Precision Analog Controller UC19432 UC29432 UC39432 UC39432B FEATURES DESCRIPTION • Programmable Transconductance for Optimum Current Drive The UC39432 is an adjustable precision analog controller with 100mA sink capability if the ISET pin is grounded. A resistor between ISET and ground will modify the transconductance while decreasing the maximum current sink. This will add further control in the optocoupler configuration. The trimmed precision reference along with the non-inverting error amplifier inputs are accessible for custom configuration. A sister device, the UC39431 adjustable shunt regulator, has an on-board resistor network providing six preprogrammed voltage levels, as well as external programming capability. • Accessible 1.3V Precision Reference • Both Error Amplifier Inputs Available • 0.7% Overall Reference Tolerance • 0.4% Initial Accuracy • 2.2V to 36.0V Operating Supply Voltage and User Programmable Reference • Reference Accuracy Maintained for Entire Range of Supply Voltage • Superior Accuracy and Easier Compensation for Optoisolator Application • Low Quiescent Current (0.50mA Typ) BLOCK DIAGRAM UDG-95093 03/99 UC19432 UC29432 UC39432 UC39432B CONNECTION DIAGRAM ABSOLUTE MAXIMUM RATINGS DIL-8, SOIC-8 (Top View) N or J, D Package Supply Voltage: VCC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36V Regulated Output: VCOLL . . . . . . . . . . . . . . . . . . . . . . . . . . . 36V EA Input: SENSE, EA+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V EA Compensation: COMP. . . . . . . . . . . . . . . . . . . . . . . . . . . 6V Reference Output: REF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V Output Sink Current: ICOLL . . . . . . . . . . . . . . . . . . . . . . . 140mA Output Source Current: ISET . . . . . . . . . . . . . . . . . . . . –140mA Power Dissipation at TA ≤ 25°C (DIL-8) . . . . . . . . . . . . . . . . 1W Derate 8mW/°C for TA > 25°C Storage Temperature Range . . . . . . . . . . . . . –65°C to +150°C Junction Temperature . . . . . . . . . . . . . . . . . . . –55°C to +150°C Lead Temperature (Soldering, 10 sec.) . . . . . . . . . . . . . +300°C Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages. ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications apply for TA = –55°C to +125°C and COLL Output = 2.4V to 36.0V for the UC19432, TA = –25°C to +85°C and COLL Output = 2.3V to 36.0V for the UC29432, and TA = 0°C to +70°C and COLL Output = 2.3V to 36.0V for the UC39432, VCC = 15V, ICOLL = 10mA, TA = TJ. PARAMETER Reference Voltage Tolerance Reference Temperature Tolerance TEST CONDITIONS TA = 25°C VCOLL = 5.0V Reference Line Regulation VCC = 2.4V to 36.0V, VCOLL = 5V Reference Load Regulation ICOLL = 10mA to 50mA, VCOLL = 5V MIN TYP MAX UNITS 19432* 1.295 1.3 1.305 V 39432B 1.29 1.3 1.31 V 19432* 1.291 1.3 1.309 V 39432B 1.286 1.3 1.314 V 10 38 mV 19432* 39432B 10 57 mV 19432* 10 38 mV 39432B 10 57 mV 10 A –10 A Reference Sink Current Reference Source Current EA Input Bias Current –0.5 EA Input Offset Voltage A –0.2 19432* 4.0 mV 39432B 4.0 mV EA Output Current Sink (Internally Limited) 16 A EA Output Current Source –1 mA Minimum Operating Current VCC = 36.0V, VCOLL = 5V 0.50 0.80 mA Collector Current Limit (Note) VCOLL = VCC = 36.0V, Ref = 1.35V ISET = GND 130 145 mA Collector Saturation ICOLL = 20mA 1.1 1.5 V Transconductance (gm) (Note) VCC = 2.4V to 36.0V, VCOL = 3V, ICOLL = 20mA ISET = GND 0.7 Error Amplifier AVOL Error Amplifier GBW (Note 1) Transconductance Amplifier GBW 19432* –170 –140 –110 mS 39432B –180 –140 –100 mS 60 90 dB 3.0 5 MHz 3 MHz * Also applies to the UC29432 and UC39432 Note: Programmed transconductance and collector current limit equations are specified in the ISET pin description. Note 1: Guaranteed by design. Not 100% tested in production. 2 UC19432 UC29432 UC39432 UC39432B PIN DESCRIPTIONS COLL: The collector of the output transistor with a maximum voltage of 36V. This pin is the output of the transconductance amplifier. The overall open loop voltage gain of the transconductance amplifier is gm • RL, where gm is designed to be –140mS ±30mS and RL represents the output load. REF: The output of the trimmed precision reference. It can source or sink 10 A and still maintain the 1% temperature specification. SENSE: The inverting terminal of the error amplifier used as both the voltage sense input to the error amplifier and its other compensation point. The error amplifier uses the SENSE input to compare against the 1.3V on-chip reference. COMP: The output of the error amplifier and the input to the transconductance amplifier. This pin is available to compensate the high frequency gain of the error amplifier. It is internally voltage limited to approximately 2.0V. The SENSE pin is also used as the undervoltage lockout (UVLO). It is intended to keep the chip from operating until the internal reference is properly biased. The threshold is approximately 1V. It is important that once the UVLO is released, the error amplifier can drive the transconductance amplifier to stabilize the loop. If a capacitor is connected between the SENSE and COMP pins to create a pole, it will limit the slew rate of the error amplifier. To increase the bandwidth and ensure startup at low load current, it is recommended to create a zero along with the pole as shown in the UC39431 shunt regulator application. The error amplifier must slew 2.0V to drive the transconductance amplifier initially on. EA+: The non-inverting input to the error amplifier. GND: The reference and power ground for the device. The power ground of the output transistor is isolated on the chip from the substrate ground used to bias the remainder of the device. ISET: The current set pin for the transconductance amplifier. The transconductance will be –140mS as specified in the electrical table if this pin is grounded. If a resistance RL is added to the ISET pin, the resulting new transconductance is calculated using the following equation: gm = –0.714V • (5.1 + RL). The maximum current will be approximately I MAX = VCC: The power connection for the device. The minimum to maximum operating voltage is 2.2V to 36.0V. The quiescent current is typically 0.50mA. 0.6V 5 .1Ω + R L UDG-95094 Figure 1. 5.0V Optocoupler application. 3 UC19432 UC29432 UC39432 UC39432B OVERVOLTAGE COMPARATOR APPLICATION OPTOCOUPLER APPLICATION The signal VIN senses the input voltage. As long as the input voltage is less than 5.5V, the output is equal to the voltage on VIN. During this region of operation, the diode is reversed biased which keeps the EA+ pin at 1.3V. When VIN exceeds the over voltage threshold of 5.5V, the output is driven low. This forward biases the diode and creates hysteresis by changing the threshold to 4.5V. The optocoupler application shown takes advantage of the accessible pins REF and ISET. The ISET pin has a 33 ohm resistor to ground that protects the opto-coupler by limiting the current to about 16mA. This also lowers the transconductance to approximately 19mS. The ability to adjust the transconductance gives the designer further control of the loop gain. The REF pin is available to satisfy any high precision voltage requirements. UDG-95096 UDG-95095 Figure 2. 5.5V Overvoltage comparator with hysteresis. UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. 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