Distributor of Equinox Technologies: Excellent Integrated System Limited
Datasheet of ISPNANO S3 KIT - ISP PORTABLE PROGRAMMER
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ISPnano Series Programmer - User Manual – V1.11 – 12
th
May 2011
70
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
Target
Voltage Regulator
circuit
Measure
V
TARGET
Line
Driver
Circuit
Programmer
I/O Lines
to Target
System
Target
IC
Vin
V
TARGET_REG
Target System (UUT)
V
TPS
V
TARGET
IDC PIN 1+2
V
EXT
Programmer Signal
0V (IDC PIN 5+6)
V
TARGET_REG
Programming
lines
RESET
External
Target
Power Supply
1.6 - 24.0V
Programmer
Power Supply
9.0 - 24.0V
Power 0V
Signal 0V
Programmer
POWER 0V (DC IN
connector pin 2)
POWER 0V
DC-IN
Programmer
POWER Input
(DC IN connector
pin 1)
EXT DC
SWITCH
IDC PIN 3+4
DC-EXT
connector
pin1
ISPnano Programmer
STAR connected EARTH point
C
T
R
T
•
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.
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