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MC145191F View Datasheet(PDF) - Motorola => Freescale

Part Name
Description
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MC145191F
Motorola
Motorola => Freescale Motorola
MC145191F Datasheet PDF : 24 Pages
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A counter, and N counter. The divide ratio between the fin in-
put and the fV signal is N × 64 + A. N is the divide ratio of the
N counter and A is the divide ratio of the A counter. These
ratios are determined by bits loaded into the A register. See
Figure 16. The maximum frequency at which the phase
detectors operate is 2 MHz. Therefore, the frequency of fV
should not exceed 2 MHz.
If A23 = low and A22 = high, OUTPUT A is configured as
Data Out. This signal is the serial output of the 24–1/2–stage
shift register. The bit stream is shifted out on the high–to–low
transition of the CLK input. Upon power up, OUTPUT A is
automatically configured as Data Out to facilitate cascading
devices.
If A23 = A22 = low, OUTPUT A is configured as Port. This
signal is a general–purpose digital output which may be used
as an MCU port expander. This signal is low when the Port
bit (C1) of the C register is low, and high when the Port bit is
high.
OUTPUT B
Open–Drain Digital Output (Pin 15)
This signal is a general–purpose digital output which
may be used as an MCU port expander. This signal is low
when the Out B bit (C0) of the C register is low. When the
Out B bit is high, OUTPUT B assumes the high–imped-
ance state. OUTPUT B may be pulled up through an
external resistor or active circuitry to any voltage less
than or equal to the potential of the VPD pin. Note: the
maximum voltage allowed on the VPD pin is 9.5 V for the
MC145190 and 5.5 V for the MC145191.
Upon power–up, power–on reset circuitry forces OUTPUT
B to a low level.
REFERENCE PINS
REFin and REFout
Reference Input and Reference Output (Pins 20 and 1)
Configurable pins for a Crystal or an External Reference.
This pair of pins can be configured in one of two modes: the
crystal mode or the reference mode. Bits R13, R14, and R15
in the R register control the modes as shown in Figure 17.
In crystal mode, these pins form a reference oscillator
when connected to terminals of an external parallel–reso-
nant crystal. Frequency–setting capacitors of appropriate
values as recommended by the crystal supplier are con-
nected from each of the two pins to ground (up to a maximum
of 30 pF each, including stray capacitance). An external re-
sistor of 1 Mto 15 Mis connected directly across the pins
to ensure linear operation of the amplifier. The device is de-
signed to operate with crystals up to 15 MHz; the required
connections are shown in Figure 9. To turn on the oscillator,
bits R15, R14, and R13 must have an octal value of one (001
in binary, respectively). This is the active–crystal mode
shown in Figure 17. In this mode, the crystal oscillator runs
and the R Counter divides the crystal frequency, unless the
part is in standby. If the part is placed in standby via the C
register, the oscillator runs, but the R counter is stopped.
However, if bits R15 to R13 have a value of 0, the oscillator is
stopped, which saves additional power. This is the shut–
down crystal mode (shown in Figure 17) and can be engaged
whether in standby or not.
In the reference mode, REFin (Pin 20) accepts a signal up
to 27 MHz from an external reference oscillator, such as a
TCXO. A signal swinging from at least the VIL to VIH levels
listed in the Electrical Characteristics table may be directly
coupled to the pin. If the signal is less than this level, ac cou-
pling must be used as shown in Figure 8. Due to an on–
board resistor which is engaged in the reference modes, an
external biasing resistor tied between REFin and REFout is
not required.
With the reference mode, the REFout pin is configured as
the output of a divider. As an example, if bits R15, R14, and
R13 have an octal value of seven, the frequency at REFout is
the REFin frequency divided by 16. In addition, Figure 17
shows how to obtain ratios of eight, four, and two. A ratio of
one–to–one can be obtained with an octal value of three.
Upon power up, a ratio of eight is automatically initialized.
The maximum frequency capability of the REFout pin is
10 MHz. Therefore, for REFin frequencies above 10 MHz,
the one–to–one ratio may not be used. Likewise, for REFin
frequencies above 20 MHz, the ratio must be more than two.
If REFout is unused, an octal value of two should be used
for R15, R14, and R13 and the REFout pin should be floated.
A value of two allows REFin to be functional while disabling
REFout, which minimizes dynamic power consumption and
electromagnetic interference (EMI).
LOOP PINS
fin and fin
Frequency Inputs (Pins 11 and 10)
These pins are frequency inputs from the VCO. These pins
feed the on–board RF amplifier which drives the 64/65 pres-
caler. These inputs may be fed differentially. However, they
usually are used in a single–ended configuration (shown in
Figure 7). Note that fin is driven while fin must be tied to
ground via a capacitor.
Motorola does not recommend driving fin while terminating
fin because this configuration is not tested for sensitivity. The
sensitivity is dependent on the frequency as shown in the
Loop Specifications table.
PDout
Single–Ended Phase/Frequency Detector Output (Pin 6)
This is a three–state current–source/sink output for use as
a loop error signal when combined with an external low–pass
filter. The phase/frequency detector is characterized by a lin-
ear transfer function (no dead zone). The operation of the
phase/frequency detector is described below and is shown in
Figure 18.
POL bit (C7) in the C register = low (see Figure 15)
Frequency of fV > fR or Phase of fV Leading fR: current–
sinking pulses from a floating state
Frequency of fV < fR or Phase of fV Lagging fR: current–
sourcing pulses from a floating state
Frequency and Phase of fV = fR: essentially a floating
state; voltage at pin determined by loop filter
POL bit (C7) = high
Frequency of fV > fR or Phase of fV Leading fR: current–
sourcing pulses from a floating state
Frequency of fV < fR or Phase of fV Lagging fR: current–
sinking pulses from a floating state
Frequency and Phase of fV = fR: essentially a floating
state; voltage at pin determined by loop filter
This output can be enabled, disabled, and inverted via the
C register. If desired, PDout can be forced to the floating state
by utilization of the disable feature in the C register (bit C6).
This is a patented feature. Similarly, PDout is forced to the
MC145190MC145191
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MOTOROLA
 

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