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參數(shù)資料
| 型號(hào)： | QEM77-AH |
| 英文描述： | Analog IC |
| 中文描述： | 模擬IC |
| 文件頁(yè)數(shù)： | 4/7頁(yè) |
| 文件大?。?/td> | 105K |
| 代理商： | QEM77-AH |
QEM77-AH
41 x 41 mm / 19 pins
MCXO
Operating Procedure
SALES OFFICES:
Benelux:
+33 (0) 1 46 90 23 00 /
Germany:
+49 (0)
89 820 796-27
/
Nordic:
+46 (0) 8 59030300
France:
+33 (0) 1 46 90 23 00 /
Italy:
+39 (0) 738 8869 /
Spain:
+33 (0) 1 46 90 23 00 /
UK:
+44 (0) 1256 883340
USA:
+1 (623) 780-1995 /
Asia-Pacific
: +33 (0) 5 56 46 66 84
WEB SITE: http://www.temex-components.com
Specifications are subject to change without notice - Page 4 / 7
TEMEX
TIME &
FREQUENCY
QEM77AH
04-05-2001
Synchronization of FM
The 1 Hz frequency output on FM1 is derived by division of the 10 MHz FMCXO, it has therefore the same relative
stability. I n order to provide the function of a 1 pps generator in time keeping applications, the FM1 output can be
synchronized with an external 1 Hz source. I n this case, the synchronization is effected between two positive-going edges
of the compared signals after applying the synchronization validation signal. The maximum error between the two signals is
±
1
μ
s.
(
Warning !
Synchronization is not possible when the oscillator is in stand-by mode).
After synchronization and switching to stand-by mode, an additional error inferior to
±
50
μ
s is introduced.
Synchronization on PDS by rising front.
Phase measurement
This function provides the means to measure the difference between rising fronts at 1 Hz on FM1 and FM2 with a precision
of
±
1 % or
±
1
μ
s (whichever is the greater). During phase measurement, temperature compensation of the frequency
cannot be effected. I t is therefore important that the temperature remains constant.
The result of this measurement is given by the RS232 link in the form of 3 bytes, the first of which is the most
significant. The phase-offset value on 10 MHz is given by
offset (
μ
s) = decimal value of the 3 bytes.
Stand- by mode (reduced power consumption)
I n stand-by mode, the temperature compensation intervals are increased. This means the frequency precision is attained
after a longer stabilization time. I n this mode, only the 1 Hz-output is available. The dividing stages and certain other
functions are switched-off, thereby reducing the consumption to 4 mA.
RS232 Port Communication parameters
Format : NRZ
Speed : 2400 bits/s.
1 start bit/1 stop bit/8 data bits
no parity
logic levels : HCMOS 3 V
N.B. : the pin-outs 1, 3, 8, 17, 19 are used for initial setting during manufacture. They must not be connected, any connection
can either cause malfunctioning or cause permanent damage.
Digital frequency adjustment
Adjustments effected by means of the RS 232 port differ in their hierarchy : $BF, $FB, $AB, $BA, change temporarily the
FMCXO and can be cancelled by $BD or by $BB. Factory setting while $BB returns FMCXO to its original value.
I nputting $BC or $CB superimposes an additional frequency offset that can only be cancelled by $BB.
Amplitude of the frequency adjustment is limited to
±
100 Hz
Computing the 3 correcting bytes (low, medium, high) :
value in Hex = Hex(I nt(26.948 x
F(Hz)))
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