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Constant Current Configuration #1: (PI3740-00-EVAL1 Board)
Low Side Current Sense Using PI3740 Internal Amplifier
This configuration senses the current through R106 and uses the internal general purpose amplifier of
the PI3740 to regulate the current. The jumpers need to be installed as shown. This configuration can
be used for super-cap charging as well as battery charging. The benefit of this configuration is that you
can use a standard value current sense resistor and adjust the current by changing a single 0603 resistor.
It does require 6 resistors and a reference to implement the circuit. These components are contained
within the evaluation board.
Install: JSHUNT, JVSN, JVSP, JLGH, JGP. Also install JISP & JISN between the 2 pins closest to JGP. This
will short IS+ and IS- to ground.
Adjusting the Charging Current
The charging current can be adjusted by changing R104 per the following equation.
Icharge= (0.62-(62µA*R104))/R106. In this example it would be: (0.62-(62µA*5.11k)/0.1 or 3.03A
LOAD
V
IN
Figure 3
Jumper Placement for
Constant Current Operation
Configuration #1 (EVAL1)
