6253 DC Voltage Current Source/Monitor Operation Manual
4.4 Operational Principles
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4.4 Operational Principles
4.4.1 Block Diagram
4.4.2 Operational Principles
• The 6253 contains a DA converter SrcDAC, for setting the voltage source or current source.
It also has two DA converters, HiLimitDAC and LoLimitDAC for setting the current limits and
voltage limit.
The SrcDAC has 18-bit conversion accuracy, and the HiLimitDAC and LoLimitDAC have 16-bit
conversion accuracy.
The output from the DA converters is input to three error amplifiers, Src (A1), HiLmt (A2), and
LoLmt (A3) respectively.
• For voltage source, the SrcDAC becomes a voltage-source DAC, and the Src error amplifier (A1)
becomes a voltage-source error amplifier.
Also, HiLimitDAC becomes a DAC for current limit on the Hi side and the HiLmt error amplifier
(A2) becomes an error amplifier for current limit on the Hi side.
Likewise, the LoLimitDAC and the LoLmt error amplifier (A3) work as current limit on the Lo side.
At this time, 0 is ON for SW1 in the feedback circuit and 1 is ON for SW2.
For current source, the usage is switched between each DAC and error amplifier; for SW1 1 is ON
and for SW2 0 is ON to generate current.
• The roles of source and limit are switched by the switching circuit shown in the above figure,
comparing the feedback amount for each, then switching to the larger one.
• Current range switching is done by switching the current detection resistor Rs. Consequently, the
current measurement always takes place in the same range as that of current source or current-limit.
HiLimit
DAC
Src
DAC
LoLimit
DAC
ADC
A1
A2
A3
HiLmt
Src
LoLmt
Switching circuit
A4
RS2
A6
SW
SW
VM
IM
RS1
A5
A7
HI SENSE
HI OUTPUT
LO SENSE
LO OUTPUT
A9
SW
VM
IM
0
1
0
1
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