W25Q40BLSVIP datasheet(57/74 Pages) WINBOND

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W25Q40BL

Publication Release Date: May 04, 2012

- 57 -

Revision D

7.2.39 Read Security Registers (48h)

The Read Security Register instruction is similar to the Fast Read instruction and allows one or more data

bytes to be sequentially read from one of the three security registers. The instruction is initiated by driving

the /CS pin low and then shifting the instruction code “48h” followed by a 24-bit address (A23-A0) and

eight “dummy” clocks into the DI pin. The code and address bits are latched on the rising edge of the CLK

pin. After the address is received, the data byte of the addressed memory location will be shifted out on

the DO pin at the falling edge of CLK with most significant bit (MSB) first. The byte address is

automatically incremented to the next byte address after each byte of data is shifted out. Once the byte

address reaches the last byte of the register (byte FFh), it will reset to 00h, the first byte of the register,

and continue to increment. The instruction is completed by driving /CS high. The Read Security Register

instruction sequence is shown in figure 37. If a Read Security Register instruction is issued while an

Erase, Program or Write cycle is in process (BUSY=1) the instruction is ignored and will not have any

effects on the current cycle. The Read Security Register instruction allows clock rates from D.C. to a

maximum of FR (see AC Electrical Characteristics).

ADDRESS

A23-16

A15-12

A11-8

A7-0

Security Register #1

00h

0 0 0 1

0 0 0 0

Byte Address

Security Register #2

00h

0 0 1 0

0 0 0 0

Byte Address

Security Register #3

00h

0 0 1 1

0 0 0 0

Byte Address

Figure 37. Read Security Registers Instruction Sequence

Instruction (48h)

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