Cypress CY14B104LA, CY14B104NA manual Preventing AutoStore, Data Protection, Noise Considerations

PRELIMINARY

CY14B104LA, CY14B104NA

Table 1. Mode Selection (continued)

					[3]	A15 - A0[7]	Mode	I/O	Power
CE	WE	OE,	BHE,	BLE
L	H		L			0x4E38	Read SRAM	Output Data	Active[8]
						0xB1C7	Read SRAM	Output Data
						0x83E0	Read SRAM	Output Data
						0x7C1F	Read SRAM	Output Data
						0x703F	Read SRAM	Output Data
						0x4B46	AutoStore Enable	Output Data
L	H		L			0x4E38	Read SRAM	Output Data	Active ICC2[8]
						0xB1C7	Read SRAM	Output Data
						0x83E0	Read SRAM	Output Data
						0x7C1F	Read SRAM	Output Data
						0x703F	Read SRAM	Output Data
						0x8FC0	Nonvolatile Store	Output High Z
L	H		L			0x4E38	Read SRAM	Output Data	Active[8]
						0xB1C7	Read SRAM	Output Data
						0x83E0	Read SRAM	Output Data
						0x7C1F	Read SRAM	Output Data
						0x703F	Read SRAM	Output Data
						0x4C63	Nonvolatile	Output High Z
							Recall

Preventing AutoStore

The AutoStore function is disabled by initiating an AutoStore disable sequence. A sequence of read operations is performed in a manner similar to the software STORE initiation. To initiate the AutoStore disable sequence, the following sequence of CE controlled read operations must be performed:

1.Read address 0x4E38 Valid READ

2.Read address 0xB1C7 Valid READ

3.Read address 0x83E0 Valid READ

4.Read address 0x7C1F Valid READ

5.Read address 0x703F Valid READ

6.Read address 0x8B45 AutoStore Disable

The AutoStore is re-enabled by initiating an AutoStore enable sequence. A sequence of read operations is performed in a manner similar to the software RECALL initiation. To initiate the AutoStore enable sequence, the following sequence of CE controlled read operations must be performed:

1.Read address 0x4E38 Valid READ

2.Read address 0xB1C7 Valid READ

3.Read address 0x83E0 Valid READ

4.Read address 0x7C1F Valid READ

5.Read address 0x703F Valid READ

6.Read address 0x4B46 AutoStore Enable

Data Protection

The CY14B104LA/CY14B104NA protects data from corruption during low voltage conditions by inhibiting all externally initiated STORE and write operations. The low voltage condition is

detected when VCC < VSWITCH. If the CY14B104LA/CY14B104NA is in a write mode (both CE and WE are LOW) at power up, after a RECALL or STORE, the write is inhibited until the SRAM is enabled after tLZHSB (HSB to output active). This protects against inadvertent writes during power up or brown out conditions.

Noise Considerations

Refer to CY application note AN1064.

If the AutoStore function is disabled or re-enabled, a manual STORE operation (hardware or software) must be issued to save the AutoStore state through subsequent power down cycles. The part comes from the factory with AutoStore enabled.

Document #: 001-49918 Rev. *A Page 6 of 23

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