John,
If you know the output pull down current of the driver then what ever that
current is should be applied to the schottky and this should not exceed 0.55
volts drop in the schottkys forward direction. Is my guess.
Ray


"John Popelish" wrote in message
. ..
Ray King wrote:
Jerry,
I think you are correct. these are schottkys. these 100uf caps can put
quite a negative punch with out limiting the charge current. I would use
no less than the IN5817 no 18 nor 19.

The capacitors are not the limiting impedance for these
signals. The outputs are not low impedance sources. That
is why buffer amps are needed.

Here is a clip from the data sheet:

"The LMH1251 is designed to interface with an ADC or
preamplifier through an AC coupling capacitor as shown
below in Figure 1. The RGB outputs of the LMH1251 are 700
mVPP video signals with the black level at approximately 2V,
which is the chip’s internal voltage reference level."

"The RGBHV outputs cannot be used drive standard 150-
ohm video loads and require high-bandwidth buffers for this
kind of application. For example, if the LMH1251 is to be
designed into a stand-alone converter box application, the
configuration in Figure 2 is recommended. To drive a display
monitor over a standard VGA cable, a wideband, low distortion
triple video buffer, such as the LMH6739, can be used
with a gain of +2 to drive the RGB video signals of the
LMH1251, and logic inverters can be used to drive its H and
V sync signals."

I don't see that spec on the output impedance, but it must
be quite a bit higher than 150 ohms.

So any small signal Schottky should be big enough.