1 Features
1• Input Operating Voltage Range: 3 V to 20 V
• PMBus Enabled Analog Controller
• Reference 600 mV ± 1%
• Remote Voltage Sense Amplifier
• Internal 6-V Regulator and 6-V Gate Drive
• Programmable Overcurrent Protection
• Inductor Resistance or Series Resistance Used
for Current Sensing
• Programmable Switching Frequency: 200 kHz to 2
MHz
• Powergood Indicator
• Thermal Shutdown
• Programmable Soft-Start
• Internal Bootstrap Diode
• Prebias Output Safe
• 24-Pin QFN Package

2 Applications
• Smart Power Systems
• Power Supply Modules
• Communications Equipment
• Computing Equipment

3 Description
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.