required,
take care to ensure that the low state noise margin and
timing requirement of the SMBus specification is not
violated. Also, the fall time of an SMBus line will also be
increased by using a high value series resistor.
APPLICATIOU
W
U
U
SDA
R
S
R
ON
1694 F02
DATA
IN
DATA
OUT
Figure 2
Low State Noise Margin
An acceptable V
OL
noise margin is easily achieved with the
low pull-up current (350
μ
A maximum) of the LTC1694.
The maximum value of R
S
is calculated from a desired low
state noise margin (NM
L
):
R
V
NM
I
R
S MAX
(
OL MAX
(
L
PU
MAX
(
ON MAX
(
)
)
)
)
=
LL-UP
(1)
V
OL(MAX)
:
The maximum V
OL
of the SMBus specifica-
tion is 0.4V
相關PDF資料 |
PDF描述 |
|---|---|
| LTC1695 | SMBus/I 2 C Fan Speed Controller in SOT-23(SMBus/I 2 C 風扇速度控制器（SOT-23封裝）) |
| LTC1699-80 | SMBus VID Voltage Programmers(SMBus 接口VID電壓編程器) |
| LTC1699-81 | SMBus VID Voltage Programmers(SMBus接口 VID電壓編程器) |
| LTC1699-82 | SMBus VID Voltage Programmers(SMBus 接口VID電壓編程器) |
| LTC1701 | Synchronous 8-Bit Up/Down Binary Counters 24-SOIC 0 to 70 |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1694-1CS5 | 制造商:Linear Technology 功能描述:SMBus/I2C Accelerator 5-Pin TSOT-23 |
| LTC1694-1CS5#PBF | 制造商:Linear Technology 功能描述:SMBus/I2C Accelerator 5-Pin TSOT-23 制造商:Linear Technology 功能描述:IC I2C / SMBUS ACCELERATOR 5 制造商:Linear Technology 功能描述:IC, I2C / SMBUS ACCELERATOR, 5SOT-23 |
| LTC1694-1CS5#TR | 功能描述:IC ACCEL SMBUS DUAL TSOT23-5 RoHS:否 類別:集成電路 (IC) >> 接口 - 專用 系列:- 特色產(chǎn)品:NXP - I2C Interface 標準包裝:1 系列:- 應用:2 通道 I²C 多路復用器 接口:I²C，SM 總線 電源電壓:2.3 V ~ 5.5 V 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:16-TSSOP 包裝:剪切帶 (CT) 安裝類型:表面貼裝 產(chǎn)品目錄頁面:825 (CN2011-ZH PDF) 其它名稱:568-1854-1 |
| LTC1694-1CS5#TRM | 功能描述:IC ACCEL SMBUS DUAL TSOT23-5 RoHS:否 類別:集成電路 (IC) >> 接口 - 專用 系列:- 特色產(chǎn)品:NXP - I2C Interface 標準包裝:1 系列:- 應用:2 通道 I²C 多路復用器 接口:I²C，SM 總線 電源電壓:2.3 V ~ 5.5 V 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:16-TSSOP 包裝:剪切帶 (CT) 安裝類型:表面貼裝 產(chǎn)品目錄頁面:825 (CN2011-ZH PDF) 其它名稱:568-1854-1 |
| LTC1694-1CS5#TRMPBF | 功能描述:IC ACCEL SMBUS DUAL TSOT23-5 RoHS:是 類別:集成電路 (IC) >> 接口 - 專用 系列:- 特色產(chǎn)品:NXP - I2C Interface 標準包裝:1 系列:- 應用:2 通道 I²C 多路復用器 接口:I²C，SM 總線 電源電壓:2.3 V ~ 5.5 V 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應商設備封裝:16-TSSOP 包裝:剪切帶 (CT) 安裝類型:表面貼裝 產(chǎn)品目錄頁面:825 (CN2011-ZH PDF) 其它名稱:568-1854-1 |
發(fā)布緊急采購，3分鐘左右您將得到回復。