AN2946 Datasheet, PDF (15/38 Pages) STMicroelectronics – Solar-LED streetlight controller with 25 W LED lamp driver

AN2946
Figure 13. Temperature sensing circuits
Hardware design
For the LED lamp, if the sensed temperature rises to a certain level, the LED lamp current is
reduced to correspond to entering LP (low power) mode. The LED lamp is dimmed then
without further increasing temperature, the LED lamp is shut down only when the sensed
temperature rises to an even higher level. For all the voltage and current sensing, an RC
filter and clamp circuit are added before the signal feeds to the MCU. Track routing of these
sensing circuits should be done very carefully to avoid picking up noise, otherwise the noise
influences the MCU and results in an unpredictable result.
Figure 14. Voltage and current detection circuit
3.2
3.2.1
Test results
Battery charger
As discussed in Section 2.4.1, the battery charger operation is divided into 3 stages. This
section shows us the test results for each stage.
● Stage 1:
In this stage, when V_BATTERY < 11 V, the controller executes the MPPT algorithm with
current constraint I_BATTERY < 0.5 A. The charging current is shown in Figure 15.
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