Teledyne Lecroy DA1855A User manual

Operator’s
Manual
DA1855A
Differential Amplifier

DA1855A Differential Amplifier
Operator’s Manual
February, 2018

© 2018 Teledyne LeCroy, Inc. All rights reserved.
Unauthorized duplication of Teledyne LeCroy documentation materials other than for internal sales
and distribution purposes is strictly prohibited. Customers are permitted to duplicate and distribute
Teledyne LeCroy documentation for internal training purposes.
Teledyne LeCroy is a registered trademark of Teledyne LeCroy, Inc. Windows is a registered
trademark of Microsoft Corporation. Other product or brand names are trademarks or requested
trademarks of their respective holders. Information in this publication supersedes all earlier
versions. Specifications are subject to change without notice.
929404-00 Rev A
February, 2018

Operator’s Manual
i
Table of Contents
Safety Instructions................................................................................................................... 1
Symbols..............................................................................................................................1
Precautions.........................................................................................................................1
Operating Environment.......................................................................................................2
Cooling................................................................................................................................2
Cleaning..............................................................................................................................2
Calibration...........................................................................................................................3
Power..................................................................................................................................3
Specifications........................................................................................................................... 4
Nominal Characteristics......................................................................................................4
Warranted Characteristics ..................................................................................................6
Typical Characteristics........................................................................................................7
Physical Characteristics......................................................................................................8
Overview................................................................................................................................... 9
Models.............................................................................................................................. 10
Standard Accessories....................................................................................................... 10
Optional Accessories........................................................................................................ 10
Operation................................................................................................................................ 11
General Information.......................................................................................................... 11
Dynamic Range................................................................................................................ 11
Front Panel....................................................................................................................... 12
Rear Panel........................................................................................................................ 17
Instrument Settings........................................................................................................... 21
General Operating Information............................................................................................. 24
Power Connection ............................................................................................................ 24
Comparator Mode............................................................................................................. 24
Differential Mode............................................................................................................... 24
Set Up Using the ProBus Interface................................................................................... 25
Set Up Without ProBus Interface...................................................................................... 30
Determining the Proper Offset Mode ................................................................................ 31
Avoiding Common Problems ............................................................................................ 31
Care and Maintenance........................................................................................................... 34
Cleaning............................................................................................................................ 34
Calibration Interval............................................................................................................ 34
Service Strategy ............................................................................................................... 34
Troubleshooting................................................................................................................ 34
Returns............................................................................................................................. 34

DA1855A Differential Amplifier
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Applications............................................................................................................................35
Voltage Measurements.....................................................................................................35
Measuring Current............................................................................................................35
Effects of Probes on Saturation Voltage Measurements...................................................36
Saturation Voltage Measurement......................................................................................38
Gate Drive Voltage............................................................................................................39
Upper and Lower Gate Drive ............................................................................................40
Avoiding Measurement Errors...........................................................................................40
Remote Control Commands..................................................................................................41
Command List...................................................................................................................41
Gain Control Mode............................................................................................................42
Attenuation........................................................................................................................42
Auto-Zero..........................................................................................................................43
Bandwidth Limit.................................................................................................................43
Coupling............................................................................................................................44
Gain ..................................................................................................................................45
Offset................................................................................................................................46
Input-Resistance...............................................................................................................47
Probe Attenuation.............................................................................................................48
Precision Voltage Generator.............................................................................................49
Volt / DIV...........................................................................................................................50
Performance Verification....................................................................................................... 51
Test Equipment Required.................................................................................................51
Preliminary Procedure ......................................................................................................53
Functional Check..............................................................................................................54
Verification Procedure.......................................................................................................55
DA1855A Performance Verification Test Record..............................................................72
Reference................................................................................................................................75
Differential Mode and Common Mode ..............................................................................75
Differential Mode Range and Common Mode Range .......................................................75
Common Mode Rejection Ratio........................................................................................75
Certifications.....................................................................................................................77
Warranty...........................................................................................................................80
Returning a Product..........................................................................................................81
Technical Support.............................................................................................................82

Operator’s Manual
1
Safety Instructions
This section contains instructions that must be observed to keep this oscilloscope accessory
operating in a correct and safe condition. Follow generally accepted safety procedures in addition to
the precautions specified in this section. The overall safety of any system incorporating this
accessory is the responsibility of the assembler of the system.
Symbols
These symbols appear on the instrument's front or rear panels and in its documentation to alert you
to important safety considerations.
CAUTION
of potential damage to instrument, or
WARNING
of potential bodily injury.
Attend to the accompanying information to protect against personal injury or damage. Do
not proceed until conditions are fully understood and met.
High voltage
. Risk of electric shock.
Measurement ground connection.
Safety (protective) ground connection.
Alternating Current.
Power On; connected to AC mains.
Power Off; disconnected from AC mains.
Precautions
Use proper power cord. Use only the power cord shipped with this instrument and certified for the
country of use.
Maintain ground. This product is grounded through the power cord grounding conductor. To avoid
electric shock, connect only to a grounded mating outlet.
Connect and disconnect properly. Do not connect/disconnect probes or test leads while they are
connected to a voltage source.
Observe all terminal ratings. Do not apply a voltage to any input that exceeds the maximum rating of
that input. Refer to the specifications for maximum input ratings.
Use only within operational environment listed. Do not use in wet or explosive atmospheres.
Use indoors only.

DA1855A Differential Amplifier
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Keep product surfaces clean and dry.
Do not block the cooling vents. Leave a minimum six-inch (15 cm) gap around the sides and back
between the instrument and the nearest object. The feet provide adequate bottom clearance. Keep
the underside clear of papers and other objects.
Do not remove the covers or inside parts. Refer all maintenance to qualified service personnel.
Do not operate with suspected failures. Do not use the product if any part is damaged. Obviously
incorrect measurement behaviors (such as failure to calibrate) might indicate impairment due to
hazardous live electrical quantities. Cease operation immediately and sequester the instrument
from inadvertent use.
Operating Environment
Temperature: 0 to 50 °C.
Humidity: Maximum relative humidity 80 % for temperatures up to 31 °C decreasing linearly to 50 %
relative humidity at 50 °C.
Altitude: Up to 2,000 m (6,562 ft).
Cooling
The instrument relies on forced air cooling with internal fans and vents. Take care to avoid
restricting the airflow to any part of the amplifier. Around the sides and rear, leave a minimum of 15
cm (6 inches) between the instrument and the nearest object. At the bottom, the amplifier feet (up
or down) provide adequate clearance.
CAUTION. Do not block vents. Always keep the area beneath the amplifier clear of paper and
other items.
The instrument also has internal fan control circuitry that regulates the fan speed based on the
ambient temperature. This is performed automatically after start-up.
Cleaning
Clean only the exterior of the amplfier using a damp, soft cloth. Do not use harsh chemicals or
abrasive elements. Under no circumstances submerge the instrument or allow moisture to
penetrate it. Avoid electric shock by unplugging the power cord from the AC outlet before cleaning.
CAUTION. Do not attempt to clean internal parts. Refer to qualified service personnel.

Operator’s Manual
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Calibration
The amplifier is calibrated at the factory prior to being shipped. The recommended calibration
interval is one year. Calibration should be performed by qualified personnel only. Schedule an
annual factory calibration as part of your regular maintenance. Extended warranty, calibration, and
upgrade plans are available for purchase. Contact your Teledyne LeCroy sales representative or
[e-mail] to purchase a service plan.
Power
AC Power Source
100 to 240 VAC (±10%) at 50/60 Hz (± 10%).
Manual voltage selection is not required because the instrument automatically adapts to line
voltage.
Power Consumption
DA1855A: 28 Watts (39 VA)
DA1855A-PR2: 56 Watts (78 VA)
Power and Ground Connections
The amplifier is provided with a 10A/250V 18AWG rated grounded cord set containing a molded
three-terminal polarized plug and a standard IEC320 (Type C13) connector for making line voltage
and safety ground connections.
The AC inlet ground is connected directly to the frame of the instrument. For adequate protection
again electric shock, connect to a mating outlet with a safety ground contact.
WARNING. Interrupting the protective conductor inside or outside the device, or
disconnecting the safety ground terminal, creates a hazardous situation. Intentional
interruption is prohibited.
Power On/Off
The Power On/Off switch on the back of the amplifier controls the operational state of the device.
Press the side of the switch closest to either On or Off.

DA1855A Differential Amplifier
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Specifications
These specifications are valid when the following conditions have been met:
•The instrument is being operated from a power source, which meets the line voltage and
frequency specifications.
•The instrument has been operating for at least 20 minutes in an environment that is within
the operating environmental specifications.
•The instrument has been calibrated within the last 12 months. Calibration was performed in
a controlled environment of 25° C ± 5° C.
Nominal Characteristics
Nominal characteristics describe parameters and attributes which are guaranteed by design, but do
not have associated tolerances.
General
Input Configuration
True Differential, + and – Inputs Precision Voltage Generator can be
selected as – input source in VCOMP mode.
Offset Capability
Precision Voltage Generator can be used to provide true differential offset.
+Input Coupling Selections
AC, Off (Precharge), DC
–Input Coupling Selection
AC, Off (Precharge), DC, V
COMP
Input Connectors
BNC (+Input incorporates Probe Attenuation Coding sensing connector)
Maximum Input Voltage
Withstand up to ± 200 Vp continuous. Automatic input disconnect with
manual reset.
Output Configuration
Single ended, Ground referenced
Output Impedance
50 Ω
Intended Output Load
50 Ω
Output Connector
BNC
Amplifier Gain
X1 or X10
Input Attenuation
÷1 or ÷10
Bandwidth Limit Filters
100 kHz, 1 MHz, 20 MHz or
(Low Pass)
None (full bandwidth)
Bandwidth Limit Filter
Characteristics 3-pole Bessel, 18 dB/octave