一种用于升压型DC-DC变换器的过温保护电路

设计了一种用于升压型DC-DC变换器的过温保护电路。采用具有正负温度系数的电流相减,得到随温度变化更加明显的电流,经过电阻分压控制三极管的通断,并采用推挽反相器整形滤波后得到输出信号,实现了芯片过温关断和迟滞开启的功能。采用HHNEC BCD 0.35μm工艺,使用Cadence软件进行仿真验证。仿真结果显示,在各个工艺角及电源电压波动情况下,电路均能在芯片温度上升到170℃时关断、在芯片温度下降到140℃时开启,迟滞值为30℃(±2℃)。

Thermal Shutdown Circuit for Boost DC-DC Converters

A thermal shutdown circuit for boost DC-DC converter was presented.By subtracting IPTAT current from PTAT current,a current more sensitive to temperature was generated,which was flowing through resistors to gain a voltage to control transistor.A push-pull inverter was used to filter output of the transistor to obtain an over-temperature protection(OTP) signal,thus achieving thermal shutdown and hysteresis function.Simulation using Cadence’s software based on HHNEC’s 0.35 μm BCD process showed that,at different process corners and various supply voltages,the circuit could shut down when temperature of the chip rose to 170 ℃ and re-open when the temperature dropped to 140 ℃.The hysteresis was 30 ℃ ±2 ℃.