| 摘要 |
A digital LSI chip comprises the principal element of a printer controller. On the chip are output transistors for driving connection pads and external loads connected thereto. The chip performance is influenced by variations in the manufacturing Process, supply Voltage, and Temperature (PVT). All of these influence the time delay and risetime characteristics of the output transistors, as does varying the gain of predrivers supplying drive signals for the output transistors. To minimize the influence of PVT variables on these characteristics, a table of predrive gain needed to compensate the effect of PVT variables is generated for several points over the PVT range. Likewise, the frequency of a ring oscillator sensor is tabulated over the same points. These data are paired and stored in a memory. At startup and other times, a microprocessor determines the sensor frequency, accesses the table and sets appropriate predriver gains, thereby maintaining the output transistor characteristics nominally constant.
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