Two voltage supervisors constantly check the level of the voltages " />
參數(shù)資料
型號(hào)： 73S8024C-DB
廠商： Maxim Integrated Products
文件頁(yè)數(shù)： 21/22頁(yè)
文件大?。?/td> 0K
描述： BOARD DEMO 73S8024C 28-SOIC
產(chǎn)品培訓(xùn)模塊： Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
標(biāo)準(zhǔn)包裝： 1
系列： *
73S8024C Data Sheet
DS_8024C_023
8
Rev. 1.3
6
Voltage Supervision
Two voltage supervisors constantly check the level of the voltages VDD and VCC. A card deactivation
sequence is triggered upon a fault of any of 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 18 in the
SO package, pin 17 in the QFN package) 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) and 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
7
Power Down
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.
If the 2.3 V default threshold is used, this pin must be left unconnected.
A power down function is provided via the PWRDN pin (active high). When activated, the Power Down
(PD) mode disables all the internal analog functions, including the card analog interface, the oscillators
and the DC-DC converter, to put the 73S8024C in its lowest power consumption mode. PD mode is only
allowed in the deactivated condition (out of a card session, when the
CMDVCC signal is driven high from
the host controller).
The host controller invokes the power down state when it is desirable to save power. The signals PRES
and
PRES remain functional in PD mode such that a card insertion sets OFF high. The micro-controller
must then set PWRDN low and wait for the internal stabilization time prior to starting any card session
(prior to turning
CMDVCC low).
Resumption of the normal mode occurs at approximately 10 ms (stabilization of the internal oscillators
and reset of the circuitry) after PWRDN is set low. No card activation should be invoked during this 10 ms
time period. If a card is present,
OFF can be used as an indication that the circuit has completed its
recovery from the power down state.
OFF will go high at the end of the stabilization period. Should
CMDVCC go low during PWRDN = 1, or within the 10 ms internal stabilization / reset time, it will not be
taken into account and the card interface will remain inactive. Since
CMDVCC is taken into account on
its edges, it should be toggled high and low again after the 10 ms to activate a card.
Figure 2 illustrates the sequencing of the PD and Normal modes. PWRDN must be connected to GND if
the power down function is not used.
相關(guān)PDF資料
PDF描述
M3CWK-2018R IDC CABLE - MKC20K/MC20M/MPL20K
M3AWK-2018R IDC CABLE - MSC20K/MC20M/MPL20K
73S8014RN-DB BOARD DEMO 73S8010RN 20-SOIC
73S8014R-DB BOARD DEMO 73S8010R 20-SOIC
73S8024RN-DB BOARD DEMO 73S8024RN 28-SOIC
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
73S8024C-IL/F 功能描述:I2C 接口集成電路 Smart Card Interface ISO7816-3 & EVM4.0 RoHS:否 制造商:NXP Semiconductors 電源電壓-最大:5.5 V 電源電壓-最小:2.3 V 最大工作頻率:400 KHz 最大工作溫度:+ 85 C 封裝 / 箱體:TSSOP-16
73S8024C-ILR/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(chǎn)品: 輸入/輸出端數(shù)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(fēng)格:SMD/SMT 封裝 / 箱體:QFN-64 封裝:Tray
73S8024RN 制造商:TERIDIAN 制造商全稱:TERIDIAN 功能描述:Low Cost Smart Card Interface
73S8024RN-20IM/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(chǎn)品: 輸入/輸出端數(shù)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(fēng)格:SMD/SMT 封裝 / 箱體:QFN-64 封裝:Tray
73S8024RN-20IM/F1 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(chǎn)品: 輸入/輸出端數(shù)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(fēng)格:SMD/SMT 封裝 / 箱體:QFN-64 封裝:Tray
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*