CS61318

DS441PP2

17

The amplitude of each phase is described by a 7-bit,

2’s compliment number, where a positive value de-

scribes pulse amplitude, and a negative value de-

scribes pulse undershoot. The positive full value is

hex 3F. The negative full value is hex 40. For E1

shielded twisted pair, the typical output voltage is

27 mV/LSB. All voltages are peak voltages across

the TTIP and TRING outputs.

Using the circuits given in the Applications section

of the data sheet, the output impedance of the de-

vice will be approximately equal to the impedance

of the line. This means that the voltage on the trans-

former secondary will be twice the values stated

above. Note that although the full scale digital in-

put is 3F, it is recommended that full scale output

voltage on the transformer primary be limited to

2.4 Vpk. At higher output voltages, the driver may

not drive the requested output voltage.

The amplitude information for all phases is written

via the serial-port to Arbitrary Waveform RAM

registers (see Arbitrary Waveform RAM register

for description). Each phase amplitude is written as

an eight-bit byte, where the first phase of the sym-

bol is written first.

The contents of the Arbitrary Waveform RAM can

be verified by performing a read operation. Read-

ing the waveform RAM requires first writing the

Address/Command Byte with the R/W bit set to

“1” (see Figure 10) followed by a data byte which

specifies the RAM address to be read. On subse-

quent SCLK’s the contents of the specified RAM

location will be clocked out on SDO.

Notes: 1. In Hardware Mode the Diagnostic Modes are selected by directly setting the pins on the device; in Host

Mode, the appropriate register bits are written for Diagnostic Modes.

2. In Host Mode the interrupts can be masked by writing a “1” to the LOS bit; there is no masking in the

Hardware Mode.

Diagnostic Mode

Availability (Note 1)

H/W

Host

Host Mode (Note 2)

Maskable

Loopback Modes

Local Loopback (LLOOP)

Yes

Yes

No

Remote Loopback (RLOOP)

Yes

Yes

No

In-band Network Loopback (NLOOP)

Yes

Yes

Yes

Internal Data Pattern Generation and Detection

Transmit All Ones (TAOS)

Yes

Yes

No

In-band Loop-up/down Code Generator

No

Yes

No

Error Detection

Bipolar Violation Detection (BPV)

Yes

Yes

No

Alarm Condition Monitoring

Receive Loss of Signal Monitoring (LOS)

Yes

Yes

Yes

Receive Alarm Indication Signal Monitoring (AIS)

No

Yes

Yes

Other Diagnostic Reports

Receive Line Attenuation Indicator (LATN)

Yes

Yes

No

Table 4. CS61318 Diagnostic Mode Availability