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參數資料
| 型號： | NCP346SN1T1G |
| 廠商： | ON SEMICONDUCTOR |
| 元件分類： | 電源管理 |
| 英文描述： | Overvoltage Protection IC |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO5 |
| 封裝： | LEAD FREE, TSOT-23, 5 PIN |
| 文件頁數： | 7/15頁 |
| 文件大?。?/td> | 386K |
| 代理商： | NCP346SN1T1G |
NCP346
http://onsemi.com
7
Normal Operation
Figure 1 illustrates a typical configuration. The external
adapter provides power to the protection system so the
circuitry is only active when the adapter is connected. The
OVP monitors the voltage from the charger and if the
voltage exceeds the overvoltage threshold, V
th
, the OUT
signal drives the gate of the MOSFET to within 1.0 V of
V
CC
, thus turning off the FET and disconnecting the source
from the load. The nominal time it takes to drive the gate to
this state is 400 nsec (1.0
capacitance of < 12 nF). The CNTRL input can be used to
interrupt charging and allow the microcontroller to measure
the cell voltage under a normal condition to get a more
accurate measure of the battery voltage. Once the
overvoltage is removed, the NCP346 will turn on the
MOSFET. The turn on circuitry is designed to turn on the
MOSFET more gradually to limit the in
rush current. This
characteristic is a function of the threshold of the MOSFET
and will vary depending on the device characteristics such
as the gate capacitance.
There are two events that will cause the OVP to drive the
gate of the FET to a HIGH state.
Voltage on IN Rises Above the Overvoltage Detection
Threshold
CNTRL Input is Driven to a Logic HIGH
sec maximum for gate
Adjusting the Overvoltage Detection Point with
External Resistors
The separate IN and V
CC
pins allow the user to adjust the
overvoltage threshold, V
th
, upwards by adding a resistor
divider with the tap at the IN pin. However, R
in
does play a
significant role in the calculation since it is several
10’s of k . The following equation shows the effects of R
in
.
VCC
Vx(1
R1(R2
Rin))
(eq. 1)
GND
Figure 4. Voltage divider input to adjust overvoltage
detection point
V
CC
R
1
R
2
R
in
I
N
which equates to:
VCC
Vx(1
R1R2
R1Rin)
(eq. 2)
So, as R
in
approaches infinity:
VCC
Vx(1
R1R2)
(eq. 3)
This shows that R
in
shifts the V
th
detection point in
accordance to the ratio of R
1
/ R
in
. However, if R
1
<< R
in
,
this shift can be minimized. The following steps show this
procedure.
Designing around the Maximum Voltage Rating
Requirements, V(V
CC
, IN)
The NCP346’s maximum breakdown voltage between
pins V
CC
and IN is 15 V. Therefore, care must be taken that
the design does not exceed this voltage. Normally, the
designer shorts V
CC
to IN, V(V
CC
, IN) is shorted to 0 V, so
there is no issue. However, one must take care when
adjusting the overvoltage threshold.
In Figure 4, the R1 resistor of the voltage divider divides
the V(V
CC
, IN) voltage to a given voltage threshold equal to:
(VCC,IN)
VCC* (R1 (R1
(R2
Rin)))
(eq. 4)
V(V
CC
, IN) worst case equals 15 V, and V
CC
worst case
equals 30 V, therefore, one must ensure that:
R1 (R1
(R2
Rin))
0.5
(eq. 5)
Where 0.5 = V(V
CC
, IN)max/V
CCmax
Therefore, the NCP346 should only be adjusted to
maximum overvoltage thresholds which are less than 15 V.
If greater thresholds are desired than can be accommodated
by the NCP346, ON Semiconductor offers the NCP345
which can withstand those voltages.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| NCP346SN2T1G | 功能描述:監(jiān)控電路 5.5V Overvoltage Supervisor RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數: 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關:No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| NCP347AE AV51D WAF | 制造商:ON Semiconductor 功能描述: |
| NCP347AI BB58A WAF | 制造商:ON Semiconductor 功能描述: |
| NCP347MTAETBG | 功能描述:電池管理 OVER VLTG PROTECTION RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| NCP347MTAFTBG | 功能描述:電池管理 OVER VLTG PROTECTION RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
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