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參數資料
| 型號： | W28V400BT85C |
| 廠商： | WINBOND ELECTRONICS CORP |
| 元件分類： | PROM |
| 英文描述： | 4M(512K x 8/256K x 16) SMARTVOLTAGE FLASH MEMORY |
| 中文描述： | 256K X 16 FLASH 2.7V PROM, 120 ns, PDSO48 |
| 封裝： | 12 X 20 MM, TSOP-48 |
| 文件頁數： | 22/48頁 |
| 文件大小： | 1822K |
| 代理商： | W28V400BT85C |
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W28V400B/T
- 22 -
10. DESIGN CONSIDERATIONS
Three-line Output Control
This device will often be used in large memory arrays. Winbond provides three control inputs to
accommodate multiple memory connections. Three-line control provides for:
a. Lowest possible memory power dissipation.
b. Complete assurance that data bus contention will not occur.
To use these control inputs efficiently, an address decoder should enable #CE while #OE should be
connected to all memory devices and the system’s #READ control line. This assures that only
selected memory devices have active outputs while deselected memory devices are in standby mode.
#RESET should be connected to the system POWERGOOD signal to prevent unintended writes
during system power transitions. POWERGOOD should also toggle during system reset.
RY/#BY, Block Erase and Word/Byte Write Polling
RY/#BY is a full CMOS output that provides a hardware
method of detecting block erase and
word/byte write
completion. It transitions low after block erase or
word/byte write commands and
returns to V
OH
when the
WSM has finished executing the internal algorithm.
RY/#BY can be connected to an interrupt input of the
system CPU or controller. It is active at all times.
RY/#BY
is also V
OH
when the device is in block erase suspend (with word/byte write inactive),
word/byte write suspend or deep power-down modes.
Power Supply Decoupling
Flash memory power switching characteristics require careful device decoupling. System designers
are interested in three supply current issues; standby current levels, active current levels and transient
peaks produced by falling and rising edges of #CE and #OE. Transient current magnitudes depend on
the device outputs’ capacitive and inductive loading. Two-line control and proper decoupling capacitor
selection will suppress transient voltage peaks.
Each device should have a 0.1
μ
F ceramic capacitor connected between V
DD
and V
SS
and between
V
PP
and V
SS
. These high frequency, low inductance capacitors should be placed as close as possible
to package leads. Additionally, for every eight devices, a 4.7
μ
F electrolytic capacitor should be placed
at the array’s power supply connection between V
DD
and V
SS
. The bulk capacitor will overcome
voltage drops caused by PC board trace inductance.
V
PP
Trace on Printed Circuit Boards
Updating flash memories that reside in the target system requires that the printed circuit board
designer pay attention to the V
PP
power supply trace. The V
PP
pin supplies the memory cell current for
word/byte writing and block erasing. Use similar trace widths and layout considerations given to the
V
DD
power bus. Adequate V
PP
supply traces and decoupling will decrease V
PP
voltage spikes and
overshoots.
V
DD
, V
PP
, #RESET Transitions
Block erase and word/byte write are not guaranteed if V
PP
falls outside of a valid V
PPH1/2/3
range, V
DD
falls outside of a valid V
DD1/2/3/4
range, or #RESET
≠
V
IH
or V
HH
. If V
PP
error is detected, status register
bit SR.3 is set to "1" along with SR.4 or SR.5, depending on the attempted operation. If #RESET
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相關代理商/技術參數 |
參數描述 |
|---|---|
| W28V400T | 制造商:WINBOND 制造商全稱:Winbond 功能描述:4M(512K x 8/256K x 16) SMARTVOLTAGE FLASH MEMORY |
| W28V400TT85C | 制造商:WINBOND 制造商全稱:Winbond 功能描述:4M(512K x 8/256K x 16) SMARTVOLTAGE FLASH MEMORY |
| W28WH | 制造商:ETERNA 功能描述:TRACKLIGHT, FLEXIBLE TRACK COUPLER |
| W28-X01B-3 | 制造商:TE Connectivity 功能描述: |
| W28-X1015-3.70 | 功能描述:斷路器 W28-X1015-3.70=W28 RoHS:否 制造商:Phoenix Contact 產品:Device Circuit Breakers 產品類型:Thermomagnetic 電流額定值:2 A 電壓額定值 AC:240 V, 277 V 電壓額定值 DC:50 V 極數:1 Pole 執行器類型:Slide 電路功能:Trip Free 系列:CB TM1 工作溫度范圍:- 30 C to + 60 C 照明:No |
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