UC1835 UC1836 UC2835 UC2836 UC3835 UC3836 High Efficiency Regulator Controller FEATURES DESCRIPTION • Complete Control for a High Current, Low Dropout, Linear Regulator • Fixed 5V or Adjustable Output Voltage • Accurate 2.5A Current Limiting with Foldback • Internal Current Sense Resistor The UC1835/6 families of linear controllers are optimized for the design of low cost, low dropout, linear regulators. Using an external pass element, dropout voltages of less than 0.5V are readily obtained. These devices contain a high gain error amplifier, a 250mA output driver, and a precision reference. In addition, current sense with foldback provides for a 2.5A peak output current dropping to less than 0.5A at short circuit. • Remote Sense for Improved Load Regulation • External Shutdown • Under-Voltage Lockout and Reverse Voltage Protection • Thermal Shutdown Protection • 8 Pin Mini-Dip Package (Surface Mount also Available) BLOCK DIAGRAM Note: Pin numbers refer to 8-Pin DIL Package 8/94 These devices are available in fixed, 5V, (UC1835), or adjustable, (UC1836), versions. In the fixed 5 volt version, the only external parts required are an external pass element, an output capacitor, and a compensation capacitor. On the adjustable version the output voltage can be set anywhere from 2.5V to 35V with two external resistors. Additional features of these devices include under-voltage lockout for predictable start-up, thermal shutdown and short circuit current limiting to protect the driver device. On the fixed voltage version, a reverse voltage comparator minimizes reverse load current in the event of a negative input to output differential. UC1835 UC1836 UC2835 UC2836 UC3835 UC3836 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage (+VIN) . . . . . . . . . . . . . . . . –1.0V to + 40V Driver Output Current (Sink or Source) . . . . . . . . . . . . . 600mA Driver Source to Sink Voltage . . . . . . . . . . . . . . . . . . . . . + 40V Maximum Current Through Sense Resistor. . . . . . . . . . . . . . 4A VOUT Sense Input Voltage . . . . . . . . . . . . . . . . . . –.3V to + 40V Power Dissipation at TA = 25°C (Note 2) . . . . . . . . . . . 1000mW Power Dissipation at TC = 25°C (Note 2) . . . . . . . . . . . 2000mW Operating Junction Temperature . . . . . . . . . . . -55°C to +150°C Storage Temperature . . . . . . . . . . . . . . . . . . . . -65°C to +150°C Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . . 300°C Note 1: Voltages are referenced to ground, (Pin 3). Currents are positive into, negative out of, the specified terminals. Consult Packaging Section of Databook for thermal considerations and limitations of packages. CONNECTION DIAGRAMS DIL-8, SOIC-8 (TOP VIEW) N or J Package, D Package PLCC-20, LCC-20 (TOP VIEW) Q, L Packages PACKAGE PIN FUNCTION FUNCTION PIN N/C +VIN +VIN N/C Compensation/ Shutdown N/C Ground N/C N/C Driver Source N/C VOUT Sense N/C N/C Driver Sink N/C Current Limit (-) N/C Sense Resistor Out Sense Resistor Out SOIC-16 (TOP VIEW) DW Package 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ELECTRICAL CHARACTERISTICS: Unless otherwise stated, specifications hold for TA = 0°C to + 70°C for the UC3835/6, –25°C to + 85°C for the UC2835/6, and –55°C to +125°C for the UC1835/6, +VIN = 6V, Driver Source= 0V, Driver Sink = 5V, TA = TJ. PARAMETER Input Supply Supply Current TEST CONDITIONS +VIN = 6V +VIN = 40V +VIN Low to High, VOUT Sense = 0V UVLO Threshold Threshold Hysteresis Reverse Current +VIN = -1.0V, Driver Sink Open Regulating Voltage and Error Amplifier (UC1835 Family Only) Driver Current = 10mA, TJ = 25°C Regulating Level at VOUT Sense (VREG) Over Temperature Line Regulation +VIN = 5.2V + 35V Load Regulation Driver Current = 0 to 250mA VOUT Sense = 5.0V Bias Current at VOUT Sense Error Amp Transconductance ±100µA at Compensation/Shutdown Pin Maximum Compensation Output Current Sink or Source, Driver Source Open 2 MIN. TYP. MAX. UNITS 3.9 2.75 3.75 4.4 0.1 6.0 4.0 6.0 4.9 0.35 20 mA mA V V mA 5.0 5.06 5.1 40 25 210 2.0 260 V V mV mV µA mS µA 4.94 4.9 75 0.8 90 15 6.0 125 1.3 200 UC1835 UC1836 UC2835 UC2836 UC3835 UC3836 ELECTRICAL CHARACTERISTICS: Unless otherwise stated, specifications hold for TA = 0°C to + 70°C for the UC3835/6, –25°C to + 85°C for the UC2835/6, and –55°C to +125°C for the UC1835/6, +VIN = 6V, Driver Source= 0V, Driver Sink = 5V, TA = TJ. PARAMETER TEST CONDITIONS MIN. TYP. Regulating Voltage and Error Amplifier (UC1836 Family Only) Driver Current = 10mA, TJ = 25°C 2.47 2.5 Regulating Level at VOUT Sense (VREG) Over Temperature 2.45 6.0 Line Regulation +VIN = 5.2V to 35V Load Regulation Driver Current = 0 to 250mA 3.0 VOUT Sense =2.5V -1.0 -0.2 Bias Current at VOUT Sense Error Amp Transconductance ±100µA at Compensation/Shutdown Pin 0.8 1.3 Maximum Compensation Output Current Sink or Source, Driver Source Open 90 200 Driver Maximum Current 250 500 Saturation Voltage Driver Current = 250mA, Driver Sink 2.0 Pull-Up Current at Driver Sink Compensation/Shutdown=0.45V 140 250 Driver Sink Leakage In UVLO In Reverse Voltage (UC1835 Family Only) Thermal Shutdown 165 Foldback Current Limit 2.2 2.5 Current Limit Levels at Sense Resistor Out VOUT Sense = (0.99) VREG VOUT Sense = (0.5) VREG 1.3 1.5 0.25 0.4 VOUT Sense = 0V 12 24 Current Limit Amp Tansconductance ±100µA at Compensation/Shutdown, VOUT Sense = (0.9) VREG Limiting Voltage at Current Limit (-) VOUT Sense = (0.9) VREG 80 100 (Note 2) Volts Below +VIN, TJ = 25°C Sense Resistor Value (Note 3) VOUT Sense = (0.9) VREG, 40 IOUT = IA, TJ = 25°C Note 2: This voltage has a positive temperature coefficient of approximately 3500ppm/°C. Note 3: This resistance has a positive temperature coefficient of approximately 3500ppm/°C. The total resistance from Pin 1 to Pin 8 will include an additional 60 to 100mΩ of package resistance. MAX. UNITS 2.53 2.55 20 15 2.0 260 2.8 300 10 10 mA V µA µA µA °C 2.8 1.7 0.55 42 A A A mS 140 mV APPLICATION AND OPERATION INFORMATION UC 1835 − Typical configurations for a 2A, Low Dropout 5V Regulator UC1836 − Typical Configuration for a 2A, Low Dropout Adjustable Regulator Note 4: Suggested Pass devices are TIP 32B. (Dropout Voltage ≤0.75V) or, D45H, (Dropout Voltage ≤0.5V), or equivalents. 3 V V mV mV µA mS µA mΩ UC1835 UC1836 UC2835 UC2836 UC3835 UC3836 APPLICATION AND OPERATION INFORMATION (cont.) UC1835/6 Foldback Current Limiting UC3835/36 TYPICAL APPLICATIONS Low Current Application Typical Output Current vs VIN and VOUT using the UC3836 internal drive transistor of the UC3836 internal drive transistor for PDISS = 0.5W (approx.) High Current Application Parallel Pass Transistors using drive transistor Q2 to increase Q1 base drive and reduce UC3836 power dissipation can be added for high current or high power dissipation applications EQUATIONS: R1 = 0.100 V/IOUT (MAX) R2 = (VOUT - 2.5V/1mA) R3 = ((VIN - VBE - VSAT)*BETA(min))/IOUT (max) UNITRODE INTEGRATED CIRCUITS 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. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL APPLICATIONS”). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER’S RISK. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI’s publication of information regarding any third party’s products or services does not constitute TI’s approval, warranty or endorsement thereof. Copyright 1999, Texas Instruments Incorporated