MC33411AFTA View Datasheet(PDF) - Motorola => Freescale
Part Name
Description
Manufacturer
MC33411AFTA Datasheet PDF : 43 Pages
| |||
MC33411A/B
2nd LO (LO2)
This PLL is designed to be the 2nd Local Oscillator in a
typical 900 MHz system, and is designed for frequencies up
to 80 MHz. The VCO and varactor diodes are included, and
are to be used with an external tank circuit (Pins 43–45).
Bits 4/20–18 are used to select an internal capacitor, with
a value in the range of 0 to 7.6 pF, to parallel the varactor
diodes and the tank’s external capacitor. This permits a
certain amount of fine tuning of the oscillator’s performance.
See Table 7.
A buffered output is provided to drive, e.g., a mixer. The
frequency is set with the programmable 14–bit counter
(bits 3/13–0) in conjunction with the PLL reference
frequency. For example, if the reference frequency is 50 kHz,
and the 2nd LO frequency is to be 63.3 MHz, the 14–bit
counter needs to be set to 1266d (00 0100 1111 0010). The
output level is dependent on the value of the impedance at
Pin 41, partly determined by the external pull–up resistor.
The output of the phase detector is a Three–State charge
pump which drives the varactor diodes through an external
low–pass filter. Bit 3/14 sets the gain of the charge pump to
either 100/2π µA/radian (logic 0) or 400/2π µA/radian
(logic 1). Bit 3/15 sets its polarity – if 0, the PLL is configured
to operate with a non–inverting low–pass filter/VCO
combination. If the low–pass filter/VCO combination is
inverting, the polarity bit should be set to 1. Please note that
the 2nd LO VCO on the MC33411 is of the non–inverting
type. Figures 43 through 45 describe the response of the 2nd
LO.
ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ LO2 Capacitor Select
Table 7. LO2 Capacitor Select Programming
LO2 Capacitor Select
LO2 Capacitor Select
LO2 Capacitor Select
Bit #20
Bit #19
Bit #18
Select #
Value
0
0
0
0
0 pF
0
0
1
1
1.1 pF
0
1
0
2
2.2 pF
0
1
1
3
3.3 pF
1
0
0
4
4.3 pF
1
0
1
5
5.4 pF
1
1
0
6
6.5 pF
1
1
1
7
7.6 pF
MOTOROLA RF/IF DEVICE DATA
29
Share Link: 