SY10E445

The SY10E445/100E445 are integrated 4-bit serial-to-parallel data converters. The SY10E445 is designed to operate for NRZ data rates of up to 2.5Gb/s. The chip generates a divide-by-4 and a divide-by-8 clock for both 4-bit conversion and a two-chip 8-bit conversion function. The conversion sequence was chosen to convert the first serial bit to Q0, the second to Q1, etc.

Two selectable serial inputs provide a loopback capability for testing purposes when the SY10E445 is used in conjunction with the E446 parallel-to-serial converter.

The start bit for conversion of SY10E445 can be moved using the SYNC input. A single pulse, applied asynchronously for at least two input clock cycles, shifts the start bit for conversion from Qn to Qn-1 by one bit. For each additional shift required, an additional pulse must be applied to the SYNC input. Asserting the SYNC input will force the internal clock dividers to "swallow" a clock pulse, effectively shifting a bit from the Qn to the Qn-1 output (see Timing Diagram B).

The MODE input of SY10E445 is used to select the conversion mode of the device. With the MODE input LOW (or open) the device will function as a 4-bit converter. When the mode input is driven HIGH, the data on the output will change on every eighth clock cycle, thus allowing for an 8-bit conversion scheme using two E445s. When cascaded in an 8-bit conversion scheme, the devices will not operate at the 2.5Gb/s data rate of a single device. Refer to the applications section of this data sheet for more information on cascading the E445.

For lower data rate applications, SY10E445, a VBB reference voltage is supplied for single-ended inputs. When operating at clock rates above 500MHz, differential input signals are recommended. For single-ended inputs, the VBB pin is tied to the inverting differential input and bypassed via a 0.01µF capacitor. The VBB provides the switching reference for the input differential amplifier. The VBB can also be used to AC couple an input signal.