
LM2453
Monolithic Triple 6 nS CRT Driver With Integrated Clamp
and G1 Blanking
General Description
The AC2DC driver is an integrated high voltage triple CRT
driver circuit designed for use in color monitor applications.
The input signal interface to the IC is a multiplexed signal
containing both clamp and video signal information, relative
to a 1.7 V
DC
reference.
The IC contains three high gain, high input impedance, wide
band amplifiers which directly drive the RGB cathodes of a
CRT. Each channel has its gain internally set to 52 and can
drive CRT capacitive loads as well as resistive loads present
in other applications, limited only by the package’s power
dissipation.
Integrated with the driver is triple clamp circuit for DC recov-
ery of each of the AC coupled outputs. The DC clamp circuit
amplifies the clamp signal that is multiplexed on the video
signal input. The DC clamp amplifiers are high gain, high in-
put impedance amplifiers, setting a low impedance DC level
at the clamp output which can be used to restore the DC
level of the cathode drive. Each channel has a gain that is in-
ternally set to +73.
Also integrated within the package is a 40 V
P-P
vertical
blanking driver that is designed to provide vertical retrace
blanking on G1 of the CRT. This is a current limited, low im-
pedance output capable of driving normal G1 decoupling ca-
pacitances via an external resistor. The output of the G1
driver can also be used to drive a voltage boost capacitor (22
μF). When connected between the G1 drive output and the
120V supply input pin, a 120V boost supply is achieved
which can be used to drive the internal DC clamp circuit,
thereby eliminating the requirement for a 120V clamp supply.
The IC is packaged in an industry standard 15-lead TO-220
molded plastic power package.
Features
n
Low power dissipation
n
Well matched with LM1253A video pre-amp
n
Three wideband video amplifiers
n
Three integrated active clamp circuits
n
Convenient TO-220 staggered lead package
n
Built in horizontal blanking
n
Integrated 120V supply and G1 vertical blank drive
circuit
Applications
n
1280 x 1024 Resolution displays up to 85 Hz refresh
n
Pixel clock frequencies up to 135 MHz
n
Monitors requiring horizontal video blanking
Block Diagram
Package Pinout
DS101302-1
FIGURE 1. LM2453 Block Diagram
DS101302-2
FIGURE 2. LM2453 Package Pinout
Order Number LM2453TA
April 2000
L
2000 National Semiconductor Corporation
DS101302
www.national.com