22

SLDM-06D1Ax

tech.support@psbel.com

belpowersolutions.com

.

External capacitors are usually added to the output of the module for two reasons: to reduce output ripple and noise (see Figure 38) and to

reduce output voltage deviations from the steady-state value in the presence of dynamic load current changes. Adding external capacitance

however affects the voltage control loop of the module, typically causing the loop to slow down with sluggish response. Larger values of external

capacitance could also cause the module to become unstable.

This R-C allows the user to externally adjust the voltage loop feedback compensation of the module.

Figure 46

Recommended values of RTUNE and CTUNE for different output capacitor combinations are given in Table 2. Table 2 shows the recommended

values of RTUNE and CTUNE for different values of ceramic output capacitors up to 1000uF that might be needed for an application to meet

output ripple and noise requirements. Selecting RTUNE and CTUNE according to Table 2 will ensure stable operation of the module.

In applications with tight output voltage limits in the presence of dynamic current loading, additional output capacitance will be required. Table 3

lists recommended values of RTUNE and CTUNE in order to meet 2% output voltage deviation limits for some common output voltages in the

presence of a 3A to 6A step change (50% of full load), with an input voltage of 12V.

Please contact your Bel representative to obtain more details of this feature as well as for guidelines on how to select the right value of external

R-C to tune the module for best transient performance and stable operation for other output capacitance values.

Table 2

Co

3x47F

4x47F

6x47F

10x47F

20x47F

330

300

300

240

180

1000pF

1200pF

2200pF

3300pF

8200pF

General recommended values of of RTUNE and CTUNE for Vin=12V and various external ceramic capacitor combinations.

Vo

5V

3.3V

2.5V

1.8V

1.2V

0.6V

Co

3x47F

Ceramic

3x47F

Ceramic

4x47F

Ceramic

1x47F

+

1x330

F

Polymer

1x47F

+

1x330

F

Polymer

2x47F

+

3x330

F

Polymer

300

300

300

300

300

200

1000pF

1200pF

1800pF

2700pF

399pF

15nF

V

60mV

54mV

42mV

26mV

22mV

11mV

Recommended values of RTUNE and CTUNE to obtain transient deviation of 2% of Vout for a 3A step load with Vin=12V

.

Note: The capacitors used in the Tunable Loop tables are 47 μF/3 mΩ ESR ceramic and 330 μF/12 mΩ ESR polymer capacitors

VS+

MODULE

SIG_GND

TRIM

VOUT

RTune

CTune

RTrim

CO

GND