LTC6990

1

Rev. D

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TYPICAL APPLICATION

DESCRIPTION

The LTC®6990 is a precision silicon oscillator with a pro-

grammable frequency range of 488Hz to 2MHz. It can be

used as a fixed-frequency or voltage-controlled oscillator

(VCO). The LTC6990 is part of the TimerBlox® family of

versatile silicon timing devices.

A single resistor, RSET, programs the LTC6990’s inter-

nal master oscillator frequency. The output frequency

is determined by this master oscillator and an internal

frequency divider, NDIV, programmable to eight settings

from 1 to 128.

fOUT =

1MHz

NDIV

•

50kΩ

RSET

, NDIV = 1, 2, 4 …128

Optionally, a second resistor at the SET input provides

linear voltage control of the output frequency and can be

used for frequency modulation. A narrow or wide VCO

tuning range can be configured by the appropriate selec-

tion of the two resistors.

The LTC6990 includes an enable function that is synchro-

nized with the master oscillator to ensure clean, glitch-

free output pulses. The disabled output can be configured

to be high impedance or forced low.

For easy configuration of the LTC6990, use the TimerBlox

LTC6990: Voltage Controlled Oscillator Web-Based

Design Tool.

Voltage Controlled Oscillator with 16:1 Frequency Range

FEATURES

APPLICATIONS

n

Fixed-Frequency or Voltage-Controlled Operation

n

Fixed: Single Resistor Programs Frequency with

<1.5% Max Error

n

VCO: Two Resistors Set VCO Center Frequency

and Tuning Range

n

Frequency Range: 488Hz to 2MHz

n

2.25V to 5.5V Single Supply Operation

n

72µA Supply Current at 100kHz

n

500µs Start-Up Time

n

VCO Bandwidth >300kHz at 1MHz

n

CMOS Logic Output Sources/Sinks 20mA

n

50% Duty Cycle Square Wave Output

n

Output Enable (Selectable Low or Hi-Z When Disabled)

n

55°C to 125°C Operating Temperature Range

n

Available in Low Profile (1mm) SOT-23 (ThinSOT™)

and 2mm × 3mm DFN Package

n

AEC-Q100 Qualified for Automotive Applications

n

Low Cost Precision Programmable Oscillator

n

Voltage-Controlled Oscillator

n

High Vibration, High Acceleration Environments

n

Replacement for Fixed Crystal and Ceramic Oscillators

n

Portable and Battery-Powered Equipment

VCO Transfer Function

VCTRL (V)

0

1000

750

250

500

0

0.5

6990 TA01b

2

1

1.5

6990 TA01a

LTC6990

OE

GND

SET

OUT

V+

DIV

C1

0.1µF

RSET

100k

V+

V+

VCTRL

RVCO

100k

fOUT = 2MHz − VCTRL •

MHz

V

All registered trademarks and trademarks are the property of their respective owners. Protected

by U.S. patents, including 6342817, 6614313.

TimerBlox: Voltage Controlled

Silicon Oscillator