UC1834 UC2834 UC3834 High Efficiency Linear Regulator FEATURES DESCRIPTION * Minimum VIN - VOUT Less Than 0.5V At 5A Load With External Pass Device * Equally Usable For Either Positive or Negative Regulator Design * Adjustable Low Threshold Current Sense Amplifier The UC1834 family of integrated circuits is optimized for the design of low input-output differential linear regulators. A high gain amplifier and 200mA sink or source drive outputs facilitate high output current designs which use an external pass device. With both positive and negative precision references, either polarity of regulator can be implemented. A current sense amplifier with a low, adjustable, threshold can be used to sense and limit currents in either the positive or negative supply lines. * Under And Over-Voltage Fault Alert With Programmable Delay * Over-Voltage Fault Latch With 100mA Crowbar Drive Output BLOCK DIAGRAM 6/94 In addition, this series of parts has a fault monitoring circuit which senses both under and over-voltage fault conditions. After a user defined delay for transient rejection, this circuitry provides a fault alert output for either fault condition. In the over-voltage case, a 100mA crowbar output is activated. An over-voltage latch will maintain the crowbar output and can be used to shutdown the driver outputs. System control to the device can be accommodated at a single input which will act as both a supply reset and remote shutdown terminal. These die are protected against excessive power dissipation by an internal thermal shutdown function. UC1834 UC2834 UC3834 ABSOLUTE MAXIMUM RATINGS (Note 1) Power Dissipation at TA = 25C . . . . . . . . . . . . . . . . . . 1000mW Power Dissipation at TC = 25C. . . . . . . . . . . . . . . . . . 2000mW Operating Junction Temperature . . . . . . . . . . -55C to +150C Storage Temperature . . . . . . . . . . . . . . . . . . . -65C to +150C Lead Temperature (soldering, 10 seconds). . . . . . . . . . . 300C Note 1: Voltages are reference to VIN-, Pin 5. Currents are positive into, negative out of the specified terminals. Consult Packaging section of Databook for thermal limitations and considerations of package. Input Supply Voltage, VIN + . . . . . . . . . . . . . . . . . . . . . . . . . 40V Driver Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400mA Driver Source to Sink Voltage . . . . . . . . . . . . . . . . . . . . . . . 40V Crowbar Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -200mA +1.5V Reference Output Current . . . . . . . . . . . . . . . . . . -10mA Fault Alert Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40V Fault Alert Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15mA Error Amplifier Inputs . . . . . . . . . . . . . . . . . . . . . . -0.5V to 35V Current Sense Inputs . . . . . . . . . . . . . . . . . . . . . . -0.5V to 40V O.V. Latch Output Voltage . . . . . . . . . . . . . . . . . . -0.5V to 40V O.V. Latch Output Current . . . . . . . . . . . . . . . . . . . . . . . . 15mA CONNECTION DIAGRAMS DIL-16, SOIC-16 (TOP VIEW) J or N Package, DW Package PLCC-20, LCC-20 (TOP VIEW) Q, L Packages PACKAGE PIN FUNCTION FUNCTION PIN N/C VIN + -2.0V REF +1.5V REF Threshold Adjust N/C VIN- Sense- Sense+ N.Inv. Input N/C Inv. Input Fault Alert Fault Delay Driver Sink N/C Driver Source Compensation/ Shutdown O.V. Latch Output/Reset Crowbar Gate 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 UC1834 UC2834 UC3834 ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications apply for TA=-55C to +125C for the UC1834, -40C to +85C for the UC2834, and 0C to +70C for the UC3834. VIN+ = 15V, VIN- = 0V, TA = TJ. PARAMETER Turn-on Characteristics Standby Supply Current +1.5 Volt Reference Output Voltage Line Regulation Load Regulation -2.0 Volt Reference (Note 2) Output Voltage (Referenced to VIN+) Line Regulation Output Impedance Error Amplifier Section Input Offset Voltage Input Bias Current Input Offset Current Small Signal Open Loop Gain TEST CONDITIONS UC1834 UC2834 MIN TYP MAX 5.5 TJ = 25C TJ(MIN) TJ TJ(MAX) VIN+ = 5 to 35V IOUT = 0 to 2mA 1.485 1.47 TJ = 25C TJ(MIN) TJ TJ(MAX) VIN+ = 5 to 35V -2.04 -2.06 1.5 1 1 -2 1.5 2.3 VCM = 1.5V VCM = 1.5V VCM = 1.5V Output @ Pin 14, Pin 12 = VIN+ Pin 13, 20 to VIN- VCM = 0.5 to 33V, VIN+ = 35V VIN+ = 5 to 35V, VCM = 1.5V 50 1 -1 0.1 65 UC3834 MIN UNITS TYP MAX 5.5 10 mA 1.515 1.47 1.53 1.455 10 10 1.5 1.53 1.545 15 15 V -1.96 -2.06 -1.94 -2.08 15 -2 7 6 -4 1 50 1 1 1.5 2.3 1 -1 0.1 65 -1.94 -1.92 20 10 -8 2 mV mV V mV k mV A A dB 60 80 60 80 dB CMRR PSRR 70 100 70 100 dB Driver Section Maximum Output Current 200 350 200 350 mA Saturation Voltage IOUT = 100mA 0.5 1.2 0.5 1.5 V Output Leakage Current Pin 12 = 35V, Pin 13 = VIN-, Pin 14 = VIN- 0.1 50 0.1 50 A Shutdown Input Voltage IOUT 100A, Pin 13 = VIN-, Pin 12 = 0.4 1 0.4 1 V at Pin 14 VIN+ -100 -150 -100 -150 A Shutdown Input Current Pin 14 = VIN-, Pin 12 = VIN+ IOUT 100A, Pin 13 = VIN- at Pin 14 Thermal Shutdown (Note 3) 165 165 C Fault Amplifier Section 120 150 180 110 150 190 mV Under- and Over-Voltage VCM = 1.5V, @ E/A Inputs Fault Threshold -0.4 -0.8 -0.4 -1.0 %/v Common Mode Sensitivity VIN+ = 35V, VCM = 1.5 to 33V Supply Sensitivity VCM = 1.5V, VIN+ = 5 to 35V -0.5 -1.0 -0.5 -1.2 %/V Fault Delay 30 45 60 30 45 60 ms/F Fault Alert Output Current 2 5 2 5 mA Fault Alert Saturation Voltage IOUT = 1mA 0.2 0.5 0.2 0.5 V O.V. Latch Output Current 2 4 2 4 mA O.V. Latch Saturation Voltage IOUT = 1mA 1.0 1.3 1.0 1.3 V O.V. Latch Output Reset 0.3 0.4 0.6 0.3 0.4 0.6 V Voltage Crowbar Gate Current -100 -175 -100 -175 mA Crowbar Gate Leakage VIN+ = 35V, Pin 16 = VIN- -0.5 -50 -0.5 -50 A Current Note 2: When using both the 1.5V and -2.0V references the current out of pin 3 should be balanced by an equivalent current into Pin 2. The -2.0V output will change -2.3mV per A of imbalance. Note 3: Thermal shutdown turns off the driver. If Pin 15 (O.V. Latch Output) is tied to Pin 14 (Compensation/Shutdown) the O.V. Latch will be reset. 3 UC1834 UC2834 UC3834 ELECTRICAL CHARACTERISTICS: Unless otherwise stated, these specifications apply for TA=-55C to +125C for the UC1834, -40C to +85C for the UC2834, and 0C to +70C for the UC3834. VIN+ = 15V, VIN- = 0V. TA = TJ PARAMETER TEST CONDITIONS Current Sense Amplifier Section Threshold Voltage Pin 4 Open, VCM = VIN+ or VIN- Pin 4 = 0.5V, VCM = VIN+ or VIN- Threshold Supply Sensitivity Pin 4 Open, VCM = VIN-, VIN+ = 5 to 35V Adj. Input Current Pin 4 = 0.5V Sense Input Bias Current VCM = VIN+ VCM = VIN- Current Sense Threshold Adjustment UC1834 UC2834 MIN TYP MAX MIN TYP MAX 130 40 120 30 150 50 -0.1 -2 100 -100 180 70 -0.5 -10 200 -200 150 50 -0.1 -2 100 -100 170 60 -0.3 -10 200 -200 UC3834 UNITS Current Limiting Knee Characteristics Differential Voltage at Current Sense Inputs - mV (reference to sense - input) Error Amplifier Gain and Phase Frequency Response Current Sense Amplifier Gain and Phase Frequency Response 4 mV %/V A A UC1834 UC2834 UC3834 APPLICATION INFORMATION Foldback Current Limiting The crowbar output on the UC1834 is activated following a sustained over-voltage condition. The crowbar output remains high as long as the fault condition persists, or, as long as the over-voltage latch is set. The latch is set with an over-voltage fault if the voltage at Pin 15 is above the latch reset threshold, typically 0.4V. When the latch is set, its Q- output will pull Pin 15 low through a series diode. As long as a nominal pull-up load exists, the series diode prevents Q- from pulling Pin 15 below the reset threshold. However, Pin 15 is pulled low enough to disable the driver outputs if Pins 15 and 14 are tied together. With Pin 15 and 14 common, the regulator will latch off in response to an over-voltage fault. If the fault condition is cleared and Pins 14 and 15 are momentarily pulled below the latch reset threshold, the driver outputs are re-enabled. Both the current sense and error amplifiers on the UC1834 are transconductance type amplifiers. As a result, their voltage gain is a direct function of the load impedance at their shared output pin, Pin 14. Their small signal voltage gain as a function of load and frequency is nominally given by; ZL (f) ZL (f) and AV C. S. A = 70 700 for: f 500kHz and |ZL(f)| 1 M Where: AV=Small Signal Voltage Gain to pin 14. ZL(f) = Load Impedance at Pin 14. AV EA = The UC1834 fault delay circuitry prevents the fault outputs from responding to transient fault conditions. The delay reset latch insures that the full, user defined, delay passes before an over-voltage fault response occurs. This prevents unnecessary crowbar, or latched-off conditions, from occurring following sharp under-voltage to over-voltage transients. Setting the Threshold Adjust Voltage (VADJ) 5 UC1834 UC2834 UC3834 TYPICAL APPLICATIONS 5-10 Amp Positive Regulator 5-10 Amp Negative Regulator UNITRODE CORPORATION 7 CONTINENTAL BLVD. * MERRIMACK, NH 03054 TEL. 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