LTC1504 Linear Technology, LTC1504 Datasheet
LTC1504
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LTC1504 Summary of contents
Page 1
... The synchronous buck archi- tecture allows the output to source or sink current as required to keep the output voltage in regulation. The LTC1504 is available in adjustable and fixed 3.3V output versions. An adjustable current limit circuit pro- vides protection from overloads. The internal 1% refer- ...
Page 2
... RATINGS PACKAGE/ORDER I FOR ATIO I 1 MAX + 0. GND 4 8-LEAD PLASTIC SO *FB FOR LTC1504CS8, SENSE FOR LTC1504CS8-3.3 T JMAX Consult factory for Industrial and Military grade parts 5V unless otherwise specified. (Note CONDITIONS (Note 7) LTC1504CS8 Figure 10V, LTC1504CS8 CC LTC1504CS8-3 ...
Page 3
... All voltages are referenced to ground unless otherwise specified. Note 3: This parameter is guaranteed by correlation and is not tested directly. Note 4: LTC1504 quiescent current is dominated by the gate drive current drawn by the onboard power switches. With FB or SENSE pulled TYPICAL PERFORMANCE CHARACTERISTICS ...
Page 4
... GND (Pin 4): Ground. Connect to a low impedance ground. The input and output bypass capacitors and the feedback resistor divider (adjustable parts only) should be grounded as close to this pin as possible. Pin 4 acts as a heat sink in the LTC1504 S0-8 package and should be connected ...
Page 5
... PIN FUNCTIONS during power-up. C also compensates the current limit SS loop, allowing the LTC1504 to enter and exit current limit cleanly. See the Applications Information section for more details. W BLOCK DIAGRAM SHDN SAW COMP 12V SS I LIM – MAX 12V TEST CIRCUITS ...
Page 6
... Q1 and Q2 are capable of carrying peak currents in excess of 500mA, with the continuous output power level limited primarily by the thermal dissipation of the SO-8 package. With a 5V input and a 3.3V output, the LTC1504 can supply 500mA of continuous output current with an appropriate layout. An on-chip current limit circuit, set with a single external resistor, can be used to help limit power dissipa- tion ...
Page 7
... Additional components to set up soft start and current limit are usually included as well. A minimum LTC1504 circuit can be constructed with as few as four external components; a circuit that utilizes all of the LTC1504s functionality usually includes eight or nine external components, with two additional feedback resis- tors required for adjustable parts ...
Page 8
... CD54-101 100 H 0.52A Open Output Capacitor The output capacitor affects the performance of the LTC1504 in a couple of ways: it provides the first line of Kool registered trademark of Magnetics, Inc defense during a transient load step and it has a large effect on the compensation required to keep the LTC1504 feed- back loop stable ...
Page 9
... Soft Start and Current Limit Soft start and current limit are linked in the LTC1504. Soft start works in a straightforward manner. An internal 12 A current source connected to the SS pin will pull up an ...
Page 10
... Note that the current limit is primarily designed to protect LIM the LTC1504 from damage and is not intended to be used to generate an accurate constant-current output. As the die temperature varies in a current limited condition, the R ...
Page 11
... A poorly laid out LTC1504 circuit may look nothing at all like a regulator. Wire-wrap or plug-in prototyping boards are not useful for bread- ...
Page 12
... Note that long traces at the SW node may aggravate EMI consider- ations—don’t get carried away Schottky diode is used at the SW node, it should be located at the LTC1504 end of the trace, close to the device pins. The LTC Applications Department has constructed liter- ...