LTC6903_15 Datasheet, PDF (1/14 Pages) Linear Technology – 1kHz to 68MHz Serial Port Programmable Oscillator

LTC6903/LTC6904
1kHz to 68MHz Serial
Port Programmable Oscillator
Features
n _{1kHz to 68MHz Square Wave Output}
n _{0.5% (Typ) Initial Frequency Accuracy}
n _{Frequency Error <1.1% Over All Settings}
n _{10ppm/°C Typical Frequency Drift Over}
Temperature
n _{0.1% Resolution}
n _{1.7mA Typical Supply Current (f < 1MHz, VS = 2.7V)}
n _{2.7V to 5.5V Single- Supply Operation}
n _{Jitter <0.4% Typical 1kHz to 8MHz}
n _{Easy to Use SPI (LTC6903) or I}²_{C (LTC6904) Serial}
Interface
n _{Output Enable Pin}
n _{–55°C to 125°C Operation}
n _{MS8 Package}
Applications
n _{Precision Digitally Controlled Oscillator}
n _{Power Management}
n _{Direct Digital Frequency Synthesis (DDS)}
Replacement
n _{Replacement for DAC and VCO}
n _{Switched Capacitor Filter Clock}
Description
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 set-
ting and frequency, resulting in a very simple frequency
setting equation:
f = 2^OCT • ^2078(Hz) ;1kHz < f < 68MHz


2
–
DAC
1024


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.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners. Protected by U.S. Patents, including 6342817 and 6614313.
Typical Application
A Microcontroller Controlling Its Clock
10k
5V
0.1µF
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
69034 AT01
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 (%)
69034 TA01b
69034fe
1