Operating input voltage 10 V to 40 V programmable fixed frequency up to 100 kHz to 1 MHz voltage mode controller for internal high-side and synchronous N-channel MOSFET internal gate drive output 16-pin PowerPad package (JC=2c/ w) Thermal shutdown external synchronous programmable short circuit protection programmable closed loop soft start.
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Simplified application diagram description:
The TPS40052 is part of a family of high voltage, wide input, synchronous buck converters. The TPS40052 has design flexibility for a variety of user-programmable features including soft start, operating frequency, high side current limit, and loop compensation.
The TPS40052 can also be synchronized to an external power supply. It combines a MOSFET gate driver for external n-channel high side and synchronous rectifier (SR) MOSFETs. The gate drive logic incorporates an anti-cross conduction circuit to prevent simultaneous high voltage side and synchronous rectifier conduction.
Externally programmable short-circuit protection provides pulse through pulse current limit and snoring mode operation with long-term overload with internal fault counter.
The TPS40052 allows the user to optimize the PWM controller for a specific application.
The TPS40052 is the controller of choice for synchronous buck designs whose output needs to track another voltage. It has two quadrant operations that can source or sink the output current to provide the best transient response.
Switch node resistance and diode
When both the upper and lower MOSFETs are turned off, the switching node of the converter will be negative in the dead zone. The magnitude of this negative voltage depends on the lower MOSFET body diode and the output current flowing during this dead time. This negative voltage can affect the operation of the controller, especially at low input voltages.
Therefore, as shown in Figure 10, a resistor (3.3 ohms to 4.7 ohms) and a Schottky diode must be placed between the lower MOSFET drain and the stylus 12 (sw) of the controller. The Schottky diode must have a voltage rating to accommodate the input voltage and ringing on the switch node of the converter. 30 volt Schottky (such as BAT4) or 40 volt Schottky (Zetex ZHCS400 or Vishay SD103AWS) is enough to set the switching frequency (program the clock oscillator)
The TPS40052 has a separate clock oscillator and ramp generator circuit. The clock oscillator is used as the master clock for the ramp generator circuit. The switching frequency f (kHz) of the clock oscillator is set to ground by a resistor (R). The clock frequency is related to r, expressed in kΩ, and is derived from equation (1). Short wave TT
The TPS40052 features fixed uvlo protection. The fixed uvlo monitors the input voltage. The uvlo circuit keeps the soft start low until the input voltage exceeds the undervoltage threshold.