T7503 datasheet(9/16 Pages) AGERE

9 / 16 page

Lucent Technologies Inc.

Data Sheet

February 1998

T7503 Dual PCM Codec with Filters

Transmission Characteristics (continued)

ac Transmission Characteristics (continued)

* For Table 12, crosstalk into the transmit channels (VFXIN) can be signiﬁcantly affected by parasitic capacitive feeds from GSX and VFRO out-

puts. PWB layouts should be arranged to keep these parasitics low. The resistor value of RF (from GSX to VFXIN) should also be kept as low

as possible (while maintaining the load on GSX above 10 k

Ω per Table 4) to minimize crosstalk.

* For Table 13, crosstalk into the transmit channels (VFXIN) can be signiﬁcantly affected by parasitic capacitive feeds from GSX and VFRO out-

puts. PWB layouts should be arranged to keep these parasitics low. The resistor value of RF (from GSX to VFXIN) should also be kept as low

as possible (while maintaining the load on GSX above 10 k

Ω per Table 4) to minimize crosstalk.

Table 12. Interchannel Crosstalk (Between Channels) RF =

≤400 kΩ*

Parameter

Symbol

Test Conditions

Min

Typ

Max

Unit

Transmit to Receive

Crosstalk 0 dBm0

Transmit Levels

CTXX-RY

f = 300 Hz—3400 Hz

idle PCM code for channel under test;

0 dBm0 into any other single-channel VFXIN

—

–75

Receive to Transmit

Crosstalk 0 dBm0

Receive Levels

CTRX-XY

f = 300 Hz—3400 Hz

VFXIN = 0 Vrms for channel under test;

0 dBm0 code level on any other single-channel DR

—

–75

Transmit to Trans-

mit Crosstalk

0 dBm0 Transmit

Levels

CTXX-XY

f = 300 Hz—3400 Hz

0 dBm0 applied to any single-channel

VFXIN except channel under test,

which has VFXIN = 0 Vrms

—

–75

Receive to Receive

Crosstalk 0 dBm0

Receive Levels

CTRX-RY

f = 300 Hz—3400 Hz

0 dBm0 code level on any single-channel DR except

channel under test which has idle code applied

—

–75

Table 13. Intrachannel Crosstalk (Within Channels) RF =

≤400 kΩ*

Parameter

Symbol

Test Conditions

Min

Typ

Max

Unit

Transmit to Receive

Crosstalk 0 dBm0

Transmit Levels

CTXX-RX

f = 300 Hz—3400 Hz

idle PCM code for channel under test;

0 dBm0 into VFXIN

—

–65

Receive to Transmit

Crosstalk 0 dBm0

Receive Levels

CTRX-XX

f = 300 Hz—3400 Hz

VFXIN = 0 Vrms for channel under test;

0 dBm0 code level on DR

—

–65

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