TI is active in the development of leading-edge control circuits to help engineers address specific design challenges. Since no control mode is optimal for every application, various control modes for non-isolated step-down controllers and converters are referenced with their advantages and how to learn more about each mode. The TI portfolio contains 15 types of control architectures for non-isolated TPS- and LM-series switching DC/DC converters and controllers.

Pulse-width modulation (latch output) is accomplished by comparing a voltage error signal (V_E) from the output voltage and reference voltage to a constant saw-tooth-ramp waveform. The ramp is initiated by a clock signal from an oscillator. Good noise-margin performance is attained with a fixed ramp amplitude (V_R). Voltage regulation is independent of the output current. Voltage mode uses type-3 compensation addressing a double-pole power stage to support a wide range of output filter combinations for externally compensated devices.

When to use: When a fixed, predictable switching frequency is desired. Also useful when wide output-load variations are possible.

Popular devices: TPS54610, TPS40040, LM22670

Learn more: Switching Power Supply Topology Voltage Mode vs. Current Mode

Similar to voltage mode, but ramp generator varies the PWM ramp slope with the input voltage at a constant ramp magnitude and delivers an instantaneous response to input voltage variations. The PWM does not have to wait for loop delays to change the duty cycle.

When to use: When a fixed, predictable switching frequency is desired. Also useful when wide variations of input voltage and output load are possible.

Popular devices: TPS40057, TPS40170, TPS56121

Learn more: Effect of Programmable UVLO on Maximum Duty Cycle Achievable With the TPS4005x and TPS4006x Family of Synchronous Buck Controllers