Digi BL1800 user manual Batteries and External Battery Connections, 950 mA·h = 5.4 years 20 µA

Page 86

C.2 Batteries and External Battery Connections

The soldered-in 950 mA·h lithium coin cell provides power to the real-time clock and SRAM when external power is removed from the circuit. This allows the Jackrabbit to continue to keep track of time and preserves the SRAM memory contents.

The drain on the battery is typically less than 20 µA when there is no external power applied. The battery can last more than 5 years:

950 mA·h

----------------------- = 5.4 years.

20 µA

The drain on the battery is typically less than 4 µA when there external power is applied. The battery can last for its full shelf life:

950 mA·h

------------------------ = 27 years (shelf life = 10 years).

4 µA

Since the shelf life of the battery is 10 years, the battery can last for its full shelf life when external power is applied to the Jackrabbit.

Header J2, shown in Figure C-4,allows external access to the battery. This header makes it possible to connect an external 3 V power supply while replacing the soldered-in 3 V lithium coin-type battery. This allows the Jackrabbit SRAM and real-time clock to retain data while the battery is being replaced.

		VBAT
J2 1		R1
EXT BATT	2	100 W
		100 W
	3

	4

Figure C-4. External Battery Connections at Header J2

Alternatively, header J2 can be used to accommodate an external battery. In this case, be sure to cut out the soldered-in battery on the Jackrabbit to prevent discharging the external battery into a dead battery.

82	Jackrabbit (BL1800)

Image 86

Contents Jackrabbit BL1800 Programmable Single-Board ComputerTrademarks Digi International IncTable of Contents Index Schematics Features IntroductionJackrabbit Features Development and Evaluation ToolsOnline Documentation How to Use This ManualAdditional Product Information Emissions CE ComplianceImmunity Interfacing the Jackrabbit to Other Devices SafetyDesign Guidelines General Jackrabbit BL1800 Development Kit Contents Getting StartedDevelopment Hardware Connections Board Attach Jackrabbit to Prototyping BoardConnect Programming Cable Assemble AC AdapterConnect Power Installing Dynamic C Troubleshooting Run a Sample ProgramTechnical Support Where Do I Go From Here?Real-Time Clock Subsystems BL1800Jackrabbit Pinouts HeadersDigital Inputs/Outputs Digital InputsDigital Outputs HV3 Sourcing OutputConfigurable High-Current Output Bidirectional I/O Changing HV3 to a Sinking OutputSchematic Diagram of A/D Converter A/D ConverterJackrabbit BL1800 Schematic Diagram of D/A Converters D/A ConvertersV ⋅ 1 e RC 1 DA1Typical DA1 Voltages for Various Duty Cycles 2 DA0 Typical DA0 Voltages for Various Duty CyclesUser’s Manual 2 RS-485 Serial Communication1 RS-232 Ground recommended Programming Port 485 R16User’s Manual Changing Between Program Mode and Run Mode Programming CableFlash Eprom MemorySram Clock Doubler Other HardwareExternal Interrupts Spectrum Spreader Jackrabbit BL1800 Software Reference An Overview of Dynamic CJackrabbit BL1800 Sample Programs Jackrabbit Sample ProgramsDEMOJR1.C Sample Program DEMOJR1.CSingle-Stepping Watch Expression Break PointWatching Variables Dynamically Summary of FeaturesEditing the Program User’s Manual Other Sample Programs Illustrating Digital I/O R/W pin and DB0-DB3 on 3 RS-232 Serial Communication Sample Programs 4 RS-485 Serial Communication Sample Program Cooperative Multitasking Int vswitch Advantages of Cooperative Multitasking Jackrabbit Function Calls 1 I/O DriversVoid digOutint channel, int value Void anaOutint channel, int value Void anaInint channel, int *value Serial Communication Drivers Add-On Modules Upgrading Dynamic CPatches and Bug Fixes Appendix A. Specifications Electrical and Mechanical Specifications Figure A-1shows the mechanical dimensions for the JackrabbitTable A-1. Jackrabbit Board Specifications Exclusion Zone Exclusion ZonesFigure A-3. User Board Footprint for Jackrabbit Jumper Configurations Figure A-4. Location of Jackrabbit Configurable PositionsTable A-2. Jackrabbit Jumper Configurations Conformal Coating Conformally coated areaUse of Rabbit 2000 Parallel Ports JackrabbitTable A-3. Jackrabbit Pinout Configurations PD0 PD1 Jackrabbit BL1800 Appendix B. Prototyping Board Jackrabbit Connectors User LEDs Buzzer Prototyping Board OverviewPrototyping Board Features Mechanical Dimensions and Layout Top SideUsing the Prototyping Board Top SideDemonstration Board RelayExisting Prototyping Board Top SidePE0 VCC HV0 SM1 SM0 HV2 Stat Jackrabbit BL1800 Appendix C. Power Management Power SuppliesDcin Current mA Batteries and External Battery Connections 950 mA·h = 5.4 years 20 µABattery Backup Circuit Figure C-5shows the Jackrabbit battery backup circuitryPower to Vram Switch Reset GeneratorFigure C-7shows a schematic of the chip select circuit Chip Select CircuitJackrabbit BL1800 Index SMODE0 SMODE1RABDB01.C RABDB02.C Schematics