Patent Application
20050286283
The present invention relates generally to memories and more particularly to a system and method for expanding the capacity of Flash storage devices.
The nature of non-volatile, vibration-free, small size and low power consumption has made the Flash memory an excellent component to be utilized in various Flash storage devices. Flash storage devices are widely used as memory storage for computer and consumer system products such as notebook, desktop computer, set top box, digital camera, mobile phone, PDA and GPS etc. The increasing demand for more storage in these products has driven the need to expand the capacity of the Flash storage devices.
There are two types of Flash storage devices. The first type has a pre-defined mechanical dimension. This type includes: (a) Secure Digital (SD) card, (b) Multi Media Card (MMC), (c) Memory Stick (MS) card, (d) Compact Flash (CF) card, (e) Express Flash card, (f) Serial ATA Flash disk, (g) IDE Flash disk, (h) SCSI Flash disk, etc.
The second type of Flash storage devices has no pre-defined physical dimension, which includes USB Flash disk, Disk On Module (DOM), MP3 player etc. However, corresponding based upon the need for the system compactness, it is generally desirable to make this type of Flash storage device as small in size and as high in capacity as possible.
Space constraints and available Flash memory density are the major obstacles in expanding the capacity of the Flash storage devices.
A Flash memory die is the basic element of Flash memory. A typical Flash memory chip comprises a Flash memory die mounted on a substrate within an enclosure and the electrical signals are bonded out to the metal contacts of the package.
Besides power and ground, a Flash memory includes the following electrical signals:
(a) Bidirectional signals: I/O (Input/Output) bus. It is a bidirectional bus. Flash memory uses this bus to input command, address and data, and to output data during read operation. Multiple Flash memories can share this bus with a Flash controller.
(b) Common Input Control Signals: ALE (Address Latch Enable), CLE (Command Latch Enable), RE- (Read Enable), WE- (Write Enable), WP- (Write Protect). Driven by Flash controller for various operations to Flash memory. These signals are shared among multiple Flash memories connected to a single I/O bus.
(c) Exclusive Input Control Signal: CE- (Chip Enable). Driven by Flash memory controller to enable the Flash memory for access. To ensure only one of them is enabled at a time, each Flash memory is connected to a unique CE-.
(d) Output Status Signals: R/B- (Ready/Busy-). Driven by Flash memory when it is busy, not ready to accept command from the Flash controller. It is an open-drain signal that can be shared among multiple Flash memories connecting to a single I/O bus.
The typical functional block diagram of a Flash storage device 80 is shown in
In many instances, due to cost and pin count considerations, a Flash controller has a limited number of chip enable signals. This limitation imposes a restriction on capacity expansion.
Furthermore, as the demand for Flash storage devices has increased, a shortage of certain types of Flash memory occurs during the course of a year. Flash types of the most popular density are typically out of supply during the peak seasons.
Accordingly it is desirable to provide ways to expand Flash storage devices. The present invention addresses such a need.
A Flash storage device is disclosed. The Flash storage device comprises a plurality of memories and a printed circuit board coupled to the plurality of memories. The PCB is extended beyond a predetermined dimension to accommodate the plurality of memories. By extending the length and/or the width of the PCB, additional memories can be added to the PCB, thereby adding to the memory capacity of the device.
The present invention relates generally to memories and more particularly to a system and method for expanding the capacity of Flash storage devices. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.
5. Extended PCB
Flash memories can be added to the Flash storage devices with pre-defined dimension by extending the length and/or the width of the PCB.
The above figures show some examples of the extended PCB. The Flash memories can be Flash memory chips or Flash memory dies. The PCB can be further extended at the back-end to accommodate more Flash memory chips or dies. This technique resolves the space constraint of the Flash storage devices with pre-defined dimension, including but not limited to SD card, MMC card, MS card, CF card and Express Flash card.
Although the present invention has been described in accordance with the embodiments shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiments and those variations would be within the spirit and scope of the present
