Quick Start Procedure - Linear Technology LTC6905 Series Quick Start Manual

DC814 QUICK START GUIDE
Figure 4. The DC814A2-X Buffer Board

QUICK START PROCEDURE

TEST PROCEDURE: BUFFER BOARD WITH DIP-8 CLOCK
Test Equipment:
1. A single power supply, 3V to 5V.
2. An oscilloscope with a bandwidth of at least
10x the highest clock IC frequency (for exam-
ple, the highest frequency of the LTC6905 is
170MHz and the oscilloscope bandwidth
should be at least 1.7GHz).
3. A frequency counter
4. A potentiometer screwdriver
5. A resistance meter
1. Test Procedure for the Resistor SET ICs:
IC
LTC6905
LTC1799
LTC6900
LTC6906
LTC6907
LTC6908-1
LTC6908-2
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Buffer Board
DC814A-A
DC814A-B
DC814A-C
DC814A-H
DC814A-I
DC814A-J
DC814A-K
1. Remove DIP-8 clock board from buffer board
2. Set the jumper shunt on the DIP-8 clock board
to the divider value, N, for the frequency range
of interest (refer to Table 5).
NOTE: On DC814D-J or K DIP-* board only N=1
is available in the JP1 1-2 position with spread
spectrum modulation disabled. JP1 positions 3-4,
5-6 and 7-8 set the spread spectrum modulation
rate to fout/16, fout/32 and fout/64 respectively.
3. Connect a resistance meter from the V+ turret
to pin 1 of the buffer board socket (see figure
4). Adjust the buffer board potentiometer
(RSET1) to set the total resistance (RSET1
plus RSET2) for the desired frequency. Table 5
shows the equation for RSET (RSET1 plus
RSET2). The resistor designator for the RSET
resistor on the DIP-8 clock board is RS1.
NOTE: The frequency adjustment is very coarse
when the potentiometer is turned near the fully
clockwise position.
4. Connect buffer board to a single power supply
and an oscilloscope as shown in Figure 6 (the
oscilloscope input should be set to 50 ohms
impedance internally or terminated externally
with a 50 ohm BNC thru terminator).
5. Insert the DIP-8 clock board on the buffer
board and turn on the power supply.
6. The oscilloscope waveform should be a 0V to
V+/2 squarewave (the output of the clock is di-
vided by two by 50 ohms in series with the
buffer output and the 50 ohm oscilloscope in-
put).
7. Connect the buffer board CLKOUT to a fre-
quency counter to measure the frequency pre-
cisely (the maximum frequency error at 25 °C
is listed in Table 5).
3