The TPS40400 is a cost-optimized flexible synchronous buck controller that operates from
a nominal 3-V to 20-V supply. This controller is an analog PWM controller that allows programming
and monitoring through the PMBus™ interface. Flexible
features found on this device include programmable soft-start time, programmable short circuit
limit, and programmable undervoltage lockout (UVLO).
An adaptive anti-cross conduction scheme is used to prevent shoot through current in the
power FETs. Gate drive voltage is 6 V to better enhance the power FETs for reduced losses. Short
circuit detection occurs by sensing the voltage drop across the inductor or across a resistor
placed in series with the inductor. A PMBus programmable threshold is compared to this voltage and
is used to detect overcurrent. When the overcurrent threshold is reached, a pulse by pulse current
limit scheme is used to limit the current to acceptable levels. If the overcurrent condition
persists for more than 7 clock cycles of the converter, a fault condition is declared and the
converter shuts down and goes into either a hiccup restart mode or latches off. The behavior can be
selected through the PMBus interface. Other PMBus interface features include programmable operating
frequency, soft-start time, overvoltage and undervoltage thresholds and the response to those
events, output voltage change including margining as well as status monitoring.
The TPS40400 is a cost-optimized flexible synchronous buck controller that operates from
a nominal 3-V to 20-V supply. This controller is an analog PWM controller that allows programming
and monitoring through the PMBus™ interface. Flexible
features found on this device include programmable soft-start time, programmable short circuit
limit, and programmable undervoltage lockout (UVLO).
An adaptive anti-cross conduction scheme is used to prevent shoot through current in the
power FETs. Gate drive voltage is 6 V to better enhance the power FETs for reduced losses. Short
circuit detection occurs by sensing the voltage drop across the inductor or across a resistor
placed in series with the inductor. A PMBus programmable threshold is compared to this voltage and
is used to detect overcurrent. When the overcurrent threshold is reached, a pulse by pulse current
limit scheme is used to limit the current to acceptable levels. If the overcurrent condition
persists for more than 7 clock cycles of the converter, a fault condition is declared and the
converter shuts down and goes into either a hiccup restart mode or latches off. The behavior can be
selected through the PMBus interface. Other PMBus interface features include programmable operating
frequency, soft-start time, overvoltage and undervoltage thresholds and the response to those
events, output voltage change including margining as well as status monitoring.