Semiconductor memory device suitable for mounting on portable terminal
View Patent ↗A trigger producing circuit provides a trigger signal. A delay circuit receives the trigger signal, and provides a delay signal produced by delaying the trigger signal. A clock counter receives clocks, counts the received clocks for a period from reception of the trigger signal to reception of the delay signal, and provides a result of the counting. A determining circuit stores a relationship between the number of clocks and a latency, and determines the latency corresponding to the result of counting provided from the clock counter. A latency register holds the determined latency. A WAIT control circuit externally provides a WAIT signal based on the latency held in the latency register.
1. A semiconductor memory device comprising:
a package that includes a first pseudo-SRAM chip and a second pseudo-SRAM chip, wherein each of the first pseudo-SRAM chip and the second pseudo-SRAM chip comprises:
a memory array having memory cells of a plurality of dynamic random access memories arranged in rows and columns;
a first circuit producing a first signal defining timing of refreshing;
an output terminal outputting said first signal;
an input terminal receiving a second signal externally defining the timing of the refreshing;
a switch receiving said first and second signals, and outputting one of said first and second signals;
a second circuit receiving the signal output from said switch, and performing refresh control based on the received signal; and
a wait control circuit outputting a wait signal while said second circuit is executing the refresh control;
the package further comprising:
a wait terminal that provides an external output for the package of at least one of an output of the wait control circuit of the first pseudo-SRAM chip and an output of the wait control circuit of the second pseudo-SRAM chip.
2. The semiconductor memory device according to claim 1 , wherein
said first circuit is a timer providing a signal of a constant period as said first signal.
3. A semiconductor memory device comprising:
a package that includes a first pseudo-SRAM chip and a second pseudo-SRAM chip, wherein each of the first pseudo-SRAM chip and the second pseudo-SRAM chip comprises:
a memory array having memory cells of a plurality of dynamic random access memories arranged in rows and columns;
a first circuit that includes a timer circuit, wherein the first circuit produces a first signal that defines a refresh timing based on an output of the timer circuit;
an output terminal that outputs said first signal;
an input terminal that receives a second signal that defines the refresh timing;
a select circuit that receives said first and second signals, and outputs one of said first and second signals; and
a second circuit that receives the signal output from said select circuit, and performs a refresh control based on the received signal,
wherein said output terminal of the first pseudo-SRAM chip is electrically connected to said input terminal of the second pseudo-SRAM chip, and
wherein said select circuit of the first pseudo-SRAM chip and said select circuit of the second pseudo-SRAM chip have different selective states.
4. The semiconductor memory device according to claim 3 wherein, the selective states of said select circuits are switched through bonding PADs.
5. The semiconductor memory device according to claim 3 , wherein the first pseudo-SRAM chip further includes a wait control circuit outputting a wait signal while said second circuit of the first pseudo-SRAM chip is executing the refresh control, and the second pseudo-SRAM chip further includes a wait control circuit outputting a wait signal while said second circuit of the second pseudo-SRAM chip is executing the refresh control, and
wherein the package further comprises:
a wait terminal that provides an external output for the package of at least one of an output of the wait control circuit of the first pseudo-SRAM chip and an output of the wait control circuit of the second pseudo-SRAM chip.