AN645 Datasheet
KeeLoq Security: PIC16C57 Based Code Hopping Security System Application Note
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AN645
KeeLoq Security: PIC16C57 Based Code Hopping Security System Application Note
PIC16C57 Based Code Hopping Security System
Author: Kobus Marneweck Microchip Technology
OVERVIEW
This Document Describes A Pic16c57 Based Code Hopping Automotive Security System. The Security
system implements all the basic
FEATURES found on security systems and can be changed to modify or add
Features As Required. The Code Can Also Be Moved To A Higher Functionality Picmicro Microcontroller
for more I/O or code space.
FEATURES
Code hopping alarm system
System can handle up to six transmitters
Learning of new transmitters
Arm/Disarm
Trunk release
Car nder
Locking/unlocking of doors
Door and shock sensor trigger inputs
RECOMMENDED READING
If The Reader Is Unfamiliar With Keeloq Code Hopping It Would Be Helpful To Read Introduction To
Keeloq (ds91002). This And Other Keeloq Literature Can Be Found On Microchip's Web Site Or From A
Microchip eld
Application engineer. The software described in this
Application Note Is Available On A Diskette From Microchip By Ordering Ds40149. A Complete List Of
KEELOQ literature can be found at the end of the
Application note.
PINOUT
PLIGHT
PIC16C57
UNLOCK
BLOCK DIAGRAM
Power Supply
Switch Inputs Ignition Doors Trigger Learn
PIC16C57
RF Receiver
LED Outputs LED Parking Lights Lock Unlock Trunk Immob
AN645 Datasheet
MAINS RECTIFICATION FOR THE GS100T300-x
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AN645
MAINS RECTIFICATION FOR THE GS100T300-x
Application NOTE
The Gs100t300-x Is A Family Of Dc-dc Converters With Different Output Voltages (x), That Can Deliver
An Output Power Of 100 Watt When An Unregulated Dc Voltage Source Of 300 V Typical Is Available. The
key data for GS100T300-x are:
Po = Output Power = 100 Watt Vo = Output Voltage = From 3.3 To 48 Vdc = Efficiency = 80 % Min.
Vin = Input voltage = 200 to 400 VDC IinRMS = Input RMS current = 0.88 ARMS
The Following Note Describes How To Obtain An Unregulated Dc Input Voltage From The Mains. Four
Examples Are Considered: The Europe And Usa Mains, And, For Each Of Them, With And Without The
hold-on characteristic.
The Hold-on Characteristic Is The Ability Of The Input Voltage Source To Mantain A Dc Voltage Higher
Than The Minimum Input Voltage Of The Dc-dc Converter, Even In Case Of A Mains Interruption Of 1
cycle.
1. European mains without the hold on characteristic.
The European mains characteristics are:
Vinac = 230 VRMS 15 % 240 VRMS 10 %
f = 50 Hz
The Minimum Ac Voltage Is, Therefore, 195 Vrms While The Maximum Ac Voltage Is 264 Vrms. A Bridge
Rectifier As Shown In Fig. 1 Can Be Used To Obtain The Required Unregulated Dc Voltage.
Figure 1: AC-DC converter for Europe Mains.
AC mains
AN645/0594
C Unregulated DC voltage
MAINS RECTIFICATION AND FILTERING
The typical waweform for this type of rectifier is shown in fig. 2 where:
Vc = Voltage Across Capacitor C. Vpk = Peak Value Of The Input Ac Voltage. Vmin = Minimum Voltage
Across Capacitor C. Tch = Charging Time Of The Capacitor C Tdch = Discharging Time Of The Capacitor
C Ich = Peak Charge Current For The Capacitor C Idc = Average Input Current T = Total Time For One
complete cycle
The Total Energy Win To Be Supplied By The Capacitor C During One Full Cycle Of The Mains Is:
Where Pin Is The Input Power In Watt Of The Gs100t300-x And F Is The Mains Frequency In Hz. In This
case:
100 0.8
During Each Half Cycle, The Capacitor Has To Deliver 1/2 Win And Its Voltage Will Drop From Vpk To
Vmin. The following equation applies:
C (V 2
therefore
Win V2
In this case:
Vpk = 2
VinRMSmin 4 = 1.41
195 4 = 271 V
Where 4 V Is A Good Assumption For The Voltage Drop Across The Rectifying Diodes And The Input
Filter. According To The Gs100t300-x Data, Vmin=200 V. Therefore, From Equation (3):
2.5 2712 2002