NXP Semiconductors
FXTH87E
FXTH87E, Family of Tire Pressure Monitor Sensors
4.4.1 VDD and VSS pins
The digital circuits operate from a single power supply connected to the FXTH87E
through the VDD and VSS pins. VDD is the positive supply and VSS is the ground. The
conductors to the power supply should be connected to the VDD and VSS pins and locally
decoupled as shown in Figure 6.
Care should be taken to reduce measurement signal noise by separating the VDD, VSS
,
AVDD, AVSS and RVSS pins using a "star" connection such that each metal trace does not
share any load currents with other external devices as shown in Figure 6.
4.4.2 AVDD and AVSS pins
The analog circuits operate from a single power supply connected to the FXTH87E
through the AVDD and AVSS pins. AVDD is the positive supply and AVSS is the ground.
The conductors to the power supply should be connected to the AVDD and AVSS pins and
locally decoupled as shown in Figure 6.
Care should be taken to reduce measurement signal noise by separating the VDD, VSS
,
AVDD, AVSS and RVSS pins using a "star" connection such that each metal trace does not
share any load currents with other external devices as shown in Figure 6.
Bypass capacitors
closely coupled to
the package pins
FXTH87E and other load currents
star connected to battery terminals
IDD
ILOAD
Battery
V
DD
to other loads
0.1
F
V
SS
FXTH87E
AV
The decoupling devices, although
drawn here as 0.1 F capacitors,
may be any type of passive component(s)
sufficient to block or reduce unwanted
external radiated signals from corrupting
the power input protection circuits;
application tuning may be required.
DD
0.1
F
AV
SS
SS
RV
aaa-027995
Figure 6.ꢀRecommended power supply connections
4.4.3 VREG pin
The internal regulator for the analog circuits requires an external stabilization capacitor to
AVSS
.
4.4.4 RVSS pin
Power in the RF output amplifier is returned to the supply through the RVSS pin. This
conductor should be connected to the power supply as shown in Figure 6 using a "star"
connection such that each metal trace does not share any load currents with other supply
pins.
4.4.5 RF pin
The RF pin is the RF energy data supplied by the FXTH87E to an external antenna.
FXTH87ERM
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2019. All rights reserved.
Reference manual
Rev. 5.0 — 4 February 2019
9 / 183
NXP [ NXP ]
