12
AVR430
8124C-AVR-10/08
4.5 Upgrading the MC300 As the board is shipped, its limitations are Vm
max
=40V and Im
max
=6A. These limits can
be increased by replacing the relevant components (not included).
4.5.1 Voltage limitations
If a Vm
max
higher than 40V is required, t hen some components must be changed on
the board. Components limiting Vm, listed with lowest voltage ratings first, are shown
in Table 4-1.
Table 4-1. Components influenced by Vm.
Component designator(s) Component name Limiting parameter
Q3, Q4, Q5, Q6, Q7, Q8, Q9 & Q10 IRFR3504 V
DSS
= 40V
C10, C19, C26 & C33 100nF V
max
= 50V
Q2 2N7002 V
DSmax
= 60V
C14 47uF/63V V
max
= 63V
D8, D12, D13 & D14 BAS16 V
RRM
= 85V
D9 10MQ100N V
RRM
= 100V
D11 12CWQ10FN V
RRM
= 100V
C7 10nF V
max
= 100V [2]
R7 100kOhm Pmax = 0.1W -> Vm = 108V
The integrated bridge drivers (IR2101S) can handle up to 600V, but th e layout of the
PCB (spacing between tracks) should be co nsidered before operation at high
voltages.
If filters/dividers for Vm, U, V, W, or X have been mounted, verify that they can handle
Vm.
4.5.2 Current limitations
For an Im > 5A, use power connector J3 and not DC-Ja ck J5. If an Im
max
larger than
6A is required, components listed in Table 4-2 are affected.
Table 4-2. Components conducting Im.
Component designator(s) Component name Limiting parameter
R62 50mOhm 2W I
max
= sqrt(P/R) = 6,0A
(1)
J3 & J7 MC1,5/x-G-3,81 I
max
= 8A
Q3, Q4, Q5, Q6, Q7, Q8, Q9 & Q10 IRFR3504 I
D
= 30A
Notes: 1. The pad/track area around R62 is not 300mm2 as required by datasheet for
handling 2W. Reducing P to 1,8W gives I
max
= sqrt(P/R) = 6,0A.
4.5.3 Additional decoupling capacitors on Vm
The board has provision for some extra dec oupling capacitors on Vm. They are found
close to th e MOS bridges (C11, C12, C2 0, C21, C27, C28, C34 and C35), and one
close to the power input (C13).