PLL1700
6SBOS096A
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The PLL1700 provides a very low jitter, high accuracy
clock. SCKO1 is a fixed frequency clock which is
33.8688MHz (768 x 44.1kHz) for a CD-DA DSP. The
output frequency of the remaining clocks is determined by
the sampling frequency (fS) by software or hardware
control. SCKO2 and SCKO3 output 256fS and 384fS
systems clocks, respectively. SCKO4 output is 768fS if the
sampling frequency is 32kHz, 44.1kHz, 48kHz, or the
output is 384fS if the sampling frequency is 64kHz, 88.2kHz,
or 96kHz. Table I shows each sampling frequency. The
system clock output frequencies are generated by a
27MHz master clock and programmed sampling frequen-
cies are shown in Table II.
SAMPLING
FREQUENCY SAMPLING SKCO2 SCKO3 SCKO4
(kHz) RATE (MHz) (MHz) (MHz)
32 Standard 8.192 12.288 24.576
44.1 Standard 11.2896 16.9344 33.8688
48 Standard 12.288 18.4320 36.8640
64 Double 16.384 24.576 24.576
88.2 Double 22.5792 33.8688 33.8688
96 Double 24.576 36.8640 36.8640
TABLE II. Sampling Frequencies and Master Clock
Output Frequencies.
SAMPLING
SAMPLING RATE FREQUENCY (kHz)
Standard Sampling Frequencies 32 44.1 48
Double of Standard Sampling Frequencies 64 88.2 96
TABLE I. Sampling Frequencies.
FUNCTION CONTROL
The built-in function of the PLL1700 can be controlled in
the software mode (serial mode), which uses a three-wire
interface by ML (pin 1), MC (pin 20), and MD (pin 19), when
MODE (pin 2) = L. They can also be controlled in the
hardware mode (parallel mode) which uses SR0 (pin 1),
FS1 (pin 20) and FS0 (pin 19), when MODE (pin 2) = H.
The selectable functions are shown in Table III.
HARDWARE SOFTWARE
MODE MODE
FUNCTION (MODE = H) (MODE = L)
Sampling Frequency Select
(32kHz, 44.1kHz, 48kHz) Yes Yes
Sampling Rate Select (Standard/Double) Yes Yes
Each Clock Output Enable/Disable No Yes
TABLE III. Selectable Functions.
Response time from power-on (or applying the clock to
XT1) to SCKO settling time is typically 15ms. Delay time
from sampling frequency change to SCKO settling time is
20ms maximum. Figure 4 illustrates SCKO transient
timing.
External buffers are recommended on all output clocks in
order to avoid degrading the jitter performance of the
PLL1700.
RESET
The PLL1700 has an internal power-on reset circuit, as
well as an external forced reset (RST, pin 18). Both resets
have the same effect on the PLL1700 functions. The
mode register default settings for software mode are
initialized by reset. Throughout the reset period, all clock
outputs are enabled with the default settings. Initialization
for the internal power-on reset is done automatically
during 1024 master clocks at VDD ≥ 2.2V (1.8V to 2.6V).
When using the internal power-on reset, RST should be
HIGH. Power-on reset timing is shown in Figure 5. RST
(pin 18) accepts an external forced reset by RST = L.
Initialization (reset) is done when RST = L and 1024
master clocks after RST = H. External reset timing is
shown in Figures 6 and 7.
FUNCTION DEFAULT
Sampling Frequency Select (32kHz, 44.1kHz, 48kHz) 48kHz Group
Sampling Rate Select (Standard/Double) Standard
Each Clock Output Enable/Disable Enable
TABLE IV. Selectable Functions.
FS1 (Pin 20) FS0 (Pin 19) SAMPLING GROUP
L L 48kHz
L H 44.1kHz
H L 32kHz
H H Reserved
SR0 (Pin 1) SAMPLING RATE SELECT
L Standard
H Double
HARDWARE MODE (MODE = H)
In the hardware mode, the following functions can be
selected:
Sampling Group Select
The sampling frequency group can be selected by FS1
(pin 20) and FS0 (pin 19). This selection must be made
with an interval time greater than 20µs.
Sampling Rate Select
The sampling rate can be selected by SR0 (pin 1).
SOFTWARE MODE (MODE = L)
The PLL1700 special function in software mode is shown
in Table IV. These functions are controlled using ML, MC,
and MD serial control signal.