LTC4020 Charger

Hi,

My design base on DEMO board DC2134A.

What modifications i need to do to meet the requirements bellow:

1.output voltage 48VDC.

2.MAX output current 7A.

3.input voltage 49.1VDC.

4.the battery is 12-cell Li-Ion are connected in parallel 3 times.

PLS advice.

thank you.

Ilan

  • 0
    •  Analog Employees 
    on Apr 19, 2021 1:52 PM

    Setting the battery full-charge voltage is described in the datasheet, p. 26. under the section, Battery Charge Voltage Programming. You can change the value of DC2134 R8 to achieve a 48V full-charge voltage.  Next, calculate a value for R9 by referring to the VFBMAX pin description on p. 12 of the datasheet.  I suggest setting the VOUTMAX voltage to 48V+5%=50.4V.  

    I recommend an inductor value of 4.7µH.  The inductor should pass 12A without saturating and be able to carry 8A without excessive temperature rise.  RCBRT1 and RCBRB1 can be 5mΩ.  RCBAT1 can be 7mΩ.  These calculations assume an input range of 48.1-50.1V.

    For 49.1V in you should use an external regulator to generate a lower voltage for PVIN.  You can use a linear regulator to reduce the input voltage (to PVIN) to ~6V.  This will reduce power dissipation in the LTC4020-internal INTVCC regulator.  Replace R38 with 0Ω.  You may refer to the discussion in the datasheet, p. 25, 26, but do not use the circuits in figures 9, 10 of the datasheet.  They do not work.