LMT LM – Monolithic Triple NS CRT Driver, Package: to , Pin Nb=9. The is an integrated high voltage CRT driver circuit designed for use in. Download National Semiconductor Corporation LMT pdf datasheet file. LMT Datasheet PDF Download – Monolithic Triple ns CRT Driver, LMT data sheet.
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The IC is packaged in an industry standard 9-lead TO Schematic and Connection Diagrams. Tab is at GND. Referring to Figure 9there are three components R1, R2. Increasing the values of R1. Increasing the value of L1 will speed up the circuit as. It is very important dtasheet use induc.
Ferrite core inductors from J. The NSC demo board also. Once the optimum values are determined. Figure 8 shows the effect of increased load capacitance on. This demonstrates the importance. Figure 7 shows the variation in rise and fall times when the. The rise time shows a maximum variation relative to the cen.
(PDF) LM2439T Datasheet download
The fall time shows a. Figure 4 shows the performance of the LM in the test. The figure shows that the rise time of the LM increases. This corresponds to a speed degrada. Figure 6 shows the maximum power dissipation of the. LM vs Frequency when all three channels of the device. This graph gives the designer the information.
The designer should note that if the load capacitance. The LM case temperature must be maintained below. MHz bandwidth then a maximum heat sink thermal resis. This example assumes a capacitive load of 8 pF and no re. A typical datashert of the LM is shown in Figure Used in conjunction with an LM, a complete video chan. Figure 10 is the sche.
PDF LM2439T Datasheet ( Hoja de datos )
For optimum performance, an adequate ground plane, isola. Also, the length of the. The following references are recommended: Semiconductor Application Note Because of its high small signal bandwidth, the part may os. To prevent this, leads to the. Figure 11 shows routing and component placement on the. This board provides a vatasheet. Note the location of the following components: V CC clamp diodes. Very important for arc protection.
LMT Hoja de datos ( Datasheet PDF ) – Monolithic Triple ns CRT Driver
Figure 12 shows the. Note that the components are placed so. This is done to.
Note also that D14, D15, R29 and D13 are. This minimizes parasitic capacitance in the. The anode of protection diode D14 is con. The IC is packaged in an industry standard 9-lead TO molded plastic power package. See Thermal Considerations section.
Increasing the values of R1 and R2 will slow the circuit down while decreasing over- shoot. Increasing the value of L1 will speed up the circuit as well as increase overshoot. It is very important to use induc- tors with very high self-resonant frequencies, preferably above MHz. The val- ues shown in Figure 9 can be used as a good starting point for the evaluation of the LM The NSC demo board also has a position open to add a resistor in parallel with L1.
This resistor can be used to help control overshoot. Using vari- able resistors for R1 and the parallel resistor will simplify finding the values needed for optimum performance in a given application. Once the optimum values are determined the variable resistors can be replaced with fixed values. This demonstrates the importance of knowing the load capacitance in the application.
This corresponds to a speed degrada- tion of 0.
Figure 6 shows the maximum power dissipation of the LM vs Frequency when all three channels of the device are driving an 8 pF load with a 40 V p-p alternating one pixel on, one pixel off signal. This graph gives the designer the information needed to determine the heat sink requirement for the appli- cation.
The designer should note that if the load capacitance is increased the AC component of the total power dissipation will also increase. This example assumes a capacitive load of 8 pF and no re- sistive load. Used in conjunction with an LM, a complete video chan- nel from monitor input to CRT cathode can be achieved. Per- formance is ideal for x resolution displays with pixel clock frequencies up to 75 MHz. Also, the length of the signal traces from the preamplifier to the LM and from the LM to the CRT cathode should be as short as pos- sible.
Because of its high small signal bandwidth, the part may os- cillate in a monitor if feedback occurs around the video chan- nel through the chassis wiring. To prevent this, leads to the video amplifier input circuit should be shielded, and input cir- cuit wiring should be spaced as far as possible from output circuit wiring.
The schematic of the board is shown in Figure This board provides a good example of a layout that can be used as a guide for future layouts. Figure 12 shows the routing and component placement from pin 1 of the LM to the blue cathode. Note that the components are placed so that they almost line up from the output pin of the LM to the blue cathode pin of the CRT connector.
This is done to minimize the length of the video path between these two components.
Note also that D14, D15, R29 and D13 are placed to minimize the size of the video nodes that they are attached to. This minimizes parasitic capacitance in lm439t video path and also enhances the effectiveness of the pro- tection diodes.
The anode of protection diode D14 is con- nected directly to a section of the the ground plane that has a short and direct path to the LM ground pins. The cath- ode of D15 is connected to V CC very close to decoupling ca- pacitor C55 see Figure 12 which is connected to the same section of the ground plane as D The diode placement and routing is very important for minimizing the voltage 5 www.