Digi BL1800 user manual Appendix C. Power Management, Power Supplies

Page 83

APPENDIX C. POWER MANAGEMENT

C.1 Power Supplies

Power is supplied to the Jackrabbit board from an external source through either header J1 or header J4. J1 is a 3-pin straight header with a pitch of 0.1". Vin is on pin 2 between

ground on pins 1 and 3. The symmetry allows for a 3-pin cable to be connected either way.

The Jackrabbit board itself is protected against reverse polarity by a Shottky diode at D2 as shown in Figure C-1.The Shottky diode has a low forward voltage drop, 0.3 V, which keeps the minimum DCIN required to power the Jackrabbit lower than a normal silicon diode would allow.

 

 

 

 

LINEAR POWER SUPPLY

J1

 

+RAW DCIN

 

 

 

 

Vcc

 

 

 

 

 

 

 

 

 

 

 

POWER IN

1

D2

 

 

7805

 

 

 

 

2

 

1

U1

3

 

 

 

 

 

 

 

 

3

1N5819

C1

 

2

 

 

C2

 

 

 

 

10 µF

 

 

100 nF

 

 

 

 

 

 

 

 

 

 

 

SWITCHING POWER SUPPLY

Vcc

 

 

 

14

LM2575

7

 

 

 

 

 

 

 

U2

 

 

 

 

 

 

 

15

17

 

 

 

C3

 

 

 

 

2

 

4

 

 

 

8

 

 

 

330 µF

 

 

 

1

 

18

1

330 µH

 

 

 

 

 

L1

3

 

 

 

 

 

 

10

D1

 

 

 

 

 

12

 

 

1N5819

 

 

Figure C-1. Jackrabbit Power Supply Schematic

The external power, +RAW, is provided to any daughterboard connected to the Jackrabbit via pin 38 of header J4. +RAW is not protected against reversed polarity, such as could happen if the cable was connected to header J1 offset by one pin. This absence of protec- tion is intentional so as to provide the maximum possible voltage to any daughterboard connected to the Jackrabbit.

Capacitor C1 provides surge current protection for the voltage regulator, and allows the external power supply to be located some distance away from the Jackrabbit board. A switching power supply or a linear power supply option is provided, depending on the Jackrabbit model.

User’s Manual

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Contents Programmable Single-Board Computer Jackrabbit BL1800Digi International Inc TrademarksTable of Contents Index Schematics Introduction FeaturesDevelopment and Evaluation Tools Jackrabbit FeaturesOnline Documentation How to Use This ManualAdditional Product Information Emissions CE ComplianceImmunity Interfacing the Jackrabbit to Other Devices SafetyDesign Guidelines General Jackrabbit BL1800 Getting Started Development Kit ContentsDevelopment Hardware Connections Attach Jackrabbit to Prototyping Board BoardAssemble AC Adapter Connect Programming CableConnect Power Installing Dynamic C Run a Sample Program TroubleshootingTechnical Support Where Do I Go From Here?Real-Time Clock BL1800 SubsystemsHeaders Jackrabbit PinoutsDigital Inputs Digital Inputs/OutputsHV3 Sourcing Output Digital OutputsConfigurable High-Current Output Changing HV3 to a Sinking Output Bidirectional I/OA/D Converter Schematic Diagram of A/D ConverterJackrabbit BL1800 D/A Converters Schematic Diagram of D/A Converters1 DA1 V ⋅ 1 e RCTypical DA1 Voltages for Various Duty Cycles Typical DA0 Voltages for Various Duty Cycles 2 DA0User’s Manual 2 RS-485 Serial Communication1 RS-232 Ground recommended 485 R16 Programming PortUser’s Manual Programming Cable Changing Between Program Mode and Run ModeFlash Eprom MemorySram Clock Doubler Other HardwareExternal Interrupts Spectrum Spreader Jackrabbit BL1800 An Overview of Dynamic C Software ReferenceJackrabbit BL1800 Jackrabbit Sample Programs Sample ProgramsSample Program DEMOJR1.C DEMOJR1.CWatch Expression Break Point Single-SteppingWatching 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 1 I/O Drivers Jackrabbit Function CallsVoid 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 Figure A-1shows the mechanical dimensions for the Jackrabbit Electrical and Mechanical SpecificationsTable A-1. Jackrabbit Board Specifications Exclusion Zones Exclusion ZoneFigure A-3. User Board Footprint for Jackrabbit Figure A-4. Location of Jackrabbit Configurable Positions Jumper ConfigurationsTable A-2. Jackrabbit Jumper Configurations Conformally coated area Conformal CoatingJackrabbit Use of Rabbit 2000 Parallel PortsTable A-3. Jackrabbit Pinout Configurations PD0 PD1 Jackrabbit BL1800 Appendix B. Prototyping Board Prototyping Board Overview Jackrabbit Connectors User LEDs BuzzerPrototyping Board Features Top Side Mechanical Dimensions and LayoutTop Side Using the Prototyping BoardRelay Demonstration BoardExisting Top Side Prototyping BoardPE0 VCC HV0 SM1 SM0 HV2 Stat Jackrabbit BL1800 Power Supplies Appendix C. Power ManagementDcin Current mA 950 mA·h = 5.4 years 20 µA Batteries and External Battery ConnectionsFigure C-5shows the Jackrabbit battery backup circuitry Battery Backup CircuitReset Generator Power to Vram SwitchChip Select Circuit Figure C-7shows a schematic of the chip select circuitJackrabbit BL1800 SMODE0 SMODE1 IndexRABDB01.C RABDB02.C Schematics
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