DESCRIPTIONS
SM3000
Page 3 - 2
DELTA ELEKTRONIKA B.V.
rev. February 2018
The in put cir cuit has a large se ries choke to im prove the wave form. The re -
sult is: a lower rms in put cur rent, less mains dis tor tion and no large peak cur -
rents.
The units also have an in rush cur rent lim iter and a soft start cir cuit, for
smooth switch on.
°
FUSES 16 A Slow blow.
4)
STANDBY IN PUT POWER
The unit con sumes very lit tle power when in standby. This makes it pos si ble
to leave the in put power on and use the Re mote Shut Down in put (pin 5 on
prog. connector rear panel) to dis able the out put.
5)
EFFICIENCY
The ef fi ciency is very high and con stant over a wide out put cur rent range
(see fig. 3 - 4). High ef fi ciency also means low power loss and low heat gen -
er a tion.
6)
REG U LA TION
The load reg u la tion should be mea sured di rectly on the out put ter mi nals.
A few cm of ca ble can have a volt age drop of sev eral mV (at high cur rent!).
7)
RIP PLE & NOISE
The out put rip ple is very low with al most no spikes.
The rip ple volt age has to be mea sured di rectly on the out put ter mi nals us ing
a probe with very short con nec tions (to avoid pick up of mag netic fields) (see
fig. 3 - 5 and fig. 3 - 6).
At low tem per a tures like -20
°
C the rip ple in creases. By us ing high qual ity
elec tro lytic ca pac i tors the in crease is rel a tively low.
8)
PRO GRAMMING IN PUTS
The out put volt age and cur rent can be pro grammed by an ex ter nal an a log
volt
age. This pro
gram
ming is very ac
cu
rate and lin
ear, (non-lin ear ity
<0.15%). The lev els are all stan dard ized on 5V. Al ways use a
shielded ca -
ble
for pro gram ming.
The in puts have a pro tec tion cir cuit formed by a se ries re sis tor and a par al lel
zener (see fig. 3 - 7). The ca pac i tor lim its the speed to a safe value. Note that
the an a log in puts (and out puts) are
not float ing, but the com mon is con -
nected to the neg a tive out put ter mi nal.
Wrong con nec tion of Ø can cause
earth loops which can trip the fuse. Af ter re mov ing the fault, the fuse will re -
set (PTC-fuse). To pre vent earth loops, use iso lated pro gram ming with the
ISO AMP CARD in ter nal in ter face op tion P145(
δ
-prod uct)
.
The pro gram ming mode (pro gram and man ual) can be se lected by means of
the prog. switches which are sit u ated be low the pro gram ming con nec tor
(see fig. 3- 9).
9)
IEEE488 / RS232 PRO GRAMMING
For pro gram ming use the ex ter nal in ter face
PSC-488 mod ule
or in ter nal in -
ter face
PSC-232
(both
δ
-prod ucts)
.
Volt age and cur rent can eas ily be pro grammed and read back. Also the CC
and OVP sta tus can be read by the com puter. Al ways use a
shielded ca ble
for pro gram ming.
10)
MON I TORING OUT PUTS
The mon i tor out puts give a volt age 0 - 5 V pro por tional to the out put cur rent
or volt age. The out put cur rent can eas ily be mea sured with out an ex ter nal
shunt us ing the I-mon i tor (see fig. 3 - 8). The mon i tor out puts are buf fered by
op-amp’s and pro tected by se ries re sis tors and par al lel zeners (see fig. 3 -
10). The ta ble 3 - 1 shows the im ped ance lev els of the mon i tor ing out puts.
For us ing Imon on a pul sat ing load, see para graph 17) of this chapter.
fig. 3 - 4
Ef fi ciency vs out put cur rent, SM30-100D
DC in put , Vout = 30 V
fig. 3 - 5
Mea sur ing rip ple volt age
WRONG !
fig. 3 - 6
Mea sur ing rip ple volt age
RIGHT !
fig. 3 - 7
Pro gram ming in puts
(in ter nal cir cuit)
V
A
Imon
0-5V
Vmon
0-5V
Return of
ref, prog, mon.
fig. 3 - 8
Ex ter nal me ters
us ing mon i tor out puts
