Datasheet

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23
22
EN/SYNC
VIN
BP5
TPS4009x
TLA431
12V
6V
4.7 Fm
1.1kW
13.7kW
10kW
TPS40090
TPS40091
SLUS578B –OCTOBER 2003– REVISED MAY 2006 www.ti.com
Operation with Output Voltages Higher Than 3.3 V
The TPS40090/91 controllers are designed to operate in power supplies with output voltages ranging from 0.7 V
to 3.3 V. To support higher output voltages, mainly in 12 V to 5 V power supplies, the BP5 voltage needs to be
increased slightly to provide enough headroom to ensure linearity of current sense amplifiers. The simple circuit
on Figure 13 shows a configuration that generates a 6-V voltage source to power the controller with increased
bias voltage. Both the VIN and BP5 pins should be connected to this voltage source. The differential amplifier
normally excessive for higher-output voltages can be disabled by connecting GNDS pin to the BP5 pin.
Figure 13. Biasing the TPS4009x with a 5-V Power Supply
High-Impedance State of TPS40091 Outputs
The TPS40091 controller has 3-state enabled outputs to interface various gate drivers and DRMOS devices
capable of turning all MOSFETs in the power supply into high-impedance state while remaining active. The
common binary output commands the control MOSFET on when the PWM signal is high. Alternatively, the
synchronous MOSFET is commanded on when the PWM signal is low.
The 3-state output can command both MOSFETs off when the PWM output is in the high-impedance state. This
feature simplifies design of power supplies capable of starting into precharged output or allows in VR modules
use of gate drivers that do not have the enable input to put VR module off line. Some DRMOS devices like the
Philips PIP202 are also compatible with 3-state outputs of the multiphase controller.
The TPS40091 outputs have high impedance when the EN pin is high but the soft-start sequence has not been
initiated yet. The output impedance is also high when controller is in undervoltage fault condition or disabled.
Figure 14 shows a 12-V, 80-A, all-ceramic power supply capable to start into precharged outputs.
DESIGN EXAMPLE
A design example is available. See the TPS40090EVM−001 user’s guide (SLUU175).
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