Operation Guide

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OG_LMD-401_v10e Circuit Design, Inc. 10
OPERATION GUIDE
PLL IC CONTROL
 PLL IC control
LMD-401 is equipped with an internal PLL frequency synthesizer as shown in Figure 1. The operation of the PLL
circuit enables the VCO to oscillate at a stable frequency. Transmission frequency is set externally by the controlling
IC. LMD-401 has control terminals (CLK, LE, DATA) for the PLL IC and the setting data is sent to the internal
register serially via the data line. Also LMD-401 has a Lock Detect (LD) terminal that shows the lock status of the
frequency. These signal lines are connected directly to the PLL IC through a 2 kΩ resistor.
The interface voltage of LMD-401 is 2.8 V, so the control voltage must be the same.
LMD-401 comes equipped with a Intochips DHL612 PLL IC. Please refer to the manual of the PLL IC.
The following is a supplementary description related to operation with LMD-401. In this description, the same names
and terminology as in the PLL IC manual are used, so please read the manual beforehand.
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OSCin
OSCout
Vp
VCC
Do
GND
Xf in
Fin
R
P
STD-302
Control pin name
ZC
PS
LE
Data
2kohm
MB15E03SL
Reference Oscillator
LPF
Voltage Controled
Oscillator
VCO
PLL
CLK
DATA
LE
LD
LD/f out
+2.8v
#:Control v oltage = +2.8v
21.25MHz
up to 1200MHz
Figure 1
CLK
2kohm
2kohm
2kohm
DHL612
LMD-401
connector pin name