Datasheet LTC6990 (Analog Devices)

LTC6990 TimerBlox: Voltage Controlled Silicon Oscillator
FEATURES DESCRIPTION
n
Fixed-Frequency or Voltage-Controlled Operation
The LTC®6990 is a precision silicon oscillator with a pro- –
Fixed: Single Resistor Programs Frequency
grammable frequency range of 488Hz to 2MHz. It can be
with <1.5% Max Error
used as a fixed-frequency or voltage-controlled oscillator –
VCO: Two Resistors Set VCO Center
(VCO). The LTC6990 is part of the TimerBlox® family of
Frequency and Tuning Range
versatile silicon timing devices. n
Frequency Range: 488Hz to 2MHz
A single resistor, RSET, programs the LTC6990’s internal n 2.25V to 5.5V Single Supply Operation master oscillator frequency. The output frequency is deter- n 72µA Supply Current at 100kHz mined by this master oscillator and an internal frequency n 500µs Start-Up Time divider, NDIV, programmable to eight settings from 1 to 128. n VCO Bandwidth >300kHz at 1MHz n CMOS Logic Output Sources/Sinks 20mA 1MHz 50kΩ n f • , N 50% Duty Cycle Square Wave Output OUT = DIV = 1, 2, 4 …128 n NDIV RSET Output Enable (Selectable Low or Hi-Z When Disabled) n Optionally, a second resistor at the SET input provides –55°C to 125°C Operating Temperature Range n linear voltage control of the output frequency and can be Available in Low Profile (1mm) SOT-23 (ThinSOT™) used for frequency modulation. A narrow or wide VCO and 2mm × 3mm DFN Package tuning range can be configured by the appropriate selec- tion of the two resistors.
APPLICATIONS
n Low Cost Precision Programmable Oscillator The LTC6990 includes an enable function that is synchro- n Voltage-Controlled Oscillator nized with the master oscillator to ensure clean, glitch-free n High Vibration, High Acceleration Environments output pulses. The disabled output can be configured to n Replacement for Fixed Crystal and Ceramic Oscillators be high impedance or forced low. n Portable and Battery-Powered Equipment For easy configuration of the LTC6990, download the L, LT, LTC and LTM, Linear Technology, TimerBlox and the Linear logo are registered TimerBlox Designer tool at www.linear.com/timerblox. 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, 6614313.
TYPICAL APPLICATION Voltage Controlled Oscillator with 16:1 Frequency Range VCO Transfer Function
1000 MHz V+ fOUT = 1MHz − VCTRL • 0.5 V 750 OE OUT LTC6990 V+ (kHz) 500 GND V+ f OUT C1 RVCO 0.1µF 100k VCTRL SET DIV 250 R 6990 TA01a SET 100k 0 0 0.5 1 1.5 2 VCTRL (V) 6990 TA01b 6990fc For more information www.linear.com/LTC6990 1 Document Outline Features Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Related Parts