Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsLinear ICsLTC6905CS5-100#TRMPBF

LTC6905-XXX Series

6905xfa

, LTC and LT are registered trademarks of Linear Technology Corporation.

■

No External Components to Set Frequency

■

Frequency Error: ±0.5% Typical

■

Fast Start-Up Time: 100µs Typical

■

±20ppm/°C Temperature Stability

■

Includes Output Enable

■

Includes Frequency Divide by 1, 2 or 4

■

Rise Time: 0.5ns, C

= 5pF

■

Timing Jitter: <0.8% Typical

■

Duty Cycle: 50% ±2.5%

■

= 8mA Typical (f

OSC

= 100MHz, C

= 5pF)

■

CMOS Output Drives 600Ω Load

■

Single Supply 2.7V to 5.5V

■

Low Profile (1mm) ThinSOT

Package

Fixed Frequency

SOT-23 Oscillator

■

Data Clocks for High Reliability Applications

■

High Vibration, High Acceleration Environments

■

Replacement for Fixed Crystal and Ceramic

Oscillators

The LTC

6905-XXX series are precision, fixed frequency

silicon oscillators designed to minimize board space while

maximizing accuracy and ease of use.

Programmed at the factory to a fixed frequency, the

LTC6905-XXX series of parts need no external trim com-

ponents. An internal three-state divider allows for division

of the master clock by 1, 2 or 4, providing 3 frequencies

(for each device).

The LTC6905-XXX series operate with a single 2.7V to

5.5V power supply and provide a rail-to-rail, 50% duty

cycle, square wave output. The OE pin will disable the

output when brought low and synchronously enable the

output when brought high, avoiding pulse slivers.

The four products of the LTC6905-XXX family are:

LTC6905-133: f

OSC

= 133MHz, 66.7MHz, 33.3MHz

LTC6905-100: f

OSC

= 100MHz, 50MHz, 25MHz

LTC6905-96: f

OSC

= 96MHz, 48MHz, 24MHz

LTC6905-80: f

OSC

= 80MHz, 40MHz, 20MHz

The LTC6905-XXX series of parts provides a factory trim

option to modify the divider ratios from 1, 2, 4 to 8, 16, 32.

A second trim option allows for additional master clock

frequencies. For the alternate divider ratios and unlisted

frequencies, contact LTC marketing.

Basic Connection

Typical Distribution of Frequency Error, T

= 25°C

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

ThinSOT is a trademark of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

Protected by U.S. Patents, including 6614313, 6342817.

OSC

= 133MHz

0.1µF

6905x TA01

GND

LTC6905-133

OUT

DIV

OPEN

÷2

÷1

÷4

% FREQUENCY ERROR

–1

UNITS

= 3V

–0.5 0.0 0.5

6905x TA02

Summary of content (8 pages)

PAGE 1
LTC6905-XXX Series Fixed Frequency SOT-23 Oscillator U FEATURES DESCRIPTIO ■ The LTC®6905-XXX series are precision, fixed frequency silicon oscillators designed to minimize board space while maximizing accuracy and ease of use. ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ No External Components to Set Frequency Frequency Error: ±0.5% Typical Fast Start-Up Time: 100µs Typical ±20ppm/°C Temperature Stability Includes Output Enable Includes Frequency Divide by 1, 2 or 4 Rise Time: 0.5ns, CL = 5pF Timing Jitter: <0.
PAGE 2
LTC6905-XXX Series W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage (V +) to GND ........................– 0.3V to 6V DIV to GND .................................... – 0.3V to (V + + 0.3V) OE to GND ..................................... – 0.3V to (V + + 0.3V) Output Short-Circuit Duration (Note 6) ........... Indefinite Operating Temperature Range (Note 8) LTC6905C .......................................... – 40°C to 85°C LTC6905I ................................
PAGE 3
LTC6905-XXX Series ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full specified temperature range, otherwise specifications are at TA = 25°C or as noted. OE = DIV = V+, V+ = 2.7V to 3.6V, RL = 15k, CL = 5pF, unless otherwise noted. All voltages are with respect to GND. SYMBOL V+ IS PARAMETER CONDITIONS Duty Cycle DIV = 0V Operating Supply Range Power Supply Current DIV = 0 (÷ 4), V+ = 3.
PAGE 4
LTC6905-XXX Series U W TYPICAL PERFOR A CE CHARACTERISTICS Supply Current vs Frequency 18 5.5V 2.7V 16 2.00 14 FREQUENCY ERROR (%) SUPPLY CURRENT (mA) Frequency Error vs Supply Voltage 2.50 ÷1 12 10 ÷2 8 ÷1 ÷4 6 ÷2 4 ÷4 LTC6905-133 1.50 1.00 0.50 LTC6905-100 LTC6905-96 LTC6905-80 O 2 0 –0.50 0 100 50 200 150 2.5 3 FREQUENCY (MHz) 3.5 4 4.5 SUPPLY VOLTAGE (V) Jitter vs Frequency 45 Frequency vs Temperature 1.0 1.20 0.8 40 ÷4 35 30 ÷2 ÷1 PERCENTAGE ERROR (%) 1.00 0.
PAGE 5
LTC6905-XXX Series U U U PI FU CTIO S V+ (Pin 1): Voltage Supply (2.7V ≤ V+ ≤ 5.5V). This supply must be kept free from noise and ripple. It should be bypassed directly to the GND (Pin 2) with a 0.1µF capacitor or higher. to V+ for the ÷1 setting, the highest frequency range. Floating Pin 4 divides the master oscillator by 2. Pin 4 should be tied to GND for the ÷4 setting, the lowest frequency range. To detect a floating DIV pin, the LTC6905 attempts to pull the pin toward midsupply.
PAGE 6
LTC6905-XXX Series U W U U APPLICATIO S I FOR ATIO START-UP TIME The start-up and settling time to within 1% of the final frequency is typically 100µs. MAXIMUM OUTPUT LOAD The LTC6905 output (Pin 5) can drive a capacitive load (CLOAD) of 5pF or more. Performance driving a CLOAD greater than 5pF depends on the oscillator’s frequency (fOSC) and output resistance (ROUT). The output rise time or fall time due to ROUT and CLOAD is equal to 2.2 • ROUT • CLOAD (from 10% to 90% of the rise or fall transition).
PAGE 7
LTC6905-XXX Series U PACKAGE DESCRIPTIO S5 Package 5-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1635) 0.62 MAX 0.95 REF 2.90 BSC (NOTE 4) 1.22 REF 3.85 MAX 2.62 REF 1.4 MIN 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.30 – 0.45 TYP 5 PLCS (NOTE 3) 0.95 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 0.09 – 0.20 (NOTE 3) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3.
PAGE 8
LTC6905-XXX Series U TYPICAL APPLICATIO S Driving a 50Ω Cable with the LTC6905 1 3V 0.1µF 2 3 3V 5 V+ OUT LTC6905-XXX 50Ω CABLE 950Ω VOUT 20 50Ω GND OE 6905x TA02 4 DIV Driving the DIV Pin Without Three-State Buffers A 0 0 1 1 B 0 1 0 1 DIV ÷1 ÷2 ÷2 ÷4 3V 0.