Linear Technology 1979A Manual

Description
Demonstration circuit 1979A
amplifier featuring the LTC
flyback converter provides ±62V power to the LTC6090
for evaluating large signal performance. A jumper sets
the gain of the ultrahigh-input impedance circuit to either
unity (1×) or 20×. In the 20× mode, a signal input of just
3V can provide nearly full-swing output. In the unity-gain
setting, the part operates as a precision buffer for high
voltage signals.
performance summary
SYMBOL PARAMETER
V Input Signal, Maximum Usable
IN
I V Leakage Current
IN IN
V Output Voltage Range
OUT
V Input to Supply Converter
SUPPLY
I Quiescent Supply Current
SUPPLY
UVLO Undervoltage Lockout
operating principles
The LTC6090 op amp is set up in the standard noninvert-
ing voltage-gain configuration. GAIN jumper JP2 provides
a means of controlling the gain by adding or deleting a
gain resistor in the feedback path by choosing the 1× or
20× setting.
A small LT 8300 flyback converter is used to provide about
®
±65V from a convenient low voltage supply in the 7V to
12V range. A blue LED is in series with the minus supply
to the LTC6090, so the op amp actually sees a resultant
supply of about 65V/–62V. The LED provides a pleasant
is a high voltage CMOS
6090. An onboard isolated
®
Specifications are at T
CONDITIONS
Gain = 20×, Onset of Output Clipping
Gain = 1×, V
V = Within Usable Range
IN
Gain = 20×, Onset of Output Clipping
V = 9V, No Loading of Op Amp Output
IN
DEMO MANUAL DC1979A
High Voltage CMOS Amplifier
SPECIAL FORM-FACTOR
The DC1979A includes a preassembled power converter
and amplifier circuit on a small printed circuit, so the user
only needs to furnish a 7V to 12V power source to oper-
ate the demo. The layout has provisions for optional BNC
connectors and mounting features to install the board in
a standard plastic enclosure if a permanent utility unit is
desired. Refer to the Appendix for mechanical details.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
= 25°C
A
Limited
CM
level of illumination at the 2.6mA quiescent current of
the op amp.
To minimize signal loading, no input load resistor is in-
cluded. The op amp can be connected to the instrumentation
with a coaxial cable at J2, since a 50Ω output termination
is included. No far-end termination should be used, as the
op amp cannot deliver large signals across a 100Ω DC
load. In the event of an output overload, the LTC6090,
having built-in thermal shutdown, will automatically go
into a low power state to protect itself from damage. After
LTC6090
MIN TYP MAX UNITS
±3.1
±60
3
±62
7 9 12
62
6.5
dc1979af
V
V
pA
V
V
mA
V
1