DESCRIPTION
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 device is used in conjunction with the R446 parallel to serial converter. The start bit for conversion 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. 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 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 E445’s.
Semtech Corporation
