Operating Principles; Quick Start Procedure - Linear Technology 1979A Manual

DEMO MANUAL DC1979A

operating principles

cooling down some, the part will automatically resume
(or attempt) normal operation, usually in a fraction of a
second. This safety feature can be defeated if desired by
setting the THERMAL S/D jumper JP1 to the 0 setting.
To evaluate the LTC6090 at other power supply voltages,
or without any noise contribution from the onboard flyback
circuit, supply potentials can be furnished directly to the

Quick start proceDure

Demonstration circuit 1979A is easy to set up to evalu-
ate the performance of the LTC6090. Refer to Figure 1
for proper measurement equipment setup and follow the
procedure below (CAUTION: HIGH VOLTAGES!):
1. Place jumpers in the following positions:
JP1: Position 1 (enables THERMAL S/D)
JP2: Position 20× (for GAIN of 20)
2. With power off, connect the input power supply to +V
and –V. A good setting is 9V, or a 9V battery can be
used.
NOTE: The flyback converter input is isolated from the
op amp GND, so when used for the op amp supply, the
DC input will not use the GND connection.
2
op amp without powering the LT8300. Solder tacking
wires to the C4 and C6 bypass capacitors is the most
convenient means of supplying external power. A ground
turret is provided for any alternate powering or instrument
grounding needs.
Refer to the Schematic Diagram in this document for the
circuit details.
3. Connect a signal generator at the IN+ and GND turrets.
4. Connect an oscilloscope 10× probe to the OUT and
5. Power up the system and a 20V sine wave should ap-
6. Increase the signal amplitude and observe the signal
Figure 1. Proper Measurement Equipment Setup
10kHz sine wave at 1V is a good starting point.
NOTE: If the supply and instruments share a chassis
ground connection, the isolation of the flyback con-
verter is lost.
GND turrets. Set the scaling to 20V/20µs per division.
pear on the oscilloscope.
for clipping as signals reach the supply rails. Slew and
settling behavior can be evaluated by switching the
signal generator to square wave.
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