mc145220 Freescale Semiconductor, Inc, mc145220 Datasheet - Page 20

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

MC145220
20
NOTES:
OUTPUT
VCO
1. The PD out output is fed to an external loop filter. See the Phase–Locked Loop — Low–Pass Filter Design page for additional informa-
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 VCO
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 device
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.
tion.
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).
not required when Output A is configured as f R , f R , f V , f V , DATA OUT.)
BUFFER
LOW–PASS
FILTER
Figure 21. Application Showing Use of the Two Single–Ended Phase/Frequency Detectors
NOTE 4
GENERAL PURPOSE
DIGITAL OUTPUT
+V
S
P + A; this determines the values (N, A) that must be programmed into the N and A counters,
10
1
2
3
4
5
6
7
8
9
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
MOTOROLA
OUTPUT
VCO