TS2496

2A / 150KHz Buck Switching Regulator

5/7

Version: C07

Pin Function Description

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 TS2496 is available in two packages, a TO-220-5L and TO-263-5L.

The TO-220-5L 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 TS2496 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 TS2496 (TO-220-5L package) operating as a buck switching regulator in an ambient temperature of 25

o

C (still

air). These temperature rise numbers are all approximate and there are many factors that can affect these

temperatures. Higher ambient temperatures require more heat sinking.

The TO-263-5L surface mount package tab is designed to be soldered to the copper on a printed circuit board. The

copper and the board are the heat sink for this package and the other heat producing components, such as the catch

diode and inductor. The PC board copper area that the package is soldered to should be at least 0.8 in

2

, and ideally

should have 2 or more square inches of 2 oz. Additional copper area improves the thermal characteristics, but with

copper areas greater than approximately 6 in

2

, only small improvements in heat dissipation are realized. If further

thermal improvements are needed, double sided, multilayer PC board with large copper areas and/or airflow are

recommended.

The TS2496 (TO-263-5L package) junction temperature rise above ambient temperature with a 2A load for various

input and output voltages. This data was taken with the circuit operating as a buck switching regulator with all

components mounted on a PC board to simulate the junction temperature under actual operating conditions. This

curve can be used for a quick check for the approximate junction temperature for various conditions, but be aware that

there are many factors that can affect the junction temperature. When load currents higher than 2A are used, double

sided or multilayer PC boards with large copper areas and/or airflow might be needed, especially for high ambient

temperatures and high output voltages.

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

used in the board layout. (Once exception to this is the output (switch) 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.