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参数资料
| 型号： | DS1922E-F5# |
| 厂商： | Maxim Integrated |
| 文件页数： | 35/44页 |
| 文件大小： | 0K |
| 描述： | IBUTTON TEMP LOGGER 4KBit F5 |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| RoHS指令信息： | IButton RoHS Compliance Plan |
| 标准包装： | 5 |
| 系列： | iButton® |
| 存储容量： | 512B |
| 存储器类型： | NVSRAM（非易失 SRAM） |
| 产品目录页面： | 1431 (CN2011-ZH PDF) |
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DS1922E
iButton High-Temperature Logger with
8KB Data-Log Memory
Master-to-Slave
For a write-one time slot, the voltage on the data line
must have crossed the V TH threshold before the write-one
low time t W1LMAX is expired. For a write-zero time slot,
the voltage on the data line must stay below the V TH
threshold until the write-zero low time t W0LMIN is expired.
The voltage on the data line should not exceed V ILMAX
during the entire t W0L or t W1L window. After the V TH
threshold has been crossed, the DS1922E needs a
recovery time t REC before it is ready for the next time slot.
Slave-to-Master
A read-data time slot begins like a write-one time slot.
The voltage on the data line must remain below V TL
until the read low time t RL is expired. During the t RL
window, when responding with a 0, the DS1922E starts
pulling the data line low; its internal timing generator
determines when this pulldown ends and the voltage
starts rising again. When responding with a 1, the
DS1922E does not hold the data line low at all, and the
voltage starts rising as soon as t RL is over.
The sum of t RL + δ (rise time) on one side and the inter-
nal timing generator of the DS1922E on the other side
define the master sampling window (t MSRMIN to
t MSRMAX ) in which the master must perform a read from
the data line. For most reliable communication, t RL
should be as short as permissible and the master
should read close to but no later than t MSRMAX . After
reading from the data line, the master must wait until
t SLOT is expired. This guarantees sufficient recovery
time t REC for the DS1922E to get ready for the next time
slot. Note that t REC specified herein applies only to a
single DS1922E attached to a 1-Wire line. For multiple
device configurations, t REC must be extended to
accommodate the additional 1-Wire device input
capacitance. Alternatively, an interface that performs
active pullup during the 1-Wire recovery time such as
the DS2482-x00 or DS2480B 1-Wire line drivers can be
used.
Improved Network Behavior
(Switchpoint Hysteresis)
In a 1-Wire environment line termination is possible only
during transients controlled by the bus master (1-Wire
driver). 1-Wire networks, therefore, are susceptible to
noise of various origins. Depending on the physical
size and topology of the network, reflections from end
Maxim Integrated
points and branch points can add up or cancel each
other to some extent. Such reflections are visible as
glitches or ringing on the 1-Wire communication line.
Noise coupled onto the 1-Wire line from external
sources can also result in signal glitching. A glitch dur-
ing the rising edge of a time slot can cause a slave
device to lose synchronization with the master and, as
a consequence, result in a Search ROM command
coming to a dead end or cause a device-specific func-
tion command to abort. For better performance in net-
work applications, the DS1922E uses a new 1-Wire
front-end, which makes it less sensitive to noise and
also reduces the magnitude of noise injected by the
slave device itself.
The DS1922E’s 1-Wire front-end differs from traditional
slave devices in four characteristics:
1) The falling edge of the presence pulse has a con-
trolled slew rate. This provides a better match to the
line impedance than a digitally switched transistor,
converting the high-frequency ringing known from
traditional devices into a smoother low-bandwidth
transition. The slew-rate control is specified by the
parameter t FPD , which has different values for stan-
dard and overdrive speed.
2) There is additional lowpass filtering in the circuit that
detects the falling edge at the beginning of a time
slot. This reduces the sensitivity to high-frequency
noise. This additional filtering does not apply at
overdrive speed.
3) There is a hysteresis at the low-to-high switching
threshold V TH . If a negative glitch crosses V TH but
does not go below V TH - V HY , it is not recognized
(Figure 14, Case A). The hysteresis is effective at
any 1-Wire speed.
4) There is a time window specified by the rising edge
hold-off time t REH during which glitches are ignored,
even if they extend below V TH - V HY threshold
(Figure 14, Case B, t GL < t REH ). Deep voltage
droops or glitches that appear late after crossing the
V TH threshold and extend beyond the t REH window
cannot be filtered out and are taken as the begin-
ning of a new time slot (Figure 14, Case C, t GL ≥
t REH ).
Devices that have the parameters t FPD , V HY , and t REH
specified in their electrical characteristics use the
improved 1-Wire front-end.
35
相关PDF资料 |
PDF描述 |
|---|---|
| DS1922L-F5# | IBUTTON TEMP LOGGER |
| DS1923-F5# | IBUTTON TEMP/HUMIDITY LOGGER F5 |
| DS1961S-F3# | IBUTTON EEPROM 1KBit F3 |
| DS1963S-F5+ | IBUTTON MONETARY SHA-1 |
| DS1971-F3+ | IBUTTON EEPROM 256KBIT F3 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DS1922E-F5# | 功能描述:iButton Temp Logger Ibutton w/8Kb Datalog Mem RoHS:否 存储类型:SRAM 存储容量:512 B 组织: 工作电源电压:3 V to 5.25 V 接口类型:1-Wire 最大工作温度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封装 / 箱体:F5 MicroCan 制造商:Maxim Integrated |
| DS1922F-F5# | 功能描述:iButton DS1922 RoHS:否 存储类型:SRAM 存储容量:512 B 组织: 工作电源电压:3 V to 5.25 V 接口类型:1-Wire 最大工作温度:+ 85 C 尺寸:17.35 mm x 5.89 mm 封装 / 箱体:F5 MicroCan 制造商:Maxim Integrated |
| DS1922L | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:Temperature Logger iButton with 8KB Data-Log Memory |
| DS1922L_11 | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:Temperature Logger iButton with 8KB Data-Log Memory |
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