FD77T Series Multi-Output
CMOS Clock Oscillator
February 2008
www.pletronics.com
425-776-1880
2
Description:
The FD77T series Multi-Output CMOS Clock Oscillator is a modular PLL-based low cost, high-
performance, programmable oscillator. The FD77T generates up to seven output frequencies, OUT1
through OUT7. Frequencies are mutually independent and may be programmed to any frequency from
100KHz to 230-MHZ and one output can be as low as 12KHz.
The FD77T base frequency, as noted in the device part number, is established during manufacture and is
permanently fixed. For convenience, the divider for output OUT1 and the remaining seven output
frequencies, and their characteristics may be pre-programmed at the factory, or field programmed.
The FD77T has a separate output supply pin, V
ccout, for either 2.5 or 3.3V output logic levels. The device
supply, V
DD which provides power to all the internal circuits, is nominally 1.8V.
The deep M/N PLL divider ratio allows the generation of zero-ppm clocks for applications such as WLAN,
BlueTooth, Ethernet, GPS, USB, IEEE1394, etc. from the base frequency.
Each of the four independent PLLs supports Spread Spectrum Clocking (SSC). SSC may be programmed
to be either center-spread or down-spread. This is an important technique to reduce electro-magnetic
interference (EMI).
The device supports non-volatile eePROM programming for easy customization of the device. As
shipped, the device is pre-programmed. Standard combinations are denoted by three characters in the
device part number. However, the FD77T may be reprogrammed to a different configuration.
Reprogramming may be either prior to assembly, or in-circuit via a 2-wire SDA/SCL I
2C bus.
Reference
oscillator
optional
Voltage
controlled
Vcontrol (2)
Programming
control
eePROM
SDA/SCL
Registers
Sx Control
S2/SCL (12)
S1/SDA (13)
S0
(14)
PLL Multiplier #1
optional Spread Spectrum
optional Bypass Mode
Divider #8
/1 to /127
Divider #9
/1 to /127
MUX #7
Y9
(7)
Out7
(6)
Out6
MUX #6
Y8
(8)
Out5
MUX #5
Y7
(4)
Out4
MUX #4
Y5
(9)
Out3
MUX #3
Y3
(10)
Out2
MUX #2
Y2
(11)
Out1
Y1
Divider #6
/1 to /127
Divider #7
/1 to /127
PLL Multiplier #1
optional Spread Spectrum
optional Bypass Mode
Divider #4
/1 to /127
Divider #5
/1 to /127
PLL Multiplier #1
optional Spread Spectrum
optional Bypass Mode
Divider #2
/1 to /127
Divider #3
/1 to /127
PLL Multiplier #1
optional Spread Spectrum
optional Bypass Mode
MUX #1
Divider #1
/1 to /1023
Vdd
(5)
Vdd 1.8V (1)
Ground (2)