LTC6903 Datasheet, PDF (1/12 Pages) Linear Technology – 1kHz - 68MHz Serial Port Programmable Oscillator

LTC6903/LTC6904
1kHz - 68MHz Serial
Port Programmable Oscillator
FEATURES
s _{1kHz to 68MHz Square Wave Output}
s _{0.5% (Typ) Initial Frequency Accuracy}
s _{Frequency Error <1.1% Over All Settings}
s _{10ppm/°C Typical Frequency Drift Over}
Temperature
s _{0.1% Resolution}
s _{1.7mA Typical Supply Current (f < 1MHz, VS = 2.7V)}
s _{2.7V to 5.5V Single Supply Operation}
s _{Jitter <0.4% Typical 1kHz to 8MHz}
s _{Easy to Use SPI (LTC6903) or I}²_{C (LTC6904) Serial}
Interface
s _{Output Enable Pin}
s _{–40°C to 125°C Operation}
s _{MS8 Package}
U
APPLICATIO S
s _{Precision Digitally Controlled Oscillator}
s _{Power Management}
s _{Direct Digital Frequency Synthesis (DDS)}
Replacement
s _{Replacement for DAC and VCO}
s _{Switched Capacitor Filter Clock}
DESCRIPTIO
The LTC^®6903/LTC6904 are low power self contained
digital frequency sources providing a precision frequency
from 1kHz to 68MHz, set through a serial port. The
LTC6903/LTC6904 require no external components other
than a power supply bypass capacitor, and they operate
over a single wide supply range of 2.7V to 5.5V.
The LTC6903/LTC6904 feature a proprietary feedback
loop that linearizes the relationship between digital control
setting and frequency, resulting in a very simple frequency
setting equation:
f
=
2^OCT
•
2078(Hz)
_{2 – 1D0A2C4}
;1kHz
<
f
<
68MHz
Where OCT is a 4-bit digital code and DAC is a 10-bit digital
code.
The LTC6903 is controlled by a convenient SPI compatible
serial interface. The LTC6904 uses an industry standard
I²C compatible interface.
, LTC and LT are registered trademarks of Linear Technology Corporation.
U.S. Patent Numbers 6342817 and 6614313.
TYPICAL APPLICATIO
10k
5V
0.1µF
A Microcontroller Controlling Its Clock
MICROCONTROLLER
OSC1/CLKIN
OSC2/CLKOUT
MCLR/V_P–P ^RC5/SDO
RC3/SCK/SCL
V_DD
RC2/CCP1
V_SS
V_SS
PIC16F73
5V
GND
V⁺
SDI
OE
LTC6903
SCK
CLK
SEN
CLK
POWER-UP CLOCK
FREQUENCY IS 1039Hz
10Ω
1µF
0.01µF
6903 TA01
LTC6903 Frequency Error
Distribution
40 _{VS = 3V}
T_A = 25°C
f = 1039Hz
30
443
UNITS
TESTED
20
10
0
–1.0
–0.5
0
0.5
1.0
FREQUENCY ERROR (%)
6903 TA01b
69034fa
1