Document
LH2426 Triple 80 MHz CRT Driver
June 1992
LH2426 Triple 80 MHz CRT Driver
General Description
The LH2426 contains three wide bandwidth large signal amplifiers designed for large voltage swings at high frequencies The amplifiers work on a transimpedance principal i e an input current swing of g 4 38 mA results in an output voltage swing of g 25V The device is intended for use in color CRT monitors and is a low cost solution to designs www.DataSheet4U.com conforming to the IBM 8514 graphics standard
Features
Y Y Y Y Y
Operation from 80V power supply 80 MHz bandwidth at 50 VPP swings Rise fall time less than 4 ns Output signal can swing 70V Drives CRT directly
Applications
Y Y
CRT driver for RGB monitors High voltage transimpedance amplifiers
Schematic and Connection Diagrams
(One Section)
TL H 10739 – 2
Top View Order Number LH2426S See NS Package Number HY12B
TL H 10739 – 1
IBM is a registered trademark of International Business Machines Corporation C1995 National Semiconductor Corporation
TL H 10739
RRD-B30M115 Printed in U S A
Absolute Maximum Ratings
If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Supply Voltage V a Power Dissipation PD
a 85V
Storage Temperature Range TSTG Operating Temperature Range TCASE Lead Temperature (Soldering 10 sec ) ESD Tolerance
b 25 C to a 100 C b 20 C to a 90 C
10W
300 C TBD
DC Electrical Characteristics V a e 80V R1 e 430X C1 e 82 pF CL e 8 pF 50 VPP output swing with 40V DC offset See Figure 1 TCASE e 25 C unless otherwise noted
Symbol Va V Parameter Supply Current (per Amplifier) Input Offset Voltage Output Offset Voltage Rise Time Fall Time Bandwidth Voltage Gain Overshoot Linearity Error Gain Matching VOUT from a 10V to a 70V Note 1 Note 2 10% to 90% 90% to 10%
b 3 dB
Conditions Min No Input or Output Load 14 34
LH2426 Typical 24 16 40 35 35 100 11 13 10 5 02 14 Max 30 18 46 5 5
Units
mA V V ns ns MHz V V % % dB
INDC www.DataSheet4U.com
VOUTDC tR tF BW Av OS LE D Av
Note 1 Linearity error is defined as The variation in small signal gain from a 10V to a 70V output with a 100 mVAC 1 MHz input signal Note 2 Calculated value from voltage gain test on each channel
Typical Performance Characteristics
Typical Test Circuit (One Section)
TL H 10739 – 3
FIGURE 1 Test Circuit (One Section)
Note 8 pF is total load capacitance It includes all parasitic capacitances
Figure 1 shows a typical test circuit for evaluation of the LH2426 This circuit is designed to allow testing of the LH2426 in a 50 X environment such as a pulse generator oscillosope or network analyzer To calibrate pulse generator set to 2 4 VPP into 50 X
THEORY OF OPERATION The LH2426 is a two stage amplifier (see schematic on front page) Both stages are in push pull configuration Q2 is biased with two resistors Q1 gets its bias through the 5700X feedback resistor and the input biasing current The bases of Q1 and Q2 are ca.