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LeCroy DA1855A Operation

Other manuals for DA1855A: Overview

Summary of DA1855A

  • Page 1

    Operation da1855a-om-e rev a issued: july 2002 3-1 3 operation general information the da1855a has been designed to be used with oscilloscopes equipped with a probus interface. Connecting the differential amplifier to the oscilloscope through the probus interface will automatically control all the r...

  • Page 2

    Da1855a differential amplifier 3-2 issued: july 2002 da1855a-om-e rev a front panel input connectors signals applied to the +input and the – input are connected either directly to the da1855a amplifier’s inputs or to the input attenuators. Maximum input voltage is ±200 vp a signal connected to the +...

  • Page 3

    Operation da1855a-om-e rev a issued: july 2002 3-3 input resistance when the input attenuator is set to ÷÷1 and no attenuating probe is connected, the input resistance can be increased from 1 m Ω to 100 m Ω . This is advantageous when measuring high impedance circuits or when ac coupling is needed w...

  • Page 4

    Da1855a differential amplifier 3-4 issued: july 2002 da1855a-om-e rev a the oscilloscope screen. Additionally, the risk of tripping the input overload detector and automatically disconnecting the input is eliminated. In the ac mode, the +input is connected through an ac coupling capacitor to the amp...

  • Page 5

    Operation da1855a-om-e rev a issued: july 2002 3-5 the da1855a's amplifier subtracts the voltage applied to its inverting input from the voltage applied to its non-inverting input. The da1855a output is therefore zero whenever these two voltages are equal. For this reason, the voltage applied to the...

  • Page 6

    Da1855a differential amplifier 3-6 issued: july 2002 da1855a-om-e rev a note that while in v comp mode, the amplifier is configured for single ended measurements. The –input connector is not usable when v comp is selected. The input signal applied to the + input is referenced to ground offset by the...

  • Page 7

    Operation da1855a-om-e rev a issued: july 2002 3-7 pvg absolute mode: da1855 pvg increment and decrement buttons always function to increment or decrement the voltage display respectively. When decrementing from a positive voltage, the display always stops at zero. To obtain negative voltages, the ±...

  • Page 8

    Da1855a differential amplifier 3-8 issued: july 2002 da1855a-om-e rev a offset provides much greater range than the conventional position control. For example, at 50 mv/div, the v diff mode provides up to ± 200 divisions of range. Operation of the da1855a using the v diff function is the same as v c...

  • Page 9

    Operation da1855a-om-e rev a issued: july 2002 3-9 design and is intended to drive a 50 Ω load. Without the load, the filter's frequency response and transient response are altered. 1 mhz — the 1mhz filter is of the same design as the 20 mhz filter, and the same remarks apply. 100 khz — the 100khz f...

  • Page 10

    Da1855a differential amplifier 3-10 issued: july 2002 da1855a-om-e rev a usage, the instrument may be left plugged in at all times and the power switch left in the 1 (on) position. Power up indication upon turn-on, the model number and firmware version are briefly displayed in the pvg readout. For e...

  • Page 11

    Operation da1855a-om-e rev a issued: july 2002 3-11 table 3-2. V diff range for different gain and attenuator settings when using readout encoded probes which the da1855a senses, the pvg readout calculates the effective differential offset at the probe tip. Of course, both probes must have the same ...

  • Page 12

    Da1855a differential amplifier 3-12 issued: july 2002 da1855a-om-e rev a note the effective voltage is always increased by the attenuator. It therefore follows that any probe will increase the effective voltage of both v comp and v diff by its attenuation factor. For example, a probe with a 100x att...

  • Page 13

    Operation da1855a-om-e rev a issued: july 2002 3-13 oscilloscope. The da1855a cannot be remotely controlled without a lecroy oscilloscope. Refer to section 7 for a description of the remote commands. When the probus cable is installed, the buttons on the front panel of the differential amplifier are...

  • Page 14

    Da1855a differential amplifier 3-14 issued: july 2002 da1855a-om-e rev a table 3-5. Da1855a factory default settings sensitivity, position and offset oscilloscopes are designed to maintain their accuracy for that portion of a signal that is displayed on-screen. When the signal is large enough to dri...

  • Page 15

    Operation da1855a-om-e rev a issued: july 2002 3-15 2. Set the oscilloscope deflection factor to no greater than 100mv/div. The most useful range for the oscilloscope deflection factors will be between 1mv/div and 100mv/div. Using a scale factor of 200 mv/div will allow the nonlinear portion of the ...

  • Page 16

    Da1855a differential amplifier 3-16 issued: july 2002 da1855a-om-e rev a in some situations, the user may wish to select amplifier settings optimized for the lowest noise performance with lower common mode range. Or, the user may require the amplifier not to change noise or common mode range when th...

  • Page 17

    Operation da1855a-om-e rev a issued: july 2002 3-17 probes and differential amplifiers when using a differential amplifier it is very important to understand the role probes play in the overall measurement system performance. Probes not only make attachment to the circuit under test more convenient,...

  • Page 18

    Da1855a differential amplifier 3-18 issued: july 2002 da1855a-om-e rev a (one probe always on the +input and the other always on the – input). The dxc100a differential probe pair the dxc100a is a high performance matched passive differential probe pair designed for use with lecroy da1855a series dif...