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TECHNICAL DATA
Low Power Ground Fault Interrupter
The IL4145AN is a low power controller for AC outlet ground fault interrupters. These devices detect hazardous grounding conditions, such as equipment (connected to opposite phases of the AC line) in contact with a pool of water and open circuits the line before a harmful or lethal shock occurs. Contained internally are a 26V zener shunt regulator, an op amp, and an SCR driver. With the addition of two sense transformers, a bridge rectifier, an SCR, a relay, and a few additional components, the IL4145AN will detect and protect against both hot wire to ground and neutral wire to ground faults. The simple layout and conventional design ensure ease of application and long-term reliability.
No potentiomenter required
IL4145A
Direct interface to SCR Supply voltage derived from AC line - 26V shunt Adjustable sensitivity Grounded neutral fault detection Meets U.L. 943 standards 450 A quiescent current Ideal for 120 V or 220 V systems
ORDERING INFORMATION IL4145AN Plastic DIP IL4145AD SOIC TA = -35 to 85 C for all packages.
BLOCK DIAGRAM
VFB
PIN ASSIGNMENT
+
R1 10K R2 10K
VFB
Op Amp Output
1 2 3 4
8 7 6 5
NC Op Amp Output +VS SCR Trigger
+Input
+Input VREF
VREF (+13V)
6.5 V
6.5 V
6.5 V
6.5 V
+VS (+26V)
GND
+
Ground R3 4.7K
+
SCR Trigger
ABSOLUTE MAXIMUM RATINGS
Symbol ICC PD Tstg Topr TJ TL PD Parameter Supply Current Internal Power Dissipation Storage Temperature Range Operating Temperature Range Junction Temperature Lead Temperature TA< 50C For TA> 50C Derate at Value 18 500 -65 to +150 -35 to +85 125 125 450 6 Unit mA mW C C C C mW mW/C
IL4145A
ELECTRICAL CHARACTERISTICS (IS= 1.5 mA and TA= +25C)
Symbol VOH +VS VREF IS VIO VD VOL IOH IOL BW Resistors R1 R2 Shunt Regulator Zener Voltage Reference Voltage Quiescent Current Offset Voltage +Output Voltage Swing -Output Voltage Swing +Output Source Current -Output Source Current Gain Bandwidth Product R1 R2 Pin 6 to Pin 4 Pin 3 to Pin 4 +VS = 24 V Pin 2 to Pin 3 Pin 7 to Pin 3 Pin 7 to Pin 3 Pin 7 to Pin 3 Pin 7 to Pin 3 F = 50 KHz IS = 0 mA Pin 1 to Pin 3 Pin 2 to Pin 3 Pin 5 to Pin 4 Pin 5 to Pin 4 -3.0 6.8 -13.5 -450 800 1.0 8 8 3.5 1.5 0 10 12 12 5.9 25 12.5 29.2 14.6 750 +3.0 8.1 -9.5 -850 1200 V V A mV V V A A MHz k k k V mV Parameter Detector Reference Voltage Test Condition Pin 7 to Pin 3 Min 6.8 Max 8.1 Unit V
Operational Amplifier
R3 R3 SCR Trigger Voltage VON Detector On VOFF Detector Off
ELECTRICAL CHARACTERISTICS (IS= 1.5 mA and -35C TA +85C)
Symbol VOH +VS VREF IS VIO VD VOL Resistors R1 R2 Shunt Regulator Zener Voltage Reference Voltage Quiescent Current Offset Voltage +Output Voltage Swing -Output Voltage Swing R1 R2 Pin 6 to Pin 4 Pin 3 to Pin 4 +VS = 23 V Pin 2 to Pin 3 Pin 7 to Pin 3 Pin 7 to Pin 3 IS = 0 mA Pin 1 to Pin 3 Pin 2 to Pin 3 Pin 5 to Pin 4 Pin 5 to Pin 4 -5.0 6.5 -14 7.5 7.5 3.5 1.3 0 50
24 12
Parameter Detector Reference Voltage
Test Condition Pin 7 to Pin 3
Min 6.5
Max 8.3 30 15 800 +5.0 8.3 -9 12.5 12.5 5.9
Unit V V V A mV V V k k k V mV
Operational Amplifier
R3 R3 SCR Trigger Voltage VON Detector On VOFF Detector Off
IL4145A
Principles of Operation
The 26V shunt regulator voltage generated by the string of zener diodes is divided into three reference voltages: 3/4 VS , 1/2 VS , and 1/4 VS . VREF is at 1/2VS and is used as a reference to create an artifical ground of +13V at the op amp noninverting input. Figure 1 shows a three-wire 120V AC outlet GFI application using an IL4145AN. Fault signals from the sense transformer are AC coupled into the input and are amplified according to the following equation: V7 = RSENSE x ISENSE/N Where V7 is the RMS voltage at pin 7 relative to pin 3, RSENSE is the value of the feedback resistor connected from pin 7 to pin 1, ISENSE is the fault current in amps RMS and N is the turns ratio of the transformer. When V7 exceeds plus or minus 7.2V relative to pin 3 the SCR Trigger output will go high and fire the external SCR. The formula for V7 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 transformer 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 RLINE 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 s h u n t regulator creates internal reference voltages (see above). Operational Amplifier RSENSE therefore RSENSE, current (a standard). is a feedback resistor that sets gain and sensitivity to normal faults. To adjust follow this procedure: apply the desired fault difference in current of 5mA is the UL 943 Adjust RSENSE upward until the SCR activates. A fixed resistor can be used for RSENSE, since the resultant 15% variation in sensitivity will meet UL's 943 4-6mA specification window. 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 frequency 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 200A. CF is a noise filter capacitor that prevents narrow pulses from firing 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 usually 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. Two-Wire Application Circuit Figure 2 shows the diagram of a 2-wire 120V AC outlet GFI circuit using an IL4145AN. 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.
IL4145A
RTEST 15K MOV Sense Transformer
Press To Test
Ground Neutral Transformer
1000:1 Line
Hot Neutral RSENSE 1M*
200:1
Latching Contacts K1
Load
C1 10F VFB
IL4145AN Op Amp Output
C3 0.01 F Solenoid C4 0.03 F
VREF(+13V)
+VS
GND
SCR Trigger RLINE 24 K
DB1 1N4004 (4)
Q1 ON Semi MCR100-6 C2 0.01F
CF 2.2F
* Value depends on transformer characteristics.
Figure 1. GFI Application Circuit (Three-Wire Outlet)
IL4145A
RTEST 15K MOV Sense Transformer
Press To Test
1000:1 Line
Hot Neutral RSENSE 1M*
Latching Contacts K1
Load
C1 10F VFB
IL4145AN Op Amp Output
Solenoid
VREF(+13V)
+VS
GND
SCR Trigger RLINE 24 K
DB1 1N4004 (4)
Q1 Tagi X0103DA
CF 2.2F
C2 0.01F
* Value depends on transformer characteristics.
Figure 2. GFI Application Circuit (Two-Wire Outlet)
(6) +VS(+26V) Q20 6.5V Q11 Q13 Q12 (+) Q2 Q23 Q15 Q19 6.5V (3) VREF (+13V) Q18 6.5V R13 30K R7 250K
R1 10K Q3
R10 6K R2 10K
SCHEMATIC DIAGRAM
Q22
Q21
(1)
(-)
Q1
VFB R14 1.3K
(2)
+Input R6 450 Q6 Q14 C1 Q10 4 pF Q5 Q9 R4 50K R5 50K R9 39K Z1 5.6V Q7 Q8
Q16
Q17 6.5V R12 7.2K
C2 10 pF
Q4
R3 4.7K (4) Ground Sbstrate (7) (5) Op Amp Output SCR Trigger
IL4145A
IL4145A
N SUFFIX PLASTIC DIP (MS - 001BA)
A 8 5 B 1 4
Dimension, mm Symbol A B MIN 8.51 6.1 MAX 10.16 7.11 5.33 0.36 1.14 2.54 7.62 0 2.92 7.62 0.2 0.38 10 3.81 8.26 0.36 0.56 1.78
F
L
C D
C -T- SEATING N G D 0.25 (0.010) M T K
PLANE
F G
M H J
H J K L M N
NOTES: 1. Dimensions "A", "B" do not include mold flash or protrusions. Maximum mold flash or protrusions 0.25 mm (0.010) per side.
D SUFFIX SOIC (MS - 012AA) Dimension, mm
5
A 8
Symbol A
B P
MIN 4.8 3.8 1.35 0.33 0.4 1.27 5.72 0 0.1 0.19 5.8 0.25
MAX 5 4 1.75 0.51 1.27
H
B C
1
G
4 C R x 45
D F
-TD 0.25 (0.010) M T C M K
SEATING PLANE
G
J F M
H J K M P R
8 0.25 0.25 6.2 0.5
NOTES: 1. Dimensions A and B do not include mold flash or protrusion. 2. Maximum mold flash or protrusion 0.15 mm (0.006) per side for A; for B 0.25 mm (0.010) per side.

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