參數(shù)資料
型號: DS55325J
英文描述: Memory Driver
中文描述: 記憶體驅(qū)動
文件頁數(shù): 13/14頁
文件大?。?/td> 201K
代理商: DS55325J
Applications
EXTERNAL RESISTOR CALCULATION
A typical magnetic-memory word drive requirement is shown
in Figure 11. A source-output transistor of one DS75325
delivers load current (I
L
). The sink-output transistor of an-
other DS75325 sinks this current.
The value of the external pull-up resistor (R
ext
) for a particu-
lar memory application may be determined using the follow-
ing equation:
16
[
V
CC2(Min)
b
V
S
b
2.2
]
I
L
b
1.6
[
V
CC2(Min)
b
V
S
b
2.9
]
where: R
ext
is in k
X
,
V
CC2(Min)
is the lowest expected value of V
CC2
in volts, V
S
is the source output voltage in volts with respect to ground,
I
L
is in mA.
The power dissipated in resistor R
ext
during the load current
pulse duration is calculated using Equation 2.
R
ext
e
(1)
P
Rext
&
I
L
16
[
V
CC2(Min)
b
V
S
b
2
]
(2)
where: P
Rext
is in mW.
After solving for R
ext
, the magnitude of the source collector
current (I
CS
) is determined from Equation 3.
I
CS
&
0.94 I
L
where: I
CS
is in mA.
As an example, let V
CC2(Min)
e
20V and V
L
e
3V while I
L
of 500 mA flows. Using Equation 1:
16 (20
b
3
b
2.2)
500
b
1.6 (20
b
3
b
2.9)
and from Equation 2:
(3)
R
ext
e
e
0.5 k
X
P
Rext
&
500
16
[
20
b
3
b
2
]
&
470 mW
The amount of the memory system current source (I
CS
)
from Equation 3 is:
I
CS
&
0.94 (500)
&
470 mA
In this example the regulated source-output transistor base
current through the external pull-up resistor (R
ext
) and the
source gate is approximately 30 mA. This current and I
CS
comprise I
L
.
TL/F/9755–15
Note 1:
For clarity, partial logic diagrams of two DS55325s are shown.
Note 2:
Source and sink shown are in different packages.
FIGURE 11. Typical Application Data
13
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS55325J/A+ 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Memory Driver
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