m52737sp Mitsumi Electronics, Corp., m52737sp Datasheet - Page 9

• Manufacturer Part Number: m52737sp
• Description: 3-channel Video Preamplifier With Osd Mixing, Retrace Blanking
• Manufacturer: Mitsumi Electronics, Corp.

APLLICATION METHOD FOR M52737SP
1) CLAMP PULSE INPUT
Input positive pulse.
The calculating of clamp pulse threshold voltage is by the method
as shown right.
The voltage more than 2.2V is limited.
Recommended clamp pulse voltage is as the Fig. shown right.
pulse width is recommended
The clamp pulse circuit in ordinary set is a long roundabout way,
and beside high voltage, sometimes connected to external
terminal, it is very easy affected by large surge.
Therefore, the Fig. shown right is recommended.
2) Brightness action
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above 15kHz, 1.0 sec
above 30kHz, 0.5 sec
above 64kHz, 0.3 sec .
signal
V
TH
(1.5V)
The upper figure is principle
–
+
V
brightness
(1 to 5V)
TH
= 2.2V-Diode 1
=1.5V
19
3-CHANNEL VIDEO PREAMPLIFIER WITH OSD MIXING, RETRACE BLANKING
–
+
DC level shift
18
2.5 to 5.0V
0V
2-1) Brightness terminal
Used range is 1 to 5V
Control characteristic is shown in the right Fig. .
2-2) Sub brightness
There is no sub brightness control function in this IC.
2-3) Hold capacitor
It is necessary more than 0.01 F for this IC (when fH=15kHz).
In fact it is changed according with hold time (except clamping
time). It is need more capacitance for longer the hold time. In other
way, for application. The smaller the capacitance is, the higher the
response. The more the capacitance is, the more stable the action.
According to signal, it is free to set the value. (especially the status
of pulse for vertical sync timing).
3) BLK (for OSD) input terminal
Input type is open base (reference to page 4).
Threshold voltage is 2.5V.
If input of OSD signal without input of BLK pulse, the action will
be strange. Therefore, it is necessary to input BLK pulse when
input of OSD signal.
Grounding this terminal when the OSD function is not used.
If overlay OSD display period with clamp pulse period, the action
will be strange. The method for this situation, recommended
external circuit is as the right Fig.
5
4
3
2
1
0
(for OSD)
C/P
BLK
1
Brightness Voltage (V)
2
MITSUBISHI ICs (Monitor)
1
3
V
M52737SP
CC
4
18
5
6