STK12C68
manufacturing test to ensure these system routines work
consistently.
Best Practices
nvSRAM products have been used effectively for over 15 years.
While ease-of-use is one of the product’s main system values,
experience gained working with hundreds of applications has
resulted in the following suggestions as best practices:
■ Power up boot firmware routines should rewrite the nvSRAM
into the desired state. While the nvSRAM is shipped in a preset
state, best practice is to again rewrite the nvSRAM into the
desired state as a safeguard against events that might flip the
bit inadvertently (program bugs, incoming inspection routines,
and so on).
■ The nonvolatile cells in an nvSRAM are programmed on the
test floor during final test and quality assurance. Incoming
inspection routines at customer or contract manufacturer’s
sites sometimes reprograms these values. Final NV patterns
are typically repeating patterns of AA, 55, 00, FF, A5, or 5A.
Theendproduct’sfirmwareshouldnotassumethatanNVarray
is in a set programmed state. Routines that check memory
content values to determine first time system configuration,
cold or warm boot status, and so on must always program a
unique NV pattern (for example, complex 4-byte pattern of 46
E6 49 53 hex or more random bytes) as part of the final system
■ The Vcap value specified in this data sheet includes a minimum
and a maximum value size. The best practice is to meet this
requirement and not exceed the maximumVcap valuebecause
the higher inrush currents may reduce the reliability of the
internal pass transistor. Customers who want to use a larger
Vcap value to make sure there is extra store charge should
discuss their Vcap size selection with Cypress.
Table 1. Hardware Mode Selection
CE
H
L
WE
X
HSB
H
A12–A0
Mode
I/O
Power
Standby
Active[3]
Active
X
X
X
X
Not Selected
Read SRAM
Write SRAM
Output High Z
Output Data
Input Data
H
H
L
L
H
[1]
X
X
L
Nonvolatile STORE Output High Z
ICC2
[2, 3]
L
H
H
0x0000
0x1555
0x0AAA
0x1FFF
0x10F0
0x0F0F
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Output Data
Output Data
Output Data
Output Data
Output Data
Active ICC2
Nonvolatile STORE Output High Z
L
H
H
0x0000
0x1555
0x0AAA
0x1FFF
0x10F0
0x0F0E
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Read SRAM
Output Data
Output Data
Output Data
Output Data
Output Data
Active[2, 3]
Nonvolatile RECALL Output High Z
Notes
1. HSB STORE operation occurs only if an SRAM Write is done since the last nonvolatile cycle. After the STORE (If any) completes, the part goes into standby
mode, inhibiting all operations until HSB rises.
2. The six consecutive addresses must be in the order listed. WE must be high during all six consecutive CE controlled cycles to enable a nonvolatile cycle.
3. I/O state assumes OE < V . Activation of nonvolatile cycles does not depend on state of OE.
IL
Document Number: 001-51027 Rev. *C
Page 7 of 24
[+] Feedback
5秒后页面跳转
PCF8574资料解读：主要参数分析、引脚说明
AD637数据手册解读：主要特性、引脚及其功能解读、电气参数
ADUM1201资料手册解读：参数分析、引脚说明、应用分析
一文带你了解压敏电阻器在直流电路中的过压保护作用
微信公众号
抖音公众号
浙公网安备 33010502006866号 浙ICP备10014259号-119
营业执照ICP证
数据手册
如果您发现信息不准确，
