Introduction
www.ti.com
1.1 Features
The TPS2549-Q1 features include:
• Built-in IEC 61000-4-2 protection on DP_IN and DM_IN pins
• Linear USB cable voltage-droop compensation
• Fully AEC Q100 qualified
• Built-in short to VBUS protection and notification on DP_IN and DM_IN pins
• LM53603AQ high performance 2.1-MHz automotive qualified DC/DC converter
1.2 Applications
The TPS2549-Q1 can be used in the following applications:
• Automotive infotainment system
• Automotive USB charging box
2 Description
The TPS2549Q1EVM-729 enables full evaluation of the TPS2549-Q1 device, refer to the schematic in
Figure 1. An automotive voltage range input is applied at the J3 connector. The input stage consists of an
input switch (Q1), protection (D2), and an input filter (L1, C1, C2, C3, C5). The voltage at the 5VDC node
is regulated by the LM53603AQ buck regulator (U1) and associated circuitry. This provides a nominal 5-V,
3-A output for the TPS2549-Q1 (U2).
The TPS2549-Q1 internal power switch connects the 5VDC node to VBUS at the downstream facing USB
connector, J1. When the internal power switch is ON, the D5 LED (green) will illuminate. USB 2.0 data
can be passed through the TPS2549Q1EVM-729 from J2 to J1 when the TPS2549-Q1 is configured for
either SDP or CDP mode using the J6 header. TPS2549-Q1 status and fault conditions can be detected
using the D4 (blue) and D3 (red) LEDs, respectively.
TPS2549-Q1 provides system-level ESD protection in accordance with IEC 61000-4-2 up to ±8-kV contact
and ±15-kV air discharge at the DP_IN and DM_IN signals going to J1. These pins will also provide
detection of shorts to VBUS by triggering the FAULT logic and illuminating D3.
The TPS2549-Q1 provides USB cable voltage-droop compensation at the load through the use of the CS
pin. Sinking current into the CS pin mirrors the current through the TPS2549-Q1 power switch at a rate of
75 µA/A. The CS pin current is summed with the LM53603AQ regulator feedback current through R8
causing the regulator output voltage to change with USB downstream load current. The voltage at the
5VDC node increases linearly as load current increases. This compensation will keep the load end voltage
close to 5 VDC. The default compensation resistor values (R8 and R10) target a USB cable resistance of
200 mΩ. Three additional cable resistance examples are provided in the following list.
• For 300-mΩCC: R8 = 5.11 kΩ, R10 = 17.8 kΩ
• For 400-mΩCC: R8 = 6.49 kΩ, R10 = 16.5 kΩ
• For 500-mΩCC: R8 = 7.68 kΩ, R10 = 15.4 kΩ
Refer to the TPS2549-Q1 datasheet (SLUSCE3) for more information.
NOTE: The values shown for R8 and R10 take into account the effects of the TPS2549Q1 power
switch and J1 receptacle/plug resistances (approximately 0.1 ohms, total). The effects of R5
are also included. Designs which do not need to account for these losses can exclude these
from the equations.
2TPS2549Q1EVM-729 Evaluation Module SLVUAK6–October 2015
Submit Documentation Feedback
Copyright © 2015, Texas Instruments Incorporated
