High-Side MOSFET Driver Power Supply Using the TPS61041-Q1

1 Introduction

Introduction

Designing a MOSFET driver supply for a 12-V car supply is quite challenging. The 12-V battery supply voltage is normally in the range of 9 V to 16 V under normal operating conditions depending on charge and load variation. The TPS61041-Q1 is a high-frequency, low-cost boost converter dedicated for a small to medium supply. The device allows the use of small external components, which gives a very small overall solution size. However, its input voltage range is from 1.8 V and 6 V. This application brief proposes an external circuit that can generate an output voltage following the input voltage adjustment and change.

For automotive applications that require a high-side MOSFET driver, the MOSFET gate needs a stable stepped-up voltage to ensure the MOSFET is fully turned on. The 12-V battery supply voltage is normally in the range of 9 V to 16 V under normal operating conditions depending on charge and load variation. Therefore, the driver voltage should follow the input voltage adjustment and change. Figure 1-1 shows the block diagram.

Figure 1-1 Block Diagram

Table 1-1 High-Side MOSFET Driver Circuit Specification

V_DD/V	V_OUT/V	I_OUT/mA
9 V to 16 V	V_DD + 10 V	5 V

The TPS61041-Q1 is a high-frequency boost converter dedicated for low-power applications. The device is ideal to generate output voltages up to 28 V from 1.8-V to 6-V input voltage range. The TPS61041-Q1 operates with a switching frequency up to 1 MHz.

This document introduces a circuit to generate the high-side MOSFET driver voltage using the TPS61041-Q1. Theoretical analysis and bench test results are presented to verify the proposed circuit. Table 1-1 shows the circuit specification.

2 Proposed Circuit Principle

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.

Figure 2-1 Proposed Schematic

D3 is a Zener diode that clamps the PNP transistor Q1 base voltage V_A to:

Equation 1. $V_{A} = V_{i n} - V_{Z}$

The PNP transistor Q1 turns on, IC_GND voltage follows the calculation in Equation 2:

Equation 2. $V_{I C_G N D} = V_{A} + V_{B E}$

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 V_in as in
Equation 3:

Equation 3. $V_{O U T} = V_{I C_G N D} + V_{r e f} \times (1 + \frac{R_{1}}{R_{2}}) = V_{i n} - V_{Z} + V_{r e f} \times (1 + \frac{R_{1}}{R_{2}})$

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 V_OUT – V_in equals
9.63 V.

3 Bench Test Result

Bench Test Result

Using the setup shown in Figure 2-1, the Vin line transient waveform is shown in Figure 3-1. When Vin is 9 V, the TPS61041-Q1 device output voltage is 19 V. When Vin is 16 V, the TPS61041-Q1 device output voltage is 26 V. The device V_OUT is always 10 V higher than input voltage.

Figure 3-1 V_in 9-V to 16-V Line Transient Waveform