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| EP9301-CQZ资料 | |
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EP9301-CQZ PDF Download |
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File Size : 116 KB
Manufacturer:CIRR Description:The next concern is getting the input signal to the part and the output signal to the measurement system. As stated before, the Philips Semiconductors jig is laid out for a 50Ω characteristic impedance. We recommend that the user maintain a 50Ω environment for the input signal as close as possible to the input pin and then terminate in 50Ω. On our jig, we terminate with a 50Ω chip resistor. The signal is brought on board through an SMB connector to the 50Ω trace on the top side of the board. The signal is terminated by the chip resistor, R3, see Figure 2a and 2b. the signal proceeds to the DUT pin, a distance of about 0.5 inches, through Jumper 1 (in the Input Only position), and the rest of the trace. The same pin on the opposite side of the board has a 450Ω chip resistor soldered to it. The other side of this resistor, R1, is soldered to a 50Ω trace on the bottom side of the board that runs to an SMB connector on the edge of the jig. This connects to the 50Ω input of the Sampling Oscilloscope. This 450Ω resistor in series with the 50Ω input of the scope creates a 10X divided 500Ω probe for the scope and provides impedance matching for the scope. See Figure 2b. This circuit also doubles as the resistive portion of the FAST AC Output Load and thereby allows the output to be sensed in the same fashion. When the input is not used for a signal or generator input, the line may be switched to one of three voltage sources, VS1 C VS3, by use of a DIP switch on each pin. It may also be left open and the 50Ω pull-down resistor that is used for an input terminator pulls the line to ground and can be used as a hard low level. See Figure 2b. This scheme eliminates excessive cabling to each input to provide static input levels and thereby reduces parasitic inductances and cross-talk. It also eliminates the need for bulky and sometimes unreliable high impedance probes by using the 50Ω input of the Sampling Scope. With the designed-in flexibility of Jumper 1 and Jumper 2, and the selectable nature of VCC and Ground pin designations, one can configure this board for any VCC and Ground pin designations, select which pins are outputs or inputs and even provide the proper pull-up for 3-State outputs. This makes the board entirely universal for designated VCC/Ground configurations. To explain this, the output of the device is connected to its capacitive load by Jumper 1 in the Output Only position. This means that no pin can be both output and input at the same time, but can be either. Jumper 2 allows an output to be connected to the 3-State pull-up resistor, R2, and have that connected to the needed 7V. See Figure 2a and 2b. The scope is connected in the same way as the input, with the 450Ω resistor and the 50Ω of the scope comprising the 500Ω needed for the FAST load. One other consideration exists. In small part quantity testing, the elimination of a socket is very desirable, using inserted pins that are flush with the jig. In larger quantity testing, sockets may be needed, however. If this is the case, some degradation in the performance will occur due to the increased lead inductance for each pin, which is observable, and the addition of group delay through the socket may alter or affect the readings obtained. |
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| 1PCS | 100PCS | 1K | 10K | ||
| 价 格 | |||||
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型 号：EP9301-CQZ 厂 家：CIRR 封 装： 批 号：0635 数 量：5 说 明：Bid Price |
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运 费： 所在地： 新旧程度： |
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| 联系人：刘先生，罗小姐，刘小姐，刘先生，王先生 |
| 电 话：0086-755-83576094,83576097,83576087,83576084,83979425 |
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