ELM365 Security System Controller Description Features The ELM365 provides all of the logic necessary for a complete security system in an 8 pin package. The circuit is capable of monitoring two normally closed input loops and one normally open panic circuit, provides a constant level and a pulsing alarm output, and the logic to drive a status LED. Internal timers are provided for alarm blocking during zone entry and exit as well as circuit resetting, should alarms go unacknowledged. Debouncing of all of the inputs is also provided internally, to allow for the direct interfacing to mechanical switches. Due to the digital techniques employed, no external support components are required for any of the timing functions, resulting in considerable cost savings over other designs. • • • • • • • • Low power CMOS design - typically 1mA at 5V Wide supply range - 3.0 to 5.5 volt operation Simultaneous monitoring of three circuits 45 second delay for entry and exit Automatic reset of alarm outputs after 5 minutes Status LED output driver High current drive outputs - up to 25 mA Panic input for instant triggering of the alarm Connection Diagram PDIP and SOIC (top view) Applications • • • • Home or cottage security systems Auto or RV security systems Individual zone monitoring in a multizone system High or low limit warning alarms VDD 1 8 VSS OutP 2 7 DLoop OutC 3 6 ILoop 4 5 LED panic Block Diagram VDD DLoop 7 VDD ILoop 6 45 sec Delay fast 45 sec PowerUp slow LED Flasher 5 LED 3 OutC 2 OutP Alarm Latch VDD panic 4 Alarm Latch 5 min Reset ELM365DSB Elm Electronics – Circuits for the Hobbyist < http://www.elmelectronics.com/ > 1.5s on 0.5s off 1 of 4 ELM365 Pin Descriptions VDD (pin 1) This pin is the positive supply pin, and should always be the most positive point in the circuit. Internal circuitry connected to this pin is used to provide power on reset of the microprocessor, so an external reset signal is not required. Refer to the Electrical Characteristics section for further information. OutP (pin 2) This is the (active high) pulsed alarm output. When in an alarm state, it alternates between a logic high level (VDD) for 1.5 seconds and a low level (VSS) for 0.5 seconds. This output automatically resets after 5 minutes. OutC (pin 3) This is the constant level alarm output. It is switched to a high level (VDD) during an alarm condition, and is otherwise at a logic low level. This output automatically resets to a low level after 5 minutes. panic (pin 4) This active low input is debounced and used to immediately trigger an alarm from normally open inputs such as panic pushbuttons or tamper switches. If unused, this input can be left open circuited, as there is an internal pullup resistor on the pin (see the specs). LED (pin 5) This is an active low LED drive output. It will pulse rapidly to warn that the system is in a 45 second delayed alarm period, or will pulse slowly (about 1.5 seconds on, 0.5 seconds off) if an alarm is in progress or has previously occurred. By adding a suitable series resistor, an LED can be directly driven from this pin. ILoop (pin 6) This pin is used for monitoring a normally closed loop, connected between the pin and VSS. To reduce the possibility of nuisance triggers, a 0.5 second debounce period is provided on this input. An alarm will be initiated immediately after the loop is determined to be open, but will not retrigger an alarm if the loop remains open, after the five minute timeout. This pin is not enabled for the first 45 seconds after the system is first turned on. DLoop (pin 7) This pin is similar to pin 6, with the one exception being that the alarm is delayed by 45 seconds to allow time for entry or exit. VSS (pin 8) Circuit common is connected to this pin. This is the most negative point in the circuit. Ordering Information These integrated circuits are available in either the 300 mil plastic DIP format, or in the 200 mil SOIC surface mount type of package. To order, add the appropriate suffix to the part number: 300 mil Plastic DIP............................... ELM365P 200 mil SOIC..................................... ELM365SM All rights reserved. Copyright ©1999 Elm Electronics. Every effort is made to verify the accuracy of information provided in this document, but no representation or warranty can be given and no liability assumed by Elm Electronics with respect to the accuracy and/or use of any products or information described in this document. Elm Electronics will not be responsible for any patent infringements arising from the use of these products or information, and does not authorize or warrant the use of any Elm Electronics product in life support devices and/or systems. Elm Electronics reserves the right to make changes to the device(s) described in this document in order to improve reliability, function, or design. ELM365DSB Elm Electronics – Circuits for the Hobbyist < http://www.elmelectronics.com/ > 2 of 4 ELM365 Absolute Maximum Ratings Storage Temperature....................... -65°C to +150°C Ambient Temperature with Power Applied....................................-40°C to +85°C Voltage on VDD with respect to VSS............ 0 to +7.5V Note: Stresses beyond those listed here will likely damage the device. These values are given as a design guideline only. The ability to operate to these levels is neither inferred nor recommended. Voltage on any other pin with respect to VSS........................... -0.6V to (VDD + 0.6V) Electrical Characteristics All values are for operation at 25°C and a 5V supply, unless otherwise noted. For further information, refer to note 1 below. Characteristic Minimum Typical Supply Voltage, VDD 3.0 5.0 VDD rate of rise 0.05 Average Supply Current, IDD Internal pullup resistances 300 20 Output Pulse Duration- High - Low Auto Reset Time Period Maximum Units 5.5 Conditions V V/ms see note 2 1.0 2.4 mA VDD = 5V, see note 3 500 30 600 50 KΩ KΩ Panic input, see note 4 Loop inputs, see note 4 1.5 0.5 sec sec OutP and LED outputs, see note 5 5 min see note 6 Input low voltage - reset pin VSS 0.15 VDD V Input high voltage - reset pin 0.85 VDD VDD V 0.6 V Current (sink) = 8.7mA V Current (source) = 5.4mA Output low voltage Output high voltage VDD - 0.7 Notes: 1. This integrated circuit is produced with a Microchip Technology Inc.’s PIC12C5XX as the core embedded microcontroller. For further device specifications, and possibly clarification of those given, please refer to the appropriate Microchip documentation. 2. This spec must be met in order to ensure that a correct power on reset occurs. It is quite easily achieved using most common types of supplies, but may be violated if one uses a slowly varying supply voltage, as may be obtained through direct connection to solar cells, or some charge pump circuits. 3. Pullup resistor currents are not included in this figure. 4. The value of the internal pullup resistance is both supply and temperature dependent. 5. Times are approximate. LED output can only be reset by powering down. 6. Both the OutP and OutC outputs will be internally reset after this time. If a loop continues to remain open, it will not retrigger an alarm. In contrast, the panic input will always retrigger an alarm if it remains closed. ELM365DSB Elm Electronics – Circuits for the Hobbyist < http://www.elmelectronics.com/ > 3 of 4 ELM365 Example Application Figure 1 shows the ELM365 as the controller in a typical home security system. The series resistors on pins 4, 6, and 7 have been included in this design for protection from electrostatic discharge, or induced currents. Although the circuit will function correctly without them, they are recommended for the added protection that they afford. Series connected magnetic switches monitor door positions, and connect to the delayed loop input. Several window switches are connected in series to the instant loop input, and panic switches are provided in the bedrooms to cause an alarm when pressed. The circuit supports two outputs, and both have been included with this design. The pulsed output drives an alarm buzzer, while the constant output can drive yard lights, etc. Both outputs use a conventional transistor circuit to energize a 12V relay coil. Four LEDs are included in the circuit to show power on (circuit armed), alarm, and loop status. In addition to status, these LEDs also provide loop current for switch wetting, and assist with the input pullup function. Although not essential, it is recommended that the LEDs be installed. Power for the circuit is from an AC supplied 12V DC source, with only temporary backup provided by a 9V battery. Both inputs are diode coupled, passed through the key switch, and reduced by the 78L05 regulator to 5V for the logic. +5V Panic Switches 2.2KΩ +12V 2.2KΩ +5V +5V 1N4001 Alarm Instant Loop 300Ω Constant Output 2.2KΩ 300Ω 5 4 6 3 7 2 8 1 2N3904 1.0KΩ +5V Delayed Loop +12V Power 1N4001 300Ω 2.2KΩ 300Ω 1.0KΩ Key Switch (Arm/Disarm) 2N3904 Normal 12V Supply 78L05 0.1µF Optional 9V Backup Supply ELM365DSB Pulsed Output +5V 0.1µF Figure 1. Home Security System Elm Electronics – Circuits for the Hobbyist < http://www.elmelectronics.com/ > 4 of 4