TS2596S

2A / 150KHz Buck Dc-Dc Converter

5/10

Version: A07

Function Description

Pin Function

Vcc

This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor must be presented at

this pin to minimize voltage transients and to supply the switching currents needed by the regulator.

Ground

Circuit ground

SW Output

Internal switch. The voltage at this pin switches between (+Vcc – Vsat) and approximately – 0.5V, with a duty cycle of

approximately Vout / Vcc. To minimize coupling to sensitive circuitry, the PC board copper area connected to this pin

should be minimized.

Feedback

Sense the regulated output voltage to complete the feedback loop.

Enable

Allows the switching regulator circuit to be shutdown using logic level signals thus dropping the total input supply

current to approximately 100uA. Pulling this pin below a threshold voltage of approximately 1.3V turns the regulator on,

and pulling this pin above 1.3V (up to a maximum of Vcc) shuts the regulator down. If this shutdown feature is not

needed, the EN pin can be wired to the ground pin.

Thermal Considerations

The SOP-8 package needs a heat sink under most conditions. The size of the heat sink depends on the input voltage,

the output voltage, the load current and the ambient temperature. The TS2596S junction temperature rises above

ambient temperature for a 2A load and different input and output voltages.

The data for these curves was taken with the TS2596S (SOP-8) package operating as a buck-switching regulator in an

ambient temperature of 25ºC (still air). These temperature increments are all approximate and are affected by many

factors. Higher ambient temperatures requires more heat sinker.

For the best thermal performance, wide copper traces and generous amounts of printed circuit board copper (need

connect to the Ground pin) should be used in the board layout, (one exception is the SW pin, which should not have

large areas of copper.) Large areas of copper provide the best transfer of heat (lower thermal resistance) to the

surrounding air, and moving air lowers the thermal resistance even further.

Package thermal resistance and junction temperature increments are all approximate. The increments are affected by

a lot of factors. Some of these factors include board size, shape, thickness, position, location, and even board

temperature. Other factors are, trace width, total printed circuit copper area, copper thickness, single or double-sided,

multi-layer board and the amount of solder on the board.

The effectiveness of the PC board to dissipate heat also depends on the size, quantity and spacing of other

components on the board, as well as whether the surrounding air is still or moving. Furthermore, some of these

components such as the catch diode will add heat to the PC board and the heat can vary as the input voltage changes.

For the inductor, depending on the physical size, type of core material and the DC resistance, it could either act as a

heat sink taking heat away from the board, or it could add heat to the board.