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Testability

Loopback Testing

Enable Function

PRBS Function

ABSOLUTE MAXIMUM RATINGS

(1)

TLK1201ARCP, TLK1201AIRCP

ETHERNET TRANSCEIVERS

SLLS580A – FEBRUARY 2004 – REVISED JUNE 2004

The loopback function provides for at-speed testing of the transmit/receive portions of the circuitry. The enable

function allows for all circuitry to be disabled so that an Iddq test can be performed. The PRBS function also

allows for a BIST (built-in self test). The terminal setting, TESTEN high, enables the test mode. The terminal

TESTEN has an internal pulldown resistor, so it defaults to normal operation. The TESTEN is only used for

factory testing, and is not intended for end-user control.

The transceiver can provide a self-test function by enabling (setting LOOPEN to high level) the internal loopback

path. Enabling this function causes serial transmitted data to be routed internally to the receiver. The parallel

data output can be compared to the parallel input data for functional verification. The external differential output

is held in a high-impedance state during the loopback testing.

When held low, ENABLE disables all quiescent power in both the analog and digital circuitry. This allows an

ultralow-power idle state when the link is not active.

This device has a built-in 2

enabled. A PRBS is generated and fed into the 10-bit parallel transmitter input bus. Data from the normal parallel

input source is ignored during PRBS test mode. The PRBS pattern is then fed through the transmit circuitry as if

it were normal data and sent out to the transmitter. The output can be sent to a bit error rate tester (BERT) or to

the receiver of another TLK1201AI. Since the PRBS is not really random and is really a predetermined sequence

of 1s and 0s, the data can be captured and checked for errors by a BERT. This device also has a built-in BERT

function on the receiver side that is enabled by PRBSEN. It can receive a PRBS pattern and check for errors,

and then reports the errors by forcing the SYNC/PASS terminal low. The PRBS testing supports two modes

(normal and latched), which are controlled by the SYNCEN input. When SYNCEN is low, the result of the PRBS

bit error rate test is passed to the SYNC/PASS terminal. When SYNCEN is high the result of the PRBS

verification is latched on the SYNC/PASS output (that is, a single failure forces SYNC/PASS to remain low).

over operating free-air temperature range (unless otherwise noted)

TLK1201A/TLK1201AI

–0.3 V to 3 V

–0.5 V to 4 V

Input voltage range at any other terminal

–65

°C to 150°C

Electrostatic discharge

CDM: 1 kV, HBM:2 kV

TLK1201A

0

°C to 70°C

Characterized free-air operating temperature range

TLK1201AI

–40

°C to 85°C

(1)

Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings

only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating

conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2)

All voltage values, except differential I/O bus voltages, are with respect to network ground terminal.

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