CM4 App Note 260424 issue 2.1.docx
Document No. 260424
Page 18 of 29
Output Current Measurement
The output current of the module can be measured using the I
CONTROL
signal. If this pin is not loaded its output voltage will follow the typical
equation,
V
I_OUT
= 4*I
OUT
/I
RATED
, where I
RATED
is the maximum rated current for the module.
Note that the I
CONTROL
output voltage is representative of the internal inductor current not the actual load current. However, this will only have an
influence during dynamic events. It is recommended to add an external buffer amplifier (as shown below) when using the I
CONTROL
signal to
measure the output current as loading the I
CONTROL
signal, even with microamps can cause the current limit to be reduced. If it is required to
measure the output current and adjust the output current limit simultaneously, this can be achieved by using a clamp circuit instead of a voltage
source to adjust the current limit, while continuing to use an amplifier to measure the output current. An example circuit is shown below. In this
case V
CONTROL
will control the current limit while the buffered I
CONTROL
signal will provide a measurement of the output current.
Measuring output current
Measuring & controlling output current
