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Details, datasheet, quote on part number:LM2578MDC
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Datasheet text preview:
LM1578A/LM2578A/LM3578A Switching Regulator
April 1998
LM1578A/LM2578A/LM3578A Switching Regulator
General Description
The LM1578A is a switching regulator which can easily be set up for such DC-to-DC voltage conversion circuits as the buck, boost, and inverting configurations. The LM1578A features a unique comparator input stage which not only has separate pins for both the inverting and non-inverting inputs, but also provides an internal 1.0V reference to each input, thereby simplifying circuit design and p.c. board layout. The output can switch up to 750 mA and has output pins for its collector and emitter to promote design flexibility. An external current limit terminal may be referenced to either the ground or the Vin terminal, depending upon the application. In addition, the LM1578A has an on board oscillator, which sets the switching frequency with a single external capacitor from < 1 Hz to 100 kHz (typical). The LM1578A is an improved version of the LM1578, offering higher maximum ratings for the total supply voltage and output transistor emitter and collector voltages.
Features
n n n n n n Inverting and non-inverting feedback inputs 1.0V reference at inputs Operates from supply voltages of 2V to 40V Output current up to 750 mA, saturation less than 0.9V Current limit and thermal shut down Duty cycle up to 90%
Applications
n Switching regulators in buck, boost, inverting, and single-ended transformer configurations n Motor speed control n Lamp flasher
Functional Diagram
DS008711-1
© 1998 National Semiconductor Corporation
DS008711
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Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Total Supply Voltage Collector Output to Ground Emitter Output to Ground (Note 2) Power Dissipation (Note 3) Output Current Storage Temperature Lead Temperature (soldering, 10 seconds) Maximum Junction Temperature 50V -0.3V to +50V -1V to +50V Internally limited 750 mA -65°C to +150°C 260°C 150°C
ESD Tolerance (Note 4)
2 kV
Operating Ratings
Ambient Temperature Range LM1578A LM2578A LM3578A Junction Temperature Range LM1578A LM2578A LM3578A -55°C TA +125°C -40°C TA +85°C 0°C TA +70°C -55°C TJ +150°C -40°C TJ +125°C 0°C TJ +125°C
Electrical Characteristics
These specifications apply for 2V VIN 40V (2.2V VIN 40V for TJ -25°C), timing capacitor CT = 3900 pF, and 25% duty cycle 75%, unless otherwise specified. Values in standard typeface are for TJ = 25°C; values in boldface type apply for operation over the specified operating junction temperature range. LM1578A Symbol Parameter Conditions Typical (Note 5) OSCILLATOR fOSC Frequency 20 22.4 17.6 fOSC/T Frequency Drift with Temperature Amplitude REFERENCE/COMPARATOR (Note 8) VR Input Reference Voltage VR/VIN IINV Input Reference Voltage Line Regulation Inverting Input Current Level Shift Accuracy VR/t Input Reference Voltage Long Term Stability OUTPUT VC (sat) VE (sat) ICES BVCEO(SUS) Collector Saturation Voltage Emitter Saturation Voltage Collector Leakage Current Collector-Emitter Sustaining Voltage IC = 750 mA pulsed, Emitter grounded IO = 80 mA pulsed, VIN = VC = 40V VIN = VCE = 40V, Emitter grounded, Output OFF ISUST = 0.2A (pulsed), VIN = 0 0.7 0.85/1.2 1.4 1.6/2.1 0.1 50/100 60 50 50 200/250 1.7/2.0 0.90/1.2 V V (max) V V (max) µA µA (max) V V (min) Level Shift Current = 1 mA 1.0 5/8 100 10/13 % % (max) ppm/1000h I1 = I2 = 0 mA and I1 = I2 = 1 mA ± 1% (Note 9) I1 = I2 = 0 mA and I1 = I2 = 1 mA ± 1% (Note 9) I1 = I2 = 0 mA, duty cycle = 25% 1.0 1.035/1.050 0.965/0.950 0.003 0.01/0.02 0.5 0.01/0.02 0.950/0.930 V 1.050/1.070 V (max) V (min) %/V %/V (max) µA 550 mVp-p -0.13 24 16 kHz kHz (max) kHz (min) %/°C Limit (Note 6) (Note 11) LM2578A/ LM3578A Limit (Note 7) Units
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Electrical Characteristics
(Continued)
These specifications apply for 2V VIN 40V (2.2V VIN 40V for TJ -25°C), timing capacitor CT = 3900 pF, and 25% duty cycle 75%, unless otherwise specified. Values in standard typeface are for TJ = 25°C; values in boldface type apply for operation over the specified operating junction temperature range. LM1578A Symbol Parameter Conditions Typical (Note 5) CURRENT LIMIT VCL Sense Voltage Shutdown Level VCL/T ICL Sense Voltage Temperature Drift Sense Bias Current Referred to VIN Referred to ground DEVICE POWER CONSUMPTION IS Supply Current Output OFF, VE = 0V Output ON, IC = 750 mA pulsed, VE = 0V 2.0 3.0/3.3 14 3.5/4.0 mA mA (max) mA 4.0 0.4 µA µA Referred to VIN or Ground (Note 10) 0.3 110 95 140 80 160 mV mV (min) mV (max) %/°C Limit (Note 6) (Note 11) LM2578A/ LM3578A Limit (Note 7) Units
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating the device beyond its rated operating conditions. Note 2: For TJ 100°C, the Emitter pin voltage should not be driven more than 0.6V below ground (see Application Information). Note 3: At elevated temperatures, devices must be derated based on package thermal resistance. The device in the TO-99 package must be derated at 150°C/W, junction to ambient, or 45°C/W, junction to case. The device in the 8-pin DIP must be derated at 95°C/W, junction to ambient. The device in the surface-mount package must be derated at 150°C/W, junction-to-ambient. Note 4: Human body model, 1.5 k in series with 100 pF. Note 5: Typical values are for TJ = 25°C and represent the most likely parametric norm. Note 6: All limits guaranteed and 100% production tested at room temperature (standard type face) and at temperature extremes (bold type face). All limits are used to calculate Average Outgoing Quality Level (AOQL). Note 7: All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). Room temperature limits are 100% production tested. Limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate AOQL. Note 8: Input terminals are protected from accidental shorts to ground but if external voltages higher than the reference voltage are applied, excessive current will flow and should be limited to less than 5 mA. Note 9: I1 and I2 are the external sink currents at the inputs (refer to Test Circuit). Note 10: Connection of a 10 k resistor from pin 1 to pin 4 will drive the duty cycle to its maximum, typically 90%. Applying the minimum Current Limit Sense Voltage to pin 7 will not reduce the duty cycle to less than 50%. Applying the maximum Current Limit Sense Voltage to pin 7 is certain to reduce the duty cycle below 50%. Increasing this voltage by 15 mV may be required to reduce the duty cycle to 0%, when the Collector output swing is 40V or greater (see Ground-Referred Current Limit Sense Voltage typical curve). Note 11: A military RETS specification is available on request. At the time of printing, the LM1578A RETS spec complied with the boldface limits in this column. The LM1578AH may also be procured as a Standard Military Drawing.
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