SLVAEV1 April 2022 TPS61041-Q1
Proposed Circuit Principle
Figure 2-1 shows the schematic of a boost converter using the TPS61041-Q1. Because the TPS61041-Q1 recommended input voltage maximum value is 6 V, the device VIN and GND pin cannot be connected to 12-V car battery directly. A level-shift circuit composed of D3, D2, and Q1 pulls up the IC GND pin voltage potential.
D3 is a Zener diode that clamps the PNP transistor Q1 base voltage VA to:
The PNP transistor Q1 turns on, IC_GND voltage follows the calculation in Equation 2:
In this application, a 6-V Zener diode
is selected for D3. So, the TPS61041 VIN pin to GND pin voltage is clamped to below
6 V to protect the IC. Set the TPS61041 output voltage to 10 V higher than
Vin as in
Equation 3:
Where Vref is 1.233 V.
Set R1 at 1.87 MΩ and
R2 at 167 kΩ. Assume the PNP transistor VBE is 0.3 V, the
VOUT – Vin equals
9.63 V.