CS61582 datasheet(27/32 Pages) CIRRUS

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nected together at the device. A 4.99k

Ω ± 1% re-

sistor must be connected from BGREF to ground

to provide an internal current reference.

De-coupling and filtering of the power supplies is

crucial for the proper operation of the analog cir-

cuits. A capacitor should be connected between

each supply and its respective ground. For capaci-

tors smaller than 1

µF, use mylar or ceramic

capacitors and place them as close as possible to

their respective power supply pins. Wire-wrap

bread boarding of the line interface is not recom-

mended because lead resistance and inductance

defeat the function of the de-coupling capacitors.

Crystal Oscillator

When a reference clock signal is not available, a

CMOS crystal oscillator operating at either the

1X or 8X rate can be connected at the REFCLK

pin. The oscillator must have a minimum symme-

try of 40-60% and minimum stability of

±100

ppm for T1 and E1 applications. Based on these

specifications, some suggested crystal oscillators

for use with the CS61582 are shown in Table

Α2.

Transformers

Recommended transformer specifications are

shown in Table A3. Based on these specifications,

the transformers recommended for use with the

CS61582 are listed in Table A4.

Line Protection

Secondary protection components can be added

to the line interface circuitry to provide lightning

surge and AC power-cross immunity. For addi-

tional information on the different electrical

safety standards and specific application circuit

recommendations, refer to the Crystal Semicon-

ductor Application Note "Secondary Line

Protection for T1 and E1 Line Cards."

Manufacturer

Part Number

Contact Number

Comclok

CT31CH

(800) 333-9825

CTS

CXO-65HG-5-I (815) 786-8411

M-tron

MH26TAD

(800) 762-8800

SaRonix

NTH250A

(800) 227-8974

Notes:

Frequency tolerances are

±32 ppm with a -40 to +85 °C

operating temperature range.

All are 8-pin DIP packages and can be tristated.

Table A2. Suggested Crystal Oscillators

Turns ratio

1:1.15 step-up transmit

1:1.15 step-down receive

Primary inductance

1.5 mH min at 772 kHz

Primary leakage

inductance

0.3

µH max at 772 kHz

with secondary shorted

Secondary leakage

inductance

0.4

µH max at 772 kHz

Interwinding

capacitance

18 pF max, primary to

secondary

ET-constant

16 V-

µs min

Table A3. Transformer Specifications

DS224PP1

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