Programmer / Target System Power Supply Schematic - Equinox Systems EPSILON5 MKII User Manual

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3.2 Programmer / Target System Power Supply Schematic

The schematic shown in fig. 3.2.2 details the possible power supply scenarios for powering both the
programmer and the Target System.
The key points to note are as follows:
•
The programmer can be powered from an external power supply via CON1 (V_EXT_PSU)
using the DC power cable provided with the programmer.
•
The programmer can power the Target System if J9 is fitted and external power is supplied via
CON1
•
The programmer can be powered from the Target System if Jumper J9 is fitted and the Target
System is powered.
•
If Jumper J9 is fitted then the Target Vcc is connected to the CON1 Vin terminal.
•
The internal circuitry of the programmer is powered at +3.0V via an on-board +3.0V supply.
fig. 3.2.1. Explanation of all Power Supply Circuit Schematic labels
# Item Description
1 V_EXT_PSU This is the voltage applied to the CON1 connector from an external power
supply.
2 GND This is common ground of the programmer which is connected to CON1
GROUND and to the TARGET GROUND via one of the ISP Headers.
3 V_TVCC This is the voltage measured between the Vcc and Ground of the Target
System.
4 I/O Driver Circuit This is the circuitry which translates the 3.0V I/O signals from the programmer
'Supervisor Microcontroller' to the Target System voltage levels.
5 Target Load This is the load presented to the programmer across the PROG_VCC and
GROUND terminals of any ISP Header.
6 Bench Power This simply indicates a stable DC power supply with a current limit facility.
Supply
7 F1 This is an internal resettable fuse rated at 1.0A.
8 F2 This is an optional fuse which should be placed in the PROG_VCC line if the
jumper J9 is fitted and the programmer is powering the Target System.
9 D1 This is a 6V2 5W zener diode which is connected directly across the
programmer DC Input (CON1). This diode will limit the supply to <6.2V.
10 D2 This is an optional 6V3 5W zener diode which can be connected across the
Target Vcc and GROUND within the Test Fixture. This diode would help to
prevent damage to the programmer due to the Target Vcc being > 5V.
11 J9 Jumper (J9) – Vcc Jumper
Fitted – CON1 V_EXT_PSU is connected to TARGET_VCC
Not Fitted – Programmer PSU is independent of Target Vcc
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EPSILON5 MKII Programmer - User Guide V1.12 – 1
st
August 2007