CHT-CG-050 Datasheet, PDF (6/9 Pages) List of Unclassifed Manufacturers – Versatile High Temperature Clock Generator

CHT-CG-050 - Preliminary datasheet - Version 0.4 (08/2005)
6
Circuit functionality
Operating conditions
The CHT-CG-050 has been qualified for
supply voltages ranging from 3V up to
5.5V. The upper limit is imposed by the
technology on which the CHT-CG-050 is
implemented.
The qualification temperature range ex-
tends from -30°C to +225°C, though func-
tionality is above +250°C is achieved with
little increase of the current consumption.
Crystal driver
XtalDR_0 and XtalDR_1 allow the crystal
driver to change its strength to be able to
oscillate with a wide range of crystals, un-
der any supply (3V to 5V) and temperature
(up to 225°C) condition.
The presence of integrated passive com-
ponents offers a great versatility to the
final user. Highly temperature-stable ca-
pacitors allow for a nearly-constant crystal
load along the whole temperature range.
Internal passive components can be by-
passed or tied to ground if needed.
/XtalEn enables or disables the crystal
oscillator to operate, allowing the CHT-
CG-050 to be embedded into power-
optimized high-temperature applications.
Clock source selector
By means of ExtClkEn and ExtClkIn, the
CHT-CG-050 is able to operate either from
its internal crystal oscillator or from an ex-
ternal clock source.
Frequency divider
Four division factors (1, 2, 4 and 8) can be
selected depending on the levels at the
control lines DIV_0 and DIV_1.
Output buffer
A programmable-strength output buffer,
controlled by DRI_0 and DRI_1, enables
the CHT-CG-050 to drive a large range of
output loads, improving the output signal
integrity. The four possible output
strengths are 8mA, 16mA, 24mA and
32mA.
The output buffer has supply terminals
independent from the rest of the circuit,
allowing the system designer to properly
decouple them in noise-sensitive applica-
tion.
Figure 2. Effect of DRI_0 and DRI_1 on the output
signal.
Figure 2 shows the superposition of the out-
put signal when DRI_0, DRI_1 = LOW and
DRI_1 is then set to HIGH, V_DD=3V,
T=235°C, Freq = 27MHz. As a result, the
signal integrity is improved.
Packaging options
As mentioned above, the layout of the
CHT-CG-050 allows for a very high level of
flexibility for the system designer. Several
packaging configurations are possible,
from 8-pin to 24-pin standard carriers.
At the packaging stage, many functional
features can be enabled or safely disabled
in order to optimize the form factor accord-
ing to the final user needs.
Typical application
The CHT-CG-050 offers the final user
several possible configurations depending
upon the characteristics of the target ap-
plication.
Figure 3. Full configuration.
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