1A, 52kHz, Step-Down Switching Regulator

LM2575

This pin is the positive input supply for the LM2575 step–down switching

regulator.In order to minimize voltage transients and to supply the switching

currents needed by the regulator, a suitable input bypass capacitor must be

present .(Cin in Figure 1).

This is the emitter of the internal switch. The saturation voltage Vsat of this

output switch is typically 1.5 V. It should be kept in mind that the PCB area

connected to this pin should be kept to a minimum in order to minimize

coupling to sensitive circuitry.

Circuit ground pin. See the information about the printed circuit board layout.

This pin senses regulated output voltage to complete the feedback loop.

The signal is divided by the internal resistor divider network R2, R1 and

applied to the non–inverting input of the internal error amplifier. In the

Adjustable version of the LM2575 switching regulator this pin is the direct

input of the error amplifier and the resistor network R2, R1 is connected

externally to allow programming of the output voltage.

It allows the switching regulator circuit to be shut down using logic level

signals, thus dropping the total input supply current to approximately 80 mA.

The threshold voltage is typically 1.4 V. Applying a voltage above this value

(up to +Vin) shuts the regulator off. If the voltage applied to this pin is lower

than 1.4V or if this pin is left open, the regulator will be in the "on" condition

Feedback

HTC

−

8 −

4

5

ON/OFF

2

Gnd

3

Description

Symbol

1

Vin

Output

PIN FUNCTION DESCRIPTION