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參數(shù)資料
| 型號： | ADG465BRT |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 小信號晶體管 |
| 英文描述： | Single Channel Protector in an SOT-23 Package |
| 中文描述： | 20 mA, 3 CHANNEL, N AND P-CHANNEL, Si, SMALL SIGNAL, MOSFET |
| 封裝： | PLASTIC, RT-6, 6 PIN |
| 文件頁數(shù)： | 5/8頁 |
| 文件大?。?/td> | 108K |
| 代理商： | ADG465BRT |
ADG465
–5–
REV. A
CIRCUIT INFORMATION
Figure 6 below shows a simplified schematic of a channel pro-
tector circuit. The circuit is comprised of four MOS transis-
tors—two NMOS and two PMOS. One of the PMOS devices
does not lie directly in the signal path, but is used to connect the
source of the second PMOS device to its backgate. This has the
effect of lowering the threshold voltage and increasing the
input signal range of the channel for normal operation. The
source and backgate of the NMOS devices are connected for the
same reason. During normal operation the channel protectors
have a resistance of 80
typ. The channel protectors are very
low power devices; even under fault conditions the supply cur-
rent is limited to sub-microampere levels. All transistors are
dielectrically isolated from each other using a trench isolation
method. This makes it impossible to latch up the channel pro-
tectors. For an explanation, see Trench Isolation section.
V
SS
PMOS
NMOS
NMOS
PMOS
V
SS
V
DD
V
DD
Figure 6. The Channel Protector Circuit
Overvoltage Protection
When a fault condition occurs on the input of a channel pro-
tector, the voltage on the input has exceeded some threshold
voltage set by the supply rail voltages. The threshold voltages
are related to the supply rails as follows: for a positive overvolt-
age, the threshold voltage is given by V
DD
– V
T
where
V
TN
is the
threshold voltage of the NMOS transistor (1.5V typ). In the
case of a negative overvoltage the threshold voltage is given by
V
SS
– V
TP
where
V
TP
is the threshold voltage of the PMOS
device (2V typ). If the input voltage exceeds these threshold
voltages, the output of the channel protector (no load) is
clamped at these threshold voltages. However, the channel
protector output will clamp at a voltage inside these thresholds
if the output is loaded. For example, with an output load of
1k
, V
DD
= 15V and a positive overvoltage. The output will
clamp at V
DD
– V
TN
–
V = 15V – 1.5V – 0.6V = 12.9V
where
V is due to I. R voltage drops across the channels of the
MOS devices (see Figure 8). As can be seen from Figure 8, the
current during fault condition is determined by the load on the
output (i.e., V
CLAMP
/R
L
). However, if the supplies are off, the
fault current is limited to the nanoampere level.
Figures 7, 9 and 10 show the operating conditions of the signal
path transistors during various fault conditions. Figure 7 shows
how the channel protectors operate when a positive overvoltage
is applied to the channel protector.
NMOS
NMOS
V
SS
(–15V)
V
DD
(+15V)
V
DD
(+15V)
V
– V
TN
*
(+13.5V)
PMOS
POSITIVE
OVERVOLTAGE
(+20V)
SATURATED
NON-
SATURATED
NON-
SATURATED
*V
TN
= NMOS THRESHOLD VOLTAGE (+1.5V)
Figure 7. Positive Overvoltage on the Channel Protector
The first NMOS transistor goes into a saturated mode of opera-
tion as the voltage on its Drain exceeds the Gate voltage (V
DD
) –
the threshold voltage (V
TN
). This situation is shown in Figure 8.
The potential at the source of the NMOS device is equal to V
DD
–V
TN
. The other MOS devices are in a nonsaturated mode of
operation.
V
D
V
G
V
S
(V
DD
= +15V)
(+13.5V)
(+20V)
PMOS
NMOS
NONSATURATED
OPERATION
I
OUT
R
L
V
CLAMP
(V
G
– V
T
= 13.5V)
EFFECTIVE
SPACE CHARGE
REGION
N
+
N
+
N
+
V
T
= 1.5V
P
–
OVERVOLTAGE
OPERATION
(SATURATED)
N-CHANNEL
D
V
Figure 8. Positive Overvoltage Operation on the Channel Protector
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| ADG465BRT-REEL | 功能描述:IC 1CH PROTECTOR SOT23-6 RoHS:否 類別:過電壓，電流，溫度裝置 >> TVS - 其它復(fù)合 系列:ADG465 標準包裝:1 系列:- 電壓 - 工作:120V 電壓 - 箝位:- 技術(shù):混合技術(shù) 功率（瓦特）:- 電路數(shù):1 應(yīng)用:通用 封裝/外殼:模塊 供應(yīng)商設(shè)備封裝:- 包裝:散裝 其它名稱:UAK 2-PE/S-X-120AC-STUAK2-PE/S-X-120AC-ST |
| ADG465BRT-REEL7 | 功能描述:IC 1CH PROTECTOR SOT23-6 RoHS:否 類別:過電壓，電流，溫度裝置 >> TVS - 其它復(fù)合 系列:ADG465 標準包裝:1 系列:- 電壓 - 工作:120V 電壓 - 箝位:- 技術(shù):混合技術(shù) 功率（瓦特）:- 電路數(shù):1 應(yīng)用:通用 封裝/外殼:模塊 供應(yīng)商設(shè)備封裝:- 包裝:散裝 其它名稱:UAK 2-PE/S-X-120AC-STUAK2-PE/S-X-120AC-ST |
| ADG465BRTZ-REEL7 | 功能描述:IC CHANNEL PROTECTOR SGL SOT23-6 RoHS:是 類別:過電壓，電流，溫度裝置 >> TVS - 其它復(fù)合 系列:ADG465 標準包裝:1 系列:- 電壓 - 工作:120V 電壓 - 箝位:- 技術(shù):混合技術(shù) 功率（瓦特）:- 電路數(shù):1 應(yīng)用:通用 封裝/外殼:模塊 供應(yīng)商設(shè)備封裝:- 包裝:散裝 其它名稱:UAK 2-PE/S-X-120AC-STUAK2-PE/S-X-120AC-ST |
| ADG465BRTZ-REEL7 | 制造商:Analog Devices 功能描述:SINGLE CHANNEL PROTECTOR, SOT-23-6 |
| ADG466 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Triple and Octal Channel Protectors |
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