Switching External Vcc To The Target System; Overview - Equinox Systems ISPnano I Series User Manual

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Datasheet of ISPNANO S3 KIT - ISP PORTABLE PROGRAMMER
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4.5 Switching EXTERNAL VCC to the Target System

4.5.1 Overview

The ISPnano programmer features a special 'External VCC Switch' circuit which allows an 'External
Voltage (V_EXT)' in the range of 1.6V – 24V to be switched through the programmer to the Target
System under project control. This feature is useful when the Target System features a 'Voltage
Regulator Circuit' which needs to be powered from a higher voltage than +5V. In order to power
many Target Systems, it is necessary to apply a voltage of eg. 7 – 24V to the input of the Target
System regulator circuit.
The diagram below shows a typical example where an external power supply is switched to the
Target System through the programmer.
Fig. 4.5.1. ISPnano – Powering Target System using External Switched Voltage
External
Target
Power Supply
1.6 - 24.0V
V
EXT
Programmer
Power Supply
9.0 - 24.0V
STAR connected EARTH point
An 'External' voltage 'VEXT' in the range of 1.6 – 24.0V is fed into the EXT-VCC-IN
•
connector of the programmer from an external power supply.
This voltage is then switched by the 'External Vcc Switch' inside the programmer to the EXT-
•
VCC-OUT pins on the 'Target ISP Port' of the programmer.
70
ISPnano Programmer
DC-EXT
EXT DC
connector
SWITCH
pin1
DC-IN
Programmer
POWER Input
(DC IN connector
pin 1)
Measure
V
TARGET
Programmer
POWER 0V (DC IN
connector pin 2)
Power 0V
ISPnano Series Programmer - User Manual – V1.11 – 12
IDC PIN 3+4
IDC PIN 1+2
V
V
TARGET
V
TARGET_REG
V
TPS
Line
RESET
Driver
Circuit
Programmer
Programming
I/O Lines
lines
to Target
System
Signal 0V
Programmer Signal
0V (IDC PIN 5+6)
Target System (UUT)
Target
Voltage Regulator
Vin
circuit
TARGET_REG
Target
IC
R
T
POWER 0V
th
May 2011
C
T