NCN5110
www.onsemi.com
19
Analog State Diagram
The analog state diagram of NCN5110 is given in
Figure 13. The status of the DC−DC converters, V20V
regulator and KNX communication during the different
(analog) states is given in Table 7.
Figure 14 gives a detailed view on the start−up behavior
of NCN5110. After applying the bus voltage, the filter
capacitor starts to charge. During this Reset State, the
current drawn from the bus is limited to I
coupler
(for details
see the KNX Standards). Once the voltage on the filter
capacitor reaches 10 V (typ.), the fixed DC−DC converter
(powering VDDA) will be enabled and the device enters the
Start−Up State. When V
DD1
gets above 2.8 V (typ.), the
OTP memory is read out to trim some analog parameters
(OTP memory is not accessible by the user). When done, the
Stand−By State is entered and the RESETB−pin is made
high. When V
FILT
is above V
FILTH
DC2 and V20V will be
started. When the VBUS−, VFILT−, VDD2− and V20V−
monitors are ok, the Normal State will be entered and
SAVEB−pin will go high.
Figure 15 gives a detailed view on the shut−down
behavior. If the KNX bus voltage drops below V
BUSL
for
more than t
bus_filter
, the Standy−By State is entered. SAVEB
will go low to signal this. When VFILT drops below V
FILTL
,
DC2 and the V20V regulator will be switched off. When
VFILT drops below 6.5 V (typ), DC1 will be switched off
and V
DD1
drops below 2.8 V (typ.) the device goes to Reset
State (RESETB low).
Figure 13. Analog State Diagram
Reset
RESETB = ‘0’
SAVEB = ‘0’
Start−Up
RESETB = ‘0’
SAVEB = ‘0’
Stand−By
RESETB = ‘1’
SAVEB = ‘0’
Normal
RESETB = ‘1’
SAVEB = ‘1’
V
FILT
> 12V
and
Temp < TSD
V
FILT
< 6.5V
V
DDA
OK
and
OTP read done
<TSD> = ‘1’
or
V
DDA
nOK
Remarks:
− <TW>, <XTAL>, <VBUS>, <VFILT>, <VDD2> and <V20V> are internal status bits.
− <TSD> is an internal signal indicating a Thermal Shutdown. This internal signal cannot be read out.
− Although Reset State could be entered from Normal State on a TSD, Stand−By State will be entered first due to a TW.
Enable DC1 Disable DC1
Enable DC2 and V20V
V
FILT
> V
FILTH
Disable DC2 and V20V
V
FILT
< V
FILTL
Disable DC1
V
FILT
< 6.5V
<TW> = ‘0’ and <XTAL> = ‘1’ and
Disable DC1, DC2 and V20V
<TSD> = ‘1’
or
V
DDA
nOK
<VBUS> = ‘1’ and <VFILT> = ‘1’ and
<VDD2> = ‘1’ and <V20V> = ‘1’
<TW> = ‘1’ or <XTAL> = ‘0’ or
<VBUS> = ‘0’ or <VFILT> = ‘0’ or
<VDD2> = ‘0’ or <V20V> = ‘0’
