www.fairchildsemi.com RV4140A Low Power Two-Wire Ground Fault Interrupter Controller Features Description • • • • • • • • • • The RV4140A is a low power controller for AC outlet appliance leakage circuit interrupters. These devices detect hazardous current paths to ground such as an appliance falling into water. The interrupter then open circuits the line before a harmful or lethal shock occurs. Powered from the AC line Built-in bridge rectifier Direct interface to SCR 350 mA quiescent current Adjustable trip current Adjustable time delay Minimum external components Meets UL 943 requirements Specifically for two-wire systems For use with 110V or 220V systems Internally, the RV4140A has a diode bridge rectifier, zener shunt regulator, op amp, current reference, time delay circuit, latch and SCR driver. An external sense transformer, SCR, relay, two resistors and three capacitors complete the design of the circuit interrupter. The simple layout and minimum component count ensure ease of application and long term reliability. Block Diagram RV4140A 8 1 2 7 Latch 4.7K Delay 6 3 Vcc 4 5 65-4140A-01 Rev. 1.0.0 RV4140A PRODUCT SPECIFICATION Functional Description Supply Current Requirements (Refer to Block Diagram and Figure 1 ) The RV4140A has a built-in diode bridge rectifier that provides power to the chip independent of the polarity of the AC line. This eliminates the external rectifier required for previous GFCI controllers. The shunt regulator generated by a 6.5V zener diode is built into the internal bridge rectifier. It is divided to create an internal reference voltage of 2.9V connected to pin 3. The secondary of the sense transformer is AC coupled to the inverting input of the sense amplifier at pin 2; the non-inverting input is referenced to pin 3. A current feedback loop around the sense amplifier ensures a virtual ground will be presented to the secondary of the sense transformer. In this manner it acts as a current transformer instead of a voltage transformer. In this mode, the transformer’s characteristics are very predictable and circuit adjustments are not necessary in production. The sense transformer has a toroidal core made of laminated steel rings or solid ferrite material. The secondary of the transformer is 500 to 1000 turns of #40 wire wound through the toroid. The primary’s one turn made by passing the AC hot and neutral wires through the center of the toroid. When a ground fault exists, a difference exists between the current flowing in hot and neutral wires. The difference primary current, divided by the number of secondary turns, flows through the secondary wire of the transformer. The AC coupled transformer secondary current then flows through the sense amplifier’s feedback loop, creating a full wave rectified version of the secondary fault current. This current passes through RSET at pin 1, generating a voltage equal to RSET times the peak fault current divided by the sense transformer turns ratio. This voltage is compared with the reference voltage at pin 3. RLlNE limits the shunt regulator current to 2 mA. The recommended value is 47K to 91K for 110V systems and 91K to 150K for 220V systems. The recommended maximum peak line current through RLlNE is 7 mA. DO NOT connect a filter capacitor between pins 5 and 6 in an attempt to filter the supply voltage at the RV4140A. Proper operaton of the RV4140A requires the internal supply voltage to be unfiltered. SCR Driver The SCR must have a high dV/dt rating to ensure that line noise (generated by electrically noisy appliances) does not falsely trigger the SCR. Also, the SCR must have a gate drive requirement less than 200 mA. C3 is a noise filter that prevents high frequency line pulses from triggering the SCR. The relay solenoid used should have a 3 ms or less response time to meet the UL 943 timing requirement. Supplier of Sense Transformers and Cores Magnetic Metals Corporation, Camden, NJ 08101, (609) 964-7842, supplies a full line of ring cores and transformers designed specifically for GFCI and related applications. Determining the Values of RSET and C2 If the voltage at pin 1 is greater than pin 3, a comparator will charge C2 through a 29 mA current source at pin 8. If the voltage at pin 1 exceeds pin 3 for longer than the delay time, a 400 mA current will pulse between pins 7 and 6 which will trigger the gate of the SCR. If the voltage at pin 1 exceeds pin 3 for less than the delay time, the SCR will not trigger. The fault current at which the controller triggers the SCR is dependent on the value of RSET and the time delay determined by C2. UL 943 requires the circuit interrupter trip when the ground fault exceeds 6 mA and not trip when the fault current is less than 4 mA. 2 Determine the ground fault trip current requirement. This will be typically 5 mA in North America (117 VAC) and 10 mA in the UK and Europe. Determine the minimum amount of time delay required to prevent nuisance tripping. This will typically be 1 to 2 ms. The value of C2 required to provide the desired delay time is: C2 = 10 x T where C2 is in nF, and T is the desired delay time in ms. PRODUCT SPECIFICATION RV4140A The value of RSET to meet nominal ground fault tip current specification is: This formula assumes an ideal sense transformer is used. The calculated value of RSET may have to be changed up to 30% when using a non-ideal transformer. 2.05 ´ N R SET = --------------------------------------------------------------I FAULT ´ COS 180 ( T ¤ P ) Where: • • • • RSET is in kW T is the time delay in ms P is the period of the line frequency in ms IFAULT is the desired ground fault trip current in mA RMS. • N is the number of sense transformer secondary turns. RTEST 15K Mov Sense Transformer 1:500 Turns Ratio 3 Ring Steel Core Press to Test Normally Latching Closed Contacts Hot Line Load Neutral C1 10 m F RSET 191K 1 8 2 3 C4 0.1m F 4 Solinoid C2 0.02 m F 7 RV4140A 6 Q1 Tag X0103DA RLINE 91K C3 10 nF 5 65-4140A-02 Figure 1. Appliance Leakage Detector Circuit Application 3 RV4140A PRODUCT SPECIFICATION Pin Assignments PDIP (Top View) SOIC (Top View) RSET 1 8 C Delay VFB 2 7 SCR Trigger 2.9V 3 6 Neutral Ground 4 5 Line RSET 1 8 C Delay VFB 2 7 SCR Trigger 2.9V 3 6 Neutral Ground 4 5 Line 65-4140A-03 Absolute Maximum Ratings Parameter Min. Supply Current Internal Power Dissipation Typ. Max. Units 7 mA 500 mW Storage Temperature Range -65 +150 °C Operating Temperature Range -35 +80 °C 60 Seconds, DIP +300 °C 10 Seconds, SOIC +260 °C Lead Soldering Temperature Thermal Characteristics Parameter 4 8 Lead Plastic SOIC 8 Lead Plastic DIP Maximum Junction Temperature +125°C +125°C Maximum PDTA<50°C 300 mW 468 mW Thermal Resistance, qJA 240°C/W 160°C/W For TA > 50°C Derate at 4.1 mW/°C 6.25 mW/°C PRODUCT SPECIFICATION RV4140A Electrical Characteristics ILINE = 1.2mA and TA = +25°C, RSET = 290kW Parameters Test Conditions Min. Typ. Max. Units Shunt Regulator (Pins 5 to 4) Regulated Voltage I2-3 = 11mA 6.8 7.2 7.6 V Regulated Voltage ILINE = 700 mA, I2-3 = 9mA 6.8 7.2 7.6 V Offset Voltage Design Value -3.0 0 3.0 mV Gain Bandwidth Design Value 2.0 Input Bias Current Design Value 30 100 nA 4.0 4.7 5.4 kW Sense Amplifier (Pins 2 to 3) MHz SCR Trigger (Pins 7 to 6) Output Resistance V5-6 = open, I2-3 = 0mA Output Voltage I2-3 = 9mA 0 0.1 10 mV Output Voltage I2-3 = 11mA 1.4 2.0 2.6 V Output Current V7-6 = 0V, I2-3 = 11mA 300 420 600 mA ILINE = 700 mA 2.6 2.9 3.2 V Delay Time1 C8-4 = 20nF — 2.0 — ms Delay Current I2-3 = 11mA 23 29 35 mA Reference Voltage (Pins 3 to 4) Reference Voltage Delay Timer (Pins 8 to 4) Note: 1. Delay time is defined as starting when the instantaneous sense current (I 2-3) exceeds 2.9V/RSET and ending when the SCR trigger voltage V7-6 goes high. 5 6 (2) (3) Common V FB Ground (4) Q2 Q6 R1 10K Q3 Q12 R4 50K Q7 VCC Q5 R3 8.5K Q8 Q44 C1 Q16 Q11 (1) R SET R6 2.5K Q15 Q10 6.5 pF Q9 R2 10K R5 50K Q13 Q14 R8 23K Q19 Q17 R7 23K Q20 Q18 Q23 Q21 Sub Q24 Q25 Q22 Q28 Q26 Q27 Q32 Q29Q30 Sub Q33 Q31 Q38 Sub Sub Q35 Q34 Q36 Q40 R9 83K Q37 Q39 Q42 Q41 Q43 Q44 Q46 Q45 Q49 Q47 R10 4.7K Q50 Q48 65-4653 Cap (8) SCR (7) Neutral (6) Line (5) RV4140A PRODUCT SPECIFICATION Schematic Diagram PRODUCT SPECIFICATION RV4140A Notes: 7 RV4140A Notes: 8 PRODUCT SPECIFICATION PRODUCT SPECIFICATION RV4140A Notes: 9 RV4140A PRODUCT SPECIFICATION Mechanical Dimensions 8-Lead Plastic DIP Package Inches Symbol A A1 A2 B B1 C D D1 E E1 e eB L Millimeters Min. Max. Min. Max. — .015 .115 .014 .045 .008 .348 .005 .300 .240 .210 — .195 .022 .070 .015 .430 — .325 .280 — .38 2.93 .36 1.14 .20 8.84 .13 7.62 6.10 5.33 — 4.95 .56 1.78 .38 10.92 — 8.26 7.11 .100 BSC — .430 .115 .160 2.54 BSC — 10.92 2.92 4.06 8¡ 8¡ N Notes: Notes 1. Dimensioning and tolerancing per ANSI Y14.5M-1982. 2. "D" and "E1" do not include mold flashing. Mold flash or protrusions shall not exceed .010 inch (0.25mm). 3. Terminal numbers are for reference only. 4. "C" dimension does not include solder finish thickness. 5. Symbol "N" is the maximum number of terminals. 4 2 2 5 D 4 1 5 8 E1 D1 E e A2 A A1 C L B1 10 B eB PRODUCT SPECIFICATION RV4140A Mechanical Dimensions (continued) 8-Lead SOIC Package Inches Symbol Min. A A1 B C D E e H h L N a ccc Millimeters Max. Min. Max. .053 .069 .004 .010 .013 .020 .008 .010 .189 .197 .150 .158 .050 BSC 1.35 1.75 0.10 0.25 0.33 0.51 0.20 0.25 4.80 5.00 3.81 4.01 1.27 BSC .228 .010 .016 5.79 0.25 0.40 .244 .020 .050 8 6.20 0.50 1.27 8 0¡ 8¡ 0¡ 8¡ — .004 — 0.10 8 Notes: Notes 1. Dimensioning and tolerancing per ANSI Y14.5M-1982. 2. "D" and "E" do not include mold flash. Mold flash or protrusions shall not exceed .010 inch (0.25mm). 3. "L" is the length of terminal for soldering to a substrate. 4. Terminal numbers are shown for reference only. 5 2 2 5. "C" dimension does not include solder finish thickness. 6. Symbol "N" is the maximum number of terminals. 3 6 5 E 1 H 4 h x 45¡ D C A1 A SEATING PLANE e B –C– LEAD COPLANARITY a L ccc C 11 RV4140A PRODUCT SPECIFICATION Ordering Information Part Number Package Operating Temperature Range RV4140AN 8-Lead Plastic DIP -35°C to +80°C RV4140AM 8-Lead Plastic SOIC -35°C to +80°C LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com 7/27/98 0.0m 002 Stock#DS20004140A Ó 1998 Fairchild Semiconductor Corporation