AN2559 datasheet(12/35 Pages) STMICROELECTRONICS

12 / 35 page

PM6680A block

AN2559

12/35

take into consideration that the influence of noise on the performance of the SMPS strictly

depends on the PCB layout. Therefore, the 30 mV is an indicative value. Virtual ESR

Networks are applied for each channel on the reference board described in this application

note. The main reason for this is the fact that the SMPS based on the PM6680A device can

generate different output voltages at a wide input voltage range. As output voltage ripple

depends also on input and output voltage level, there are configurations where the Virtual

ESR network could be mandatory. Virtual ESR networks consists of R40, R39, C35 or R27,

R38 or C34. The ESR network can be removed to observe influence of ESR network to

board function. To remove the Virtual ESR Network, R40 and R27 must be removed and

R39 and R38, respectively, must be shorted.

Figure 9.

Jumper placement for VCORE voltage level setting

Table 4.

VCORE voltage level jumper settings

Jumper settings

VCORE

2.5 V

1.8 V

1.5 V

1.2 V

1.0 V

0.9 V

AN2559 Datasheet(PDF) 12 Page - STMicroelectronics