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參數資料
| 型號： | 73S8023C-IMR |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 模擬信號調理 |
| 英文描述： | SPECIALTY ANALOG CIRCUIT, QCC32 |
| 封裝： | 5 X 5 MM, QFN-32 |
| 文件頁數： | 27/27頁 |
| 文件大?。?/td> | 389K |
| 代理商： | 73S8023C-IMR |
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DS_8023C_019
73S8023C Data Sheet
Rev. 1.5
9
5
Voltage Supervision
Two voltage supervisors constantly check the presence of the voltages VDD and VCC. A card deactivation
sequence is triggered upon a fault detected by these voltage supervisors.
The digital circuitry is powered by the power supply applied on the VDD pin. VDD also defines the voltage
range for the interface with the system controller. The VDD Voltage supervisor is also used to initialize the
ISO-7816-3 sequencer at power-on, and also to deactivate the card at power-off or upon a fault. The
voltage threshold of the VDD voltage supervisor is internally set by default to 2.3 V nominal. However, it
may be desirable, in some applications, to modify this threshold value. The pin VDDF_ADJ (pin 17) is
used to connect an external resistor REXT to ground to raise the VDD fault voltage to another value, VDDF.
The resistor value is defined as follows:
REXT = 180 k
Ω /(V
DDF
An alternative (more accurate) method of adjusting the V
- 2.33)
DD
fault voltage is to use a resistive network of
R3 from the pin to supply and R1 from the pin to ground (see
). In order to set the new threshold voltage, the equivalent resistance must be determined.
This resistance value will be designated Kx. Kx is defined as R1/(R1+R3). Kx is calculated as:
Kx = (2.649 / VTH) - 0.6042 where VTH is the desired new threshold voltage.
To determine the values of R1 and R3, use the following formulas:
R3 = 72000 / Kx
R1 = R3*(Kx / (1 – Kx))
Taking the example above, where a VDD fault threshold voltage of 2.7 V is desired, solving for Kx gives:
Kx = (2.649 / 2.7) - 0.6042 = 0.377
Solving for R3 gives:
R3 = 72000 / 0.377 = 191 k
.
Solving for R1 gives:
R1 = 191000 *(0.377 / (1 – 0.377)) = 115.6 k
.
Using standard 1 % resistor values gives R3 = 191 k
and R1 = 115 k. These values give an
equivalent resistance of Kx = 0.376, a 0.3% error.
Using 1% external resistors and a parallel resistance of 72 k ohms will result in a +/- 6% tolerance in the
value of VDD Fault. The sources of variation due to integrated circuit process variations and mismatches
include the internal reference voltage (less than +/- 1%), the internal comparator hysteresis and offset
(less than +/- 1.7% for part-to-part, processing and environment), the internal resistor value mismatch and
value variations (less than 1.8%), and the external resistor values (1%).
If the 2.3 V default threshold is acceptable, this pin must be left unconnected.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| 73S8023C-IMR/F | 功能描述:輸入/輸出控制器接口集成電路 Smart Card Interface ISO7816-3 & EVM4.0 RoHS:否 制造商:Silicon Labs 產品: 輸入/輸出端數量: 工作電源電壓: 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:QFN-64 封裝:Tray |
| 73S8023C-IMR/F1 | 功能描述:輸入/輸出控制器接口集成電路 RoHS:否 制造商:Silicon Labs 產品: 輸入/輸出端數量: 工作電源電壓: 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:QFN-64 封裝:Tray |
| 73S8023C-IMR/F2 | 功能描述:輸入/輸出控制器接口集成電路 RoHS:否 制造商:Silicon Labs 產品: 輸入/輸出端數量: 工作電源電壓: 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:QFN-64 封裝:Tray |
| 73S8023C-IMR/F3 | 功能描述:輸入/輸出控制器接口集成電路 Smart Card Interface ISO7816-3 & EVM4.0 RoHS:否 制造商:Silicon Labs 產品: 輸入/輸出端數量: 工作電源電壓: 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:QFN-64 封裝:Tray |
| 73S8024C-DB | 功能描述:界面開發工具 73S8024C Demo Brd RoHS:否 制造商:Bourns 產品:Evaluation Boards 類型:RS-485 工具用于評估:ADM3485E 接口類型:RS-485 工作電源電壓:3.3 V |
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