LTC1799CS5#TR [Linear]

LTC1799 - 1kHz to 33MHz Resistor Set SOT-23 Oscillator; Package: SOT; Pins: 5; Temperature Range: 0°C to 70°C;


型号：	LTC1799CS5#TR
厂家：	Linear
描述：	LTC1799 - 1kHz to 33MHz Resistor Set SOT-23 Oscillator; Package: SOT; Pins: 5; Temperature Range: 0°C to 70°C 振荡器
文件：	总4页 (文件大小：122K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

Final Electrical Specifications

LTC1799

1kHz to 30MHz

Resistor Set SOT-23 Oscillator

January 2001

DESCRIPTIO

FEATURES

The LTC^®1799 is a precision oscillator that is easy to use

and occupies very little PC board space. The oscillator

frequency is programmed by a single external resistor

(R_SET). TheLTC1799hasbeendesignedforhighaccuracy

operation (≤1.5% frequency error) without the need for

external trim components.

■

One External Resistor Sets the Frequency

■

1kHz to 30MHz Frequency Range

■

SOT-23 Miniature Package

■

Frequency Error ≤1.5% 5kHz to 20MHz

(T_A= 25°C)

■

Frequency Error ≤2% 5kHz to 20MHz

(T_A= 0°C to 70°C)

The LTC1799 operates with a single 2.7V to 5.5V power

supply and provides a rail-to-rail, 50% duty cycle square

waveoutput.TheCMOSoutputdriverensuresfastrise/fall

times and rail-to-rail switching. The frequency-setting

resistor can vary from 3.32k to 1M to select a master

oscillator frequency between 100kHz and 30MHz (5V

supply). Thethree-stateDIVinputdetermineswhetherthe

master clock is divided by 1, 10 or 100 before driving the

output, providing three frequency ranges spanning 1kHz

to30MHz(5Vsupply).TheLTC1799featuresaproprietary

feedback loop that linearizes the relationship between

R_SETand frequency, eliminating the need for tables to

calculate frequency. The oscillator can be easily pro-

grammed using the simple formula outlined below:

■

±40ppm/°C Temperature Stability

■

0.05%/V Supply Stability

■

50% ±1% Duty Cycle 1kHz to 2MHz

■

50% ±5% Duty Cycle 2MHz to 20MHz

■

1mA Typical Supply Current

100Ω CMOS Output Driver

■

Operates from a Single 2.7V to 5.5V Supply

APPLICATIO S

■

Low Cost Precision Oscillator

■

Charge Pump Driver

■

Switching Power Supply Clock Reference

■

Clocking Switched Capacitor Filters

100,DIV PIN = V⁺

■

Fixed Crystal Oscillator Replacement

■

10k

N• R_SET

Ceramic Oscillator Replacement

f_OSC= 10MHz •

, N = 10, DIV PIN = Hi- Z

1, DIV PIN = GND

■

Small Footprint Replacement for Econ Oscillators

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

TYPICAL APPLICATIO

Typical Distribution of Frequency Error, T_A= 25°C

Basic Connection

5kHz ≤ f

≤ 20MHz

OSC

V+

LTC1799

OUT

0.1µF

5k ≤ R

≤ 200k

SET

GND

÷100

÷10

SET

DIV

Hi-Z

1799 TA01

GND

SOT-23 Actual Size

–1.25 –0.75

–0.25 0 0.25

0.75

1.25

FREQUENCY ERROR (%)

1799 TA02

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.

LTC1799

W W

U W

ABSOLUTE AXI U RATI GS

PACKAGE/ORDER I FOR ATIO

(Note 1)

TOP VIEW

ORDER PART NUMBER

Supply Voltage (V⁺) to GND ........................–0.3V to 6V

DIV to GND .................................... –0.3V to (V⁺+ 0.3V)

SET to GND ................................... –0.3V to (V⁺+ 0.3V)

OUT to GND ................................... –0.3V to (V⁺+ 0.3V)

Operating Temperature Range

OUT

DIV

LTC1799CS5

LTC1799IS5

GND

SET

S5 PACKAGE

5-LEAD PLASTIC SOT-23

S5 PART MARKING

LTC1799C ............................................... 0°C to 70°C

LTC1799I............................................ –40°C to 85°C

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec).................. 300°C

LTND

LTNE

T_JMAX= 125°C, θ_JA= 256°C/W

Consult factory for parts specified with wider operating temperature ranges.

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V⁺= 2.7V to 5.5V, R_L=5k, C_L= 5pF, Pin 4 = V⁺unless otherwise noted.

All voltages are with respect to GND.

SYMBOL PARAMETER

∆f Frequency Accuracy

CONDITIONS

MIN

TYP

MAX

UNITS

V = 5V

5kHz < f < 20MHz

±0.5

±1.5

±2

±2.5

5kHz < f < 20MHz, LTC1799C

5kHz < f < 20MHz, LTC1799I

1kHz < f < 5kHz

●

(Notes 2, 3)

±2.5

20MHz < f < 30MHz

V = 3V

5kHz < f < 10MHz

±0.5

±1.5

±2

±2.5

5kHz < f < 10MHz, LTC1799C

5kHz < f < 10MHz, LTC1799I

1kHz < f < 5kHz

●

±2.5

10MHz < f < 20MHz

Frequency-Setting Resistor Range

Maximum Frequency

∆f < 1.5%

V = 5V

200

kΩ

SET

MAX

MIN

V = 3V

∆f < 2.5%, Pin 4= 0V

V = 5V

MHz

V = 3V

Minimum Frequency

∆f < 2.5%, Pin 4= V

kHz

%/°C

%/V

∆f/∆T

∆f/∆V

Freq Drift Over Temp (Note 3)

Freq Drift Over Supply (Note 3)

SET

= 31.6k

●

±0.004

0.05

V = 2.7V to 5.5V, R = 31.6k

0.1

SET

Timing Jitter

(Note 4)

Pin 4 = V

0.06

0.13

0.4

Pin 4 = Floating

Pin 4 = 0V

Long-Term Stability of Output Frequency

Duty Cycle

300

ppm/√kHr

Pin 4 = V or Floating (DIV Either by 100 or 10)

Pin 4 = 0V (DIV by 1)

●

Operating Supply Range

Power Supply Current

●

2.7

5.5

1.1

= 200k, Pin 4 = V , R = 0

V = 5V

0.7

SET

= 10k, Pin 4 = 0V, No Load

V = 5V

●

2.4

SET

V = 3V

High Level DIV Input Voltage

Low Level DIV Input Voltage

DIV Input Current

●

V – 0.4

0.5

Pin 4 = V

●

–5

µA

DIV

Pin 4 = 0V

LTC1799

ELECTRICAL CHARACTERISTICS

All voltages are with respect to GND.

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V⁺= 2.7V to 5.5V, R_L=5k, C_L= 5pF, Pin 4 = V⁺unless otherwise noted.

SYMBOL PARAMETER

CONDITIONS

MIN

4.8

4.5

TYP

4.95

4.8

MAX

UNITS

High Level Output Voltage

Low Level Output Voltage

V = 5V

= –1mA

= –4mA

●

V = 3V

= –1mA

= –4mA

●

2.7

2.2

2.9

2.6

V = 5V

= 1mA

= 4mA

●

0.05

0.2

0.15

0.4

V = 3V

= 1mA

= 4mA

●

0.1

0.4

0.3

0.7

OUT Rise Time

(Note 5)

V = 5V

Pin 4 = V or Floating, R = 0

Pin 4 = 0V, R = 0

V = 3V

Pin 4 = V or Floating, R = 0

Pin 4 = 0V, R = 0

OUT Fall Time

(Note 5)

V = 5V

Pin 4 = V or Floating, R = 0

Pin 4 = 0V, R = 0

V = 3V

Pin 4 = V or Floating, R = 0

Pin 4 = 0V, R = 0

Note 1: Absolute Maximum Ratings are those values beyond which the life

of the device may be impaired.

Note 2: Frequencies near 100kHz and 1MHz may be generated using two

Note 4: Jitter is the ratio of the peak-to-peak distribution of the period to

the mean of the period. This specification is based on characterization and

is not 100% tested.

different values of R (see the Table 1 in the Applications Information

section). For these frequencies, the error is specified under the following

Note 5: Output rise and fall times are measured between the 10% and

90% power supply levels. These specifications are based on

characterization.

SET

assumption: 10k < R ≤ 100k.

SET

Note 3: Frequency error (defined as the deviation from the f

equation)

OSC

includes drift over temperature and over supply.

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 a ground plane.

to GND for the ÷1 setting, the highest frequency range.

Floating Pin 4 divides the master oscillator by 10. Pin 4

should be tied to V⁺for the ÷100 setting, the lowest

frequencyrange. TodetectafloatingDIVpin, theLTC1799

attempts to pull the pin toward midsupply. Therefore,

driving the DIV pin high requires sourcing approximately

5µA. Likewise, driving DIV low requires sinking 5µA.

When floated, the DIV pin will be held near midsupply by

these current sources. When it is floated, it is recom-

mended that the DIV pin be bypassed by a 1nF capacitor

or surrounded by a ground shield to prevent excessive

coupling from other PCB traces.

GND (Pin 2): Ground. Should be tied to a ground plane for

best performance.

SET (Pin 3): Frequency-Setting Resistor Input. The value

of the resistor connected between this pin and V⁺deter-

mines the oscillator frequency. The voltage on this pin is

held by the LTC1799 to approximately 1.1V below the V⁺

voltage. For best performance, use a precision metal film

resistor with a value between 10k and 200k and limit the

capacitance on this pin to less than 2pF.

OUT (Pin 5): Oscillator Output. This pin can easily drive

5kΩ or 10pF loads. Larger loads may cause inaccuracies

due to supply bounce at high frequencies.

DIV (Pin 4): Divider-Setting Input. This three-state input

selects among three divider settings, determining the

value of N in the frequency equation. Pin 4 should be tied

LTC1799

U U

APPLICATIO S I FOR ATIO

Table 1. Frequency Range vs Divider Setting

DIVIDER SETTING FREQUENCY RANGE

Selecting the Divider Setting and Resistor

The LTC1799’s master oscillator has a frequency range

spanning 0.1MHz to 30MHz. However, accuracy may

suffer if the master oscillator is operated at greater than

10MHz with a supply voltage lower than 4V. A program-

mable divider extends the frequency range to greater than

three decades. Table 1 describes the recommended fre-

quencies for each divider setting. Note that the ranges

overlap;atsomefrequenciestherearetwodivider/resistor

combinations that result in the desired frequency.

÷1

DIV (Pin 4) = GND

>500kHz

÷10

DIV (Pin 4) = Floating

50kHz to 1MHz

< 100kHz

÷100

DIV (Pin 4) = V

At master oscillator frequencies greater than 10MHz (R < 10kΩ), the

SET

LTC1799 may suffer reduced accuracy with a supply voltage less than 4V.

After choosing the proper divider setting, determine the

correct frequency-setting resistor. Because of the linear

correspondence between oscillation period and resis-

tance,asimpleequationrelatesresistancewithfrequency.

In general, any given oscillator frequency (f_OSC) should be

obtained using the lowest master oscillator frequency.

Lower master oscillator frequencies use less power and

are more accuate. For instance, f_OSC= 100kHz can be

obtained by either R_SET= 10k, N = 100, master oscillator

=10MHzorR_SET=100k, N=10, masteroscillator=1MHz.

The R_SET= 100k is preferred for lower power and better

accuracy.

R_SET= 10k • [10MHz/(N • f_OSC)], N = 1, 10, 100

(R_SETMIN= 3.32k (5V Supply), 5k (3V Supply),

R_SETMAX= 1M)

Any resistor, R_SET, tolerance adds to the inaccuracy of the

oscillator, f_OSC

Settling Time

The settling time is proportional to R_SETand is approxi-

mately t_SETTLE≈ R_SET• (5µs/kΩ). This parameter is

guaranteed by design and not 100% tested.

PACKAGE DESCRIPTIO

Dimensions in inches (millimeters) unless otherwise noted.

S5 Package

5-Lead Plastic SOT-23

(LTC DWG # 05-08-1633)

2.60 – 3.00

(0.102 – 0.118)

2.80 – 3.00

(0.110 – 0.118)

(NOTE 3)

1.50 – 1.75

(0.059 – 0.069)

0.00 – 0.15

(0.00 – 0.006)

0.90 – 1.45

(0.035 – 0.057)

0.35 – 0.55

(0.014 – 0.022)

0.35 – 0.50

(0.014 – 0.020)

FIVE PLACES (NOTE 2)

0.90 – 1.30

(0.035 – 0.051)

0.09 – 0.20

(0.004 – 0.008)

(NOTE 2)

0.95

(0.037)

REF

1.90

(0.074)

REF

NOTE:

S5 SOT-23 0599

1. DIMENSIONS ARE IN MILLIMETERS

2. DIMENSIONS ARE INCLUSIVE OF PLATING

3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR

4. MOLD FLASH SHALL NOT EXCEED 0.254mm

5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ)

1799i LT/TP 0101 2K • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

●

(408)432-1900 FAX:(408)434-0507 www.linear-tech.com

LINEAR TECHNOLOGY CORPORATION 2001

LTC1799CS5#TR [Linear]

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