IES5521ATR Hendon Semiconductors, IES5521ATR Datasheet - Page 3

• Manufacturer Part Number: IES5521ATR
• Description: Board Mount Temperature Sensors 10mA Triac Temp control + Timer
• Manufacturer: Hendon Semiconductors

Specifications of IES5521ATR

• Package / Case: SO-8
• Supply Voltage (max): 7.6 V
• Supply Voltage (min): 6.3 V
• Maximum Operating Temperature: + 100 C
• Minimum Operating Temperature: - 25 C
• Supply Current: 210 uA
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

6.5
The triac gate drive output is
designed to be connected directly to
the triac gate without the need for an
external current setting resistor. It has
inbuilt protection to withstand
transient signals which may be
induced on the gate of the triac by
mains transients during firing. The
gate drive is designed for a triac with
a gate sensitivity which requires less
than 10 mA of triggering current, and
a suitable latching current. One triac
with suitable characteristics is the
BT137 series E when used with a
load of more than 400 watts.
The gate drive has a negative
temperature coefficient designed to
match the gate temperature
characteristic of typical triacs.
6.6
The timing capacitor is connected
between this pin and V
discharge time of this capacitor sets
the triac ON time, and is proportional
to the capacitance value
(approximately 4 seconds per micro
farad). The charging period, or OFF
time, varies with the magnitude of the
input signal from the sensor. The ON
period is synchronised with the mains
zero crossing signals so that an
integral number of full cycles makes
up the ON period, and no nett DC
signal is generated in the supply line.
The initiation of an ON period is
suppressed until the chip power
supply reaches its regulated value.
After reaching a valid V
stay in operation even if the supply
falls to about 4 volts. Triac gate
pulses will not start until the internal
voltage limiting “zener” begins to
conduct.
6.7
The sensor input is designed to
accept an input which is an AC signal
2006 Sep 01, Revision 1.1
GATE − Triac gate drive
CAP − Timing capacitor
SENS − Sensor input
EE
EE
. The
the chip will
referenced to common; thereby
avoiding problems associated with
the power dissipation involved in
generating sufficient DC current to
drive the sensor over its full operating
resistance range. If a suitable
resistive sensor is used with a parallel
level setting potentiometer to apply a
proportion of the AC sensor signal to
the SENS input, a typical circuit will
power this via a 160 kΩ resistor from
the AC supply. The SENS input signal
threshold is one VBE below the V
rail. Signals with a magnitude greater
than this VBE charge the timing
capacitor towards the V
reaches the threshold which initiates
an ON cycle. Signals with a
magnitude less than this do not
charge the capacitor, and the triac
drive remains OFF.
External circuits may be used to give
greater temperature linearity and
accuracy, and improved performance
with variation in ambient temperature.
The SENS input is only active on
negative signals with respect to V
and therefore either a full AC input
may be used, or a signal that is only
negatively going with respect to V
6.8
6.8.1
The RC oscillator can be disabled by
connecting the RC pin to the V
through a 470 kΩ pull-up resistor
(figure 5). The resistor tolerance is not
critical. This resistor acts to limit
current into pin 5 to approximately
4 / 470 kΩ = 8.5 µA. Other values may
be used, however, this current must
be accounted for in the determination
of the appropriate power supply
resistor R3 (figure 5).
With the RC oscillator disabled, the
time-out circuit will run from the AC
supply frequency, counting down
RC − Setting the time-out
period
U
FREQUENCY
SING THE
3
Simple Zero-Crossing Triac Control
AC
Circuit with Adjustable Time-out
CC
MAINS
rail until it
CC
CC
CC
CC
pin
,
.
212992 cycles, whereupon it disables
the gate signal to the triac. The
time-out period is thus determined by
the frequency of the AC supply, but is
precisely controlled for a particular
frequency.
Should a different accurate time-out
period be required for a particular
mains frequency (other than
described here), please contact
Integrated Electronic Solutions to
discuss your needs.
6.8.2
A period other than this may be
chosen by removing the pull-up
resistor between RC and V
replacing it with parallel resistor and
capacitor network between the RC
pin and V
A typical resistor value would be
470 kΩ, with a corresponding
capacitor chosen to give the desired
time-out period. Lower resistances
(for example, 100 kΩ) are possible
but will cause a small shift in the
oscillator frequency compared to the
above calculation, while timing at
larger resistances may be affected by
leakage currents on the printed circuit
board.
Figure 3 shows the multiplication
factor for the period of the oscillation
1.6
1.5
1.4
1.3
Fig.3 RC period multiplication factor
RC Factor
0.1
R=100kΩ
U
R=470kΩ
EE
1.0
SING THE
IES5521A
(figure 6).
Product Specification
Capacitance, C3 (nF)
10
RC
Error Bars
OSCILLATOR
100
CC
, and
100°C
0°C
25°C
5521-RCfac
1000