UC1838A UC2838A UC3838A Magnetic Amplifier Controller FEATURES DESCRIPTION • Independent 1% Reference The UC1838A family of magnetic amplifier controllers contains the circuitry to generate and amplify a low-level analog error signal along with a high voltage-compliant current source. This source will provide the reset current necessary to enable a magnetic amplifier to regulate and control a power supply output in the range of 2A to 20A. • Two Uncommitted, Identical Operational Amplifiers • 100mA Reset Current Source with –120V Capability • 5V to 40V Analog Operation • 5W DIL Package By controlling the reset current to a magnetic amplifier, this device will define the amount of volt-seconds the magnetic amplifier will block before switching to the conducting state. Magnetic amplifiers are ideal for post-regulators for multiple-output power supplies where each output can be independently controlled with efficiencies up to 99%. With a square or pulse-width-modulated input voltage, a magnetic amplifier will block a portion of this input waveform, allowing just enough to pass to provide a regulated output. With the UC1838A, only the magnetic amplifier coil, three diodes, and an output L-C filter are necessary to implement a complete closed-loop regulator. The UC1838A contains a precision 2.5V reference, two uncommitted high-gain op amps and a high-gain PNP-equivalent current source which can deliver up to 100mA of magnetic amplifier reset current and with –120 volt capability. These devices are available in a plastic “bat-wing” DIP for operation over a –20°C to +85°C temperature range and, with reduced power, in a hermetically sealed cerdip for –55°C to +125°C operation. Surface mount versions are also available. This improved “A” version replaced the non “A” version formerly introduced. BLOCK DIAGRAM VCC 10 VREF 9 2.5V REFERENCE 11 INV. IN 6 3.5V E/A N.I. IN 7 E/A OUT 8 INV. IN 3 5k 20 14 RESET C/L N.I. IN 1k VM 15 DR 1 2 16 DR 2 C/L OUT 1 4 5 12 13 GND GND GND GND 04/99 UDG-97174 UC1838A UC2838A UC3838A CONNECTION DIAGRAMS ABSOLUTE MAXIMUM RATINGS Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V Magnetic Amp. Source Voltage, VM . . . . . . . . . . . . . . . . . . . . . . . . 40V Reset Output Voltage, VR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –120V Total Current Source Voltage, VM - VR . . . . . . . . . . . . . . . . . . –140V Amplifier Input Range . . . . . . . . . . . . . . . . . . . . . . –0.3V to VCC Reset Input Current, IDR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –10mA Power Dissipation at TA = 25°C Q, N, DP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2W J, L Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1W Power Dissipation at T (leads/case) = 25°C Q, N, DP Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5W J, L Package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2W Operating Temperature Range . . . . . . . . . . . . –55°C to +125°C Storage Temperature Range . . . . . . . . . . . . . –65°C to +150°C Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . . 300°C DIL-16, SOIC-16 (TOP VIEW) J or N Package, DP Package Note: All voltages are with respect to ground pins. All currents are positive into the specified terminal. Consult Packaging section of Databook for thermal limitations and considerations of package. TEMPERATURE RANGE –55°C to +125°C –20°C to +85°C 0°C to +70°C 1 16 DR 2 C/L N.I. In 2 15 DR 1 C/L INV. In 3 14 Reset Gnd 4 13 Gnd Gnd 5 12 Gnd E/A Inv. In 6 11 VM E/A N.I. In 7 10 VCC E/A Out 8 9 VREF Note: All four ground pins must be connected to a common ground ORDERING INFORMATION UC1838AJ UC1838AL UC2838ADP UC2838AN UC2838AQ UC3838ADP UC3838AN UC3838AQ C/L Out PACKAGE Ceramic Dip CLCC Power SOIC Plastic Dip PLCC Power SOIC Plastic Dip PLCC PLCC-20, LCC-20 (TOP VIEW) Q, L Packages N/C C/L Out C/L N.I. In DR2 DR1 3 1 20 19 C/L Inv. In 4 18 Reset GND 5 17 N/C N/C 6 16 N/C N/C 7 15 GND E/A Inv. In 8 14 VM 9 E/A N.I. In E/A Out 2 2 10 11 12 13 VCC VREF N/C UC1838A UC2838A UC3838A ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications apply for TA = –55°C to +125°C for the UC1838A, –20°C to +85°C for the UC2838A, and 0°C to +70°C for the UC3838A, VCC = 20V, VM = 5V, TA = TJ. UC1838A / UC2838A PARAMETER TEST CONDITIONS MIN TYP MAX 4 8 2.47 2.5 2.53 UC3838A UNITS MIN TYP MAX 4 8 mA 2.45 2.5 2.55 V Reference Section Supply Current VCC = VM = 40V Reference Output TA = 25°C Line Regulation VCC = 5 to 30V 1 5 1 10 mV Load Regulation IO = 0 to –2mA 5 20 5 20 mV Short Circuit Current VREF = 0V –30 –60 –30 –60 mA Temperature Stability* Over Operating Temp. Range 15 25 10 25 mV 10 mV –1 –1 µA 100 100 nA Amplifier Section (Each Amplifier) Offset Voltage VCM = 2.5V Input Bias Current VIN = 0V 5 Input Offset Current Minimum Output Swing Output Sink Current 0.4 VO = 5V 1 18 0.4 10 30 1 –20 18 V 10 30 mA –20 mA Output Source Current VO = 0V –1 –10 –1 –10 AVOL VO = 1 to 11V 100 120 100 120 dB CMRR VIN = 1 to 11V 70 80 70 80 dB PSRR VCC = 10 to 20V 70 100 70 100 dB 0.6 0.8 0.6 0.8 MHz Gain Bandwidth* Reset Drive Section Input Leakage VDR = 40V Output Leakage VR = –120V Input Current IR = –50mA Maximum Reset Current IDR = –3mA Transconductance IR = –10 to –50mA +12V, 4A output with switching frequency = 50 kHz. 3 10 µA –100 µA –1 –2 –1 –2 mA –100 –120 –200 –100 –120 –200 mA .03 .042 .055 .03 .042 .055 A/V * These parameters are guaranteed by design but not 100% tested in production. TYPICAL APPLICATION 10 –100 UC1838A UC2838A UC3838A APPLICATION INFORMATION Figure 1. Amplifier open loop response. Figure 4. Reset driver response. Figure 2. Reset driver-input current. Figure 5. Reset driver-input voltage. Figure 3. Reset driver-output impedance. Figure 6. Reference temperature coefficient. UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. (603) 424-2410 • FAX (603) 424-3460 4 IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. 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