NXP Semiconductors
TEA19051BT
USB-PD 2.0/USB-PD 3.0/QC 2.0/QC 3.0/QC 4 (+) controller for SMPS
TEA19051BT All information provided in this document is subject to legal disclaimers. © NXP B.V. 2018. All rights reserved.
Product data sheet Rev. 1 — 13 February 2018
27 / 36
13.2 Sense resistor
The accuracy of the sense resistor R1 is very important. Any deviation from the value in
MTP gives an offset in the current measurement. Because the sense resistor is very low-
ohmic, the layout of the connections in the PCB can give major deviations from its initial
value.
To overcome these deviations, several options are available:
• Change the sense resistor value such that the complete value is matching the typical
MTP value (5 mΩ or 10 mΩ).
• Trim the value with a resistor divider so that the (R7 / (R5 + R7)) × (R1 + R
PCB
)
matches the MTP default value. R
PCB
is the resistance of copper wires and the
resistance change of the sense resistor due to its soldering profile.
To maximize accuracy and temperature stability, keep R
pcb
as low as possible. The
sense resistor must have a temperature coefficient that is as low as possible. To prevent
magnetic coupling, keep the length and the area of the connections between the sense
resistor and the SGND and ISNS pins as small as possible.
13.3 Voltage loop
In the application diagram, an integrator network is connected between the VSNS pin
and the optocoupler. The recommended values of these components are:
• R2 = 160 kΩ to 180 kΩ
• R4 = 1 kΩ
• C1 = 10 nF; for the integral part
To prevent magnetic coupling to these parts, which results in pollution in output voltage,
the length and the area of the connection must be kept as small as possible.
13.4 Current loop
For applications using the CC loop in the application, an integrator network is connected
between the ISNS pin and the optocoupler. The recommended values for these
components are:
• R5 = 330 Ω when R1 = 10 mΩ; R5 = 160 Ω when R1 = 5 mΩ; connected between
sense resistor and the ISNS pin for the proportional part.
• R6 = 5 kΩ
• C2 = 100 nF; for the integral part
To prevent magnetic coupling to these parts, which results in pollution in output currents,
the length and the area of the connection must be kept as small as possible.
For applications that use OCP mode, these three components can be omitted.
