L6932H1.2

Components selection

9/13

7.3

Loop Stability

The stability of the loop is affected by the zero introduced by the output capacitor. The time

constant of the zero is given by:

This zero helps to increase the phase margin of the loop until the time constant is higher

than some hundreds of nsec, depending also on the output voltage and current.

So, using very low ESR ceramic capacitors could produce oscillations at the output, in

particular when regulating high output voltages (adjustable version).

To solve this issue is sufficient to add a small capacitor (e.g. 1nF to 10nF) in parallel to the

high side resistor of the external divider, as shown in Figure 9.

Figure 9.

Compensation network

The thermal resistance junction to ambient of the demoboard is approximately 34°C/W.

This mean that, considering an ambient temperature of 60°C and, a maximum junction

temperature of 150°C, the maximum power that the device can handle is 2.7W.

This means that the device is able to deliver a DC output current of 2A only with a very low

dropout.

T

ESR

C

OUT

×

=

F

ZERP

1

2

π ESR C

OUT

×

×

-----------------------------------------------

=

L6932H1.2

R1

R2

R3

C1

C2

Vout=1.2V to 5V

Vin=2V to 14V

1

2

3

4

5

6

7

8

EN

Vin

Vout

PGOOD

FB

GND

NC2

NC1

C3

L6932H1.2

R1

R2

R3

C1

C2

Vout=1.2V to 5V

Vin=2V to 14V

1

2

3

4

5

6

7

8

EN

Vin

Vout

PGOOD

FB

GND

NC2

NC1

C3