STBB3JCC Datasheet, PDF (17/27 Pages) STMicroelectronics – 2 A, high efficiency single inductor buck-boost DC-DC converter and high brightness WLED driver

STBB3JCC
Application information
7.4.3
Overtemperature protection
An internal temperature sensor continuously monitors the IC junction temperature. If the IC
temperature exceeds 160 °C (typ.), the device stops operating. As soon as the temperature
falls below 140 °C (typ.), normal operation is restored.
8
8.1
Application information
Programming the output voltage
The external resistor divider must be connected between V_OUT and GND and the middle
point of the divider must be connected to FB.
The value for the resistor R2, placed between FB and GND, should be chosen in order to
set the divider current at 10 µA. The recommended value for this resistor is in the range of
50 kΩ but to reduce the power consumption a maximum value of 20 kΩ can be used.
The value of the resistor R1, connected between V_OUT and FB, is function of the output
voltage and can be calculated using the equation 1:
Equation 1
R1
=
R2
×


-^V--_V--^O--_F--^U-_B--^T--
–
1_
& & & &
Figure 30. Application schematic
/

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8.2
Programming the output constant current for HB WLED
Sensing resistor
The STBB3JCC feedback pin voltage is 100 mV, this makes the STBB3JCC suitable for
LED driver applications, minimizing the power dissipation across the external sensing
resistor and improving the overall system efficiency. The sensing resistor value is got by the
following formula:
DocID025425 Rev 5
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