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M750000004 数据表(PDF) 81 Page - SPANSION |
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M750000004 数据表(HTML) 81 Page - SPANSION |
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81 / 129 page ![]() January 14, 2004 Am75PDL191CHHa/Am75PDL193CHHa 79 ADV ANCE I N FO RMAT I O N DEVICE BUS OPERATIONS This section describes the requirements and use of the device bus operations, which are initiated through the internal command register. The command register itself does not occupy any addressable memory loca- tion. The register is a latch used to store the com- mands, along with the address and data information needed to execute the command. The contents of the register serve as inputs to the internal state machine. The state machine outputs dictate the function of the device. Table 1 lists the device bus operations, the in- puts and control levels they require, and the resulting output. The following subsections describe each of these operations in further detail. Table 1. Am29DL640H Device Bus Operations Legend: L = Logic Low = V IL, H = Logic High = VIH, VID = 11.5–12.5 V, VHH = 9.0 ± 0.5 V, X = Don’t Care, SA = Sector Address, A IN = Address In, DIN = Data In, DOUT = Data Out Notes: 1. Addresses are A21:A0 in word mode. 2. The sector protect and sector unprotect functions may also be implemented via programming equipment. See the “Sector/Sector Block Protection and Unprotection” section. 3. If WP#/ACC = V IL, sectors 0, 1, 140, and 141 remain protected. If WP#/ACC = VIH, protection on sectors 0, 1, 140, and 141 depends on whether they were last protected or unprotected using the method described in “Sector/Sector Block Protection and Unprotection”. If WP#/ACC = V HH, all sectors will be unprotected. Word/Byte Configuration The BYTE# pin controls whether the device data I/O pins operate in the byte or word configuration. If the BYTE# pin is set at logic ‘1’, the device is in word con- figuration, DQ15–DQ0 are active and controlled by CE# and OE#. If the BYTE# pin is set at logic ‘0’, the device is in byte configuration, and only data I/O pins DQ7–DQ0 are active and controlled by CE# and OE#. The data I/O pins DQ14–DQ8 are tri-stated, and the DQ15 pin is used as an input for the LSB (A-1) address function. Requirements for Reading Array Data To read array data from the outputs, the system must drive the CE# and OE# pins to V IL. CE# is the power control and selects the device. OE# is the output con- trol and gates array data to the output pins. WE# should remain at V IH . The BYTE# pin deter m ines whether the device outputs array data in words or bytes. The internal state machine is set for reading array data upon device power-up, or after a hardware reset. This ensures that no spurious alteration of the memory content occurs during the power transition. No com- mand is necessary in this mode to obtain array data. Standard microprocessor read cycles that assert valid addresses on the device address inputs produce valid data on the device data outputs. Each bank remains enabled for read access until the command register contents are altered. Operation CE# OE# WE# RESET# WP#/ACC Addresses (Note 2) DQ15–DQ8 DQ7– DQ0 Read L L H H L/H A IN D OUT D OUT Write L H L H (Note 3) AIN DIN DIN Standby V CC ± 0.3 V XX V CC ± 0.3 V L/H X High-Z High-Z Output Disable L H H H L/H X High-Z High-Z Reset X X X L L/H X High-Z High-Z Sector Protect (Note 2) L H L VID L/H SA, A6 = L, A1 = H, A0 = L XDIN Sector Unprotect (Note 2) L H L V ID (Note 3) SA, A6 = H, A1 = H, A0 = L XD IN Temporary Sector Unprotect XX X VID (Note 3) AIN DIN DIN |
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