tda1023t NXP Semiconductors, tda1023t Datasheet - Page 4

• Manufacturer Part Number: tda1023t
• Description: Proportional-control Triac Triggering Circuit
• Manufacturer: NXP Semiconductors

Philips Semiconductors
FUNCTIONAL DESCRIPTION
The TDA1023 generates pulses to trigger a triac. These
pulses coincide with the zero excursions of the mains
voltage, thus minimizing RF interference and mains supply
transients. In order to gate the load on and off, the trigger
pulses occur in bursts thus further reducing mains supply
pollution. The average power in the load is varied by
modifying the duration of the trigger pulse burst in
accordance with the voltage difference between the
control input CI and the reference input, either UR or BR.
Power supply: V
The TDA1023 is supplied from the AC mains via a resistor
R
13) is linked to the neutral line (see Fig.4a). A smoothing
capacitor C
connections.
A rectifier diode is included between the RX and V
connections whilst the DC supply voltage is limited by a
chain of stabilizer diodes between the RX and V
connections (see Fig.3).
A stabilized reference voltage (V
power an external temperature sensing bridge.
Supply operation
During the positive mains half-cycles the current through
the external voltage dropping resistor R
external smoothing capacitor C
stabilizing potential of the internal stabilizing diodes. R
should be selected to be capable of supplying the current
I
recharge the smoothing capacitor C
supply for an external temperature bridge. (see Figs 9 to
12). Any excess current is by-passed by the internal
stabilizer diodes. The maximum rated supply current,
however, must not be exceeded.
During the negative mains half-cycles external smoothing
capacitor C
described above. Its capacitance must be sufficiently high
to maintain the supply voltage above the specified
minimum.
Dissipation in resistor R
in series (see Fig.4b and 9 to 12). A further reduction in
dissipation is possible by using a high quality dropping
capacitor C
14). Protection of the TDA1023 and the triac against
mains-borne transients can be provided by connecting a
suitable VDR across the mains input.
May 1991
CC
D
Proportional-control triac triggering circuit
to the RX connection (pin 16); the V
for the TDA1023, the average output current I
S
D
S
should be coupled between the V
in series with a resistor R
supplies the sum of the current demand
CC
, RX and V
D
is halved by connecting a diode
z
S
Z
(pins 14, 16 and 11)
until RX attains the
) is available at pin 11 to
S
and provide the
SD
EE
D
(see Figs 4c and
charges the
connection (pin
CC
EE
and V
3(AV)
CC
,
D
EE
4
Control and reference inputs CI, BR and UR
(pins 6, 9 and 7)
For the control of room temperature (5 C to 30 C)
optimum performance is obtained by using the translation
circuit. The buffered reference input BR (pin 9) is used as
a reference input whilst the output reference buffer QR (pin
8) is connected to the unbuffered reference input UR
(pin 7). This ensures that the range of room temperature is
encompassed in most of the rotation of the potentiometer
to give a linear temperature scale with accurate setting.
Should the translation circuit not be required, the
unbuffered reference input UR (pin 7) is used as a
reference input. The buffered reference input BR (pin 9)
must then be connected to the reference supply output V
(pin 11).
For proportional power control the unbuffered reference
input UR (pin 7) must be connected to the firing burst
repetition time control input TB (pin 12).The buffered
reference input BR (pin 9), which is in this instance
inactive, must then be connected to the reference supply
output V
Proportional range control input PR (pin 5)
The output duty factor changes from 0% to 100% by a
variation of 80 mV at the control input CI (pin 6) with the
proportional range control input PR open. For temperature
control this corresponds to a temperature difference of 1 K.
By connecting the proportional range control input PR
(pin 5) to ground the range may be increased to 400 mV,
i.e. 5 K. Intermediate values may be obtained by
connecting the PR input to ground via a resistor R5
(see Table 1).
Hysteresis control input HYS (pin 4)
With the hysteresis control input HYS (pin 4) open, the
device has a built-in hysteresis of 20 mV. For temperature
control this corresponds with 0.25 K.
Hysteresis is increased to 320 mV, corresponding to 4 K,
by grounding HYS (pin 4). Intermediate values are
obtained by connecting pin 4 via resistor R4 to ground.
Table 1 provides a set of values for R4 and R5 giving a
fixed ratio between hysteresis and proportional range.
Z
(pin 11).
Product specification
TDA1023/T
Z