1. A synchronous semiconductor memory device comprising:
a data output circuit adapted to generate data output up and down signals and to perform a data output operation synchronously to an external clock in response to the data output up and down signals; and
an on-die termination (ODT) circuit adapted to generate ODT up and down signals for performing an ODT operation synchronously to said external clock in response to the ODT up and down signals.
2. The device as claimed in 1, wherein the data output circuit comprises:
a data output multiplexer adapted to multiplexing read data applied from at least one memory cell using at least one clock signal, to generate the data output up and down signals; and
an output driver adapted to perform the data output operation synchronized to the external clock, the output driver comprising,
a pull-up driver, and
a pull-down driver,
wherein the output driver controls an on operation and an off operation of the pull-up driver and the pull-down driver in response to a state of the data output up and down signals.
3. The device as claimed in 1, wherein the ODT circuit comprises an ODT synchronous buffer adapted to receive an ODT command applied in response to a buffered clock signal generated by buffering the external clock, and outputting a synchronous ODT command in response to a first clock signal delay-locked to the external clock.
4. The device as claimed in 3, wherein the ODT circuit further comprises:
an ODT gate adapted to pass through and latch the synchronous ODT command in response to the first clock signal and a second clock signal that has a fixed phase difference with respect to the first clock signal, to generate the ODT up and down signals.
5. The device as claimed in 3, further comprising a delay-locked loop adapted to generate the first clock signal delay-locked to the external clock.
6. The device as claimed in 3, wherein the phase difference between the first and second clock signals is based on a half cycle of the external clock.
7. The device as claimed in 3, wherein the ODT synchronous buffer comprises:
a delay adapted to delay the ODT command for a fixed time;
a first flip-flop adapted to latch an output of the delay in response to the buffered clock signal; and
a second flip-flop adapted to latch an output of the first flip-flop in response to the first clock signal, to generate the synchronous ODT command.
8. The device as claimed in 1, wherein the ODT circuit comprises an ODT driver adapted to perform an ODT driving operation synchronized to the external clock, by controlling an ON operation and an OFF operation of a pull-up resistance and a pull-down resistance in response to a state of the ODT up and down signals.
9. The device as claimed in 8, wherein the ODT driver comprises:
an output pad; and
a plurality of unit drivers, wherein each of said unit drivers comprises,
a pull-up resistance having a first end directly connected to a common node,
a pull-down resistance having a first end directly connected to the common node,
a pull-up transistor having a drain connected to a second end of the pull-up resistance, a source connected to a power voltage, and a gate adapted to respond to the ODT up signal, and
a pull-down transistor having a drain connected to second end of the pull-down resistance, a source connected to a ground voltage, and a gate adapted to respond to the ODT down signal,
wherein the common node of each of the unit drivers is connected to the output pad.
10. The device as claimed in 9, wherein the plurality of unit drivers comprise:
at least two pull-up resistances with different values; and
at least two pull-down resistances with different values.
11. The device as claimed in 1, wherein the ODT circuit comprises an ODT controller adapted to output an up enable signal and a down enable signal in response to an external or internal control signal.
12. The device as claimed in 11, wherein said ODT controller includes at least one fuse for generating an internal control signal.
13. The device as claimed in 11, wherein when said ODT controller outputs the up and down enable signals in response to an external control signal, a mode register set code is externally received.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A sphygmomanometer for use by more than one user, comprising:
a main body having a displaying screen mounted thereon;
an inner unit mounted inside the main body and including a memory;
a belt connected to said inner unit through a gas pipe;
a plurality of power buttons mounted on said main body, each of said power buttons for actuating said sphygmomanometer and storing of blood pressure measurement results;
a plurality of memory buttons mounted on said main body, whereby actuation of one memory button recalls and displays said blood pressure measurement results on said displaying screen; and
a selecting switch mounted on said sphygmomanometer, said selecting switch is employed to control a selected user’s power button to be inactivated;
wherein each of said power buttons has a corresponding memory button, all of said power and memory buttons being electrically connected to said inner unit,
wherein actuation of said selected user’s power button transmits a signal sent to said inner unit to initiate measurement and storing of blood pressure results into said memory, and
wherein inactivating said selected user’s power button by said selecting switch denies the storing of the blood pressure results to said memory.
2. The sphygmomanometer according to claim 1, wherein said power buttons comprise a first and a second power buttons, and said memory buttons comprise a first and a second memory button.
3. The sphygmomanometer according to claim 1, wherein each memory button is mounted at a position which corresponds to that of each power button, and each power button and each memory button are correspondingly communicated with one another.
4. The sphygmomanometer according to claim 1, wherein each power button is a large button whose size is far larger than that of said memory button.
5. The sphygmomanometer according to claim 1, wherein each power button and each memory button are in a one-on-one corresponding manner for communicating with one another.
6. The sphygmomanometer according to claim 1, wherein said main body further comprises a setting button and a mode selecting button mounted thereon and said setting button and said mode selecting button are electrically connected to said inner unit respectively.
7. The sphygmomanometer according to claim 1, wherein each of said power buttons is employed to individually turn on or turn off said sphygmomanometer.
8. The sphygmomanometer according to claim 1, wherein said selecting switch comprises a switching body mounted on said sphygmomanometer, and an inner-edge portion formed at an inner edge of said switching body, said inner-edge portion of said selecting switch being stopped at an inside edge of said power buttons so that after a position of said switching body is selected, said inside edge of said selected power button is blocked by said inner-edge portion and can not be used.
9. The sphygmomanometer according to claim 8, wherein said selecting switch further comprises an indentation formed between adjacent power buttons, a movement of said switching body being guided by said indentation.
10. The sphygmomanometer according to claim 8, wherein said selecting switch further comprises a connecting body connected between said switching body and said inner-edge portion, said connecting body being penetrated through said sphygmomanometer.
11. The sphygmomanometer according to claim 1, wherein said selecting switch comprises a switching body mounted at said main body and a control circuit arranged in said main body and electrically connected to said inner unit, whereby said control circuit is activated by a position selection of said switching body so that an electrical connection of said selected power button is disconnected accordingly.
12. The sphygmomanometer according to claim 11, wherein said selecting switch further comprises an inner-edge portion formed at an inner edge of said switching body and extended into said main body, and a passive switch mounted at said main body and electrically connected to said control circuit, whereby after said position selection of said switching body makes said inner-edge portion act on said passive switch so as to activate said control circuit, said electrical connection of said selected power button is disconnected accordingly.
13. The sphygmomanometer according to claim 1, wherein said selecting switch is a selecting switch in a protective-cover fashion and has plural positioning bodies, and also comprises plural positioning holes mounted on said main body, wherein each positioning body is employed to position a random positioning hole of said positioning holes so as to cover and therefore inactivate said selected power button by said switching body.
14. The sphygmomanometer according to claim 1, wherein said selecting switch is a selecting switch in a protective-cover fashion and has plural guiding bodies, and also comprises a sliding track pair mounted on said main body, wherein each guiding body of said selecting switch is slid in said sliding track pair so that said switching body is slid to cover and therefore inactivate said selected power button.