UC1832/3 UC2832/3 UC3832/3 Precision Low Dropout Linear Controllers FEATURES DESCRIPTION • Precision 1% Reference • Over-Current Sense Threshold Accurate to 5% • Programmable Duty-Ratio Over-Current Protection • 4.5V to 36V Operation • 100mA Output Drive, Source or Sink • Under-Voltage Lockout The UC1832 and UC1833 series of precision linear regulators include all the control functions required in the design of very low dropout linear regulators. Additionally, they feature an innovative duty-ratio current limiting technique which provides peak load capability while limiting the average power dissipation of the external pass transistor during fault conditions. When the load current reaches an accurately programmed threshold, a gated-astable timer is enabled, which switches the regulator’s pass device off and on at an externally programmable duty-ratio. During the on-time of the pass element, the output current is limited to a value slightly higher than the trip threshold of the duty-ratio timer. The constant-current-limit is programmable on the UCx832 to allow higher peak current during the on-time of the pass device. With duty-ratio control, high initial load demands and short circuit protection may both be accommodated without extra heat sinking or foldback current limiting. Additionally, if the timer pin is grounded, the duty-ratio timer is disabled, and the IC operates in constant-voltage/constant-current regulating mode. Additional Features of the UC1832 series: • Adjustable Current Limit to Current Sense Ratio • Separate +VIN terminal • Programmable Driver Current Limit • Access to VREF and E/A(+) • Logic-Level Disable Input These IC’s include a 2 Volt (±1%) reference, error amplifier, UVLO, and a high current driver that has both source and sink outputs, allowing the use of either NPN or PNP external pass transistors. Safe operation is assured by the inclusion of under-voltage lockout (UVLO) and thermal shutdown. The UC1833 family includes the basic functions of this design in a low-cost, 8pin mini-dip package, while the UC1832 series provides added versatility with the availability of 14 pins. Packaging options include plastic (N suffix), or ceramic (J suffix). Specified operating temperature ranges are: commercial (0°C to 70°C), order UC3832/3 (N or J); industrial (–25°C to 85°C), order UC2832/3 (N or J); and military (–55°C to 125°C), order UC1832/3J. Surface mount packaging is also available. BLOCK DIAGRAMS UDG-92040 6/94 UC1832/3 UC2832/3 UC3832/3 ABSOLUTE MAXIMUM RATINGS Supply Voltage +VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V Driver Output Current (Sink or Source) . . . . . . . . . . . . . 450mA Driver Sink to Source Voltage . . . . . . . . . . . . . . . . . . . . . . . 40V TRC Pin Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V to 3.2V Other Input Voltages. . . . . . . . . . . . . . . . . . . . . . . –0.3V to +VIN Operating Junction Temperature (note 2) . . . –55°C to +150°C Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . . 300°C Note 1: Unless otherwise indicated, voltages are referenced to ground and currents are positive into, negative out of, the specified terminals. Note 2: See Unitrode Integrated Circuits databook for information regarding thermal specifications and limitations of packages. CONNECTION DIAGRAMS UC1832 UC1833 DIL-14 (Top View) J Or N Package DIL-8 (Top View) J Or N Package SOIC-16 (Top View) DW Package SOIC-16 (Top View) DW Package LCC-20 & PLCC-20 L & Q Package (Top View) PACKAGE PIN FUNCTION FUNCTION N/C +VIN Comp/Shutdown E/A(+) +2V REF N/C Gnd Logic Disable Limit Source N/C E/A(-) Sink VADJ N/C Timer RC Current Sense(-) Current Sense(+) LCC-20 & PLCC-20 L & Q Package (Top View) PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15-17 18 19 20 2 PACKAGE PIN FUNCTION FUNCTION +VIN & C/S(+) N/C N/C N/C Comp/Shutdown Gnd N/C N/C N/C Source N/C E/A(-) N/C N/C Sink Timer RC Current Sense(+) N/C PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18-20 UC1832/3 UC2832/3 UC3832/3 ELECTRICAL CHARACTERISTICS: Unless otherwise stated, specifications hold for TA = 0°C to 70°C for the UC3832/3, –25°C to 85°C for the UC2832/3, and –55°C to 125°C for the UC1832/3, +VIN = 15V, Driver sink = +VIN, C/S(+) voltage = +VIN. TA=TJ. PARAMETER Input Supply Supply Current TEST CONDITIONS MIN TYP MAX UNITS +VIN = 6V 6.5 10 mA +VIN = 36V 9.5 15 mA Logic Disable = 2V (UCx832 only) 3.3 mA Reference Section Output Voltage (Note 3) Load Regulation (UCx832 only) Line Regulation TJ = 25°C, IDRIVER = 10mA 1.98 2.00 2.02 V over temperature, IDRIVER = 10mA 1.96 2.00 2.04 V IOUT = 0 to 10mA +VIN = 4.5 to 36V, IDRIVER = 10mA -10 -5.0 0.033 0.5 mV mV/V 3.6 4.5 V 1.5 Under-Voltage Lockout Threshold Logic Disable Input (UCx832 only) Threshold Voltage Input Bias Current Logic Disable = 0V 1.3 1.4 -5.0 -1.0 V 95 100 105 mV 93 110 100 135 107 170 mV mV µA Current Sense Section Comparator Offset Over Temperature Amplifier Offset (UCx833 only) Amplifier Offset (UCx832 only) VADJ = Open 110 135 170 mV VADJ = 1V 180 235 290 mV VADJ = 0V 250 305 360 mV Input Bias Current VCM = +VIN 65 100 135 µA Input Offset Current (UCx832 only) VCM = +VIN -10 10 µA Amplifier CMRR (UCx832 only) Transconductance VCM = 4.1V to +VIN+0.3V ICOMP = ±100µA VADJ Input Current (UCx832 only) VADJ = 0V 80 dB -10 65 -1 mS µA 0.25 1.0 µA -345 -270 -175 µA Timer Inactive Leakage Current C/S(+) = C/S(-) = +VIN; TRC pin = 2V Active Pullup Current C/S(+) = +VIN, C/S(-) = +VIN - 0.4V; TRC pin = 0V Duty Ratio (note 4) ontime/period, RT = 200k, CT = 0.27µF 4.8 % Period (notes 4,5) ontime + offtime, RT = 200k, CT = 0.27µF 36 ms Upper Trip Threshold (Vu) 1.8 V Lower Trip Threshold (Vl) Trip Threshold Ratio 0.9 2.0 V V/V Vu/Vl Error Amplifier Input Offset Voltage (UCx832 only) VCM = VCOMP = 2V -8.0 Input Bias Current VCM = VCOMP = 2V -4.5 Input Offset Current (UCx832 only) VCM = VCOMP = 2V -1.5 AVOL VCOMP = 1V to 13V 50 70 dB CMRR (UCx832 only) VCM = 0V to +VIN - 3V 60 80 dB PSRR (UCx832 only) Transconductance VCM = 2V, +VIN = 4.5 to 36V ICOMP = ±10µA 90 4.3 dB mS VOH ICOMP = 0, Volts below +VIN .95 1.3 V VOL ICOMP = 0 .45 0.7 V IOH VCOMP = 2V -500 -100 µA -700 3 8.0 mV µA -1.1 1.5 µA UC1832/3 UC2832/3 UC3832/3 Unless otherwise stated, specifications hold for TA = 0°C to 70°C for the UC3832/3, –25°C to ELECTRICAL CHARACTERISTICS (cont.) 85°C for the UC2832/3, and –55°C to 125°C for the UC1832/3, +VIN = 15V, Driver sink = +VIN, C/S(+) voltage = +VIN. TA=TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS VCOMP = 2V, C/S(-) = +VIN VCOMP = 2V, C/S(-) = +VIN - 0.4V 100 500 700 2 6 Driver Limit & Source pins common; TJ = 25°C 200 300 400 mA Over Temperature 100 300 450 mA Error Amplifier (cont.) IOL µA mA Driver Maximum Current Limiting Voltage (UCx832 only) Driver Limit to Source voltage at current limit, Internal Current Sense Resistance Pull-Up Current at Driver Sink ISOURCE = -10mA; TJ = 25°C (Note 6) .72 V TJ = 25°C (Note 6) 2.4 Ω Compensation/Shutdown = 0.4V; Driver Sink = +VIN - 1V -100 µA -300 -75 µA 300 700 µA -800 -300 -1000 150 Compensation/Shutdown = 0.4V, +VIN = 36V; Driver Sink = 35V Pull-Down Current at Driver Source Compensation/Shutdown = 0.4V; Driver Source = 1V Saturation Voltage Sink to Source Driver Source = 0V; Driver Current = 100mA Maximum Source Voltage Driver Sink = +VIN, Driver Current = 100mA Volts below +VIN 1.5 V 3.0 V UVLO Sink Leakage +VIN = C/S(+) = C/S(-) = 2.5V, Driver Sink = 15V, Driver Source = 0V, TA = 25°C Compensation/Shutdown = 0V; ISOURCE = 100µA, 25 µA Maximum Reverse Source Voltage +VIN = 3V 1.6 V Thermal Shutdown 160 °C Note 3: On the UCx833 this voltage is defined as the regulating level at the error amplifier inverting input, with the error amplifier driving VSOURCE to 2V. Note 4: These parameters are first-order supply-independent, however both may vary with supply for +VIN less than about 4V. This supply variation will cause a slight change in the timer period and duty cycle, although a high off-time/on-time ratio will be maintained. Note 5: With recommended RT value of 200k, TOFF ≈ RT CT * ln(Vu/Vl) ±10%. Note 6: The internal current limiting voltage has a temperature dependence of approximately -2.0mV/°C, or -2800ppm/°C. The internal 2.4 Ω sense resistor has a temperature dependance of approximately +1500ppm/°C. APPLICATION AND OPERATION INFORMATION NPN Pass (Local 100mA Regulator) (UCx833) UDG-92041-1 4 APPLICATION AND OPERATION INFORMATION (cont.) UC1832/3 UC2832/3 UC3832/3 PNP Pass (Low Drop-Out Regulator) (UCx833) UDG-92042-1 NPN Pass (Medium Power, Low Drop-Out Regulator) (UCx832) UDG-92043-1 Estimating Maximum Load Capacitance For any power supply, the rate at which the total output Current Sense Amplifier Offset Voltage and K= capacitance can be charged depends on the maximum 100mA output current available and on the nature of the load. For ≈1.35 for UCx833, and is variable from 1.35 to 3.05 a constant-current current-limited power supply, the outwith VADJ for the UCx832. put will come up if the load asks for less than the maxiFor a worst-case constant-current load of value just less mum available short-circuit limit current. than ITH, CMAX can be estimated from: To guarantee recovery of a duty-ratio current-limited TON CMAX = ((K−1)ITH) ( ), power supply from a short-circuited load condition, there VOUT is a maximum total output capacitance which can be where VOUT is the nominal regulator output voltage. charged for a given unit ON time. The design value of ON time can be adjusted by changing the timing capacitor. For a resistive load of value RL, the value of CMAX can be estimated from: Nominally, TON = 0.693 x 10k x CT. TON 1 CMAX = • . Typically, the IC regulates output current to a maximum of RL VOUT In [(1− ) −1] IMAX = K x ITH, where ITH is the timer trip-point current, K • ITH • RL 5 UC1832/3 UC2832/3 UC3832/3 APPLICATION AND OPERATION INFORMATION (cont.) Current Sense Amplifier Offset Voltage vs VADJ UCx832/33 Timer Function UCx832/33 Current Sense Input Configuration Load current, timing capacitor voltage, and output voltage of the regulator under fault conditions. 6 APPLICATION AND OPERATION INFORMATION (cont.) UNITRODE CORPORATION 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. (603) 424-2410 • FAX (603) 424-3460 7 UC1832/3 UC2832/3 UC3832/3 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. 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