MB15F03 Datasheet, PDF (12/22 Pages) Fujitsu Component Limited. – Dual Serial Input PLL Frequency Synthesizer

MB15F03
s POWER SAVING MODE (INTERMITTENT MODE CONTROL CIRCUIT)
Setting a PSIF(RF) pin to Low, IF-PLL (RF-PLL) enters into power saving mode resultant current consumption can
be limited to 10µA (typ.). Setting PS pin to High, power saving mode is released so that the device works normally.
In addition, the intermittent operation control circuit is included which helps smooth start up from stand by mode.
In general, the power consumption can be saved by the intermittent operation that powering down or waking up the
synthesizer. Such case, if the PLL is powered up uncontrolled, the resulting phase comparator output signal is
unpredictable due to an undefined phase relation between reference frequency (fr) and comparison frequency (fp)
and may in the worst case take longer time for lock up of the loop.
To prevent this, the intermittent operation control circuit enforces a limited error signal output of the phase detector
during power up. Thus keeping the loop locked.
PS pin must be set “L” at Power-ON.
Allow 1 µs after frequency stabilization on power-up for exiting the power saving mode (PS: L to H)
Serial data can be entered during the power saving mode.
During the power saving mode, the corresponding section except for indispensable circuit for the power saving
function stops working, then current consumption is reduced to 10µA per one PLL section.
At that time, the Do and LD become the same state as when a loop is locking. That is, the Do becomes high
impedance.
A VCO control voltage is naturally kept at the locking voltage which defined by a LPF’s time constant. As a result
of this, VCO’s frequency is kept at the locking frequency.
PSIF
PSRF
IF-PLL counters RF-PLL counters OSC input buffer
L
L
OFF
OFF
OFF
H
L
ON
OFF
ON
L
H
OFF
ON
ON
H
H
ON
ON
ON
ON
V CC
Clock
Data
LE
PS
i1j
i2j
i3j
(1) PS = L (power saving mode) at Power-ON.
(2) Set serial data after power supply remains stable.
(3) Release saving mode (PS: LfiH) after setting serial data.
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