UAA2016 データシートの表示（PDF） - Motorola => Freescale
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UAA2016 Datasheet PDF : 8 Pages
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UAA2016
CIRCUIT FUNCTIONAL DESCRIPTION
Power Supply (Pin 5 and Pin 7)
The application uses a current source supplied by a single
high voltage rectifier in series with a power dropping resistor.
An integrated shunt regulator delivers a VEE voltage of
– 8.6 V with respect to Pin 7. The current used by the total
regulating system can be shared in four functional blocks: IC
supply, sensing bridge, triac gate firing pulses and zener
current. The integrated zener, as in any shunt regulator,
absorbs the excess supply current. The 50 Hz pulsed supply
current is smoothed by the large value capacitor connected
between Pins 5 and 7.
Temperature Sensing (Pin 3)
The actual temperature is sensed by a negative
temperature coefficient element connected in a resistor
divider fashion. This two element network is connected
between the ground terminal Pin 5 and the reference voltage
– 5.5 V available on Pin 1. The resulting voltage, a function of
the measured temperature, is applied to Pin 3 and internally
compared to a control voltage whose value depends on
several elements: Sawtooth, Temperature Reduction and
Hysteresis Adjust. (Refer to Application Information.)
Temperature Reduction
For energy saving, a remotely programmable temperature
reduction is available on Pin 4. The choice of resistor R1
connected between Pin 4 and VCC sets the temperature
reduction level.
Comparator
When the positive input (Pin 3) receives a voltage greater
than the internal reference value, the comparator allows the
triggering logic to deliver pulses to the triac gate. To improve
the noise immunity, the comparator has an adjustable
hysteresis. The external resistor R3 connected to Pin 2 sets
the hysteresis level. Setting Pin 2 open makes a 10 mV
hysteresis level, corresponding to 0.15°C. Maximum
hysteresis is obtained by connecting Pin 2 to VCC. In that
case the level is set at 5°C. This configuration can be useful
for low temperature inertia systems.
Sawtooth Generator
In order to comply with European norms, the ON/OFF
period on the load must exceed 30 seconds. This is achieved
by an internal digital sawtooth which performs the
proportional regulation without any additional component.
The sawtooth signal is added to the reference applied to the
comparator negative input. Figure 2 shows the regulation
improvement using the proportional band action.
Noise Immunity
The noisy environment requires good immunity. Both the
voltage reference and the comparator hysteresis minimize
the noise effect on the comparator input. In addition the
effective triac triggering is enabled every 1/3 sec.
Failsafe
Output pulses are inhibited by the “failsafe” circuit if the
comparator input voltage exceeds the specified threshold
voltage. This would occur if the temperature sensor circuit is
open.
Sampling Full Wave Logic
Two consecutive zero–crossing trigger pulses are
generated at every positive mains half–cycle. This ensures
that the number of delivered pulses is even in every case.
The pulse length is selectable by Rsync connected on Pin 8.
The pulse is centered on the zero–crossing mains waveform.
Pulse Amplifier
The pulse amplifier circuit sinks current pulses from Pin 6
to VEE. The minimum amplitude is 70 mA. The triac is then
triggered in quadrants II and III. The effective output current
amplitude is given by the external resistor Rout. Eventually,
an LED can be inserted in series with the Triac gate (see
Figure 1).
Figure 4. Output Resistor versus
Triac Gate Current
200
180
160
140
TA = +10°C
120
100
80
TA = – 20°C
TA = 0°C
60
40
TA = –10°C
20
30
40
50
60
IGT, TRIAC GATE CURRENT SPECIFIED AT 25°C (mA)
Figure 5. Minimum Output Current
versus Output Resistor
100
80
60
40
TA = + 85°C
20
TA = – 20°C
0
40 60 80 100 120 140 160 180 200
Rout, OUTPUT RESISTOR (Ω)
MOTOROLA ANALOG IC DEVICE DATA
5
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