收藏本站
NCP346
Normal Operation
which equates to:
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
VCC + Vx(1 ) R1 R2 ) R1 Rin)
So, as R in approaches infinity:
VCC + Vx(1 ) R1 R2)
(eq. 2)
(eq. 3)
(VCC, IN) + VCC * (R1 (R1 ) (R2 Rin)))
R1 (R1 ) (R2 Rin)) t 0.5
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 m sec maximum for gate
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
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 W . The following equation shows the effects of R in .
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:
(eq. 4)
V(V CC , IN) worst case equals 15 V, and V CC worst case
equals 30 V, therefore, one must ensure that:
(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.
VCC + Vx(1 ) R1 (R2
V CC
R 1
I N
R 2
Rin))
R in
(eq. 1)
GND
Figure 4. Voltage divider input to adjust overvoltage
detection point
http://onsemi.com
7
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
NCP347MTAITBG IC OVERVOLTAGE PROT CTRLR 10WDFN
NCP348AEMUTBG IC MOSFET DRIVER DUAL 12V 10LLGA
NCP360MUTXG IC CTLR USB POS OVP FET 6-UDFN
NCP361MUTBG IC USB OVERVOLT PROT CTRLR 6UDFN
NCP3712ASNT3 IC SWITCH OVP HIGH SIDE SC74-6
NCP374MU075TXG IC CTLR OVP POS/NEG 30V 12TLLGA
NCP5104BA36WGEVB EVAL BOARD FOR NCP5104BA36WG
NCP5181BAL36WEVB BOARD EVAL NCP5181 36 W BALLAST
相关代理商/技术参数
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:电池管理 OVER VLTG PROTECTION RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel
NCP347MTAFTBG 功能描述:电池管理 OVER VLTG PROTECTION RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel
NCP347MTAHTBG 功能描述:电池管理 OVER VLTG PROTECTION RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel
NCP347MTAITBG 功能描述:电池管理 OVER VLTG PROTECTION RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel
NCP3488DR2G 功能描述:功率驱动器IC ANA 12V MOSFET DR RoHS:否 制造商:Micrel 产品:MOSFET Gate Drivers 类型:Low Cost High or Low Side MOSFET Driver 上升时间: 下降时间: 电源电压-最大:30 V 电源电压-最小:2.75 V 电源电流: 最大功率耗散: 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Tube
NCP348AEMTTBG 功能描述:监控电路 POS OVERVLTG PROTECT CONTROLLER RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel