All data assumes retrace time equal to 30% of frame time and a 60Hz refresh rate.

RESOLUTION TABLE FOR TYPICAL CRT'S

APPLICATION NOTES CON'T

182nS

52nS

38nS

26nS

12.6nS

11nS

8.9nS

5.8nS

2.8nS

860pS

320 x 200

640 x 350

640 x 480

800 x 560

1024 x 900

1024 x 1024

1280 x 1024

1664 x 1200

2048 x 2048

4096 x 3300

5MHz

19MHz

26MHz

38MHz

80MHz

90MHz

112MHz

170MHz

360MHz

1.2GHz

60nS

17nS

12.5nS

8.6nS

4.2nS

3.7nS

2.9nS

1.9nS

1nS

280pS

6MHz

20MHz

28MHz

41MHz

84MHz

95MHz

120MHz

180MHz

380MHz

1.23GHz

The brightness (output offset) can be linearly adjusted by

output quiescent voltage range is from approximately

input pin should be bypassed with a 0.1µF capacitor to ground

placed as close as possible to the hybrid. This DC voltage can

be any stable system source.

Keep hybrid power dissipation in mind when adjusting the

output quiescent voltage. Practically all of the voltage is seen

across Rp. This power must be taken into account when high

Rp currents are used. If the quiescent level is set almost to

will suffer somewhat. If the quiescent level is set too far from

output fall time will be limited. The output black level is obvi-

ously dependent on system requirements but a little experimen-

tation will strike the optimum balance between power dissipa-

tion and bandwidth. Total current through Rp should be limited

to less than 370mA when operating from power supplies greater

than 65V. The gain adjust alone can set the AC current to

250mA (ie: 250mApp=50Vpp/200Ω).

The video input can be electrically disconnected from the

amplifier by applying a TTL high input to the blank pin. When

put when it is in blank mode.

When the TTL compatible blank input is not used, the pin

must be connected to ground to enable the amplifier. The blank

input will float high when left unconnected which will disable

the video.

BLANK INPUT

The MSK 1911 has an on board buffered DC zener reference

temperature test limits of 5.2V to 5.8V DC. This output is

provided for gain and offset adjustment and can source up to

4mA of current.

Required System

Bandwidth

Display

Resolution

Maximum

Pixel

Time

Minimum Pixel

Clock

Frequency

Required Rise Time

at CRT

Cathode

To achieve transition times of less than 3 nS with the MSK

1911, all stray and intrinsic capacitances must be compensated

for. Two external inductors can accomplish this task easily.

(Refer to the figure below). The 200Ω resistor (Rp) and the

capacitance of the output driver collector form a high frequency

pole which limits the rise and fall time. To compensate for this

effect, the series inductor (Lp) is placed in the circuit between

tor is typically 100nH. Since all applications are slightly differ-

ent, it is likely that the designer will need to select this inductor

value to achieve the desired response. The second inductor

(L2) is only necessary when a series CRT isolation resistor (Rs)

is used. An inductor in the range of 30nH is placed in series

with the resistor to compensate for the pole formed by the

resistor and the CRT capacitance. The value of this inductor

may be varied as well for optimum response time.

TRANSITION TIME MINIMIZATION

1.6

13.9

11.4

15.6

0

35

35

50

Duty Cycle %

0

100

80

80

Ω

Ω

Ω

Ω (Internal)

The MSK 1911 package has mounting holes that allow the

user to connect the amplifier to a heat sink or chassis. Since

the package is electrically isolated from the internal circuitry,

mounting insulators are not required or desired for best thermal

performance.

The power dissipation of the amplifier depends mainly on

the load requirements, bandwidth, pixel size, black level and

the value of Rp. The following table illustrates an example:

THERMAL MANAGEMENT

4

Rev. D 8/00