L9216G データシートの表示（PDF） - Agere -> LSI Corporation

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L9216G

Short-Loop Ringing SLIC with Ground Start

Agere -> LSI Corporation 

L9216A/G

Short-Loop Ringing SLIC with Ground Start

Preliminary Data Sheet

September 2001

Description (continued)

The L9216 uses a voltage feed-current sense architec-

ture; thus, the transmit gain is a transconductance. The

L9216 transconductance is set via a single external

resistor, and this device is designed for optimal perfor-

mance with a transconductance set at 300 V/A.

The L9216 offers an option for a single-ended to differ-

ential receive gain of either 8 or 2. These options are

mask programmable at the factory and are selected by

choice of code.

A receive gain of 8 is more appropriate when choosing

a first-generation type codec where termination imped-

ance, hybrid balance, and overall gains are set by

external analog filters. The higher gain is typically

required for synthesization of complex termination

impedance.

A receive gain of 2 is more appropriate when choosing

a third-generation type codec. Third-generation codecs

will synthesize termination impedance and set hybrid

balance and overall gains. To accomplish these func-

tions, third-generation codecs typically have both ana-

log and digital gain filters. For optimal signal to noise

performance, it is best to operate the codec at a higher

gain level. If the SLIC then provides a high gain, the

SLIC output may be saturated causing clipping distor-

tion of the signal at tip and ring. To avoid this situation,

with a higher gain SLIC, external resistor dividers are

used. These external components are not necessary

with the lower gain offered by the L9216. See the Appli-

cations section of this data sheet for more information.

The L9216 is internally referenced to 1.5 V. This refer-

ence voltage is output at the VREF output of the device.

The SLIC output VITR is also referenced to 1.5 V;

therefore, it must be ac coupled to the codec input.

However, the SLIC inputs RCVP/RCVN are floating

inputs. If there is not feedback from RCVP/RCVN to

VITR, RCVP/RCVN may be directly coupled to the

codec output. If there is feedback from RCVP/RCVN to

VITR, RCVP/RCVN must be ac coupled to the codec

output.

The L9216 is packaged in a 28-pin PLCC package and

an ultrasmall 48-pin MLCC package. Use L9216A for

gain of eight applications and L9216G for gain of two

applications.

6

Agere Systems Inc.

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