DS26503 datasheet(21/123 Pages) DALLAS

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DS26503 T1/E1/J1 BITS Element

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4.5 JTAG

NAME

TYPE

FUNCTION

JTCLK

JTAG Clock. This clock input is typically a low frequency (less than 10MHz)

50% duty cycle clock signal.

JTMS

JTAG Mode Select (with Pullup). This input signal is used to control the

JTAG controller state machine and is sampled on the rising edge of JTCLK.

JTDI

JTAG Data Input (with Pullup). This input signal is used to input data into

the register that is enabled by the JTAG controller state machine and is sampled

on the rising edge of JTCLK.

JTDO

JTAG Data Output. This output signal is the output of an internal scan shift

falling edge of JTCLK. The pin is in the high-impedance mode when a register

is not selected or when the

JTRST signal is high. The pin goes into and exits the

high impedance mode after the falling edge of JTCLK

JTRST

JTAG Reset (Active Low). This input forces the JTAG controller logic into

the reset state and forces the JTDO pin into high impedance when low. This pin

should be low while power is applied and set high after the power is stable.

The pin can be driven high or low for normal operation, but must be high for

JTAG operation.

4.6 Line Interface

NAME

TYPE

FUNCTION

MCLK

Master Clock Input. A (50ppm) clock source. This clock is used internally for

both clock/data recovery and for the jitter attenuator for both T1 and E1 modes.

The clock rate can be 16.384MHz, 8.192MHz, 4.096MHz, or 2.048MHz. When

using the DS26503 in T1-only operation, a 1.544MHz (50ppm) clock source

can be used.

RTIP

Receive Tip. Analog input for clock recovery circuitry. This pin connects via a

1:1 transformer to the network. See the Line Interface Unit section for details.

RRING

Receive Ring. Analog input for clock recovery circuitry. This pin connects via

a 1:1 transformer to the network. See the Line Interface Unit section for details.

TTIP

Transmit Tip. Analog line-driver output. This pin connects via a 1:2 step-up

transformer to the network. See the Line Interface Unit section for details.

TRING

Transmit Ring. Analog line-driver output. This pin connects via a 1:2 step-up

transformer to the network. See the Line Interface Unit section for details.

THZE

Transmit High-Impedance Enable. When high, TTIP and TRING will be

placed into a high-impedance state.

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