Texas Instruments TPS54380EVM-001, User Manual

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Background
1-2
1.1 Background
The TPS54380 tracking dc/dc converter provides accurate power sequencing
in applications where two or more voltages are required for a load. These types
of applications include core and I/O power supplies for microprosessors,
DSPs, and FPGAs. Typically, some specific relation between the core and I/O
supply voltages has to be provided during the power-up and power-down
sequences. The TPS54380 tracking dc/dc converter is capable of direct
tracking, ratiometric tracking, and voltage sequencing with a second power
source. The TPS54380EVM-001 is a two-channel EVM demonstrating the
flexibility inherent in the TPS54380 design for tracking and sequencing core
and I/O voltages. The TPS54380 generates the core voltage and is nominally
set at 1.8 V. The nominal 3.3-V I/O voltage is provided by a TPS2013
distribution switch. Rated input voltage and output current range is given in
Table 1–1. This evaluation module demonstrates the small PCB areas that are
achieved when designing with the TPS54380 regulator. The switching
frequency is set at a nominal 700 kHz, allowing the use of a small footprint
1.0-
µ
H output inductor. The MOSFETs of the TPS54380 are incorporated
inside the TPS54380 package. This eliminates the need for external
MOSFETs and their associated drivers. The low drain-to-source on resistance
of the MOSFETs gives the TPS54380 high efficiency and helps to keep the
junction temperature low at high output currents. The compensation
components are provided external to the IC, and allow for an adjustable output
voltage and a customizable loop response. The TPS54380 device uses the
TRACKIN pin to access the tracking and sequencing capabilities. An internal
multiplexer circuit compares the voltage at this pin with the internal reference
voltage and uses the lesser of the two as the reference for the output voltage
regulation. When the output of another power supply or distribution switch is
connected to the TRACKIN pin of TPS54380, the output of the TPS54380
tracks the output of this other channel during power up or down, until the
voltage at TRACKIN pin becomes higher then the internal reference voltage.
By applying the other power supply output to the TRACKIN pin through an
appropriate resistor divider network, any required power up and power down
relation between two output voltages of regulators can be set by changing the
ratio of the divider network.
Table 1–1. Input Voltage and Output Current Summary
EVM Input Voltage Range Output Current Range
TPS54380EVM–001 3.0 to 5.5 V Core, –3 A to 3 A
I/O, 0–1.5 A
Input voltage range is limited by the TPS2013 distribution switch.