LM2405T National Semiconductor, LM2405T Datasheet - Page 3

• Manufacturer Part Number: LM2405T
• Description: IC DRIVER MONOLITHIC TO-220-11
• Manufacturer: National Semiconductor

Specifications of LM2405T

• Display Type: CRT
• Current - Supply: 18mA
• Voltage - Supply: 60 V ~ 85 V
• Operating Temperature: -20°C ~ 100°C
• Mounting Type: Through Hole
• Package / Case: TO-220-11 (Bent and Staggered Leads)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Interface: -
• Configuration: -
• Digits Or Characters: -
• Other names: *LM2405T

AC Test Circuit
(Continued)
DS012682-7
FIGURE 6. Pulse Response
Theory of Operation
DS012682-4
The LM2405 is a high voltage monolithic triple CRT driver
FIGURE 3. V
vs V
OUT
IN
suitable for SVGA and XGA display applications. The
LM2405 features +80V operation and low power dissipation.
The part is housed in the industry standard 11-lead TO-220
molded plastic power package.
The circuit diagram of the LM2405 is shown in Figure 1 . A
PNP emitter follower, Q5, provides input buffering. Q1 and
Q2 form a fixed gain cascode amplifier, with a gain of −14.
Emitter followers Q3 and Q4 isolate the high output imped-
ance of the amplifier from the capacitance of the CRT cath-
ode, and make the circuit relative insensitive to load capaci-
tance. Q6 provides biasing to the output emitter follower
stage to reduce crossover distortion at low signal levels.
Figure 2 shows a typical test circuit for evaluation of the
LM2405. This circuit is designed to allow testing of the
LM2405 in a 50
environment, such as a pulse generator
and a scope, or a network analyzer. In this test circuit, two
low inductance resistors in series totaling 4.95 k
form a
DS012682-5
100:1 wideband low capacitance probe when connected to a
FIGURE 4. Power Dissipation vs V
50
cable and load. The input signal from the generator is
CC
AC coupled to the base of Q5.
Application Hints
INTRODUCTION
National Semiconductor is committed to providing applica-
tion information that assists our customers in obtaining the
best performance possible from our products. The following
information is provided in order to support this commitment.
The reader should be aware that the optimization of perfor-
mance was done using a specific printed circuit board de-
signed at National. Variations in performance can be realized
due to physical changes in the printed circuit board and the
application. Therefore, the designer should be aware that
DS012682-6
component value changes may be required in order to opti-
FIGURE 5. Large Signal Frequency Response
mize performance in a given application. The values shown
in this document can be used as a starting point for evalua-
tion purposes. When working with high bandwidth circuits,
good layout practices are also critical to achieving maximum
performance.
POWER SUPPLY BYPASS
Since the LM2405 is a wide bandwidth amplifier, proper
power supply bypassing is critical for optimum performance.
Improper power supply bypassing can result in large over-
shoot, ringing and oscillation. A 0.01 µF capacitor should be
connected from the supply pin, V
, to ground, as close to
CC
3
www.national.com