| 摘要 |
<p>A nonvolatile memory subsystem includes DRAMs (520) and a battery-backed controller chip (500). The controller chip (500) monitors the system power supply level to ascertain power fault conditions. When a power fault is detected, the controller provides the DRAMs (520) with both a regulated supply voltage and appropriately timed refresh signals until the system commands it to stop. The controller chip's time base is provided by an oscillator (310) with reduced temperature-dependence. A time-delay circuit (710) uses both pull-up resistor (712) and a pull-down resistor (720), of two different types to charge a capacitor (730). The material with the smallest available thermal coefficient of resistance (TCR) is used for the pull-up resistor (712). Another material, with a larger TCR, is used for the pull-down resistor (720).</p> |
