DS3173N datasheet(63/232 Pages) DALLAS

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and automatic FEBE is enabled. Transmit clock comes from the CLAD CLKA pin. The pin inversion on all pins is

disabled.

Individual blocks are reset and powered down when not used determined by the settings in the line mode bits

PORT.CR2.LM[2:0] and framer mode bits PORT.CR2.FM[2:0].

10.4 Global Resources

10.4.1 Clock Rate Adapter (CLAD)

The clock rate adapter is used to create multiple clocks for LIU reference clocks or transmit clocks from a single

clock reference input on the CLKA pin. The clock frequency applied to this pin must be at the DS3 (44.736 MHz),

E3 (34.368 MHz) and STS-1 (51.84 MHz) clock rates. Given one of these clocks the other two clocks will be

generated. The internally generated signals can be driven on output pins (CLKB and CLKC) for external use.

The receive LIU is supplied a reference clock from the CLAD. The receive LIU selects the clock frequency based

upon the mode the user selects via the FM bits. The CLAD output is also available as a transmit clock source if

selected via the PORT.CR2.CLADC register bit.

The user must supply at least one of the three rates (DS3, E3, STS-1) to the CLKA pin. The CLAD[3:0] bits inform

the PLL of the frequency applied to the pins. Selection of the output clock of the CLAD applied to the LIU and

optionally the transmitter is controlled by the FM bits (located in PORT.CR2). The CLAD allows maximum flexibility

to the user. The user may supply any of the three clock rates and use the CLAD to convert the rate to the particular

clock rate needed for his application.

Figure 10-6. CLAD Block

CLKA

CLKB

CLKC

DS3 clock

E3 clock

CC52 clock

CLAD

CLAD MODE

The clock rate adapter can also be disabled and all three clocks supplied externally using the CLKA, CLKB and

CLKC pins as clock inputs. When the CLAD is disabled, the three reference clocks DS3, E3 and STS-1 will need to

be applied to the CLKA, CLKB and CLKC pins, respectively. If any of the three frequencies is not required, it does

not need to be applied to the CLAD CLK pins.

DS3173N Datasheet(PDF) 63 Page - Dallas Semiconductor