DS1090 Просмотр технического описания (PDF) - Maxim Integrated

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DS1090

Low-Frequency, Spread-Spectrum EconOscillator

Maxim Integrated 

DS1090

Low-Frequency, Spread-Spectrum EconOscillator

Table 2. Dither Percentage Setting

J1

J0

DITHER PERCENT (%)

0

0

0

0

1

2

1

0

4

1

1

8

Dither Percentage Settings

Dither amplitude (measured in percent ± from the master

oscillator center frequency) is set using input pins J0 and

J1. This circuit uses a sense current from the master

oscillator bias circuit to adjust the amplitude of the tri-

angle-wave signal to a voltage level that modulates the

master oscillator to a percentage of its resistor-set center

frequency. This percentage is set in the end application to

be 0%, 2%, 4%, or 8% (see Table 2).

Application Information

Pin Connection

The DS1090 is intended to provide a fixed-frequency,

dithered clock to be used as a clock driver for DC-DC

converters and other applications requiring a low-

frequency EMI-reduced clock oscillator. All control pins

must be biased per Tables 1 and 2 for proper operation

for the individual application’s requirements. RSET must

be tied to ground (GND) by a customer-supplied resistor.

RSET Resistor Selection

The value of the resistor used to select the desired

frequency is calculated using the formula in the Master

Oscillator section (see also Figure 1). It is recommended

to use, at minimum, a 1%-tolerance, 1/16th-watt component

with a temperature coefficient that satisfies the overall

stability requirements desired of the end-equipment.

Place the external RSET resistor as close as possible to

minimize lead inductance.

Power-Supply Decoupling

To achieve best results, it is highly recommended that a

decoupling capacitor is used on the IC power-supply pins.

Typical values of decoupling capacitors are 0.01µF and

0.1µF. Use a high-quality, ceramic, surface-mount capaci-

tor, and mount it as close as possible to the VCC and GND

pins of the IC to minimize lead inductance.

Chip Information

SUBSTRATE CONNECTED TO GROUND

Package Information

For the latest package outline information and land patterns

(footprints), go to www.maximintegrated.com/packages. Note

that a “+”, “#”, or “-” in the package code indicates RoHS status

only. Package drawings may show a different suffix character, but

the drawing pertains to the package regardless of RoHS status.

www.maximintegrated.com

Maxim Integrated │  8

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