Date: 8/30/05 SP3220E/EB/EU High ESD RS-232 Driver/Receiver Copyright 2005 Sipex Corporation
Dae 82205 SP3220EEBEUHghESDRS232Dve/Receve
Copyigh 2005SpexCopoaion
Table 2. Truth Table Logic for Shutdown and
Enable Control
N
D
0
0
1
1
H
S
N
0
1
0
1
E
T
e
e
e
e
U
a
a
v
v
O
s
s
i
i
x
T
i
i
c
c
T
e
e
e
e
U
v
a
v
a
O
i
s
i
s
x
-
-
R
c
i
c
i
t
t
t
t
-
-
T
T
t
t
T
t
t
T
Thereceve convetsEATA232evestoTTLo
CMOSogcoupu leves Thereceve hasan
invetinghghimedanceoupu. Thsreceve
oupu (ROUT isa hghimedancewhenthe
enabeconro EN=HGHInheshudownmde
thereceve canbeaciveo inacive ENhasno
efec onTxOUT Thetruhtabelogco the
SP3220EEBEU
dive andreceve oupuscan
befoundn
Tabe2
.
Sncereceve npu susuayfromaransmsson
linewheelongcabelenghsandsysem
inefeencecandegadethesgna, theinpus
haveatypca hyseessmrgno 300mV
Thsensuestha thereceve isvrtualy
immnetonosytransmssonlines Shoudan
inpu belet unconneced a5k
pudown
resso togoundw commtheoupu o the
receve toaHGHsae
Thechagepum isa
Spex
–paeneddesgn
(US5306954 andusesaunqueappoach
comaedtoode less–eficen desgns The
chagepum sill requresfou exena
capactos bu usesafou–phasevotageshfting
technquetoatansymmtrca 55Vpowe sup
pes Theinena powe suppyconssso a
reguaeddua chagepum tha povdesoupu
votages55Vegadesso thenpu votage(V
ove the+30Vo+55Vrange
CC
)
Inms crcumances decoupngthepowe
suppycanbeachevedadequaeyusnga01
F
bypasscapacto a C5(
ree toFgue11
).
Inappcaionstha aesenstivetopowe-
suppynose decoupeV
pacto o hesam vaueas togoundwhaca
to C1 Physcayconnec bypass capactosas
cosetotheICaspossbe
Thechagepumsopeaeinadsconnuous
mdeusnganinena osclao. If theoupu
votagesae
lessthan
amgntudeo 55Vthe
chagepumsae
enabed
; f theoupu votages
exceed
amgntudeo 55Vthechagepums
ae
d
sa
bed
. Thsosclao conrosthefou
phaseso thevotageshfting Adescipono
eachphasefoow.
V
coc chagesoage Duingthsphaseand
C
t aentiaychagedtoV
transeredtoC
thevotagepo. SnceC
timsV
. C
–
–
is
+
sthenswched
+
isconnecedtoV
,
2
snow2
.
V
conn transe Phasetwo totheV
soagecapacto andhepostiveemna o C
GNDThstransesanegavegeneaedvot o
toC
regu. Thsgeneaedvotageis
Smtaneouswhheranse o hevotageoC
thepostivesdeo capacto C
andthenegavesdesconnecedtoGND
SS
3
,
CC
sswchedtoV
V
cock chagesoage Thethrd thechage
transeredinC
temna o C
o capacto, whchsappedoh, thevotage
poena acossC
1
poduces–V
. SnceC
inthenegave
+
isa V
is2timsV
.