M28W640CB

The M28W640CB is a 64 Mbit (4 Mbit x 16) non-volatile Flash memory that can be erased electrically at the block level and programmed in-system on a Word-by-Word basis. These operations can be performed using a single low voltage (2.7 to 3.6V) supply. VDDQ allows to drive the I/O pin down to 1.65V. An optional 12V VPP power supply is provided to speed up customer programming.

The M28W640CB features an asymmetrical blocked architecture. The M28W640C has an array of 135 blocks: 8 Parameter Blocks of 4 KWord and 127 Main Blocks of 32 KWord. M28W640CT has the Parameter Blocks at the top of the memory address space while the M28W640CB locates the Parameter Blocks starting from the bottom. The memory maps are shown in Figure 5, Block Addresses.

The M28W640CB features an instant, individual block locking scheme that allows any block to be locked or unlocked with no latency, enabling instant code and data protection. All blocks have three levels of protection. They can be locked and locked-down individually preventing any accidental programming or erasure. There is an additional hardware protection against program and erase. When VPP £ VPPLK all blocks are protected against program or erase. All blocks are locked at Power Up.

Each block M28W640CB can be erased separately. Erase can be suspended in order to perform either read or program in any other block and then resumed. Program can be suspended to read data in any other block and then resumed. Each block can be programmed and erased over 100,000 cycles. The device includes a 192 bit Protection Register and a Security Block to increase the protection of a system design. The Protection Register is divided into a 64 bit segment and a 128 bit segment. The 64 bit segment contains a unique device number written by ST, while the second one is onetime-programmable by the user. The user programmable segment can be permanently protected. The Security Block, parameter block 0, can be permanently protected by the user. Figure 6, shows the Security Block Memory Map.

Program and Erase commands M28W640CB are written to the Command Interface of the memory. An on-chip Program/Erase Controller takes care of the timings necessary for program and erase operations. The end of a program or erase operation can be detected and any error conditions identified. The command set required to control the memory is consistent with JEDEC standards.

The memory is offered in M28W640CB (12 X 20mm) and TFBGA48 (0.75mm pitch) packages and is supplied with all the bits erased (set to '1').