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参数资料
| 型号： | LTC1756EGN |
| 厂商： | Linear Technology |
| 文件页数： | 3/16页 |
| 文件大小： | 0K |
| 描述： | IC SMART CARD 16-SSOP |
| 标准包装： | 100 |
| 应用： | 智能卡 |
| 电源电压： | 2.7 V ~ 6 V |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SSOP |
| 包装： | 管件 |
| 安装类型： | 表面贴装 |
| 其它名称： | Q1274157 |
11
LTC1755/LTC1756
10kV ESD Protection
All Smart Card pins (CLK, RST, I/O, AUX1, AUX2, VCC and
GND) can withstand over 10kV of human body model ESD
in situ. In order to ensure proper ESD protection, careful
board layout is required. The GND pin should be tied
directly to a ground plane. The VCC capacitor should be
located very close to the VCC pin and tied immediately to
the ground plane.
Capacitor Selection
The style and value of capacitors used with the LTC1755/
LTC1756 determine several parameters such as output
ripple voltage, charge pump strength, Smart Card switch
debounce time and VCC discharge rate.
Due to the switching nature of a capacitive charge pump,
low equivalent series resistance (ESR) capacitors are
recommended for the capacitors at VIN and VCC. When-
ever the flying capacitor is switched to the VCC charge
storage capacitor, considerable current flows. The prod-
uct of this high current and the ESR of the output capacitor
can generate substantial voltage spikes on the VCC output.
These spikes may cause problems with the Smart Card or
may interfere with the regulation loop of the LTC1755/
LTC1756. Therefore, ceramic or tantalum capacitors are
recommended rather than higher ESR aluminum capaci-
tors. Between ceramic and tantalum, ceramic capacitors
generally have the lowest ESR. Some manufacturers have
developed low ESR tantalum capacitors but they can be
expensive and may still have higher ESR than ceramic
types. Thus, while they cannot be avoided, ESR spikes will
typically be lowest when using ceramic capacitors.
For ceramic capacitors there are several different materi-
als available to choose from. The choice of ceramic
material is generally based on factors such as available
capacitance, case size, voltage rating, electrical perfor-
mance and cost. For example, capacitors made of Y5V
material have high packing density, which provides high
capacitance for a given case size. However, Y5V capaci-
tors tend to lose considerable capacitance over the – 40
°C
to 85
°C temperature range. X7R ceramic capacitors are
more stable over temperature but don’t provide the high
packing density. Therefore, large capacitance values are
generally not available in X7R ceramic.
The value and style of the flying capacitor are important
not only for the charge pump but also because they
provide the large debounce time for the Smart Card
detection channel. A 0.68
F X7R capacitor is a good
choice for the flying capacitor because it provides fairly
constant capacitance over temperature and its value is not
prohibitively large.
The charge storage capacitor on the VCC pin determines
the ripple voltage magnitude and the discharge time of the
Smart Card voltage. To minimize ripple, generally, a large
value is needed. However, to meet the VCC discharge rate
specification, the value should not exceed 20
F. A 10F
capacitor can be used but the ripple magnitude will be
higher leading to worse apparent DC load regulation.
Typically a 15
F to 18F Y5V ceramic capacitor is the best
choice for the VCC charge storage capacitor. For best
performance, this capacitor should be connected as close
as possible to the VCC and GND pins. Note that most of the
electrostatic discharge (ESD) current on the Smart Card
pins is absorbed by this capacitor.
The bypass capacitor at VIN is also important. Large dips
on the input supply due to ESR may cause problems with
the internal circuitry of the LTC1755/LTC1756. A good
choice for the input bypass capacitor is a 10
F Y5V style
ceramic
Dynamic Pull-Up Current Sources
The current sources on the bidirectional pins (DATA,
AUX2IN, AUX1IN, I/O, AUX2 and AUX1) are dynamically
activated to achieve a fast rise time with a relatively small
static current (Figure 1). Once a bidirectional pin is relin-
quished, a small start-up current begins to charge the
node. An edge rate detector determines if the pin is
Figure 1. Dynamic Pull-Up Current Sources
–
+
δV
δt
ISTART
17556 F01
VREF
BIDIRECTIONAL PIN
VCC OR DVCC
APPLICATIO S I FOR ATIO
WU
UU
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| LTC1756EGN#PBF | 功能描述:IC SMART CARD INTERFACE 16SSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 专用 系列:- 特色产品:NXP - I2C Interface 标准包装:1 系列:- 应用:2 通道 I²C 多路复用器 接口:I²C，SM 总线 电源电压:2.3 V ~ 5.5 V 封装/外壳:16-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:16-TSSOP 包装:剪切带 (CT) 安装类型:表面贴装 产品目录页面:825 (CN2011-ZH PDF) 其它名称:568-1854-1 |
| LTC1756EGN#TR | 功能描述:IC SMART CARD INTERFACE 16SSOP RoHS:否 类别:集成电路 (IC) >> 接口 - 专用 系列:- 特色产品:NXP - I2C Interface 标准包装:1 系列:- 应用:2 通道 I²C 多路复用器 接口:I²C，SM 总线 电源电压:2.3 V ~ 5.5 V 封装/外壳:16-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:16-TSSOP 包装:剪切带 (CT) 安装类型:表面贴装 产品目录页面:825 (CN2011-ZH PDF) 其它名称:568-1854-1 |
| LTC1756EGN#TRPBF | 功能描述:IC SMART CARD INTERFACE 16SSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 专用 系列:- 特色产品:NXP - I2C Interface 标准包装:1 系列:- 应用:2 通道 I²C 多路复用器 接口:I²C，SM 总线 电源电压:2.3 V ~ 5.5 V 封装/外壳:16-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:16-TSSOP 包装:剪切带 (CT) 安装类型:表面贴装 产品目录页面:825 (CN2011-ZH PDF) 其它名称:568-1854-1 |
| LTC1757A-1EMS8 | 功能描述:IC CTRLR RF POWER SINGLE 8MSOP RoHS:否 类别:RF/IF 和 RFID >> RF 电源控制器 IC 系列:- 标准包装:3,000 系列:- RF 型:GSM 频率:450MHz ~ 2GHz 特点:四频带 封装/外壳:8-VFBGA 供应商设备封装:8-MicroSMD（1.51x1.51） 包装:带卷 (TR) 其它名称:LMV243BLX |
| LTC1757A-1EMS8#PBF | 功能描述:IC CTRLR RF POWER SINGLE 8MSOP RoHS:是 类别:RF/IF 和 RFID >> RF 电源控制器 IC 系列:- 标准包装:3,000 系列:- RF 型:GSM 频率:450MHz ~ 2GHz 特点:四频带 封装/外壳:8-VFBGA 供应商设备封装:8-MicroSMD（1.51x1.51） 包装:带卷 (TR) 其它名称:LMV243BLX |
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