Circuit for improving IO speed

Abstract

The invention provides a circuit structure for improving the IO speed, i.e. an acceleration conversion pulse is additionally provided with a clock period on an open-drain structure when '0-1' level is converted and an up-pulling resistor and a tristate transmission door are arranged in a structure. The circuit structure comprises tristate bidirectional open-drain IO PAD and a group of logic gate circuits for generating a tristate gate enable signal (EEO). The circuit structure can output a strong drive high level of a period when IO output data generate '0-1' level is converted, also shorten the raising time of the level and effectively improve the communication speed of a 7816 serial port.

Description

technical field [0001] The invention relates to an IO circuit, in particular to a circuit for a contact smart card chip capable of improving the IO communication speed. Background technique [0002] In the field of contact smart cards, the mainstream communication standard is ISO / IEC 7816. The characteristic of this standard is that the bidirectional data transmission pins between the card and the card reader need to be connected in a "wired-AND" manner. Therefore, the IO pins for chip data transmission usually use an open-drain structure PAD, such as figure 1 , when the open-drain PAD outputs low-level to high-level conversion, it is completely completed by the pull-up resistor, and the pull-up resistor is generally tens of K ohms, so that the level rises for a long time and the data output rate is low, the highest is only a few Hundred Kbps baud rate. As a result, the communication speed of the ISO7816 serial port is slow and the communication time is too long. On the o...

AI Technical Summary

Problems solved by technology

Therefore, the IO pins for chip data transmission usually use an open-drain structure PAD, such as figure 1 , when the open-drain PAD outputs low-level to high-level conversion, it is completely completed by the pull-up resistor, and the pull-up resistor is generally tens of K ohms, so that the level rises for a long time and the data output rate is low, the highest is only a few Hundred Kbps baud rate

The communication speed of the ISO7816 serial port is slow and the communication time is too long

On the other hand, with the development of smart card technology, smart cards require higher and higher ETU frequency division ratios, and if the IO speed is too slow, it will also cause functional errors

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