Linear Technology LTC6930 Series User manual

1
DESCRIPTION
Demonstration Circuit 1141A features the LTC6930-
X.XX series family of very low power precision sili-
con oscillators with a frequency error less than
0.09% at 25 ˚C. For each oscillator, the user can
select one of 8 frequencies between 32.768 kHz
and 8.192 MHz. Based on fixed master oscillator
frequency internal frequency dividers between 1 and
128 provide the 8 different frequencies.
The LTC6930 requires no external components
other than power supply bypass capacitors and op-
erates with a single 1.7V to 5.5V supply.
A DC1141A PCB assembly consists of a 2 inch X 2
inch buffer board with a BNC output and a DIP-8
oscillator board mounted on an 8-pin socket. The
DIP-8 oscillator board can be removed from the
buffer board and used for prototyping.
The three digitally controlled inputs of an LTC6930-
X.XX (DIVA, DIVB and DIVC) can be set on a
DC1141A-X with three jumblers or set externally by
connecting wires to the on board turrets.
The Digital Input and Divider Setting:
DIVC DIVB DIVA DIVIDE BY
0 0 0 1
0 0 1 2
0 1 0 4
0 1 1 8
1 0 0 16
1 0 1 32
1 1 0 64
1 1 1 128
Note: DIVC is the MSB
There are five DC1141A boards:
1. DC1141A-A with an LTC6930-4.19
2. DC1141A-B with an LTC6930-5.00
3. DC1141A-C with an LTC6930-7.37
4. DC1141A-D with an LTC6930-8.00
5. DC1141A-E with an LTC6930-8.19
Design files for these circuit boards are available.
Call the LTC factory.
, LTC and LT are registered trademarks of Linear Technology Corporation.
THE LTC6930-X.XX FREQUENCIES
The LTC6930-4.19 (DC1141A-A)
DIVC DIVB DIVA Frequency
0 0 0 4.194304MHz
0 0 1 2.097152MHz
0 1 0 1.048576MHz
0 1 1 524.288kHz
1 0 0 262.144kHz
1 0 1 131.072kHz
1 1 0 65.536kHz
1 1 1 32.768kHz
The LTC6930-5.00 (DC1141A-B)
DIVC DIVB DIVA Frequency
0 0 0 5.0000MHz
0 0 1 2.5000MHz
0 1 0 1.2500MHz
0 1 1 625.000kHz
1 0 0 312.500kHz
1 0 1 156.250kHz
1 1 0 78.1250kHz
1 1 1 39.0625kHz
The LTC6930-7.37 (DC1141A-C)
DIVC DIVB DIVA Frequency
0 0 0 7.3728MHz
0 0 1 3.6864MHz
0 1 0 1.8432MHz
0 1 1 921.6kHz
1 0 0 460.8kHz
1 0 1 230.4kHz
1 1 0 115.2kHz
1 1 1 57.6kHz
DEMO CIRCUIT 1141A/B
QUICK START GUIDE
LTC6930-X.XX, PRECISION DIGITALLY CONTROLLED OSCILLATO
RS
LTC6930-4.19, LTC6930-5.00, LTC6930-7.37, LTC6930-8.00, LTC6930-
8.19
32.768KHZ - 8.192MHZ

DC1141A QUICK START QUIDE
2
The LTC6930-8.00 (DC1141A-D)
DIVC DIVB DIVA Frequency
0 0 0 8.000MHz
0 0 1 4.000MHz
0 1 0 2.000MHz
0 1 1 1.000MHz
1 0 0 500.0kHz
1 0 1 250.0kHz
1 1 0 125.0kHz
1 1 1 62.5kHz
The LTC6930-8.19 (DC1141A-E)
DIVC DIVB DIVA Frequency
0 0 0 8.192MHz
0 0 1 4.096MHz
0 1 0 2.048MHz
0 1 1 1.024MHz
1 0 0 512.0kHz
1 0 1 256.0kHz
1 1 0 128.0kHz
1 1 1 64.0kHz
QUICK START PROCEDURE
Test Equipment:
1. A single power supply, 3V – 5V.
2. An oscilloscope with at least 100MHz bandwidth.
3. A frequency counter
Test Procedure:
1. On the DC1141A-X.XX board set the DIVA, DIVB and DIVC jumpers to the “0” position.
2. Set power supply for 3.00V.
3. Connect power supply as shown in Figure 1.
4. Connect the VOUT BFR (J1) of the board to an oscilloscope input terminated with 50ohms.
5. Turn on the power supply.
6. The oscilloscope should show a “clean” squarewave 0V to 1.375V (the LTC6930 output is 0V to 3V
and is divided by two thru the on board buffer with a typical 2.75V logic high).
7. Remove the board connection to the oscilloscope and connect to a frequency counter.
8. The counter’s frequency should be equal to the highest LTC6930-X.XX frequency ±0.9%.
Highest Frequency (DIVC, DIVB, DIVA is 000)
DC1141A-A 4.194304MHz
DC1141A-B 5.000MHz
DC1141A-C 7.3728MHz
DC1141A-D 8.000MHz
DC1141A-E 8.192MHz
End of test.

DC1141A QUICK START GUIDE
3
100MHz Oscilloscope
50ohm
input
000000
000000000000
000000
Frequency Cou
n
ter
50
ohm input
Connect board to oscilloscope or counter
with a 50ohm BNC to BNC cable 3ft
Power Supply
3.00V
+
-
DIVA, DIVB, DIV C 000
Figure 1. Quick Test Set
-
Up

DC1141A QUICK START QUIDE
4

DC1141A QUICK START GUIDE
5

Mouser Electronics
Authorized Distributor
Click to View Pricing, Inventory, Delivery & Lifecycle Information:
Analog Devices Inc.:
DC1141A-B DC1141A-E DC1141A-A DC1141A-C DC1141A-D