参数资料
| 型号： | RV4145AM |
| 厂商： | Fairchild Semiconductor |
| 文件页数： | 4/10页 |
| 文件大小： | 0K |
| 描述： | IC CTRLR LP AC GFI 8-SOIC |
| 标准包装： | 95 |
| 应用： | 接地故障保护 |
| 电流 - 电源： | 18mA |
| 工作温度： | -35°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOICN |
| 包装： | 管件 |
PRODUCT SPECIFICATION
Principles of Operation
The 26V shunt regulator voltage generated by the string of
zener diodes is divided into three reference voltages: 3/4 V S ,
1/2 V S , and 1/4 V S . V REF is at 1/2VS and is used as a refer-
ence to create an arti?cal ground of +13V at the op amp non-
inverting input.
Figure 1 shows a three-wire 120V AC outlet GFI application
using an RV4145A. Fault signals from the sense transformer
are AC coupled into the input and are ampli?ed according to
the following equation:
V 7 = R SENSE × I SENSE /N
Where V 7 is the RMS voltage at pin 7 relative to pin 3,
R SENSE is the value of the feedback resistor connected from
pin 7 to pin 1, I SENSE is the fault current in amps RMS and
N is the turns ratio of the transformer. When V 7 exceeds plus
or minus 7.2V relative to pin 3 the SCR Trigger output will
go high and ?re the external SCR.
The formula for V 7 is approximate because it does not
include the sense transformer characteristics.
Grounded neutral fault detection is accomplished when a
short or fault closes a magnetic path between the sense trans-
former and the grounded neutral transformer. The resultant
AC coupling closes a positive feedback path around the op
amp, and therefore the op amp oscillates. When the peaks of
the oscillation voltage exceed the SCR trigger comparator
thresholds, the SCR output will go high.
Shunt Regulator
R LINE limits the current into the shunt regulator; 220V
applications will require substituting a 47k ? 2W resistor. In
addition to supplying power to the IC, the shunt regulator
creates internal reference voltages (see above).
Operational Ampli?er
R SENSE is a feedback resistor that sets gain and therefore
sensitivity to normal faults. To adjust R SENSE , follow this
procedure: apply the desired fault current (a difference in
current of 5mA is the UL 943 standard). Adjust R SENSE
upward until the SCR activates. A ?xed resistor can be used
for R SENSE , since the resultant ±15% variation in sensitivity
will meet UL’s 943 4-6mA speci?cation window.
4
RV4145A
The roll-off frequency is greater than the grounded neutral
fault oscillation frequency, in order to preserve loop gain for
oscillation (which is determined by the inductance of the
200:1 transformer and C4).
The senstivity to grounded neutral faults is adjusted by
changing the frequency of oscillation. Increasing the fre-
quency reduces the sensitivity by reducing the loop gain of
the positive feedback circuit. As frequency increases, the
signal becomes attenuated and the loop gain decreases. With
the values shown the circuit will detect a grounded neutral
fault having resistance of 2 ? or less.
The input to the op amp are protected from overvoltage by
back-toback diodes.
SCR Driver
The SCR used must have a high dV/dt rating to ensure that
line noise (generated by noisy appliances such as a drill
motor) does not falsely trigger the SCR. Also, the SCR must
have a gate drive requirement of less than 200μA. C F is a
noise ?lter capacitor that prevents narrow pulses from ?ring
the SCR.
The relay solenoid used should have a 3ms or less response
time in order to meet the UL 943 timing requirement.
Sense Transformers and Cores
The sense and grounded neutral transformer cores are usu-
ally fabricated using high permeability laminated steel rings.
Their single turn primary is created by passing the line and
neutral wires through the center of its core. The secondary is
usually from 200 to 1500 turns.
Magnetic Metals Corporation, Camden, NJ 08101,
(609) 964-7842, and Magnetics, 900 E. Butler Road,
P.O. Box 391, Butler, PA 16003, (412) 282-8282 are full line
suppliers of ring cores and transformers designed speci?-
cally for GFI applications.
Two-Wire Application Circuit
Figure 2 shows the diagram of a 2-wire 120V AC outlet GFI
circuit using an RV4145A. This circuit is not designed to
detect grounded neutral faults. Thus, the grounded neutral
transformer and capacitors C3 and C4 of Figure 1 are not
used.
REV. 1.0.5 12/7/04
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相关代理商/技术参数 |
参数描述 |
|---|---|
| RV4145AMT | 功能描述:电流和电力监控器、调节器 Low Pwr Ground Fault Interrupt Cont RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| RV4145AMT_32 | 功能描述:电流和电力监控器、调节器 Improved Lo Pwr GFI RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| RV4145AMU | 制造商:FAIRCHILD 制造商全称:Fairchild Semiconductor 功能描述:Low Power Ground Fault Interrupter |
| RV4145AN | 功能描述:电流和电力监控器、调节器 Low Pwr Ground Fault Interrupt Cont RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| RV4145AN_32 | 功能描述:电流和电力监控器、调节器 Improved Lo Pwr GFI RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
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