CF5072 series
FUNCTIONAL DESCRIPTION
Oscillator Equivalent Circuit
The oscillator can be represented by the equivalent circuit shown below. The crystal unit is connected to XIN,
and the other terminal is connected to the L
S
and R
P
network. A varicap is added with cathode connected to
XR, and anode connected to XC.
R
P
L
S
X'tal
XIN
XC
HVC350B
XR
VC
VC input
Oscillator internal capacitors
Version
CF5072AA
lim
Internal capacitance [pF] (design value)
C1
C2
11.2
14.4
OUT
OUTN
CLK output
CLK output
High impedance
High impedance
OE = HIGH: ON
OE = LOW: OFF
From pre-buffer
OE = HIGH: OFF
OE = LOW: ON
ina
100pF
R
VC
C2
R
S
C1
VSS1
Recommended external constants
Oscillator
frequency
155.52MHz
180
1.8
L
S
[nH]
220
R
P
[k
Ω
]
1
2.2
1. R
P
is a damping resistor to prevent parasitic oscillation due the
combined effects of the external inductor (expander coil) and varicap
capacitance/internal capacitance. It is recommended that R
P
be
connected in parallel with L
S
.
Output Circuit
pre
OE
HIGH or open
LOW
The output is enabled/disabled using the OE pin. Outputs are high impedance when disabled. The OE pin logic
is shown in the following table.
ry
To differential
converter
VDD1
OUTN
OUT
The control voltage is applied to the VC pin, with high-resistance element connected between VC and XR
built-in.
NIPPON PRECISION CIRCUITS INC.—2
SEIKO [ SEIKO EPSON CORPORATION ]
