TS2596

3A / 150KHz Buck Dc-Dc Converter

4/9

Version: E13

Typical Application Circuit (Continue)

2. Fixed Output Voltage Version

C2

0.1uF

D1

B340A

L1

47uH

1

2

C3

470uF

C1

470uF

U1

1

2

3

4

5

Vcc

SW

FB

EN

Vss

Vout=5.0V/3A

VIN=24V

C6

0.1uF

2.5V

3.3V

5V

12V

33uH

33uH

33~47uH

NA

33uH

33uH

47uH

68uH

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 TS2596 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 TS2596 junction temperature rises

above ambient temperature for a 3A load and different input and output voltages. The data for these curves was

taken with the TS2596 (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,