SL441C

ADVANCE INFORMATION
DS3848 -1.0

SL441C
ZERO VOLTAGE SWITCH

The SL441C is a symmetrical burst control integrated

circuit in an 8 pin DIL package. When used with a triac, AC
power may be regulated by varying the number of mains
cycles applied to the load in a fixed timing period. The
device is especially suited to room temperature control
applications including panel heaters, fan heaters etc. Zero
Voltage Switching has the advantage of minimising radio
frequency interference.
FEATURES
■ Balanced zero voltage point crossing detector, DP8
spike filter and pulse generator for reliable
triggering of the triac. Fig.1 Pin Connections (top view)
■ A period pulse generator and bistable which are
arranged to provide symmetrical burst control ■ The comparison amplifier has inbuilt hysteresis
and eliminate 1 / 2 wave firing. (EN50.006 to eliminate switching jitter and a spike filter/
BS5406,1976) sampling circuit to provide high immunity to both
■ A ramp generator whose output is used to modify spikes and coherent 50Hz/60Hz.
an internal reference voltage which is then ■ Thermistor malfunction may be sensed and power
compared with the voltage appearing on the automatically removed.
thermistor to form a proportional control system. ■ A supply voltage sensing circuit which inhibits
The period of the ramp generator is defined firing pulses when the supply is inadequate to
externally and may be chosen to limit 'lamp flicker' guarantee proper circuit operation. This eliminates
in accordance with EN50.006/BS5406, 1976. stressing of the triac at switch-on.

Fig. 2 Block Schematic of SL441C

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SL441C

ELECTRICAL CHARACTERISTICS

These Characteristics are guaranteed at the following temperatures (unless otherwise stated).
Tamb = +25°C
All voltages measured with respect to common (pin 1)

Characteristics Min Typ Max Units

Shunt regulating voltage pin 3 @ 16mA 14.7 V
Shunt regulating voltage pin 3 @ 16mA @ 75°C 16 V
Supply voltage trip level pin 3 12.2 V
Supply current (less I4AV, I5) (see Note 1) 7.5 mA
Regulated voltage pin 5 8.0 8.5 9.0 V
Regulated voltage temperature coefficient pin 5 -1 +1 mV/ °C
Triac gate drive pin 4 (see Note 2)
Open circuit ON voltage 8.5 V
Open circuit OFF voltage 0.1 V
Output current into 2V drain 100 130 mA
Output current into 4V drain 65 80 mA
Output current into short circuit 200 mA
Internal drain resistance 800 Ω
Control input pin 8
Bias current 1 µA
Hysteresis 20 mV
Sensor malfunction circuit operates at 150 200 250 mV
Input working voltage range 0 12 V
Internal reference voltage (Ramp start) (see Note 3) 4.0 4.25 4.5 V
Internal reference voltage (Ramp finish) (see Note 3) 4.35 V
Peak-to-peak amplitude of ramp 70 100 130 mV
Pin 6 output impedance (R6) (see Note 2) 21.5 27 32.5 kΩ
Maximum ripple voltage pin 3 1 VP-P

NOTES
1. The supply current is 0.45 x (RMS current fed into pin 2). I5 is the current drained from pin 5 externally. I4AV is the average triac
gate current supplied each mains cycle.
2. Triac firing pulse. tp Pulse width = 0.69 R6CD microseconds typical
tf Pulse finish = 1.09 R6CD microseconds minimum after zero voltage point R6 in kohms. CD in nF.
See Application circuit
tp Nominal (CD = 2.7nF) = 50 microseconds
tp Minimum (CD = 2.7nF) = 63 microseconds
3. Ramp period = 0.85 ± 0.15 x RTCT sec. See Application circuit. The actual value of Rt must lie between 500kohms and 3Mohms.

ABSOLUTE MAXIMUM RATINGS

VOLTAGES CURRENTS
Voltage on pin V8 - I Max. 12V Supply current (pin 2) Peak value ± I2M 50mA.
Voltage on pin V4 - I Max. 10V Non-repetitive peak current (tp <250µs) ±I2SM 200mA.
Output current (pin 5) Max. 5mA Short circuit protected.
TEMPERATURE Output current (pin 4) average value I4 (AV) Max 5mA Short
Operating ambient temperature TAMB -10°C to +75°C circuit protected
Storage temperature TSTG -55°C to +150°C

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 SL441C

AVERAGE
POWER
IN LOAD
(%)

R thj - a = 200°C/W

CONTROL
VOLTAGE
(PIN 8)

0.2V SENSOR RAMP FINISH 14.7V (V3)

MALFUNCTION
12V ABSOLUTE
CIRCUIT TRIP
100mV TYP. 8.5V (V5) MAX. RATING
POINT
0V
OPERATIONAL 4.25V RAMP
LIMIT START

Fig. 3 Power Dissipation Fig. 4 Control Characteristic of Pin 8

8.5V

TP = 0.69RC TP = 0.69RC

TF = 1.09RC TF = 1.09RC

R = PIN 6 OUTPUT C = CD CAPACITOR

IMPEDANCE (R6) CONNECTED TO PIN 6

Fig. 5 Pulse Timing

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SL441C

HEADQUARTERS OPERATIONS CUSTOMER SERVICE CENTRES

GEC PLESSEY SEMICONDUCTORS • FRANCE & BENELUX Les Ulis Cedex Tel: (1) 64 46 23 45 Tx: 602858F
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• NORTH AMERICA Integrated Circuits and Microwave Products, Scotts Valley, USA
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P.O. Box 66017, 1500 Green Hills Road, Scotts Hybrid Products, Farmingdale, USA Tel (516) 293 8686 Fax: (516) 293 0061.
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Swindon Tel: (0793) 518510 Tx: 444410 Fax : (0793) 518582
These are supported by Agents and Distributors in major countries world-wide.

© GEC Plessey Semiconductors 1993 Publication No.DS3848 Issue No. 1.0 June 1993
This publication is issued to provide information only which (unless agreed by the Company in writing) may not be used, applied or reproduced for any purpose nor form part of any order or contract nor to be
regarded as a representation relating to the products or services concerned. No warranty or guarantee express or implied is made regarding the capability, performance or suitability of any product or service.
The Company reserves the right to alter without prior knowledge the specification, design or price of any product or service. Information concerning possible methods of use is provided as a guide only and
does not constitute any guarantee that such methods of use will be satisfactory in a specific piece of equipment. It is the user's responsibility to fully determine the performance and suitability of any
equipment using such information and to ensure that any publication or data used is up to date and has not been superseded. These products are not suitable for use in any medical products whose failure to
perform may result in significant injury or death to the user. All products and materials are sold and services provided subject to the Company's conditions of sale, which are available on request.

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appearing in this publication are subject to change by Zarlink without notice. No warranty or guarantee express or implied is made regarding the capability, performance or
suitability of any product or service. Information concerning possible methods of use is provided as a guide only and does not constitute any guarantee that such methods of
use will be satisfactory in a specific piece of equipment. It is the user’s responsibility to fully determine the performance and suitability of any equipment using such
information and to ensure that any publication or data used is up to date and has not been superseded. Manufacturing does not necessarily include testing of all functions or
parameters. These products are not suitable for use in any medical products whose failure to perform may result in significant injury or death to the user. All products and
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