ICS308 Datasheet, PDF (3/9 Pages) Integrated Circuit Systems – SERIAL PROGRAMMABLE QUAD PLL VERSACLOCK SYNTHESIZER

ICS308
SERIAL PROGRAMMABLE QUAD PLL VERSACLOCK SYNTHESIZER
SER PROG CLOCK SYNTHESIZER
Configuring the ICS308
Initial State: The ICS308 may be configured to have up to nine frequency outputs, utilizing the four
on-board PLLs. Unprogrammed, the part has the following outputs, related to the reference input clock:
Default Outputs
Output
Frequency
Clock 1-9 (Pins 4, 10 - 14) Reference Output
The STROBE pin must have an external 250 kOhm pull-up resistor to achieve the Initial State.
The input crystal range for the ICS308 is 5 MHz to 27 MHz.
The ICS308 can be programmed to set the output functions and frequencies. 160 data bits generated by
the VersaClock^TM software are written in DATA pin in this order: MSB (left most bit) first.
As show in Figure 2, after these 160 bits are clocked into the ICS308, taking STROBE high will send this
data to the internal hatch and the CLK output will lock within 10 ms.
Note: STROBE utilizes a transparent latch that is latched when in the high state. If STROBE is in the high
state and SCLK is pulsed, DATA is clocked directly to the internal latch and the output conditions will
change accordingly. Although this will not damage the ICS308, it is recommended that STROBE be kept
low while DATA is being clocked into the ICS308 in order to avoid unintended changes on the output clocks.
All outputs may be turned off during initialization by bringing the PDTS pin to Ground. When PDTS is
brought high, after the Strobe pin in brought high, the programmed output frequencies will be available.
AC Parameters for Writing to the ICS308
Parameter
t_SETUP
t_HOLD
t_W
t_S
Condition
Setup time
Hold time after SCLK
Data wait time
Strobe pulse width
SCLK Frequency
Min.
10
10
10
40
Max.
30
Units
ns
ns
ns
ns
MHz
DATA Bit160 Bit159 Bit158
t_setup
t_hold
Bit3 Bit2 Bit1
SCLK
STROBE
t_w
t_s
Figure 2. Timing Diagram for Programming the ICS308
IDT™ / ICS™ SERIAL PROGRAMMABLE QUAD PLL VERSACLOCK SYNTHESIZER 3
ICS308
REV J 120507