Semiconductor device having nonvolatile memory element and data processing system including the same
View Patent ↗A semiconductor device includes a fuse element, a read-out circuit that reads out a memory content of the fuse element in response to a first internal reset signal that is activated in response to transition of an external reset signal, and a latch circuit that holds therein the memory content read out by the read-out circuit and is reset by a second internal reset signal that is activated based on an activation period of the external reset signal. With this configuration, even when the activation period of the external reset signal is long, the time for which a current flows through the fuse element can be shortened, thereby making it possible to reduce a current consumption at the time of a reset operation.
1. A semiconductor device comprising:
a timing control circuit that activates a first internal reset signal in response to transition of an external reset signal and activates a second internal reset signal based on an activation period of the external reset signal;
a nonvolatile memory element;
a read-out circuit that reads out a content of the nonvolatile memory element in response to the first internal reset signal; and
a first latch circuit that holds therein the content read out by the read-out circuit and that is reset by the second internal reset signal, wherein
the read-out circuit includes a second latch circuit that holds therein the content read out from the nonvolatile memory element, and
the first latch circuit is an SR latch circuit that is set based on the content held in the second latch circuit and reset by the second internal reset signal.
2. The semiconductor device as claimed in claim 1 , wherein the read-out circuit further includes:
first and second transistors connected to each other in parallel and to the nonvolatile memory element in series; and
an inverter having an input terminal that is connected to a connection node of the first transistor, the second transistor, and the nonvolatile memory element and an output terminal that is connected to a control electrode of the second transistor, wherein
the first internal reset signal is supplied to a control electrode of the first transistor, and
the second latch circuit is constituted by the second transistor and the inverter.
3. The semiconductor device as claimed in claim 1 , further comprising a power-on reset-signal generating circuit that generates a power-on reset signal in response to a power-on of the semiconductor device, wherein
the timing control circuit activates the first internal reset signal in response to activation of the power-on reset signal regardless of the transition of the external reset signal.
4. The semiconductor device as claimed in claim 1 , further comprising a mode setting circuit in which an operation mode of the semiconductor memory device is set, wherein
the mode setting circuit is reset by the second internal reset signal.
5. The semiconductor device as claimed in claim 4 , wherein
the nonvolatile memory element stores therein information in an irreversible manner, and
the mode setting circuit stores therein the operation mode in a reversible manner.
6. The semiconductor device as claimed in claim 1 , wherein the external reset signal is activated at least when a power source voltage is applied to the semiconductor device.
7. The semiconductor device as claimed in claim 6 , wherein the external reset signal may be also activated in a steady state after the power source voltage is applied to the semiconductor device.
8. The semiconductor device as claimed in claim 1 , wherein the timing control circuit resets the first latch circuit by activating the second internal reset signal and makes the first latch circuit store the content by activating the first internal reset signal for a predetermined period.
9. The semiconductor device as claimed in claim 8 , wherein an activation period of the first internal reset signal is shorter than the activation period of the external reset signal.
10. The semiconductor device as claimed in claim 8 , wherein the timing control circuit includes one-shot pulse circuit which activates the first internal reset signal for the predetermined period.
11. The semiconductor device as claimed in claim 8 , wherein the timing control circuit activates the second internal reset signal when the external reset signal is activated, activates the first internal reset signal and inactivates the second internal reset signal when the external reset signal is inactivated, and inactivates the first internal reset signal after a predetermined period elapses.
12. The semiconductor device as claimed in claim 8 , further comprising a power-on reset signal generating circuit that generates a power-on reset signal in response to a power-on of the semiconductor device, wherein
the timing control circuit activates the second internal reset signal in response to activation of the power-on reset signal.
13. The semiconductor device as claimed in claim 12 , wherein the timing control circuit activates the second internal reset signal in response to activation of the power-on reset signal and then activates the first internal reset signal for a predetermined period.
14. The semiconductor device as claimed in claim 12 , wherein the timing control circuit activates the second internal reset signal for a predetermined period in response to state transition of the external reset signal.
15. The semiconductor device as claimed in claim 12 , wherein the timing control circuit temporarily activates the second internal reset signal when the power-on reset signal is activated, activates the first internal reset signal in response to inactivation of the external reset signal which is activated simultaneously with the power-on reset signal and inactivates the first internal reset signal when a predetermined period elapses.
16. The semiconductor device as claimed in claim 12 , wherein the timing control circuit further activates the first internal reset signal when the power-on reset signal is activated.
17. The semiconductor device as claimed in claim 8 , further comprising a power-on reset-signal generating circuit that generates a power-on reset signal in response to a power-on of the semiconductor device, wherein
the timing control circuit activates the first internal reset signal in response to activation of the power-on reset signal and activates the second internal reset signal in response to activation of the external reset signal.
18. The semiconductor device as claimed in claim 17 , wherein the timing control circuit temporarily activates the first internal reset signal when the power-on reset signal is activated, activates the second internal reset signal in response to the external reset signal which is activated simultaneously with the power-on reset signal and inactivates the second internal reset signal in response to inactivation of the external reset signal.
19. A data processing system comprising a semiconductor device and a controller that issues an external reset signal to the semiconductor device,
wherein the semiconductor device includes:
a timing control circuit that activates a first internal reset signal in response to transition of the external reset signal and activates a second internal reset signal based on an activation period of the external reset signal;
a nonvolatile memory element;
a read-out circuit that reads out a content of the nonvolatile memory element in response to the first internal reset signal; and
a first latch circuit that holds therein the content read out by the read-out circuit and that is reset by the second internal reset signal,
wherein the controller activates the external reset signal at least when a power is applied to the semiconductor device,
the read-out circuit includes a second latch circuit that holds therein the content read out from the nonvolatile memory element, and
the first latch circuit is an SR latch circuit that is set based on the content held in the second latch circuit and reset by the second internal reset signal.
20. The data processing system as claimed in claim 19 , wherein the controller may also activate the external reset signal in a steady state after the power is applied to the semiconductor device.