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| CA3274 April 1994 Current Limiting Power Switch with Current Limiter Sense Flag Description The CA3274 is a controlled current switch and may be used in general purpose switching applications that require specified maximum levels of current. The functional block diagram of the CA3274 is shown and a typical application circuit is shown in Figure 1. An internal emitter follower has 200mA of source drive output capability. The Control Input is a Schmitt trigger buffer amplifier for noise immunity in the environments typical of industrial and automotive control systems. Current sensing in the emitter circuit of a power-darlington output stage is fed back from a sampling resistor to the sense input of the CA3274 which has a 335mV typical offset. For the example shown in Figure 1, a sampling resistor of 0.056 permits 6.0A (0.335/0.056) of current in the emitter of the output driver. When the current limiter is activated, the flag output changes state conditionally. If the control input is the "0" state, the flag output will remain in a "1" state. If the control input is in the "1" state and the sense input is less than the voltage reference level of 335mV, the flag output will remain in the "1" state. If the control input is the "1" state and the sense input is equal to or greater than the 335mV reference level, the flag output goes to the "0" state. The output flag switch may be used to accurately establish dwell timing in automotive applications. When the control input goes to "0", the flag is reset to "1". Noiseimmunity hold-off is used to prevent pre-triggering of the flag output and is noted as tD in the timing diagram of Figure 2. The flag output may be used for diagnostic feedback via the current sense input to detect a fault mode. In this case the sampled drive current is either from the emitter of the CA3274 internal power transistor or an external output amplifier, such as a darlington power transistor or power-FET output stage. The CA3274 has separate power and signal grounds to minimize transient-loop feedback to the input ground and thus prevent false triggering of the output. Optionally, the output from the CA3274 may be taken from the open collector (DRIVE IN) at pin 6. An external resistor at pin 6 may be used to set the level at which Q2 will saturate, providing additional limiting protection for the maximum forward-drive from the CA3274. Features * Drive-Current Limiting at Output * Current-Sense Buffer and Reference * 200mA Driver Current Capability * Logic-Level Control Input * Current Limiting Flag Output * 50dB Minimum PSRR * 5s Typical Switch Time * Separate Signal and Power Grounds Applications * Solenoid Switch Driver * Relay Driver * Lamp Control Switch * Ignition Coil Pre-Driver * Constant Current Driver * Current Limiting Switch * Fault Output Sense Appliance * Power Supply Fault Mode Control Ordering Information PART NUMBER CA3274E TEMPERATURE RANGE -40oC to +85oC PACKAGE 8 Lead Plastic DIP Pinout CA3274 (PDIP) TOP VIEW FLAG OUT SENSE IN POWER GND SIGNAL GND 1 2 3 4 8 7 6 5 VCC SUPPLY CONTROL IN DRIVE IN DRIVE OUT CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. http://www.intersil.com or 407-727-9207 | Copyright (c) Intersil Corporation 1999 File Number 2222.2 10-40 CA3274 Block Diagram VCC 8 D1 CONTROL LOGIC AND CURRENT LIMITER 6 Q2 5 DRIVE IN DRIVE OUT R4 RELAY OR SOLENOID LOAD CONTROL IN 7 R3 FLAG OUT 1 R2 Q1 4 LATCH + SENSE IN 2 SENSE SIGNAL GROUND 335mV R1 3 POWER GROUND VCC VCC1 8 LOAD CONTROL LOGIC & CURRENT LIMITER 6 Q2 DRIVE 5 6A CONTROL IN 7 DARLINGTON FLAG OUT 1 4 Q1 LATCH + SENSE IN 2 SIGNAL GROUND 335mV 0.056 3 POWER GROUND SENSE LEVEL EQUALS 335mV = 6A 0.056 FIGURE 1. TYPICAL APPLICATION AS A POWER SWITCH PRE-DRIVER SWITCH 10-41 Specifications CA3274 Absolute Maximum Ratings Operating Drive Supply, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . 16V Maximum Output Current, IO . . . . . . . . . . . . . . . . . . . . . . . . . 200mA Control, Sense Input. . . . . . . . . . . . . . . . . . . Gnd - 0.5V, VCC + 0.5V Signal, Power Differential Ground Voltage. . . . . . . . . . . . . . . . . . . 1V Thermal Information Thermal Resistance JA Plastic DIP Package 8 Lead . . . . . . . . . . . . . . . . . . . . . 130oC/W Power Dissipation, PD Up to 70oC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 630mW Above 70oC . . . . . . . . . . . . . . . . . . . . Derate linearly at 7.7mW/oC Operating Temperature Range . . . . . . . . . . . . . . . . . -40oC to +85oC Storage Temperature Range. . . . . . . . . . . . . . . . . . -55oC to +150oC Lead Temperature (During Soldering) At distance 1/16in. (1.59mm 0.79mm) from case for 10s Max. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +265oC CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Electrical Specifications PARAMETERS Power Supply Current: S1 = 2 At TA = -40oC to +85oC, Unless Otherwise Specified SYMBOL ICCH ICCL TEST CONDITIONS Control = High (Output On) Control = Low (Output Off) Thd. Voltage, High Thd. Voltage, Low Hysteresis Leakage, 0.0 to 5.5V Output Saturation Voltage, ICC1 = 200mA, VCONTROL = High Collector Output Leakage, VCONTROL = Low VSENSE = High, IFLAG = 3mA Output Leakage, VCC = VFLAG = 10V Control In to Drive Out Drive Off to Flag Off Flag Delay from Control In MIN 0.9 0.4 -20 TYP 0.65 MAX 25 5 3.5 2.0 +20 0.5 UNITS mA mA V V V A V Control Input: S1 = 3 VTHDH VTHDL VTHDH-VTHDL IIL Driver In, Out (Pin 6, 5): S1 = 3 VSAT ILEAK - - 100 A Flag Output Low: S1 = 2 Flag Output High: S1 = 3 Prop. Delay: S1 = 1 VFSAT VFLEAK tON, tOFF tFLAG tD 150 310 50 5 10 335 - 0.8 10 600 360 - V A s s s mV dB Sense Input Thd. Level: S1 = 1 Power Supply Rejection Ratio NOTES: VSENTHD PSSR 1. Refer to Figure 3 Test Diagram for electrical test connections. 2. Refer to Figure 2 Timing Diagram for logic switching and prop delay. 3. Unless otherwise specified: VCC = VCC1 = VCC2 = 7V to 10V; VSENSE = "Low"; VCONTROL = "Low"; Control in levels are defined as "Low" equals 0.0V and "High" equals 5.0V. 10-42 CA3274 tRISE tFALL tON DELAY CONTROL IN - PIN 7 tOFF DELAY DRIVE OUT- PIN 5 CURRENT LIMITING ON TIME SYSTEM NOISE 3.35mV SENSE LEVEL SENSE IN - PIN 2 tSENSE FLAG OUT- PIN 1 (NOISE HOLD-OFF DELAY) OUTPUT LOAD CURRENT tD (SEE NOTE) tFLAG NOTE: For VCC = 7V to 10V; tD (MAX) = 600S, if Control In = High, Sense In = High; Pin 1, Flag Out can go low only if tSENSE tD DELAY FIGURE 2. CA3274 TIMING DIAGRAM POWER SUPPLY +VCC ICC OUTPUT LOAD POWER SUPPLY +VCC1 8 IN 6 IN 51 (ADJ. FOR 200mA IN VSAT TEST) 1 S1 3 IN VCONTROL +VCC2 (ADJ. FOR 3mA IN FLAG-OUT VSAT TEST FLAG OUT 7 CONTROL LOGIC Q2 DRIVER 5 OUT (PSSROUT) 2.1V 10K 1 2 SENSE S1 IN 3 1 2.1V 120 120 4 Q1 LATCH + SIGNAL GROUND 335mV VSENSE 3 POWER GROUND FIGURE 3. CA3274 TEST CIRCUIT 10-43 CA3274 All Intersil semiconductor products are manufactured, assembled and tested under ISO9000 quality systems certification. Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see web site http://www.intersil.com Sales Office Headquarters NORTH AMERICA Intersil Corporation P. O. Box 883, Mail Stop 53-204 Melbourne, FL 32902 TEL: (407) 724-7000 FAX: (407) 724-7240 EUROPE Intersil SA Mercure Center 100, Rue de la Fusee 1130 Brussels, Belgium TEL: (32) 2.724.2111 FAX: (32) 2.724.22.05 ASIA Intersil (Taiwan) Ltd. Taiwan Limited 7F-6, No. 101 Fu Hsing North Road Taipei, Taiwan Republic of China TEL: (886) 2 2716 9310 FAX: (886) 2 2715 3029 File Number 10-44 |
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