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Specifications subject to change

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Copyright © 2012, Triune Systems, LLC

TS33000

Version 1.4

FUNCTIONAL DESCRIPTION

This voltage-mode Point of Load (POL) synchronous step-down power supply product can be used in the consumer, industrial,

and automotive market segments. It includes flexibility to be used for a wide range of output voltages and is optimized for high

facilitates low cost LC filter combinations and improved transient response. Additionally, the fixed output version, with

integrated Power on Reset and Fault circuitry enables a minimal external component count to provide a complete power

supply solution for a variety of applications.

DETAILED PIN DESCRIPTION

Unregulated input, VCC

This terminal is the unregulated input voltage source for the IC. It is recommended that 2 4.7uF bypass capacitors be placed

close as possible to the VCC pins for best performance. Since this is the main supply for the IC, good layout practices need to

be followed for this connection.

Feedback, FB

This is the voltage feedback input terminal for the adjustable version. For the fixed mode versions, this pin should be left

floating and not connected.

The connection on the PCB should be kept as short as possible from the feedback resistors, kept away from the VSW

connections or other switching/high frequency nodes, and should not be shared with any other connection. This should

minimize stray coupling, reduce noise injection, and minimize voltage shift cause by output load.

To choose the resistors for the adjustable version, use the following equation:

For stability, RTOP should be 270K Ohms to 330K Ohms.

This is the input terminal for the voltage output feedback and is needed for both adjustable and fixed voltage versions. This

should be connected to the main output capacitor, and the same good layout practices should be followed as for the FB

connection. Keep this line as short as possible, keep it away from the VSW and other switching or high frequency traces,

and do not share this connection with any other connection on the PCB.

Switching output, VSW

This is the switching node of the regulator. It should be connected directly to the 1.5uH inductor with a wide, short trace. It

is switching between VCC and PGND at the switching frequency.

Ground, GND

This ground is used for the majority of the device including the analog reference, control loop, and other circuits.

Power Ground, PGND

This is a separate ground connection used for the low side synchronous FET to isolate switching noise from the rest of the

device.

Enable, EN

This is an input terminal to activate the entire device. This will enable the internal reference, oscillator, TSD, etc, and allow

the fault detection circuitry to work correctly. Notice that the EN needs to low for the part to exhibit 100nA quiescent

current.