LT1581 LINER [Linear Technology], LT1581 Datasheet
LT1581
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LT1581 Summary of contents
Page 1
... The device can also be used as a single supply device where dropout is comparable to an LT1584. Several other new features have been added to the LT1581. A remote SENSE pin is brought out. This feature virtually eliminates output voltage variations due to load changes. ...
Page 2
... Pulse Thermal Resistance, Junction-to-Case Control Circuitry/Power Transistor 2 U RATINGS PACKAGE/ORDER TAB IS OUTPUT *PIN2 = NC FOR LT1581CT7, GND FOR LT1581CT7-2.5 Consult factory for Industrial and Military grade parts. The denotes specifications which apply over the full operating = 25 C. (Note 5V 3.3V 0mA ...
Page 3
... LOAD J = 2.75V 10A LOAD Note 4: For the LT1581 adjustable device the minimum load current is the minimum current required to maintain regulation. Normally, the current in the resistor divider used to set the output voltage is selected to meet the . For the LT1581 minimum load current requirement. ...
Page 4
... OUTPUT (Pin 4): This is the power output of the device. V (Pin 5): This is the collector to the power device POWER of the LT1581. The output load current is supplied through this pin. For the device to regulate, the voltage at this pin must be between 0.1V and 0.7V greater than the output voltage (see Dropout specifications). ...
Page 5
... ADJ U U APPLICATIONS INFORMATION The LT1581 is a low dropout regulator designed to power the new generation of microprocessors. Low dropout regulators have become more common in desktop com- puter systems as microprocessor manufacturers have moved away from 5V only CPUs. A wide range of supply requirements exists today with new voltages just over the horizon ...
Page 6
... The output can never come up unregulated. The LT1581 can also be operated as a single supply device by tying the control and power inputs together. Dropout in single supply operation will be determined by the mini- mum control voltage ...
Page 7
... Figure 2 or outside the loop as in Figure 1. This means that the W U LT1581 can control the voltage at the load as long as the input/output voltage is greater than the total of the dropout voltage of the LT1581 plus the voltage drop across R Stability ...
Page 8
... An internal diode POWER between the OUTPUT pin and the V LT1581 can handle microsecond surge currents of 50A to 100A. Even with large value output capacitors it is difficult to obtain those values of surge currents in normal opera- tion. Only with large values of output capacitance, such as ...
Page 9
... DIODES: 1N4002 Figure 6. Optional Clamp Diodes Protect Against Input Crowbar Circuits If the LT1581 is connected as a single supply device with the control and power input pins shorted together, the internal diode between the output and the power input pins will protect the control input pin. ...
Page 10
... Please consult Linear Technology’s “Mount- ing Considerations for Power Semiconductors,” 1990 Linear Applications Handbook, Volume 1 , Pages RR3-1 to RR3-20. Note that the case of the LT1581 is electrically connected to the output. The following example illustrates how to calculate maximum junction temperature. Using an LT1581 and ...
Page 11
... LT1581/LT1581-2 25V MICROPROCESSOR 2 10 SOCKET V SS 1581 TA03 0.165 – ...
Page 12
... C1 12V 220 F LT1587 10V C8 ADJ 0 1N4148 470 LT1006 R4 – 178 1N4148 R14 SENSE CONT + C11 C10 LT1581 1 F 35V POWER OUT ADJ 0.33 F 107 107 0.35% 0.25 10k Q1 89.8 ZVN4206 0.5% 2N3904 E3 CPU TYPE 0 P55C ...