UAA2016
S2
S1
R
S
UAA2016
Failsafe
R
R
R
R
3
def
2
1
MAC212A8
3
Sampling
Full Wave
Logic
R
6
7
out
+
−
Pulse
Amplifier
Sense Input
Output
4
Internal
Reference
+
+
+
1/2
+V
CC
Temp. Red.
C
F
4−Bit DAC
2
Supply
Voltage
Hys
Adj
Load
11−Bit Counter
Synchronization
1
V
ref
5
8
Sync
V
EE
R
R
S
sync
Figure 1. Application Schematic
APPLICATION INFORMATION
(For simplicity, the LED in series with R is omitted in
The load current is then:
out
the following calculations.)
Ǹ
I
+ (Vrms 2 sin(2pft)–V )ńR
Load
TM
L
Triac Choice and Rout Determination
where V is the maximum on state voltage of the triac, f is
the line frequency.
TM
Depending on the power in the load, choose the triac that
has the lowest peak gate trigger current. This will limit the
output current of the UAA2016 and thus its power
Set ILoad = ILatch for t = TP/2 to calculate TP.
consumption. Use Figure 4 to determine R according to
Figures 6 and 7 give the value of T which corresponds to
P
out
the triac maximum gate current (I ) and the application
the higher of the values of I
and I
, assuming that
GT
Hold
Latch
low temperature limit. For a 2.0 kW load at 220 Vrms, a good
triac choice is the ON Semiconductor MAC212A8. Its
maximum peak gate trigger current at 25°C is 50 mA.
V
= 1.6 V. Figure 8 gives the R
that produces the
TM
sync
corresponding T .
P
RSupply and Filter Capacitor
For an application to work down to − 20°C, R should be
out
With the output current and the pulse width determined as
above, use Figures 9 and 10 to determine R , assuming
that the sinking current at V pin (including NTC bridge
60 W. It is assumed that: I (T) = I (25°C) ꢀ exp (−T/125)
GT
GT
Supply
with T in °C, which applies to the MAC212A8.
ref
Output Pulse Width, Rsync
current) is less than 0.5 mA. Then use Figure 11 and 12 to
The pulse with T is determined by the triac’s I
, I
determine the filter capacitor (C ) according to the ripple
P
Hold Latch
F
together with the load value and working conditions
(frequency and voltage):
desired on supply voltage. The maximum ripple allowed is
1.0 V.
Given the RMS AC voltage and the load power, the load
value is:
Temperature Reduction Determined by R1
RL = V2rms/POWER
(Refer to Figures 13 and 14.)
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