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參數(shù)資料
| 型號(hào)： | DS2482-800 |
| 英文描述： | Eight-Channel 1-Wire Master |
| 中文描述： | 八通道1-Wire主控制器 |
| 文件頁數(shù)： | 7/22頁 |
| 文件大?。?/td> | 261K |
| 代理商： | DS2482-800 |
DS2482-800: Eight-Channel 1-Wire Master
7 of 22
Presence Pulse Masking (PPM)
The PPM bit controls whether the DS2482 will mask the leading edge (falling) of presence pulses. When PPM = 0,
masking is disabled. Presence pulse masking applies only to standard 1-Wire speed (1WS = 0); this bit has no
function if 1WS = 1 (Overdrive speed). Presence pulse masking can improve the performance of large 1-Wire
networks since it prevents the fast falling edge of a presence pulse generated by a 1-Wire slave device from
propagating through the network and getting reflected. Reflections can cause glitches in the network that in turn
may cause slave devices to lose synchronization with the 1-Wire master.
Figure 3 shows the timing references for the PPM. If enabled (PPM = 1), the DS2482 begins pulling the 1-Wire line
low at t
PPM1
after the reset low time t
RSTL
is expired. The pulldown ends at t
PPM2
, at which a 1-Wire slave, if present,
will be pulling the 1-Wire line low. The falling edge of the presence pulse mask is slew rate controlled.
Figure 3. Presence Pulse Masking
Pull-up
DS2482 Pull-down
1-W Slave Pull-down
DS2482 pull-down with PPM = 1; Standard speed only
t
RSTL
t
RSTH
RESET PULSE
PRESENCE PULSE
V
CC
0V
t
PPM1
t
PPM2
APU con-
trolled edge
Resistive
pull-up
Strong Pullup (SPU)
The SPU bit controls whether the DS2482 applies a low-impedance pullup to V
CC
on the 1-Wire line after the last
bit of either a
1-Wire Write Byte
command or after a
1-Wire Single Bit
command has completed. The strong
pullup feature is commonly used with 1-Wire EEPROM devices when copying scratchpad data to the main memory
or when performing a SHA-1 computation, and with parasitically powered temperature sensors or A-to-D
converters. The respective device data sheets specify the location in the communications protocol after which the
strong pullup should be applied. The SPU bit in the configuration register of the DS2482 must be set immediately
prior to issuing the command that puts the 1-Wire device into the state where it needs the extra power.
If SPU is 1, the DS2482 applies
active pullup
to the rising edge of the time slot in which the strong pullup starts,
regardless of the APU bit setting. However, in contrast to setting APU = 1 for active pullup, the low-impedance
pullup will not end after t
APUOT
is expired. Instead, as shown in Figure 4, the low-impedance pullup remains active
until: a) the next 1-Wire communication command (the typical case), b) by writing to the Configuration Register with
the SPU bit being 0 (alternative), or c) by issuing the Device Reset command. Additionally, when the pullup ends,
the SPU bit is automatically reset to 0. Using the strong pullup does not change the state of the APU bit in the
Configuration Register.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS2482-100 | Single-Channel 1-Wire Master |
| DS2482S-100 | Single-Channel 1-Wire Master |
| DS2482S-800 | Eight-Channel 1-Wire Master |
| DS2502-E48 | 48-Bit Node Address Chip |
| DS26401 | Ultraframer DS3/E3/DS2/E2/DS1/E1/DS0 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS2482-800_12 | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:8-Channel 1-Wire Master |
| DS2482S-100 | 功能描述:接口 - 專用 RoHS:否 制造商:Texas Instruments 產(chǎn)品類型:1080p60 Image Sensor Receiver 工作電源電壓:1.8 V 電源電流:89 mA 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:BGA-59 |
| DS2482S-100/R | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:Single-Channel 1-Wire Master |
| DS2482S-100/T | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:Single-Channel 1-Wire Master |
| DS2482S-100/T&R | 功能描述:接口 - 專用 RoHS:否 制造商:Texas Instruments 產(chǎn)品類型:1080p60 Image Sensor Receiver 工作電源電壓:1.8 V 電源電流:89 mA 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:BGA-59 |
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