mc145220 Freescale Semiconductor, Inc, mc145220 Datasheet - Page 21

• Manufacturer Part Number: mc145220
• Description: Dual Frequency Synthesizer
• Manufacturer: Freescale Semiconductor, Inc

MOTOROLA
NOTES:
OUTPUT
VCO
1. The R and V outputs are fed to an external combiner/loop filter. See the Phase–Locked Loop — Low–Pass Filter Design page
2. For optimum performance, bypass the V+ and V+
3. The R counter is programmed for a divide value = REF in /f R . Typically, f R is the tuning resolution required for the VCO. Also, the
4. Pull–up voltage must be at the same potential as the V+ pin or less. Pull–up device other than a resistor may be used. (Pull–up
5. LD and LD are open–drain outputs. This allows the wired–OR configuration shown. Note that R1 and Q1 form the “pull–up device”.
6. Use of Q1 is optional and depends on loading.
for additional information. The R and V outputs swing rail–to–rail. Therefore, the user should be careful not to exceed the common
mode input range of the op amp used in the combiner/loop filter.
VCO frequency divided by f R = N T = N
respectively. P is the lower divide ratio of the dual–modulus prescaler (i.e., 32 or 64).
device not required when Output A is configured as f R , f R , f V , f V , DATA OUT.)
BUFFER
LOW–PASS
FILTER
Figure 22. Application Showing Use of the Two Double–Ended Phase/Frequency Detectors
NOTE 4
GENERAL PURPOSE
DIGITAL OUTPUT
+V
10
S
1
2
3
4
5
6
7
8
9
P + A; this determines the values (N, A) that must be programmed into the N and A counters,
REF in
REF out
LD
PD out / R
Rx/ V
GND
f in
f in
V+
OUTPUT A
(PORT)
i
pins to GND and GND
MC145220
PD out
Rx
i
i
GND
NOTE 5
/ R
/ V
ENB
CLK
LD
V+
D in
f in
f in
i
i
i
i
i
i
i
i
with low–inductance capacitors.
R1
20
19
18
17
16
15
14
13
12
11
Q1
+V
NOTE 6
+V
LOW–PASS
FILTER
MCU
+V
BUFFER
MC145220
OUTPUT
VCO
21