Memory system having a plurality of serially connected devices
View Patent ↗A semiconductor memory device and system are disclosed. The memory device includes a memory, a plurality of inputs, and a device identification register for storing register bits that distinguish the memory device from other possible memory devices. Circuitry for comparing identification bits in the information signal with the register bits provides positive or negative indication as to whether the identification bits match the register bits. If the indication is positive, then the memory device is configured to respond as having been selected by a controller. If the indication is negative, then the memory device is configured to respond as having not been selected by the controller. A plurality of outputs release a set of output signals towards a next device.
1. A system comprising:
a first semiconductor device; and
a second semiconductor device including first and second data strobe pins, the second semiconductor device being a memory device, and
the first semiconductor device being configured to output a first data strobe signal providing synchronous reference for input data to be received by the second semiconductor device via the first data strobe pin, and
the second semiconductor device configured to output, via the second data strobe pin, a second data strobe signal providing synchronous reference for output data, and
wherein the first and second data strobes are both intermittently driven timing signals.
2. The system as claimed in claim 1 wherein the second data strobe signal is an echo of the first data strobe signal.
3. The system as claimed in claim 1 wherein at least the second semiconductor device further includes an input for receiving a mode signal indicative of whether the second semiconductor device has been placed in a read mode or a write mode by a controller of the system.
4. The system as claimed in claim 1 wherein the second semiconductor device further includes a plurality of additional pins for receiving a command latch enable signal and an address latch enable signal from the first semiconductor device.
5. The system as claimed in claim 1 wherein first and second data strobe pins are unidirectional pins.
6. The system as claimed in claim 1 wherein the first data strobe pin is configured to operate as a bidirectional data strobe pin when the system is a multi-drop system.
7. The system as claimed in claim 1 further comprising a third semiconductor device, and wherein the first, second and third semiconductor device are arranged in a point-to-point ring topology.
8. The system as claimed in claim 1 wherein the memory device is a flash memory device.
9. The system as claimed in claim 8 wherein the flash memory device is a NAND flash memory device.
10. The system as claimed in claim 1 wherein the second semiconductor device further includes a device identification register and an identification comparator, and the identification comparator is configured to compare device identification information receivable by the second semiconductor device with information stored in the device identification register to determine whether the second semiconductor device is a target device for a command.
11. The system as claimed in claim 1 wherein the second semiconductor device further includes a clock input pin configured to receive a device-external clock signal.
12. A method comprising:
receiving, via a first data strobe pin of a semiconductor memory device, a first data strobe signal that provides synchronous reference for input data; and
outputting, via a second data strobe pin of the semiconductor memory device, a second data strobe signal providing synchronous reference for output data, and
wherein the first and second data strobes are both intermittently driven timing signals.
13. The method as claimed in claim 12 wherein the second data strobe signal is an echo of the first data strobe signal.
14. The method as claimed in claim 12 further comprising receiving a mode signal indicative of whether the semiconductor memory device has been placed in a read mode or a write mode by a controller.
15. The method as claimed in claim 12 further comprising receiving a command latch enable signal and an address latch enable signal.
16. The method as claimed in claim 12 wherein the semiconductor memory device is a flash memory device.
17. The method as claimed in claim 16 wherein the flash memory device is a NAND flash memory device.