L6726A

Application details

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8

Application details

8.1

Output voltage selection

L6726A is capable to precisely regulate an output voltage as low as 0.8V. In fact, the device

comes with a fixed 0.8V internal reference that guarantees the output regulated voltage to

be within ±1% tolerance over line and temperature variations (excluding output resistor

divider tolerance, when present).

and ground. Referring to Figure 1, the steady state DC output voltage will be:

8.2

Compensation network

The control loop shown in Figure 8 is a voltage mode control loop. The error amplifier is a

transconductance type with fixed gain (3.3mS typ.). The FB voltage is regulated to the

internal reference, thus the output voltage is fixed accordingly to the output resistor divider

(when present).

compared to oscillator saw-tooth waveform to provide PWM signal to the driver section.

filtered by the output filter.

Figure 8.

PWM control loop

The converter transfer function is the small signal transfer function between the voltage at

V

OUT

V

REF

1

R

FB

R

OS

-----------

+

⎝⎠

⎛⎞

⋅

=

L

R

C

OUT

ESR

R

FB

OSC

V

IN

+

+

_

_

V

OUT

V

REF

OUTPUT

DIVIDER

PWM

COMPARATOR

OTA

R

F

C

F

C

P

FB

COMP