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參數(shù)資料
| 型號(hào)： | RV4141AN |
| 廠商： | RAYTHEON SEMICONDUCTOR |
| 元件分類： | 電源管理 |
| 英文描述： | Low Power Ground Fault Interrupter |
| 中文描述： | POWER SUPPLY SUPPORT CKT, PDIP8 |
| 封裝： | PLASTIC, DIP-8 |
| 文件頁(yè)數(shù)： | 4/8頁(yè) |
| 文件大?。?/td> | 345K |
| 代理商： | RV4141AN |
PRODUCT SPECIFICATION
RV4141A
4
REV. 1.0.1 7/8/03
Circuit Operation
(Refer to Block Diagram and Figure 1)
The precision op amp connected to Pins 1 through 3 senses
the fault current flowing in the secondary of the sense trans-
former, converting it to a voltage at Pin 1. The ratio of sec-
ondary current to output voltage is directly proportional to
feedback resistor, R
SET
.
R
voltage at Pin 1. Due to the virtual ground created at the
sense amplifier input by its negative feedback loop, the sense
transformer's burden is equal to the value of R
transformer's point of view, the ideal value for R
This will cause it to operate as a true current transformer
with minimal error. However, making R
ates a large offset voltage at Pin 1 due to the sense amplifier's
very high DC gain. R
IN
should be selected as high as possi-
ble consistent with preserving the transformer's operation as
a true current mode transformer. A typical value for R
between 200 and 1000
.
SET
converts the sense transformer secondary current to a
IN
. From the
IN
is 0
.
IN
equal to zero cre-
IN
is
As seen by the equation below, maximizing R
the DC offset error at the sense amplifiers output. The DC
offset voltage at Pin 1 contributes directly to the trip current
error. The offset voltage at Pin 1 is:
IN
minimizes
V
OS
x R
SET
/(R
IN
+ R
SEC
)
Where:
V
OS
R
SET
R
IN
R
SEC
= Input offset voltage of sense amplifier
= Feedback resistor
= Input resistor
= Transformer secondary winding resistance
The sense amplifier has a specified maximum offset voltage
of 200 μV to minimize trip current errors.
Two comparators connected to the sense amplifier output are
configured as a window detector, whose references are -6.5
volts and +6.5 volts referred to Pin 3. When the sense trans-
former secondary RMS current exceeds 4.6/R
of the window detector starts the delay circuit. If the second-
ary current exceeds the predetermined trip current for longer
than the delay time a current pulse appears at Pin 7, trigger-
ing the SCR.
SET
the output
The SCR anode is directly connected to a solenoid or relay
coil. The SCR can be tripped only when its anode is more
positive than its cathode.
Supply Current Requirements
The RV4141A is powered directly from the line through a
series limiting resistor called R
24 k
and 91 k
. The controller IC has a built-in diode
rectifier eliminating the need for external power diodes.
LINE
, its value is between
The recommended value for R
110V systems and 47 k
R
LINE
is 47 k
3.6 mA. The recommended maximum peak line current
through R
LINE
is 10 mA.
LINE
is 24 k
for 220V systems. When
to 47 k
for
to 91 k
the shunt regulator current is limited to
GFCI Application
The GFCI detects a ground fault by sensing a difference cur-
rent in the line and neutral wires. The difference current is
assumed to be a fault current creating a potentially hazardous
path from iine to ground. Since the line and neutral wires
pass through the center of the sense transformer, only the dif-
ferential primary current is transferred to the secondary.
Assuming the turns ratio is 1:1000 the secondary current is
1/1000th the fault current. The RV4141A’s sense amplifier
converts the secondary current to a voltage which is com-
pared with either of the two window detector reference volt-
ages. If the fault current exceeds the design value for the
duration of the programmed time delay, the RV4141A will
send a current pulse to the gate of the SCR.
(Refer to Figure 1)
Detecting ground to neutral faults is more difficult. R
sents a normal ground fault resistance, R
tance of the electrical circuit between load/ neutral and earth
ground. R
G
represents the ground to neutral fault condition.
According to UL 943, the GFCI must trip when R
R
G
= 1.6
and the normal ground fault is 6 mA.
B
repre-
N
is the wire resis-
N
= 0.4
,
Assuming the ground fault to be 5 mA, 1 mA and 4 mA will
go through R
G
and R
N
, respectively, causing an effective 1
mA fault current. This current is detected by the sense trans-
former and amplified by the sense amplifier. The ground/
neutral and sense transformers are now mutually coupled by
R
G
, R
N
and the neutral wire ground loop, producing a posi-
tive feedback loop around the sense amplifier. The newly
created feedback loop causes the sense amplifier to oscillate
at a frequency determined by ground/neutral transformer
secondary inductance and C4. Typically it occurs at 8 KHz.
C2 is used to program the time required for the fault to be
present before the SCR is triggered. Refer to the equation
below for calculating the value of C2. Its typical value is
12 nF for a 2 ms delay.
R
When used with a 1:1000 sense transformer, its typical value
is 1 M
for a GFCI designed to trip at 5 mA.
SET
is used to set the fault current at which the GFCI trips.
R
If R
IN
is set too high, normal production variations in the
transformer permeability will cause unit to unit variations in
the secondary current. If it is too low, a large offset voltage
error at Pin 1 will be present. This error voltage in turn cre-
ates a trip current error proportional to the input offset volt-
age of the sense amplifier. As an example, if R
IN
should be the highest value possible which insures a
IN
is 500
,
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| RV4141AN_11 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Low-Power, Ground-Fault Interrupter |
| RV4141AN_32 | 功能描述:其他電源管理 GFI Controller Low Power RoHS:否 制造商:Texas Instruments 輸出電壓范圍: 輸出電流:4 mA 輸入電壓范圍:3 V to 3.6 V 輸入電流: 功率耗散: 工作溫度范圍:- 40 C to + 110 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-48 封裝:Reel |
| RV4141M | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Ground Fault Interrupter |
| RV4141N | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Ground Fault Interrupter |
| RV4145 | 制造商:FAIRCHILD 制造商全稱:Fairchild Semiconductor 功能描述:Low Power Ground Fault Interrupter |
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