Linear Technology LTC6905 Series Quick Start Manual

DC814 QUICK START GUIDE
DESCRIPTION
Demonstration circuit DC814 provides a simple evaluation
circuit for Linear Technology's resistor-set and fixed frequency
silicon oscillators. For each silicon oscillator, there are two
demo boards:
Board 1, a DIP-8 Clock Board
(a silicon oscillator is mounted on this board).
Board 2, a Buffer Board
(a board with a high speed driver for the DIP-8 Clock Board).
DIP-8 CLOCK BOARDS
A DIP-8 Clock Board is a small printed circuit board containing
a silicon oscillator that is pin compatible with "half-size"
canned crystal oscillators (13mm X 13mm). For the resistor-
settable versions, the DIP-8 Clock Boards have surface mount
pads for installing 0603 size resistors to program the output
frequency (RS1 on clock board).
All of the resistor-settable oscillators, except for the LTC6908-
x, have a divider input. For these DIP-8 Clock Boards, an op-
tional jumper is provided to set the divider value.
The LTC6905-xxx series are fixed frequency oscillators and
their DIP-8 Clock Boards do not require a frequency setting
resistor.
The LTC6908-x boards have a modulation control input (MOD)
and the corresponding DIP-8 Clock Boards provide an optional
jumper to configure the spread spectrum frequency modula-
tion (SSFM). A jumper can be used to disable the SSFM or set
the rate to 1 of 3 rates (see datasheet for details on the SSFM
rate selection).
A DIP-8 Board is ordered independently (see Table 1).
BUFFER BOARDS
The Buffer Boards contain a buffering circuit designed specifi-
cally for DIP-8 Clock Boards. The DIP-8 Clock Board mounts
onto a DIP-8 socket on the Buffer Board. A multi-turn potenti-
ometer on the Buffer Board is provided to adjust oscillator
frequency of a DIP-8 Clock Board (a potentiometer is not re-
quired for the LTC6905-X series).
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DEMO CIRCUIT DC814
QUICK START GUIDE
DEMONSTRATION CIRCUIT:
LTC1799, LTC6900, LTC6905, LTC6905-XXX,
LTC6906, LTC6907, LTC6908-X
A unique Buffer Board is available for each DIP-8 Board
(see Table 2).
A high-speed driver with a maximum output current of
±100mA buffers the output of the DIP-8 clock. The output of
the buffer is connected through a 50ohm resistor to a BNC
connector for driving 50-ohm coaxial cables.
NOTE: The DC814D-J and DC814D-K (DIP-8 Clock Boards for
the LTC6908-1 & LTC6908-2) have an additional output
(OUT2). The user can install a pin for access to this output.
However, the DIP-8 board will not fit into the buffer board with
an installed pin for OUT2. The user must bend this pin or in-
stall a 90° pin to use the DC814D-x DIP-8 Clock Boards with
the buffer boards.
Design files for this circuit board are available.
Call the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Table 1. DIP-8 Clock Board Part Numbers
DIP-8 Clock Board
DC814B-A
DC814B-B
DC814B-C
DC814B-D
DC814B-E
DC814B-F
DC814B-G
DC814C-H
DC814C-I
DC814D-J
DC814D-K
SILICON OSCILLATOR
Clock IC
LTC6905
LTC1799
LTC6900
LTC6905-133
LTC6905-100
LTC6905-96
LTC6905-80
LTC6906
LTC6907
LTC6908-1
LTC6908-2
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