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參數(shù)資料
| 型號： | SI3232DCX-EVB |
| 廠商： | Silicon Laboratories Inc |
| 文件頁數(shù)： | 76/128頁 |
| 文件大小： | 0K |
| 描述： | DAUGHTER CARD W/DISCRETE INTRFC |
| 標準包裝： | 1 |
| 系列： | ProSLIC® |
| 主要目的： | 接口，模擬前端（AFE） |
| 已用 IC / 零件： | Si3232 |
| 已供物品： | 板，CD |
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Si3232
Preliminary Rev. 0.96
51
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The pulldown resistor on the SDO pin is required to
allow this node to discharge after a logic high state to a
tri-state condition. The discharge occurs while SDO is
tri-stated during an 8 kHz transmission frame. The value
of the pulldown resistor depends on the capacitance
seen on the SDO pin. In the case of using a single
Si3232, the value of the pulldown resistor is 39 k
. This
assumes a 5 pF SDO pin capacitance and about a
15 pF load on the SDO pin. For applications using
multiple Si3232 devices or different capacitive loads on
the SDO pin, a different pulldown resistance needs to
be calculated.
The following design procedure is an example for
calculating the pulldown resistor on the SDO pin in a
system using eight Si3232 devices. A pullup resistor is
not allowed on the SDO pin.
1. The SDO node must discharge and remain discharged for
244 ns. The discharge occurs during the Hi-Z state;
therefore, the time to discharge is equal to the time in Hi-Z
time minus the 244 ns.
2. Allow five time constants for discharge where the
time constant, t = RC
3. SDO will be in Hi-Z while SDI is sending control and
address which are each 8 bits. Using the maximum
SCLK frequency of 16.13 MHz, the SDO will be in
Hi-Z for 16 / 16.13 MHz = 992 ns.
4. We want to discharge and remain discharged for
244 ns. Therefore, the discharge time is:
992 ns – 244 ns = 748 ns
5. To allow for some margin, let’s discharge in 85% of
this time. 748nS x 85% = 635.8 ns
6. Determine capacitive load on the SDO pin:
a.Allow 5 pF for each Si3220 SDO pin that
connected together.
b.Allow ~2 pF/inch (~0.8 pF/cm) for PCB trace.
c.Include the load capacitance of the host IC input.
7. For a system with eight Si3220 devices, the
capacitance seen on the SDO pin would be:
a.8 x 5 pF for each Si3220 = 40 pF
b.Assume 5 inch of PCB trace: 5inch x 2 pF/
inch = 10 pF
c.Host IC input of 5 pF
d.Total capacitance is 55 pF
8. Using the equation t = RC, allowing five time
constants to decay, and solving for R
a.R = t / 5C = 635.8 ns / (5 x 55 pF)
b.R = 2.3 k
So, R must be less than 2.3 k
to allow the node to
discharge.
Table 31. SPI Control Interface
7
BRDCST
Indicates a broadcast operation that is intended for all devices in the daisy chain. This is
only valid for write operations since it would cause contention on the SDO pin during a
read.
6R/W
Read/Write Bit.
0 = Write operation.
1 = Read operation.
5
REG/RAM Register/RAM Access.
0 = RAM access.
1 = Register access.
4
Reserved
3:0
CID[3:0]
This field indicates the channel that is targeted by the operation. The 4-bit channel value is
provided LSB first. The devices reside on the daisy chain such that device 0 is nearest to
the controller, and device 15 is furthest down the SDI/SDU_THRU chain. (See Figure 26.)
As the CID information propagates down the daisy chain, each channel decrements the
CID by 1. The SDI nodes between devices will reflect a decrement of 2 per device since
each device contains two channels. The device receiving a value of 0 in the CID field will
respond to the SPI transaction. (See Figure 27.) If a broadcast to all devices connected to
the chain is requested, the CID will not decrement. In this case, the same 8-bit or 16-bit
data is presented to all channels regardless of the CID values.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SI3232-FQ | 功能描述:電信線路管理 IC DUAL CH SLIC RoHS:否 制造商:STMicroelectronics 產(chǎn)品:PHY 接口類型:UART 電源電壓-最大:18 V 電源電壓-最小:8 V 電源電流:30 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray |
| SI3232-FQR | 制造商:Silicon Laboratories Inc 功能描述: |
| SI3232-G-FQ | 功能描述:電信線路管理 IC Dual-Channel SLIC RoHS:否 制造商:STMicroelectronics 產(chǎn)品:PHY 接口類型:UART 電源電壓-最大:18 V 電源電壓-最小:8 V 電源電流:30 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray |
| SI3232-G-FQR | 功能描述:電信線路管理 IC Dual-CH SLIC only Internal 65 Vrms RoHS:否 制造商:STMicroelectronics 產(chǎn)品:PHY 接口類型:UART 電源電壓-最大:18 V 電源電壓-最小:8 V 電源電流:30 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray |
| SI3232-G-GQ | 功能描述:電信線路管理 IC Dual-Channel SLIC RoHS:否 制造商:STMicroelectronics 產(chǎn)品:PHY 接口類型:UART 電源電壓-最大:18 V 電源電壓-最小:8 V 電源電流:30 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:VFQFPN-48 封裝:Tray |
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